Commit Graph

1262 Commits

Author SHA1 Message Date
Linus Torvalds
09d1c6a80f Generic:
- Use memdup_array_user() to harden against overflow.
 
 - Unconditionally advertise KVM_CAP_DEVICE_CTRL for all architectures.
 
 - Clean up Kconfigs that all KVM architectures were selecting
 
 - New functionality around "guest_memfd", a new userspace API that
   creates an anonymous file and returns a file descriptor that refers
   to it.  guest_memfd files are bound to their owning virtual machine,
   cannot be mapped, read, or written by userspace, and cannot be resized.
   guest_memfd files do however support PUNCH_HOLE, which can be used to
   switch a memory area between guest_memfd and regular anonymous memory.
 
 - New ioctl KVM_SET_MEMORY_ATTRIBUTES allowing userspace to specify
   per-page attributes for a given page of guest memory; right now the
   only attribute is whether the guest expects to access memory via
   guest_memfd or not, which in Confidential SVMs backed by SEV-SNP,
   TDX or ARM64 pKVM is checked by firmware or hypervisor that guarantees
   confidentiality (AMD PSP, Intel TDX module, or EL2 in the case of pKVM).
 
 x86:
 
 - Support for "software-protected VMs" that can use the new guest_memfd
   and page attributes infrastructure.  This is mostly useful for testing,
   since there is no pKVM-like infrastructure to provide a meaningfully
   reduced TCB.
 
 - Fix a relatively benign off-by-one error when splitting huge pages during
   CLEAR_DIRTY_LOG.
 
 - Fix a bug where KVM could incorrectly test-and-clear dirty bits in non-leaf
   TDP MMU SPTEs if a racing thread replaces a huge SPTE with a non-huge SPTE.
 
 - Use more generic lockdep assertions in paths that don't actually care
   about whether the caller is a reader or a writer.
 
 - let Xen guests opt out of having PV clock reported as "based on a stable TSC",
   because some of them don't expect the "TSC stable" bit (added to the pvclock
   ABI by KVM, but never set by Xen) to be set.
 
 - Revert a bogus, made-up nested SVM consistency check for TLB_CONTROL.
 
 - Advertise flush-by-ASID support for nSVM unconditionally, as KVM always
   flushes on nested transitions, i.e. always satisfies flush requests.  This
   allows running bleeding edge versions of VMware Workstation on top of KVM.
 
 - Sanity check that the CPU supports flush-by-ASID when enabling SEV support.
 
 - On AMD machines with vNMI, always rely on hardware instead of intercepting
   IRET in some cases to detect unmasking of NMIs
 
 - Support for virtualizing Linear Address Masking (LAM)
 
 - Fix a variety of vPMU bugs where KVM fail to stop/reset counters and other state
   prior to refreshing the vPMU model.
 
 - Fix a double-overflow PMU bug by tracking emulated counter events using a
   dedicated field instead of snapshotting the "previous" counter.  If the
   hardware PMC count triggers overflow that is recognized in the same VM-Exit
   that KVM manually bumps an event count, KVM would pend PMIs for both the
   hardware-triggered overflow and for KVM-triggered overflow.
 
 - Turn off KVM_WERROR by default for all configs so that it's not
   inadvertantly enabled by non-KVM developers, which can be problematic for
   subsystems that require no regressions for W=1 builds.
 
 - Advertise all of the host-supported CPUID bits that enumerate IA32_SPEC_CTRL
   "features".
 
 - Don't force a masterclock update when a vCPU synchronizes to the current TSC
   generation, as updating the masterclock can cause kvmclock's time to "jump"
   unexpectedly, e.g. when userspace hotplugs a pre-created vCPU.
 
 - Use RIP-relative address to read kvm_rebooting in the VM-Enter fault paths,
   partly as a super minor optimization, but mostly to make KVM play nice with
   position independent executable builds.
 
 - Guard KVM-on-HyperV's range-based TLB flush hooks with an #ifdef on
   CONFIG_HYPERV as a minor optimization, and to self-document the code.
 
 - Add CONFIG_KVM_HYPERV to allow disabling KVM support for HyperV "emulation"
   at build time.
 
 ARM64:
 
 - LPA2 support, adding 52bit IPA/PA capability for 4kB and 16kB
   base granule sizes. Branch shared with the arm64 tree.
 
 - Large Fine-Grained Trap rework, bringing some sanity to the
   feature, although there is more to come. This comes with
   a prefix branch shared with the arm64 tree.
 
 - Some additional Nested Virtualization groundwork, mostly
   introducing the NV2 VNCR support and retargetting the NV
   support to that version of the architecture.
 
 - A small set of vgic fixes and associated cleanups.
 
 Loongarch:
 
 - Optimization for memslot hugepage checking
 
 - Cleanup and fix some HW/SW timer issues
 
 - Add LSX/LASX (128bit/256bit SIMD) support
 
 RISC-V:
 
 - KVM_GET_REG_LIST improvement for vector registers
 
 - Generate ISA extension reg_list using macros in get-reg-list selftest
 
 - Support for reporting steal time along with selftest
 
 s390:
 
 - Bugfixes
 
 Selftests:
 
 - Fix an annoying goof where the NX hugepage test prints out garbage
   instead of the magic token needed to run the test.
 
 - Fix build errors when a header is delete/moved due to a missing flag
   in the Makefile.
 
 - Detect if KVM bugged/killed a selftest's VM and print out a helpful
   message instead of complaining that a random ioctl() failed.
 
 - Annotate the guest printf/assert helpers with __printf(), and fix the
   various bugs that were lurking due to lack of said annotation.
 
 There are two non-KVM patches buried in the middle of guest_memfd support:
 
   fs: Rename anon_inode_getfile_secure() and anon_inode_getfd_secure()
   mm: Add AS_UNMOVABLE to mark mapping as completely unmovable
 
 The first is small and mostly suggested-by Christian Brauner; the second
 a bit less so but it was written by an mm person (Vlastimil Babka).
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm

Pull kvm updates from Paolo Bonzini:
 "Generic:

   - Use memdup_array_user() to harden against overflow.

   - Unconditionally advertise KVM_CAP_DEVICE_CTRL for all
     architectures.

   - Clean up Kconfigs that all KVM architectures were selecting

   - New functionality around "guest_memfd", a new userspace API that
     creates an anonymous file and returns a file descriptor that refers
     to it. guest_memfd files are bound to their owning virtual machine,
     cannot be mapped, read, or written by userspace, and cannot be
     resized. guest_memfd files do however support PUNCH_HOLE, which can
     be used to switch a memory area between guest_memfd and regular
     anonymous memory.

   - New ioctl KVM_SET_MEMORY_ATTRIBUTES allowing userspace to specify
     per-page attributes for a given page of guest memory; right now the
     only attribute is whether the guest expects to access memory via
     guest_memfd or not, which in Confidential SVMs backed by SEV-SNP,
     TDX or ARM64 pKVM is checked by firmware or hypervisor that
     guarantees confidentiality (AMD PSP, Intel TDX module, or EL2 in
     the case of pKVM).

  x86:

   - Support for "software-protected VMs" that can use the new
     guest_memfd and page attributes infrastructure. This is mostly
     useful for testing, since there is no pKVM-like infrastructure to
     provide a meaningfully reduced TCB.

   - Fix a relatively benign off-by-one error when splitting huge pages
     during CLEAR_DIRTY_LOG.

   - Fix a bug where KVM could incorrectly test-and-clear dirty bits in
     non-leaf TDP MMU SPTEs if a racing thread replaces a huge SPTE with
     a non-huge SPTE.

   - Use more generic lockdep assertions in paths that don't actually
     care about whether the caller is a reader or a writer.

   - let Xen guests opt out of having PV clock reported as "based on a
     stable TSC", because some of them don't expect the "TSC stable" bit
     (added to the pvclock ABI by KVM, but never set by Xen) to be set.

   - Revert a bogus, made-up nested SVM consistency check for
     TLB_CONTROL.

   - Advertise flush-by-ASID support for nSVM unconditionally, as KVM
     always flushes on nested transitions, i.e. always satisfies flush
     requests. This allows running bleeding edge versions of VMware
     Workstation on top of KVM.

   - Sanity check that the CPU supports flush-by-ASID when enabling SEV
     support.

   - On AMD machines with vNMI, always rely on hardware instead of
     intercepting IRET in some cases to detect unmasking of NMIs

   - Support for virtualizing Linear Address Masking (LAM)

   - Fix a variety of vPMU bugs where KVM fail to stop/reset counters
     and other state prior to refreshing the vPMU model.

   - Fix a double-overflow PMU bug by tracking emulated counter events
     using a dedicated field instead of snapshotting the "previous"
     counter. If the hardware PMC count triggers overflow that is
     recognized in the same VM-Exit that KVM manually bumps an event
     count, KVM would pend PMIs for both the hardware-triggered overflow
     and for KVM-triggered overflow.

   - Turn off KVM_WERROR by default for all configs so that it's not
     inadvertantly enabled by non-KVM developers, which can be
     problematic for subsystems that require no regressions for W=1
     builds.

   - Advertise all of the host-supported CPUID bits that enumerate
     IA32_SPEC_CTRL "features".

   - Don't force a masterclock update when a vCPU synchronizes to the
     current TSC generation, as updating the masterclock can cause
     kvmclock's time to "jump" unexpectedly, e.g. when userspace
     hotplugs a pre-created vCPU.

   - Use RIP-relative address to read kvm_rebooting in the VM-Enter
     fault paths, partly as a super minor optimization, but mostly to
     make KVM play nice with position independent executable builds.

   - Guard KVM-on-HyperV's range-based TLB flush hooks with an #ifdef on
     CONFIG_HYPERV as a minor optimization, and to self-document the
     code.

   - Add CONFIG_KVM_HYPERV to allow disabling KVM support for HyperV
     "emulation" at build time.

  ARM64:

   - LPA2 support, adding 52bit IPA/PA capability for 4kB and 16kB base
     granule sizes. Branch shared with the arm64 tree.

   - Large Fine-Grained Trap rework, bringing some sanity to the
     feature, although there is more to come. This comes with a prefix
     branch shared with the arm64 tree.

   - Some additional Nested Virtualization groundwork, mostly
     introducing the NV2 VNCR support and retargetting the NV support to
     that version of the architecture.

   - A small set of vgic fixes and associated cleanups.

  Loongarch:

   - Optimization for memslot hugepage checking

   - Cleanup and fix some HW/SW timer issues

   - Add LSX/LASX (128bit/256bit SIMD) support

  RISC-V:

   - KVM_GET_REG_LIST improvement for vector registers

   - Generate ISA extension reg_list using macros in get-reg-list
     selftest

   - Support for reporting steal time along with selftest

  s390:

   - Bugfixes

  Selftests:

   - Fix an annoying goof where the NX hugepage test prints out garbage
     instead of the magic token needed to run the test.

   - Fix build errors when a header is delete/moved due to a missing
     flag in the Makefile.

   - Detect if KVM bugged/killed a selftest's VM and print out a helpful
     message instead of complaining that a random ioctl() failed.

   - Annotate the guest printf/assert helpers with __printf(), and fix
     the various bugs that were lurking due to lack of said annotation"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (185 commits)
  x86/kvm: Do not try to disable kvmclock if it was not enabled
  KVM: x86: add missing "depends on KVM"
  KVM: fix direction of dependency on MMU notifiers
  KVM: introduce CONFIG_KVM_COMMON
  KVM: arm64: Add missing memory barriers when switching to pKVM's hyp pgd
  KVM: arm64: vgic-its: Avoid potential UAF in LPI translation cache
  RISC-V: KVM: selftests: Add get-reg-list test for STA registers
  RISC-V: KVM: selftests: Add steal_time test support
  RISC-V: KVM: selftests: Add guest_sbi_probe_extension
  RISC-V: KVM: selftests: Move sbi_ecall to processor.c
  RISC-V: KVM: Implement SBI STA extension
  RISC-V: KVM: Add support for SBI STA registers
  RISC-V: KVM: Add support for SBI extension registers
  RISC-V: KVM: Add SBI STA info to vcpu_arch
  RISC-V: KVM: Add steal-update vcpu request
  RISC-V: KVM: Add SBI STA extension skeleton
  RISC-V: paravirt: Implement steal-time support
  RISC-V: Add SBI STA extension definitions
  RISC-V: paravirt: Add skeleton for pv-time support
  RISC-V: KVM: Fix indentation in kvm_riscv_vcpu_set_reg_csr()
  ...
2024-01-17 13:03:37 -08:00
Paolo Bonzini
7f26fea9bc KVM x86 MMU changes for 6.8:
- Fix a relatively benign off-by-one error when splitting huge pages during
    CLEAR_DIRTY_LOG.
 
  - Fix a bug where KVM could incorrectly test-and-clear dirty bits in non-leaf
    TDP MMU SPTEs if a racing thread replaces a huge SPTE with a non-huge SPTE.
 
  - Relax the TDP MMU's lockdep assertions related to holding mmu_lock for read
    versus write so that KVM doesn't pass "bool shared" all over the place just
    to have precise assertions in paths that don't actually care about whether
    the caller is a reader or a writer.
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Merge tag 'kvm-x86-mmu-6.8' of https://github.com/kvm-x86/linux into HEAD

KVM x86 MMU changes for 6.8:

 - Fix a relatively benign off-by-one error when splitting huge pages during
   CLEAR_DIRTY_LOG.

 - Fix a bug where KVM could incorrectly test-and-clear dirty bits in non-leaf
   TDP MMU SPTEs if a racing thread replaces a huge SPTE with a non-huge SPTE.

 - Relax the TDP MMU's lockdep assertions related to holding mmu_lock for read
   versus write so that KVM doesn't pass "bool shared" all over the place just
   to have precise assertions in paths that don't actually care about whether
   the caller is a reader or a writer.
2024-01-08 08:10:32 -05:00
Paolo Bonzini
8ecb10bcbf KVM x86 support for virtualizing Linear Address Masking (LAM)
Add KVM support for Linear Address Masking (LAM).  LAM tweaks the canonicality
 checks for most virtual address usage in 64-bit mode, such that only the most
 significant bit of the untranslated address bits must match the polarity of the
 last translated address bit.  This allows software to use ignored, untranslated
 address bits for metadata, e.g. to efficiently tag pointers for address
 sanitization.
 
 LAM can be enabled separately for user pointers and supervisor pointers, and
 for userspace LAM can be select between 48-bit and 57-bit masking
 
  - 48-bit LAM: metadata bits 62:48, i.e. LAM width of 15.
  - 57-bit LAM: metadata bits 62:57, i.e. LAM width of 6.
 
 For user pointers, LAM enabling utilizes two previously-reserved high bits from
 CR3 (similar to how PCID_NOFLUSH uses bit 63): LAM_U48 and LAM_U57, bits 62 and
 61 respectively.  Note, if LAM_57 is set, LAM_U48 is ignored, i.e.:
 
  - CR3.LAM_U48=0 && CR3.LAM_U57=0 == LAM disabled for user pointers
  - CR3.LAM_U48=1 && CR3.LAM_U57=0 == LAM-48 enabled for user pointers
  - CR3.LAM_U48=x && CR3.LAM_U57=1 == LAM-57 enabled for user pointers
 
 For supervisor pointers, LAM is controlled by a single bit, CR4.LAM_SUP, with
 the 48-bit versus 57-bit LAM behavior following the current paging mode, i.e.:
 
  - CR4.LAM_SUP=0 && CR4.LA57=x == LAM disabled for supervisor pointers
  - CR4.LAM_SUP=1 && CR4.LA57=0 == LAM-48 enabled for supervisor pointers
  - CR4.LAM_SUP=1 && CR4.LA57=1 == LAM-57 enabled for supervisor pointers
 
 The modified LAM canonicality checks:
  - LAM_S48                : [ 1 ][ metadata ][ 1 ]
                               63               47
  - LAM_U48                : [ 0 ][ metadata ][ 0 ]
                               63               47
  - LAM_S57                : [ 1 ][ metadata ][ 1 ]
                               63               56
  - LAM_U57 + 5-lvl paging : [ 0 ][ metadata ][ 0 ]
                               63               56
  - LAM_U57 + 4-lvl paging : [ 0 ][ metadata ][ 0...0 ]
                               63               56..47
 
 The bulk of KVM support for LAM is to emulate LAM's modified canonicality
 checks.  The approach taken by KVM is to "fill" the metadata bits using the
 highest bit of the translated address, e.g. for LAM-48, bit 47 is sign-extended
 to bits 62:48.  The most significant bit, 63, is *not* modified, i.e. its value
 from the raw, untagged virtual address is kept for the canonicality check. This
 untagging allows
 
 Aside from emulating LAM's canonical checks behavior, LAM has the usual KVM
 touchpoints for selectable features: enumeration (CPUID.7.1:EAX.LAM[bit 26],
 enabling via CR3 and CR4 bits, etc.
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Merge tag 'kvm-x86-lam-6.8' of https://github.com/kvm-x86/linux into HEAD

KVM x86 support for virtualizing Linear Address Masking (LAM)

Add KVM support for Linear Address Masking (LAM).  LAM tweaks the canonicality
checks for most virtual address usage in 64-bit mode, such that only the most
significant bit of the untranslated address bits must match the polarity of the
last translated address bit.  This allows software to use ignored, untranslated
address bits for metadata, e.g. to efficiently tag pointers for address
sanitization.

LAM can be enabled separately for user pointers and supervisor pointers, and
for userspace LAM can be select between 48-bit and 57-bit masking

 - 48-bit LAM: metadata bits 62:48, i.e. LAM width of 15.
 - 57-bit LAM: metadata bits 62:57, i.e. LAM width of 6.

For user pointers, LAM enabling utilizes two previously-reserved high bits from
CR3 (similar to how PCID_NOFLUSH uses bit 63): LAM_U48 and LAM_U57, bits 62 and
61 respectively.  Note, if LAM_57 is set, LAM_U48 is ignored, i.e.:

 - CR3.LAM_U48=0 && CR3.LAM_U57=0 == LAM disabled for user pointers
 - CR3.LAM_U48=1 && CR3.LAM_U57=0 == LAM-48 enabled for user pointers
 - CR3.LAM_U48=x && CR3.LAM_U57=1 == LAM-57 enabled for user pointers

For supervisor pointers, LAM is controlled by a single bit, CR4.LAM_SUP, with
the 48-bit versus 57-bit LAM behavior following the current paging mode, i.e.:

 - CR4.LAM_SUP=0 && CR4.LA57=x == LAM disabled for supervisor pointers
 - CR4.LAM_SUP=1 && CR4.LA57=0 == LAM-48 enabled for supervisor pointers
 - CR4.LAM_SUP=1 && CR4.LA57=1 == LAM-57 enabled for supervisor pointers

The modified LAM canonicality checks:
 - LAM_S48                : [ 1 ][ metadata ][ 1 ]
                              63               47
 - LAM_U48                : [ 0 ][ metadata ][ 0 ]
                              63               47
 - LAM_S57                : [ 1 ][ metadata ][ 1 ]
                              63               56
 - LAM_U57 + 5-lvl paging : [ 0 ][ metadata ][ 0 ]
                              63               56
 - LAM_U57 + 4-lvl paging : [ 0 ][ metadata ][ 0...0 ]
                              63               56..47

The bulk of KVM support for LAM is to emulate LAM's modified canonicality
checks.  The approach taken by KVM is to "fill" the metadata bits using the
highest bit of the translated address, e.g. for LAM-48, bit 47 is sign-extended
to bits 62:48.  The most significant bit, 63, is *not* modified, i.e. its value
from the raw, untagged virtual address is kept for the canonicality check. This
untagging allows

Aside from emulating LAM's canonical checks behavior, LAM has the usual KVM
touchpoints for selectable features: enumeration (CPUID.7.1:EAX.LAM[bit 26],
enabling via CR3 and CR4 bits, etc.
2024-01-08 08:10:12 -05:00
Paolo Bonzini
01edb1cfbd KVM x86 PMU changes for 6.8:
- Fix a variety of bugs where KVM fail to stop/reset counters and other state
    prior to refreshing the vPMU model.
 
  - Fix a double-overflow PMU bug by tracking emulated counter events using a
    dedicated field instead of snapshotting the "previous" counter.  If the
    hardware PMC count triggers overflow that is recognized in the same VM-Exit
    that KVM manually bumps an event count, KVM would pend PMIs for both the
    hardware-triggered overflow and for KVM-triggered overflow.
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Merge tag 'kvm-x86-pmu-6.8' of https://github.com/kvm-x86/linux into HEAD

KVM x86 PMU changes for 6.8:

 - Fix a variety of bugs where KVM fail to stop/reset counters and other state
   prior to refreshing the vPMU model.

 - Fix a double-overflow PMU bug by tracking emulated counter events using a
   dedicated field instead of snapshotting the "previous" counter.  If the
   hardware PMC count triggers overflow that is recognized in the same VM-Exit
   that KVM manually bumps an event count, KVM would pend PMIs for both the
   hardware-triggered overflow and for KVM-triggered overflow.
2024-01-08 08:10:08 -05:00
Bjorn Helgaas
54aa699e80 arch/x86: Fix typos
Fix typos, most reported by "codespell arch/x86".  Only touches comments,
no code changes.

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Randy Dunlap <rdunlap@infradead.org>
Link: https://lore.kernel.org/r/20240103004011.1758650-1-helgaas@kernel.org
2024-01-03 11:46:22 +01:00
Vitaly Kuznetsov
b4f69df0f6 KVM: x86: Make Hyper-V emulation optional
Hyper-V emulation in KVM is a fairly big chunk and in some cases it may be
desirable to not compile it in to reduce module sizes as well as the attack
surface. Introduce CONFIG_KVM_HYPERV option to make it possible.

Note, there's room for further nVMX/nSVM code optimizations when
!CONFIG_KVM_HYPERV, this will be done in follow-up patches.

Reorganize Makefile a bit so all CONFIG_HYPERV and CONFIG_KVM_HYPERV files
are grouped together.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Tested-by: Jeremi Piotrowski <jpiotrowski@linux.microsoft.com>
Link: https://lore.kernel.org/r/20231205103630.1391318-13-vkuznets@redhat.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
2023-12-07 09:34:57 -08:00
Vitaly Kuznetsov
cfef5af3cb KVM: x86: Move Hyper-V partition assist page out of Hyper-V emulation context
Hyper-V partition assist page is used when KVM runs on top of Hyper-V and
is not used for Windows/Hyper-V guests on KVM, this means that 'hv_pa_pg'
placement in 'struct kvm_hv' is unfortunate. As a preparation to making
Hyper-V emulation optional, move 'hv_pa_pg' to 'struct kvm_arch' and put it
under CONFIG_HYPERV.

While on it, introduce hv_get_partition_assist_page() helper to allocate
partition assist page. Move the comment explaining why we use a single page
for all vCPUs from VMX and expand it a bit.

No functional change intended.

Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Tested-by: Jeremi Piotrowski <jpiotrowski@linux.microsoft.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Link: https://lore.kernel.org/r/20231205103630.1391318-3-vkuznets@redhat.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
2023-12-07 09:34:01 -08:00
Vitaly Kuznetsov
87562052c9 KVM: x86/xen: Remove unneeded xen context from kvm_arch when !CONFIG_KVM_XEN
Saving a few bytes of memory per KVM VM is certainly great but what's more
important is the ability to see where the code accesses Xen emulation
context while CONFIG_KVM_XEN is not enabled. Currently, kvm_cpu_get_extint()
is the only such place and it is harmless: kvm_xen_has_interrupt() always
returns '0' when !CONFIG_KVM_XEN.

No functional change intended.

Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Tested-by: Jeremi Piotrowski <jpiotrowski@linux.microsoft.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Link: https://lore.kernel.org/r/20231205103630.1391318-2-vkuznets@redhat.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
2023-12-07 09:33:42 -08:00
Paolo Bonzini
250ce1b4d2 KVM: x86/mmu: always take tdp_mmu_pages_lock
It is cheap to take tdp_mmu_pages_lock in all write-side critical sections.
We already do it all the time when zapping with read_lock(), so it is not
a problem to do it from the kvm_tdp_mmu_zap_all() path (aka
kvm_arch_flush_shadow_all(), aka VM destruction and MMU notifier release).

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Link: https://lore.kernel.org/r/20231125083400.1399197-4-pbonzini@redhat.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
2023-12-01 07:52:08 -08:00
Sean Christopherson
fd89499a51 KVM: x86/pmu: Track emulated counter events instead of previous counter
Explicitly track emulated counter events instead of using the common
counter value that's shared with the hardware counter owned by perf.
Bumping the common counter requires snapshotting the pre-increment value
in order to detect overflow from emulation, and the snapshot approach is
inherently flawed.

Snapshotting the previous counter at every increment assumes that there is
at most one emulated counter event per emulated instruction (or rather,
between checks for KVM_REQ_PMU).  That's mostly holds true today because
KVM only emulates (branch) instructions retired, but the approach will
fall apart if KVM ever supports event types that don't have a 1:1
relationship with instructions.

And KVM already has a relevant bug, as handle_invalid_guest_state()
emulates multiple instructions without checking KVM_REQ_PMU, i.e. could
miss an overflow event due to clobbering pmc->prev_counter.  Not checking
KVM_REQ_PMU is problematic in both cases, but at least with the emulated
counter approach, the resulting behavior is delayed overflow detection,
as opposed to completely lost detection.

Tracking the emulated count fixes another bug where the snapshot approach
can signal spurious overflow due to incorporating both the emulated count
and perf's count in the check, i.e. if overflow is detected by perf, then
KVM's emulation will also incorrectly signal overflow.  Add a comment in
the related code to call out the need to process emulated events *after*
pausing the perf event (big kudos to Mingwei for figuring out that
particular wrinkle).

Cc: Mingwei Zhang <mizhang@google.com>
Cc: Roman Kagan <rkagan@amazon.de>
Cc: Jim Mattson <jmattson@google.com>
Cc: Dapeng Mi <dapeng1.mi@linux.intel.com>
Cc: Like Xu <like.xu.linux@gmail.com>
Reviewed-by: Mingwei Zhang <mizhang@google.com>
Link: https://lore.kernel.org/r/20231103230541.352265-7-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
2023-11-30 12:52:55 -08:00
Sean Christopherson
0277022a77 KVM: x86/mmu: Declare flush_remote_tlbs{_range}() hooks iff HYPERV!=n
Declare the kvm_x86_ops hooks used to wire up paravirt TLB flushes when
running under Hyper-V if and only if CONFIG_HYPERV!=n.  Wrapping yet more
code with IS_ENABLED(CONFIG_HYPERV) eliminates a handful of conditional
branches, and makes it super obvious why the hooks *might* be valid.

Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Link: https://lore.kernel.org/r/20231018192325.1893896-1-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
2023-11-29 14:44:47 -08:00
Robert Hoo
93d1c9f498 KVM: x86: Virtualize LAM for supervisor pointer
Add support to allow guests to set the new CR4 control bit for LAM and add
implementation to get untagged address for supervisor pointers.

LAM modifies the canonicality check applied to 64-bit linear addresses for
data accesses, allowing software to use of the untranslated address bits for
metadata and masks the metadata bits before using them as linear addresses
to access memory. LAM uses CR4.LAM_SUP (bit 28) to configure and enable LAM
for supervisor pointers. It also changes VMENTER to allow the bit to be set
in VMCS's HOST_CR4 and GUEST_CR4 to support virtualization. Note CR4.LAM_SUP
is allowed to be set even not in 64-bit mode, but it will not take effect
since LAM only applies to 64-bit linear addresses.

Move CR4.LAM_SUP out of CR4_RESERVED_BITS, its reservation depends on vcpu
supporting LAM or not. Leave it intercepted to prevent guest from setting
the bit if LAM is not exposed to guest as well as to avoid vmread every time
when KVM fetches its value, with the expectation that guest won't toggle the
bit frequently.

Set CR4.LAM_SUP bit in the emulated IA32_VMX_CR4_FIXED1 MSR for guests to
allow guests to enable LAM for supervisor pointers in nested VMX operation.

Hardware is not required to do TLB flush when CR4.LAM_SUP toggled, KVM
doesn't need to emulate TLB flush based on it.  There's no other features
or vmx_exec_controls connection, and no other code needed in
{kvm,vmx}_set_cr4().

Skip address untag for instruction fetches (which includes branch targets),
operand of INVLPG instructions, and implicit system accesses, all of which
are not subject to untagging.  Note, get_untagged_addr() isn't invoked for
implicit system accesses as there is no reason to do so, but check the
flag anyways for documentation purposes.

Signed-off-by: Robert Hoo <robert.hu@linux.intel.com>
Co-developed-by: Binbin Wu <binbin.wu@linux.intel.com>
Signed-off-by: Binbin Wu <binbin.wu@linux.intel.com>
Reviewed-by: Chao Gao <chao.gao@intel.com>
Reviewed-by: Kai Huang <kai.huang@intel.com>
Tested-by: Xuelian Guo <xuelian.guo@intel.com>
Link: https://lore.kernel.org/r/20230913124227.12574-11-binbin.wu@linux.intel.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
2023-11-28 17:54:07 -08:00
Binbin Wu
37a41847b7 KVM: x86: Introduce get_untagged_addr() in kvm_x86_ops and call it in emulator
Introduce a new interface get_untagged_addr() to kvm_x86_ops to untag
the metadata from linear address.  Call the interface in linearization
of instruction emulator for 64-bit mode.

When enabled feature like Intel Linear Address Masking (LAM) or AMD Upper
Address Ignore (UAI), linear addresses may be tagged with metadata that
needs to be dropped prior to canonicality checks, i.e. the metadata is
ignored.

Introduce get_untagged_addr() to kvm_x86_ops to hide the vendor specific
code, as sadly LAM and UAI have different semantics.  Pass the emulator
flags to allow vendor specific implementation to precisely identify the
access type (LAM doesn't untag certain accesses).

Signed-off-by: Binbin Wu <binbin.wu@linux.intel.com>
Reviewed-by: Chao Gao <chao.gao@intel.com>
Tested-by: Xuelian Guo <xuelian.guo@intel.com>
Link: https://lore.kernel.org/r/20230913124227.12574-9-binbin.wu@linux.intel.com
[sean: massage changelog]
Signed-off-by: Sean Christopherson <seanjc@google.com>
2023-11-28 17:54:06 -08:00
Sean Christopherson
89ea60c2c7 KVM: x86: Add support for "protected VMs" that can utilize private memory
Add a new x86 VM type, KVM_X86_SW_PROTECTED_VM, to serve as a development
and testing vehicle for Confidential (CoCo) VMs, and potentially to even
become a "real" product in the distant future, e.g. a la pKVM.

The private memory support in KVM x86 is aimed at AMD's SEV-SNP and
Intel's TDX, but those technologies are extremely complex (understatement),
difficult to debug, don't support running as nested guests, and require
hardware that's isn't universally accessible.  I.e. relying SEV-SNP or TDX
for maintaining guest private memory isn't a realistic option.

At the very least, KVM_X86_SW_PROTECTED_VM will enable a variety of
selftests for guest_memfd and private memory support without requiring
unique hardware.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20231027182217.3615211-24-seanjc@google.com>
Reviewed-by: Fuad Tabba <tabba@google.com>
Tested-by: Fuad Tabba <tabba@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2023-11-14 08:01:05 -05:00
Sean Christopherson
eed52e434b KVM: Allow arch code to track number of memslot address spaces per VM
Let x86 track the number of address spaces on a per-VM basis so that KVM
can disallow SMM memslots for confidential VMs.  Confidentials VMs are
fundamentally incompatible with emulating SMM, which as the name suggests
requires being able to read and write guest memory and register state.

Disallowing SMM will simplify support for guest private memory, as KVM
will not need to worry about tracking memory attributes for multiple
address spaces (SMM is the only "non-default" address space across all
architectures).

Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Fuad Tabba <tabba@google.com>
Tested-by: Fuad Tabba <tabba@google.com>
Message-Id: <20231027182217.3615211-23-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2023-11-14 08:01:05 -05:00
Sean Christopherson
2333afa17a KVM: Drop superfluous __KVM_VCPU_MULTIPLE_ADDRESS_SPACE macro
Drop __KVM_VCPU_MULTIPLE_ADDRESS_SPACE and instead check the value of
KVM_ADDRESS_SPACE_NUM.

No functional change intended.

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Fuad Tabba <tabba@google.com>
Tested-by: Fuad Tabba <tabba@google.com>
Message-Id: <20231027182217.3615211-22-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2023-11-14 08:01:04 -05:00
Chao Peng
90b4fe1798 KVM: x86: Disallow hugepages when memory attributes are mixed
Disallow creating hugepages with mixed memory attributes, e.g. shared
versus private, as mapping a hugepage in this case would allow the guest
to access memory with the wrong attributes, e.g. overlaying private memory
with a shared hugepage.

Tracking whether or not attributes are mixed via the existing
disallow_lpage field, but use the most significant bit in 'disallow_lpage'
to indicate a hugepage has mixed attributes instead using the normal
refcounting.  Whether or not attributes are mixed is binary; either they
are or they aren't.  Attempting to squeeze that info into the refcount is
unnecessarily complex as it would require knowing the previous state of
the mixed count when updating attributes.  Using a flag means KVM just
needs to ensure the current status is reflected in the memslots.

Signed-off-by: Chao Peng <chao.p.peng@linux.intel.com>
Co-developed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20231027182217.3615211-20-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2023-11-14 08:01:04 -05:00
Sean Christopherson
f128cf8cfb KVM: Convert KVM_ARCH_WANT_MMU_NOTIFIER to CONFIG_KVM_GENERIC_MMU_NOTIFIER
Convert KVM_ARCH_WANT_MMU_NOTIFIER into a Kconfig and select it where
appropriate to effectively maintain existing behavior.  Using a proper
Kconfig will simplify building more functionality on top of KVM's
mmu_notifier infrastructure.

Add a forward declaration of kvm_gfn_range to kvm_types.h so that
including arch/powerpc/include/asm/kvm_ppc.h's with CONFIG_KVM=n doesn't
generate warnings due to kvm_gfn_range being undeclared.  PPC defines
hooks for PR vs. HV without guarding them via #ifdeffery, e.g.

  bool (*unmap_gfn_range)(struct kvm *kvm, struct kvm_gfn_range *range);
  bool (*age_gfn)(struct kvm *kvm, struct kvm_gfn_range *range);
  bool (*test_age_gfn)(struct kvm *kvm, struct kvm_gfn_range *range);
  bool (*set_spte_gfn)(struct kvm *kvm, struct kvm_gfn_range *range);

Alternatively, PPC could forward declare kvm_gfn_range, but there's no
good reason not to define it in common KVM.

Acked-by: Anup Patel <anup@brainfault.org>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Fuad Tabba <tabba@google.com>
Tested-by: Fuad Tabba <tabba@google.com>
Message-Id: <20231027182217.3615211-8-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2023-11-13 05:29:09 -05:00
Paolo Bonzini
be47941980 KVM SVM changes for 6.7:
- Report KVM_EXIT_SHUTDOWN instead of EINVAL if KVM intercepts SHUTDOWN while
    running an SEV-ES guest.
 
  - Clean up handling "failures" when KVM detects it can't emulate the "skip"
    action for an instruction that has already been partially emulated.  Drop a
    hack in the SVM code that was fudging around the emulator code not giving
    SVM enough information to do the right thing.
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Merge tag 'kvm-x86-svm-6.7' of https://github.com/kvm-x86/linux into HEAD

KVM SVM changes for 6.7:

 - Report KVM_EXIT_SHUTDOWN instead of EINVAL if KVM intercepts SHUTDOWN while
   running an SEV-ES guest.

 - Clean up handling "failures" when KVM detects it can't emulate the "skip"
   action for an instruction that has already been partially emulated.  Drop a
   hack in the SVM code that was fudging around the emulator code not giving
   SVM enough information to do the right thing.
2023-10-31 10:22:43 -04:00
Paolo Bonzini
e122d7a100 KVM x86 Xen changes for 6.7:
- Omit "struct kvm_vcpu_xen" entirely when CONFIG_KVM_XEN=n.
 
  - Use the fast path directly from the timer callback when delivering Xen timer
    events.  Avoid the problematic races with using the fast path by ensuring
    the hrtimer isn't running when (re)starting the timer or saving the timer
    information (for userspace).
 
  - Follow the lead of upstream Xen and ignore the VCPU_SSHOTTMR_future flag.
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Merge tag 'kvm-x86-xen-6.7' of https://github.com/kvm-x86/linux into HEAD

KVM x86 Xen changes for 6.7:

 - Omit "struct kvm_vcpu_xen" entirely when CONFIG_KVM_XEN=n.

 - Use the fast path directly from the timer callback when delivering Xen timer
   events.  Avoid the problematic races with using the fast path by ensuring
   the hrtimer isn't running when (re)starting the timer or saving the timer
   information (for userspace).

 - Follow the lead of upstream Xen and ignore the VCPU_SSHOTTMR_future flag.
2023-10-31 10:21:42 -04:00
Paolo Bonzini
f292dc8aad KVM x86 misc changes for 6.7:
- Add CONFIG_KVM_MAX_NR_VCPUS to allow supporting up to 4096 vCPUs without
    forcing more common use cases to eat the extra memory overhead.
 
  - Add IBPB and SBPB virtualization support.
 
  - Fix a bug where restoring a vCPU snapshot that was taken within 1 second of
    creating the original vCPU would cause KVM to try to synchronize the vCPU's
    TSC and thus clobber the correct TSC being set by userspace.
 
  - Compute guest wall clock using a single TSC read to avoid generating an
    inaccurate time, e.g. if the vCPU is preempted between multiple TSC reads.
 
  - "Virtualize" HWCR.TscFreqSel to make Linux guests happy, which complain
     about a "Firmware Bug" if the bit isn't set for select F/M/S combos.
 
  - Don't apply side effects to Hyper-V's synthetic timer on writes from
    userspace to fix an issue where the auto-enable behavior can trigger
    spurious interrupts, i.e. do auto-enabling only for guest writes.
 
  - Remove an unnecessary kick of all vCPUs when synchronizing the dirty log
    without PML enabled.
 
  - Advertise "support" for non-serializing FS/GS base MSR writes as appropriate.
 
  - Use octal notation for file permissions through KVM x86.
 
  - Fix a handful of typo fixes and warts.
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Merge tag 'kvm-x86-misc-6.7' of https://github.com/kvm-x86/linux into HEAD

KVM x86 misc changes for 6.7:

 - Add CONFIG_KVM_MAX_NR_VCPUS to allow supporting up to 4096 vCPUs without
   forcing more common use cases to eat the extra memory overhead.

 - Add IBPB and SBPB virtualization support.

 - Fix a bug where restoring a vCPU snapshot that was taken within 1 second of
   creating the original vCPU would cause KVM to try to synchronize the vCPU's
   TSC and thus clobber the correct TSC being set by userspace.

 - Compute guest wall clock using a single TSC read to avoid generating an
   inaccurate time, e.g. if the vCPU is preempted between multiple TSC reads.

 - "Virtualize" HWCR.TscFreqSel to make Linux guests happy, which complain
    about a "Firmware Bug" if the bit isn't set for select F/M/S combos.

 - Don't apply side effects to Hyper-V's synthetic timer on writes from
   userspace to fix an issue where the auto-enable behavior can trigger
   spurious interrupts, i.e. do auto-enabling only for guest writes.

 - Remove an unnecessary kick of all vCPUs when synchronizing the dirty log
   without PML enabled.

 - Advertise "support" for non-serializing FS/GS base MSR writes as appropriate.

 - Use octal notation for file permissions through KVM x86.

 - Fix a handful of typo fixes and warts.
2023-10-31 10:15:15 -04:00
Paolo Bonzini
f233646760 KVM x86 APIC changes for 6.7:
- Purge VMX's posted interrupt descriptor *before* loading APIC state when
    handling KVM_SET_LAPIC.  Purging the PID after loading APIC state results in
    lost APIC timer IRQs as the APIC timer can be armed as part of loading APIC
    state, i.e. can immediately pend an IRQ if the expiry is in the past.
 
  - Clear the ICR.BUSY bit when handling trap-like x2APIC writes to suppress a
    WARN due to KVM expecting the BUSY bit to be cleared when sending IPIs.
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Merge tag 'kvm-x86-apic-6.7' of https://github.com/kvm-x86/linux into HEAD

KVM x86 APIC changes for 6.7:

 - Purge VMX's posted interrupt descriptor *before* loading APIC state when
   handling KVM_SET_LAPIC.  Purging the PID after loading APIC state results in
   lost APIC timer IRQs as the APIC timer can be armed as part of loading APIC
   state, i.e. can immediately pend an IRQ if the expiry is in the past.

 - Clear the ICR.BUSY bit when handling trap-like x2APIC writes.  This avoids a
   WARN, due to KVM expecting the BUSY bit to be cleared when sending IPIs.
2023-10-31 10:11:19 -04:00
Liang Chen
122ae01c51 KVM: x86: remove the unused assigned_dev_head from kvm_arch
Legacy device assignment was dropped years ago. This field is not used
anymore.

Signed-off-by: Liang Chen <liangchen.linux@gmail.com>
Link: https://lore.kernel.org/r/20231019043336.8998-1-liangchen.linux@gmail.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
2023-10-19 08:42:22 -07:00
Mingwei Zhang
5a989bbead KVM: x86: Update the variable naming in kvm_x86_ops.sched_in()
Update the variable with name 'kvm' in kvm_x86_ops.sched_in() to 'vcpu' to
avoid confusions. Variable naming in KVM has a clear convention that 'kvm'
refers to pointer of type 'struct kvm *', while 'vcpu' refers to pointer of
type 'struct kvm_vcpu *'.

Fix this 9-year old naming issue for fun.

Signed-off-by: Mingwei Zhang <mizhang@google.com>
Link: https://lore.kernel.org/r/20231017232610.4008690-1-mizhang@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
2023-10-17 16:40:01 -07:00
Like Xu
bf328e22e4 KVM: x86: Don't sync user-written TSC against startup values
The legacy API for setting the TSC is fundamentally broken, and only
allows userspace to set a TSC "now", without any way to account for
time lost between the calculation of the value, and the kernel eventually
handling the ioctl.

To work around this, KVM has a hack which, if a TSC is set with a value
which is within a second's worth of the last TSC "written" to any vCPU in
the VM, assumes that userspace actually intended the two TSC values to be
in sync and adjusts the newly-written TSC value accordingly.

Thus, when a VMM restores a guest after suspend or migration using the
legacy API, the TSCs aren't necessarily *right*, but at least they're
in sync.

This trick falls down when restoring a guest which genuinely has been
running for less time than the 1 second of imprecision KVM allows for in
in the legacy API.  On *creation*, the first vCPU starts its TSC counting
from zero, and the subsequent vCPUs synchronize to that.  But then when
the VMM tries to restore a vCPU's intended TSC, because the VM has been
alive for less than 1 second and KVM's default TSC value for new vCPU's is
'0', the intended TSC is within a second of the last "written" TSC and KVM
incorrectly adjusts the intended TSC in an attempt to synchronize.

But further hacks can be piled onto KVM's existing hackish ABI, and
declare that the *first* value written by *userspace* (on any vCPU)
should not be subject to this "correction", i.e. KVM can assume that the
first write from userspace is not an attempt to sync up with TSC values
that only come from the kernel's default vCPU creation.

To that end: Add a flag, kvm->arch.user_set_tsc, protected by
kvm->arch.tsc_write_lock, to record that a TSC for at least one vCPU in
the VM *has* been set by userspace, and make the 1-second slop hack only
trigger if user_set_tsc is already set.

Note that userspace can explicitly request a *synchronization* of the
TSC by writing zero. For the purpose of user_set_tsc, an explicit
synchronization counts as "setting" the TSC, i.e. if userspace then
subsequently writes an explicit non-zero value which happens to be within
1 second of the previous value, the new value will be "corrected".  This
behavior is deliberate, as treating explicit synchronization as "setting"
the TSC preserves KVM's existing behaviour inasmuch as possible (KVM
always applied the 1-second "correction" regardless of whether the write
came from userspace vs. the kernel).

Reported-by: Yong He <alexyonghe@tencent.com>
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=217423
Suggested-by: Oliver Upton <oliver.upton@linux.dev>
Original-by: Oliver Upton <oliver.upton@linux.dev>
Original-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Like Xu <likexu@tencent.com>
Tested-by: Yong He <alexyonghe@tencent.com>
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Link: https://lore.kernel.org/r/20231008025335.7419-1-likexu@tencent.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
2023-10-09 17:29:52 -07:00
Sean Christopherson
aeb904f6b9 KVM: x86: Refactor can_emulate_instruction() return to be more expressive
Refactor and rename can_emulate_instruction() to allow vendor code to
return more than true/false, e.g. to explicitly differentiate between
"retry", "fault", and "unhandleable".  For now, just do the plumbing, a
future patch will expand SVM's implementation to signal outright failure
if KVM attempts EMULTYPE_SKIP on an SEV guest.

No functional change intended (or rather, none that are visible to the
guest or userspace).

Link: https://lore.kernel.org/r/20230825013621.2845700-4-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
2023-10-04 15:08:53 -07:00
Peng Hao
ee11ab6bb0 KVM: X86: Reduce size of kvm_vcpu_arch structure when CONFIG_KVM_XEN=n
When CONFIG_KVM_XEN=n, the size of kvm_vcpu_arch can be reduced
from 5100+ to 4400+ by adding macro control.

Signed-off-by: Peng Hao <flyingpeng@tencent.com>
Link: https://lore.kernel.org/all/CAPm50aKwbZGeXPK5uig18Br8CF1hOS71CE2j_dLX+ub7oJdpGg@mail.gmail.com
[sean: fix whitespace damage]
Signed-off-by: Sean Christopherson <seanjc@google.com>
2023-10-04 12:26:02 -07:00
Haitao Shan
9cfec6d097 KVM: x86: Fix lapic timer interrupt lost after loading a snapshot.
When running android emulator (which is based on QEMU 2.12) on
certain Intel hosts with kernel version 6.3-rc1 or above, guest
will freeze after loading a snapshot. This is almost 100%
reproducible. By default, the android emulator will use snapshot
to speed up the next launching of the same android guest. So
this breaks the android emulator badly.

I tested QEMU 8.0.4 from Debian 12 with an Ubuntu 22.04 guest by
running command "loadvm" after "savevm". The same issue is
observed. At the same time, none of our AMD platforms is impacted.
More experiments show that loading the KVM module with
"enable_apicv=false" can workaround it.

The issue started to show up after commit 8e6ed96cdd ("KVM: x86:
fire timer when it is migrated and expired, and in oneshot mode").
However, as is pointed out by Sean Christopherson, it is introduced
by commit 967235d320 ("KVM: vmx: clear pending interrupts on
KVM_SET_LAPIC"). commit 8e6ed96cdd ("KVM: x86: fire timer when
it is migrated and expired, and in oneshot mode") just makes it
easier to hit the issue.

Having both commits, the oneshot lapic timer gets fired immediately
inside the KVM_SET_LAPIC call when loading the snapshot. On Intel
platforms with APIC virtualization and posted interrupt processing,
this eventually leads to setting the corresponding PIR bit. However,
the whole PIR bits get cleared later in the same KVM_SET_LAPIC call
by apicv_post_state_restore. This leads to timer interrupt lost.

The fix is to move vmx_apicv_post_state_restore to the beginning of
the KVM_SET_LAPIC call and rename to vmx_apicv_pre_state_restore.
What vmx_apicv_post_state_restore does is actually clearing any
former apicv state and this behavior is more suitable to carry out
in the beginning.

Fixes: 967235d320 ("KVM: vmx: clear pending interrupts on KVM_SET_LAPIC")
Cc: stable@vger.kernel.org
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Haitao Shan <hshan@google.com>
Link: https://lore.kernel.org/r/20230913000215.478387-1-hshan@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
2023-09-28 10:19:29 -07:00
Kyle Meyer
f10a570b09 KVM: x86: Add CONFIG_KVM_MAX_NR_VCPUS to allow up to 4096 vCPUs
Add a Kconfig entry to set the maximum number of vCPUs per KVM guest and
set the default value to 4096 when MAXSMP is enabled, as there are use
cases that want to create more than the currently allowed 1024 vCPUs and
are more than happy to eat the memory overhead.

The Hyper-V TLFS doesn't allow more than 64 sparse banks, i.e. allows a
maximum of 4096 virtual CPUs. Cap KVM's maximum number of virtual CPUs
to 4096 to avoid exceeding Hyper-V's limit as KVM support for Hyper-V is
unconditional, and alternatives like dynamically disabling Hyper-V
enlightenments that rely on sparse banks would require non-trivial code
changes.

Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Kyle Meyer <kyle.meyer@hpe.com>
Link: https://lore.kernel.org/r/20230824215244.3897419-1-kyle.meyer@hpe.com
[sean: massage changelog with --verbose, document #ifdef mess]
Signed-off-by: Sean Christopherson <seanjc@google.com>
2023-09-28 09:25:19 -07:00
Jim Mattson
73554b29bd KVM: x86/pmu: Synthesize at most one PMI per VM-exit
When the irq_work callback, kvm_pmi_trigger_fn(), is invoked during a
VM-exit that also invokes __kvm_perf_overflow() as a result of
instruction emulation, kvm_pmu_deliver_pmi() will be called twice
before the next VM-entry.

Calling kvm_pmu_deliver_pmi() twice is unlikely to be problematic now that
KVM sets the LVTPC mask bit when delivering a PMI.  But using IRQ work to
trigger the PMI is still broken, albeit very theoretically.

E.g. if the self-IPI to trigger IRQ work is be delayed long enough for the
vCPU to be migrated to a different pCPU, then it's possible for
kvm_pmi_trigger_fn() to race with the kvm_pmu_deliver_pmi() from
KVM_REQ_PMI and still generate two PMIs.

KVM could set the mask bit using an atomic operation, but that'd just be
piling on unnecessary code to workaround what is effectively a hack.  The
*only* reason KVM uses IRQ work is to ensure the PMI is treated as a wake
event, e.g. if the vCPU just executed HLT.

Remove the irq_work callback for synthesizing a PMI, and all of the
logic for invoking it. Instead, to prevent a vcpu from leaving C0 with
a PMI pending, add a check for KVM_REQ_PMI to kvm_vcpu_has_events().

Fixes: 9cd803d496 ("KVM: x86: Update vPMCs when retiring instructions")
Signed-off-by: Jim Mattson <jmattson@google.com>
Tested-by: Mingwei Zhang <mizhang@google.com>
Tested-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
Signed-off-by: Mingwei Zhang <mizhang@google.com>
Link: https://lore.kernel.org/r/20230925173448.3518223-2-mizhang@google.com
[sean: massage changelog]
Signed-off-by: Sean Christopherson <seanjc@google.com>
2023-09-25 14:42:52 -07:00
Sean Christopherson
0df9dab891 KVM: x86/mmu: Stop zapping invalidated TDP MMU roots asynchronously
Stop zapping invalidate TDP MMU roots via work queue now that KVM
preserves TDP MMU roots until they are explicitly invalidated.  Zapping
roots asynchronously was effectively a workaround to avoid stalling a vCPU
for an extended during if a vCPU unloaded a root, which at the time
happened whenever the guest toggled CR0.WP (a frequent operation for some
guest kernels).

While a clever hack, zapping roots via an unbound worker had subtle,
unintended consequences on host scheduling, especially when zapping
multiple roots, e.g. as part of a memslot.  Because the work of zapping a
root is no longer bound to the task that initiated the zap, things like
the CPU affinity and priority of the original task get lost.  Losing the
affinity and priority can be especially problematic if unbound workqueues
aren't affined to a small number of CPUs, as zapping multiple roots can
cause KVM to heavily utilize the majority of CPUs in the system, *beyond*
the CPUs KVM is already using to run vCPUs.

When deleting a memslot via KVM_SET_USER_MEMORY_REGION, the async root
zap can result in KVM occupying all logical CPUs for ~8ms, and result in
high priority tasks not being scheduled in in a timely manner.  In v5.15,
which doesn't preserve unloaded roots, the issues were even more noticeable
as KVM would zap roots more frequently and could occupy all CPUs for 50ms+.

Consuming all CPUs for an extended duration can lead to significant jitter
throughout the system, e.g. on ChromeOS with virtio-gpu, deleting memslots
is a semi-frequent operation as memslots are deleted and recreated with
different host virtual addresses to react to host GPU drivers allocating
and freeing GPU blobs.  On ChromeOS, the jitter manifests as audio blips
during games due to the audio server's tasks not getting scheduled in
promptly, despite the tasks having a high realtime priority.

Deleting memslots isn't exactly a fast path and should be avoided when
possible, and ChromeOS is working towards utilizing MAP_FIXED to avoid the
memslot shenanigans, but KVM is squarely in the wrong.  Not to mention
that removing the async zapping eliminates a non-trivial amount of
complexity.

Note, one of the subtle behaviors hidden behind the async zapping is that
KVM would zap invalidated roots only once (ignoring partial zaps from
things like mmu_notifier events).  Preserve this behavior by adding a flag
to identify roots that are scheduled to be zapped versus roots that have
already been zapped but not yet freed.

Add a comment calling out why kvm_tdp_mmu_invalidate_all_roots() can
encounter invalid roots, as it's not at all obvious why zapping
invalidated roots shouldn't simply zap all invalid roots.

Reported-by: Pattara Teerapong <pteerapong@google.com>
Cc: David Stevens <stevensd@google.com>
Cc: Yiwei Zhang<zzyiwei@google.com>
Cc: Paul Hsia <paulhsia@google.com>
Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20230916003916.2545000-4-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2023-09-23 05:35:48 -04:00
Sean Christopherson
338068b5be KVM: x86/mmu: Drop infrastructure for multiple page-track modes
Drop "support" for multiple page-track modes, as there is no evidence
that array-based and refcounted metadata is the optimal solution for
other modes, nor is there any evidence that other use cases, e.g. for
access-tracking, will be a good fit for the page-track machinery in
general.

E.g. one potential use case of access-tracking would be to prevent guest
access to poisoned memory (from the guest's perspective).  In that case,
the number of poisoned pages is likely to be a very small percentage of
the guest memory, and there is no need to reference count the number of
access-tracking users, i.e. expanding gfn_track[] for a new mode would be
grossly inefficient.  And for poisoned memory, host userspace would also
likely want to trap accesses, e.g. to inject #MC into the guest, and that
isn't currently supported by the page-track framework.

A better alternative for that poisoned page use case is likely a
variation of the proposed per-gfn attributes overlay (linked), which
would allow efficiently tracking the sparse set of poisoned pages, and by
default would exit to userspace on access.

Link: https://lore.kernel.org/all/Y2WB48kD0J4VGynX@google.com
Cc: Ben Gardon <bgardon@google.com>
Tested-by: Yongwei Ma <yongwei.ma@intel.com>
Link: https://lore.kernel.org/r/20230729013535.1070024-24-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2023-08-31 14:08:14 -04:00
Sean Christopherson
e998fb1a30 KVM: x86/mmu: Use page-track notifiers iff there are external users
Disable the page-track notifier code at compile time if there are no
external users, i.e. if CONFIG_KVM_EXTERNAL_WRITE_TRACKING=n.  KVM itself
now hooks emulated writes directly instead of relying on the page-track
mechanism.

Provide a stub for "struct kvm_page_track_notifier_node" so that including
headers directly from the command line, e.g. for testing include guards,
doesn't fail due to a struct having an incomplete type.

Reviewed-by: Yan Zhao <yan.y.zhao@intel.com>
Tested-by: Yongwei Ma <yongwei.ma@intel.com>
Link: https://lore.kernel.org/r/20230729013535.1070024-23-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2023-08-31 14:08:14 -04:00
Sean Christopherson
932844462a KVM: x86/mmu: Don't bounce through page-track mechanism for guest PTEs
Don't use the generic page-track mechanism to handle writes to guest PTEs
in KVM's MMU.  KVM's MMU needs access to information that should not be
exposed to external page-track users, e.g. KVM needs (for some definitions
of "need") the vCPU to query the current paging mode, whereas external
users, i.e. KVMGT, have no ties to the current vCPU and so should never
need the vCPU.

Moving away from the page-track mechanism will allow dropping use of the
page-track mechanism for KVM's own MMU, and will also allow simplifying
and cleaning up the page-track APIs.

Reviewed-by: Yan Zhao <yan.y.zhao@intel.com>
Tested-by: Yongwei Ma <yongwei.ma@intel.com>
Link: https://lore.kernel.org/r/20230729013535.1070024-15-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2023-08-31 13:49:00 -04:00
Sean Christopherson
db0d70e610 KVM: x86/mmu: Move kvm_arch_flush_shadow_{all,memslot}() to mmu.c
Move x86's implementation of kvm_arch_flush_shadow_{all,memslot}() into
mmu.c, and make kvm_mmu_zap_all() static as it was globally visible only
for kvm_arch_flush_shadow_all().  This will allow refactoring
kvm_arch_flush_shadow_memslot() to call kvm_mmu_zap_all() directly without
having to expose kvm_mmu_zap_all_fast() outside of mmu.c.  Keeping
everything in mmu.c will also likely simplify supporting TDX, which
intends to do zap only relevant SPTEs on memslot updates.

No functional change intended.

Suggested-by: Yan Zhao <yan.y.zhao@intel.com>
Tested-by: Yongwei Ma <yongwei.ma@intel.com>
Link: https://lore.kernel.org/r/20230729013535.1070024-13-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2023-08-31 13:48:59 -04:00
Paolo Bonzini
6d5e3c318a KVM x86 changes for 6.6:
- Misc cleanups
 
  - Retry APIC optimized recalculation if a vCPU is added/enabled
 
  - Overhaul emergency reboot code to bring SVM up to par with VMX, tie the
    "emergency disabling" behavior to KVM actually being loaded, and move all of
    the logic within KVM
 
  - Fix user triggerable WARNs in SVM where KVM incorrectly assumes the TSC
    ratio MSR can diverge from the default iff TSC scaling is enabled, and clean
    up related code
 
  - Add a framework to allow "caching" feature flags so that KVM can check if
    the guest can use a feature without needing to search guest CPUID
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Merge tag 'kvm-x86-misc-6.6' of https://github.com/kvm-x86/linux into HEAD

KVM x86 changes for 6.6:

 - Misc cleanups

 - Retry APIC optimized recalculation if a vCPU is added/enabled

 - Overhaul emergency reboot code to bring SVM up to par with VMX, tie the
   "emergency disabling" behavior to KVM actually being loaded, and move all of
   the logic within KVM

 - Fix user triggerable WARNs in SVM where KVM incorrectly assumes the TSC
   ratio MSR can diverge from the default iff TSC scaling is enabled, and clean
   up related code

 - Add a framework to allow "caching" feature flags so that KVM can check if
   the guest can use a feature without needing to search guest CPUID
2023-08-31 13:36:33 -04:00
Paolo Bonzini
e0fb12c673 KVM/arm64 updates for Linux 6.6
- Add support for TLB range invalidation of Stage-2 page tables,
   avoiding unnecessary invalidations. Systems that do not implement
   range invalidation still rely on a full invalidation when dealing
   with large ranges.
 
 - Add infrastructure for forwarding traps taken from a L2 guest to
   the L1 guest, with L0 acting as the dispatcher, another baby step
   towards the full nested support.
 
 - Simplify the way we deal with the (long deprecated) 'CPU target',
   resulting in a much needed cleanup.
 
 - Fix another set of PMU bugs, both on the guest and host sides,
   as we seem to never have any shortage of those...
 
 - Relax the alignment requirements of EL2 VA allocations for
   non-stack allocations, as we were otherwise wasting a lot of that
   precious VA space.
 
 - The usual set of non-functional cleanups, although I note the lack
   of spelling fixes...
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Merge tag 'kvmarm-6.6' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD

KVM/arm64 updates for Linux 6.6

- Add support for TLB range invalidation of Stage-2 page tables,
  avoiding unnecessary invalidations. Systems that do not implement
  range invalidation still rely on a full invalidation when dealing
  with large ranges.

- Add infrastructure for forwarding traps taken from a L2 guest to
  the L1 guest, with L0 acting as the dispatcher, another baby step
  towards the full nested support.

- Simplify the way we deal with the (long deprecated) 'CPU target',
  resulting in a much needed cleanup.

- Fix another set of PMU bugs, both on the guest and host sides,
  as we seem to never have any shortage of those...

- Relax the alignment requirements of EL2 VA allocations for
  non-stack allocations, as we were otherwise wasting a lot of that
  precious VA space.

- The usual set of non-functional cleanups, although I note the lack
  of spelling fixes...
2023-08-31 13:18:53 -04:00
Sean Christopherson
fe60e8f65f KVM: x86: Use KVM-governed feature framework to track "XSAVES enabled"
Use the governed feature framework to track if XSAVES is "enabled", i.e.
if XSAVES can be used by the guest.  Add a comment in the SVM code to
explain the very unintuitive logic of deliberately NOT checking if XSAVES
is enumerated in the guest CPUID model.

No functional change intended.

Reviewed-by: Yuan Yao <yuan.yao@intel.com>
Link: https://lore.kernel.org/r/20230815203653.519297-7-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
2023-08-17 11:38:28 -07:00
Sean Christopherson
42764413d1 KVM: x86: Add a framework for enabling KVM-governed x86 features
Introduce yet another X86_FEATURE flag framework to manage and cache KVM
governed features (for lack of a better name).  "Governed" in this case
means that KVM has some level of involvement and/or vested interest in
whether or not an X86_FEATURE can be used by the guest.  The intent of the
framework is twofold: to simplify caching of guest CPUID flags that KVM
needs to frequently query, and to add clarity to such caching, e.g. it
isn't immediately obvious that SVM's bundle of flags for "optional nested
SVM features" track whether or not a flag is exposed to L1.

Begrudgingly define KVM_MAX_NR_GOVERNED_FEATURES for the size of the
bitmap to avoid exposing governed_features.h in arch/x86/include/asm/, but
add a FIXME to call out that it can and should be cleaned up once
"struct kvm_vcpu_arch" is no longer expose to the kernel at large.

Cc: Zeng Guang <guang.zeng@intel.com>
Reviewed-by: Binbin Wu <binbin.wu@linux.intel.com>
Reviewed-by: Kai Huang <kai.huang@intel.com>
Reviewed-by: Yuan Yao <yuan.yao@intel.com>
Link: https://lore.kernel.org/r/20230815203653.519297-2-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
2023-08-17 11:38:27 -07:00
David Matlack
d478899605 KVM: Allow range-based TLB invalidation from common code
Make kvm_flush_remote_tlbs_range() visible in common code and create a
default implementation that just invalidates the whole TLB.

This paves the way for several future features/cleanups:

 - Introduction of range-based TLBI on ARM.
 - Eliminating kvm_arch_flush_remote_tlbs_memslot()
 - Moving the KVM/x86 TDP MMU to common code.

No functional change intended.

Signed-off-by: David Matlack <dmatlack@google.com>
Signed-off-by: Raghavendra Rao Ananta <rananta@google.com>
Reviewed-by: Gavin Shan <gshan@redhat.com>
Reviewed-by: Shaoqin Huang <shahuang@redhat.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Acked-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20230811045127.3308641-6-rananta@google.com
2023-08-17 09:40:35 +01:00
David Matlack
a1342c8027 KVM: Rename kvm_arch_flush_remote_tlb() to kvm_arch_flush_remote_tlbs()
Rename kvm_arch_flush_remote_tlb() and the associated macro
__KVM_HAVE_ARCH_FLUSH_REMOTE_TLB to kvm_arch_flush_remote_tlbs() and
__KVM_HAVE_ARCH_FLUSH_REMOTE_TLBS respectively.

Making the name plural matches kvm_flush_remote_tlbs() and makes it more
clear that this function can affect more than one remote TLB.

No functional change intended.

Signed-off-by: David Matlack <dmatlack@google.com>
Signed-off-by: Raghavendra Rao Ananta <rananta@google.com>
Reviewed-by: Gavin Shan <gshan@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Shaoqin Huang <shahuang@redhat.com>
Acked-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20230811045127.3308641-2-rananta@google.com
2023-08-17 09:35:14 +01:00
Sean Christopherson
2d63699099 KVM: x86: Always write vCPU's current TSC offset/ratio in vendor hooks
Drop the @offset and @multiplier params from the kvm_x86_ops hooks for
propagating TSC offsets/multipliers into hardware, and instead have the
vendor implementations pull the information directly from the vCPU
structure.  The respective vCPU fields _must_ be written at the same
time in order to maintain consistent state, i.e. it's not random luck
that the value passed in by all callers is grabbed from the vCPU.

Explicitly grabbing the value from the vCPU field in SVM's implementation
in particular will allow for additional cleanup without introducing even
more subtle dependencies.  Specifically, SVM can skip the WRMSR if guest
state isn't loaded, i.e. svm_prepare_switch_to_guest() will load the
correct value for the vCPU prior to entering the guest.

This also reconciles KVM's handling of related values that are stored in
the vCPU, as svm_write_tsc_offset() already assumes/requires the caller
to have updated l1_tsc_offset.

Link: https://lore.kernel.org/r/20230729011608.1065019-6-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
2023-08-03 17:16:29 -07:00
Sean Christopherson
26a0652cb4 KVM: x86: Disallow KVM_SET_SREGS{2} if incoming CR0 is invalid
Reject KVM_SET_SREGS{2} with -EINVAL if the incoming CR0 is invalid,
e.g. due to setting bits 63:32, illegal combinations, or to a value that
isn't allowed in VMX (non-)root mode.  The VMX checks in particular are
"fun" as failure to disallow Real Mode for an L2 that is configured with
unrestricted guest disabled, when KVM itself has unrestricted guest
enabled, will result in KVM forcing VM86 mode to virtual Real Mode for
L2, but then fail to unwind the related metadata when synthesizing a
nested VM-Exit back to L1 (which has unrestricted guest enabled).

Opportunistically fix a benign typo in the prototype for is_valid_cr4().

Cc: stable@vger.kernel.org
Reported-by: syzbot+5feef0b9ee9c8e9e5689@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/all/000000000000f316b705fdf6e2b4@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20230613203037.1968489-2-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2023-07-29 11:05:31 -04:00
Sean Christopherson
53550b8922 KVM: x86/pmu: Rename global_ovf_ctrl_mask to global_status_mask
Rename global_ovf_ctrl_mask to global_status_mask to avoid confusion now
that Intel has renamed GLOBAL_OVF_CTRL to GLOBAL_STATUS_RESET in PMU v4.
GLOBAL_OVF_CTRL and GLOBAL_STATUS_RESET are the same MSR index, i.e. are
just different names for the same thing, but the SDM provides different
entries in the IA-32 Architectural MSRs table, which gets really confusing
when looking at PMU v4 definitions since it *looks* like GLOBAL_STATUS has
bits that don't exist in GLOBAL_OVF_CTRL, but in reality the bits are
simply defined in the GLOBAL_STATUS_RESET entry.

No functional change intended.

Cc: Like Xu <like.xu.linux@gmail.com>
Link: https://lore.kernel.org/r/20230603011058.1038821-2-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
2023-06-06 17:31:44 -07:00
Paolo Bonzini
4a5fd41995 KVM SVM changes for 6.4:
- Add support for virtual NMIs
 
  - Fixes for edge cases related to virtual interrupts
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Merge tag 'kvm-x86-svm-6.4' of https://github.com/kvm-x86/linux into HEAD

KVM SVM changes for 6.4:

 - Add support for virtual NMIs

 - Fixes for edge cases related to virtual interrupts
2023-04-26 15:56:27 -04:00
Paolo Bonzini
48b1893ae3 KVM x86 PMU changes for 6.4:
- Disallow virtualizing legacy LBRs if architectural LBRs are available,
    the two are mutually exclusive in hardware
 
  - Disallow writes to immutable feature MSRs (notably PERF_CAPABILITIES)
    after KVM_RUN, and overhaul the vmx_pmu_caps selftest to better
    validate PERF_CAPABILITIES
 
  - Apply PMU filters to emulated events and add test coverage to the
    pmu_event_filter selftest
 
  - Misc cleanups and fixes
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Merge tag 'kvm-x86-pmu-6.4' of https://github.com/kvm-x86/linux into HEAD

KVM x86 PMU changes for 6.4:

 - Disallow virtualizing legacy LBRs if architectural LBRs are available,
   the two are mutually exclusive in hardware

 - Disallow writes to immutable feature MSRs (notably PERF_CAPABILITIES)
   after KVM_RUN, and overhaul the vmx_pmu_caps selftest to better
   validate PERF_CAPABILITIES

 - Apply PMU filters to emulated events and add test coverage to the
   pmu_event_filter selftest

 - Misc cleanups and fixes
2023-04-26 15:53:36 -04:00
Paolo Bonzini
807b758496 KVM x86 MMU changes for 6.4:
- Tweak FNAME(sync_spte) to avoid unnecessary writes+flushes when the
    guest is only adding new PTEs
 
  - Overhaul .sync_page() and .invlpg() to share the .sync_page()
    implementation, i.e. utilize .sync_page()'s optimizations when emulating
    invalidations
 
  - Clean up the range-based flushing APIs
 
  - Revamp the TDP MMU's reaping of Accessed/Dirty bits to clear a single
    A/D bit using a LOCK AND instead of XCHG, and skip all of the "handle
    changed SPTE" overhead associated with writing the entire entry
 
  - Track the number of "tail" entries in a pte_list_desc to avoid having
    to walk (potentially) all descriptors during insertion and deletion,
    which gets quite expensive if the guest is spamming fork()
 
  - Misc cleanups
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Merge tag 'kvm-x86-mmu-6.4' of https://github.com/kvm-x86/linux into HEAD

KVM x86 MMU changes for 6.4:

 - Tweak FNAME(sync_spte) to avoid unnecessary writes+flushes when the
   guest is only adding new PTEs

 - Overhaul .sync_page() and .invlpg() to share the .sync_page()
   implementation, i.e. utilize .sync_page()'s optimizations when emulating
   invalidations

 - Clean up the range-based flushing APIs

 - Revamp the TDP MMU's reaping of Accessed/Dirty bits to clear a single
   A/D bit using a LOCK AND instead of XCHG, and skip all of the "handle
   changed SPTE" overhead associated with writing the entire entry

 - Track the number of "tail" entries in a pte_list_desc to avoid having
   to walk (potentially) all descriptors during insertion and deletion,
   which gets quite expensive if the guest is spamming fork()

 - Misc cleanups
2023-04-26 15:50:01 -04:00
Paolo Bonzini
4f382a79a6 KVM/arm64 updates for 6.4
- Numerous fixes for the pathological lock inversion issue that
   plagued KVM/arm64 since... forever.
 
 - New framework allowing SMCCC-compliant hypercalls to be forwarded
   to userspace, hopefully paving the way for some more features
   being moved to VMMs rather than be implemented in the kernel.
 
 - Large rework of the timer code to allow a VM-wide offset to be
   applied to both virtual and physical counters as well as a
   per-timer, per-vcpu offset that complements the global one.
   This last part allows the NV timer code to be implemented on
   top.
 
 - A small set of fixes to make sure that we don't change anything
   affecting the EL1&0 translation regime just after having having
   taken an exception to EL2 until we have executed a DSB. This
   ensures that speculative walks started in EL1&0 have completed.
 
 - The usual selftest fixes and improvements.
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Merge tag 'kvmarm-6.4' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD

KVM/arm64 updates for 6.4

- Numerous fixes for the pathological lock inversion issue that
  plagued KVM/arm64 since... forever.

- New framework allowing SMCCC-compliant hypercalls to be forwarded
  to userspace, hopefully paving the way for some more features
  being moved to VMMs rather than be implemented in the kernel.

- Large rework of the timer code to allow a VM-wide offset to be
  applied to both virtual and physical counters as well as a
  per-timer, per-vcpu offset that complements the global one.
  This last part allows the NV timer code to be implemented on
  top.

- A small set of fixes to make sure that we don't change anything
  affecting the EL1&0 translation regime just after having having
  taken an exception to EL2 until we have executed a DSB. This
  ensures that speculative walks started in EL1&0 have completed.

- The usual selftest fixes and improvements.
2023-04-26 15:46:52 -04:00
Sean Christopherson
9ed3bf4112 KVM: x86/mmu: Move filling of Hyper-V's TLB range struct into Hyper-V code
Refactor Hyper-V's range-based TLB flushing API to take a gfn+nr_pages
pair instead of a struct, and bury said struct in Hyper-V specific code.

Passing along two params generates much better code for the common case
where KVM is _not_ running on Hyper-V, as forwarding the flush on to
Hyper-V's hv_flush_remote_tlbs_range() from kvm_flush_remote_tlbs_range()
becomes a tail call.

Cc: David Matlack <dmatlack@google.com>
Reviewed-by: David Matlack <dmatlack@google.com>
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Link: https://lore.kernel.org/r/20230405003133.419177-3-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
2023-04-10 15:17:29 -07:00
Sean Christopherson
8a1300ff95 KVM: x86: Rename Hyper-V remote TLB hooks to match established scheme
Rename the Hyper-V hooks for TLB flushing to match the naming scheme used
by all the other TLB flushing hooks, e.g. in kvm_x86_ops, vendor code,
arch hooks from common code, etc.

Reviewed-by: David Matlack <dmatlack@google.com>
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Link: https://lore.kernel.org/r/20230405003133.419177-2-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
2023-04-10 15:17:29 -07:00