Commit Graph

67 Commits

Author SHA1 Message Date
Paolo Bonzini
4f7ff70c05 KVM x86 misc changes for 6.14:
- Overhaul KVM's CPUID feature infrastructure to replace "governed" features
    with per-vCPU tracking of the vCPU's capabailities for all features.  Along
    the way, refactor the code to make it easier to add/modify features, and
    add a variety of self-documenting macro types to again simplify adding new
    features and to help readers understand KVM's handling of existing features.
 
  - Rework KVM's handling of VM-Exits during event vectoring to plug holes where
    KVM unintentionally puts the vCPU into infinite loops in some scenarios,
    e.g. if emulation is triggered by the exit, and to bring parity between VMX
    and SVM.
 
  - Add pending request and interrupt injection information to the kvm_exit and
    kvm_entry tracepoints respectively.
 
  - Fix a relatively benign flaw where KVM would end up redoing RDPKRU when
    loading guest/host PKRU due to a refactoring of the kernel helpers that
    didn't account for KVM's pre-checking of the need to do WRPKRU.
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Merge tag 'kvm-x86-misc-6.14' of https://github.com/kvm-x86/linux into HEAD

KVM x86 misc changes for 6.14:

 - Overhaul KVM's CPUID feature infrastructure to track all vCPU capabilities
   instead of just those where KVM needs to manage state and/or explicitly
   enable the feature in hardware.  Along the way, refactor the code to make
   it easier to add features, and to make it more self-documenting how KVM
   is handling each feature.

 - Rework KVM's handling of VM-Exits during event vectoring; this plugs holes
   where KVM unintentionally puts the vCPU into infinite loops in some scenarios
   (e.g. if emulation is triggered by the exit), and brings parity between VMX
   and SVM.

 - Add pending request and interrupt injection information to the kvm_exit and
   kvm_entry tracepoints respectively.

 - Fix a relatively benign flaw where KVM would end up redoing RDPKRU when
   loading guest/host PKRU, due to a refactoring of the kernel helpers that
   didn't account for KVM's pre-checking of the need to do WRPKRU.
2025-01-20 06:49:39 -05:00
Maxim Levitsky
ae81ce936f KVM: VMX: refactor PML terminology
Rename PML_ENTITY_NUM to PML_LOG_NR_ENTRIES
Add PML_HEAD_INDEX to specify the first entry that CPU writes.

No functional change intended.

Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Link: https://lore.kernel.org/r/20241219221034.903927-2-mlevitsk@redhat.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
2025-01-08 14:19:25 -08:00
Chao Gao
ca0245d131 KVM: x86: Remove hwapic_irr_update() from kvm_x86_ops
Remove the redundant .hwapic_irr_update() ops.

If a vCPU has APICv enabled, KVM updates its RVI before VM-enter to L1
in vmx_sync_pir_to_irr(). This guarantees RVI is up-to-date and aligned
with the vIRR in the virtual APIC. So, no need to update RVI every time
the vIRR changes.

Note that KVM never updates vmcs02 RVI in .hwapic_irr_update() or
vmx_sync_pir_to_irr(). So, removing .hwapic_irr_update() has no
impact to the nested case.

Signed-off-by: Chao Gao <chao.gao@intel.com>
Link: https://lore.kernel.org/r/20241111085947.432645-1-chao.gao@intel.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
2024-12-19 07:34:15 -08:00
Maxim Levitsky
3e633e7e7d KVM: x86: Add interrupt injection information to the kvm_entry tracepoint
Add VMX/SVM specific interrupt injection info the kvm_entry tracepoint.
As is done with kvm_exit, gather the information via a kvm_x86_ops hook
to avoid the moderately costly VMREADs on VMX when the tracepoint isn't
enabled.

Opportunistically rename the parameters in the get_exit_info()
declaration to match the names used by both SVM and VMX.

Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Link: https://lore.kernel.org/r/20240910200350.264245-2-mlevitsk@redhat.com
[sean: drop is_guest_mode() change, use intr_info/error_code for names]
Signed-off-by: Sean Christopherson <seanjc@google.com>
2024-12-18 15:14:48 -08:00
Sean Christopherson
f0e7012c4b KVM: x86: Bypass register cache when querying CPL from kvm_sched_out()
When querying guest CPL to determine if a vCPU was preempted while in
kernel mode, bypass the register cache, i.e. always read SS.AR_BYTES from
the VMCS on Intel CPUs.  If the kernel is running with full preemption
enabled, using the register cache in the preemption path can result in
stale and/or uninitialized data being cached in the segment cache.

In particular the following scenario is currently possible:

 - vCPU is just created, and the vCPU thread is preempted before
   SS.AR_BYTES is written in vmx_vcpu_reset().

 - When scheduling out the vCPU task, kvm_arch_vcpu_in_kernel() =>
   vmx_get_cpl() reads and caches '0' for SS.AR_BYTES.

 - vmx_vcpu_reset() => seg_setup() configures SS.AR_BYTES, but doesn't
   invoke vmx_segment_cache_clear() to invalidate the cache.

As a result, KVM retains a stale value in the cache, which can be read,
e.g. via KVM_GET_SREGS.  Usually this is not a problem because the VMX
segment cache is reset on each VM-Exit, but if the userspace VMM (e.g KVM
selftests) reads and writes system registers just after the vCPU was
created, _without_ modifying SS.AR_BYTES, userspace will write back the
stale '0' value and ultimately will trigger a VM-Entry failure due to
incorrect SS segment type.

Note, the VM-Enter failure can also be avoided by moving the call to
vmx_segment_cache_clear() until after the vmx_vcpu_reset() initializes all
segments.  However, while that change is correct and desirable (and will
come along shortly), it does not address the underlying problem that
accessing KVM's register caches from !task context is generally unsafe.

In addition to fixing the immediate bug, bypassing the cache for this
particular case will allow hardening KVM register caching log to assert
that the caches are accessed only when KVM _knows_ it is safe to do so.

Fixes: de63ad4cf4 ("KVM: X86: implement the logic for spinlock optimization")
Reported-by: Maxim Levitsky <mlevitsk@redhat.com>
Closes: https://lore.kernel.org/all/20240716022014.240960-3-mlevitsk@redhat.com
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Link: https://lore.kernel.org/r/20241009175002.1118178-2-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
2024-11-01 09:22:21 -07:00
Paolo Bonzini
41786cc5ea Merge tag 'kvm-x86-misc-6.12' of https://github.com/kvm-x86/linux into HEAD
KVM x86 misc changes for 6.12

 - Advertise AVX10.1 to userspace (effectively prep work for the "real" AVX10
   functionality that is on the horizon).

 - Rework common MSR handling code to suppress errors on userspace accesses to
   unsupported-but-advertised MSRs.  This will allow removing (almost?) all of
   KVM's exemptions for userspace access to MSRs that shouldn't exist based on
   the vCPU model (the actual cleanup is non-trivial future work).

 - Rework KVM's handling of x2APIC ICR, again, because AMD (x2AVIC) splits the
   64-bit value into the legacy ICR and ICR2 storage, whereas Intel (APICv)
   stores the entire 64-bit value a the ICR offset.

 - Fix a bug where KVM would fail to exit to userspace if one was triggered by
   a fastpath exit handler.

 - Add fastpath handling of HLT VM-Exit to expedite re-entering the guest when
   there's already a pending wake event at the time of the exit.

 - Finally fix the RSM vs. nested VM-Enter WARN by forcing the vCPU out of
   guest mode prior to signalling SHUTDOWN (architecturally, the SHUTDOWN is
   supposed to hit L1, not L2).
2024-09-17 11:38:23 -04:00
Sean Christopherson
590b09b1d8 KVM: x86: Register "emergency disable" callbacks when virt is enabled
Register the "disable virtualization in an emergency" callback just
before KVM enables virtualization in hardware, as there is no functional
need to keep the callbacks registered while KVM happens to be loaded, but
is inactive, i.e. if KVM hasn't enabled virtualization.

Note, unregistering the callback every time the last VM is destroyed could
have measurable latency due to the synchronize_rcu() needed to ensure all
references to the callback are dropped before KVM is unloaded.  But the
latency should be a small fraction of the total latency of disabling
virtualization across all CPUs, and userspace can set enable_virt_at_load
to completely eliminate the runtime overhead.

Add a pointer in kvm_x86_ops to allow vendor code to provide its callback.
There is no reason to force vendor code to do the registration, and either
way KVM would need a new kvm_x86_ops hook.

Suggested-by: Kai Huang <kai.huang@intel.com>
Reviewed-by: Chao Gao <chao.gao@intel.com>
Reviewed-by: Kai Huang <kai.huang@intel.com>
Acked-by: Kai Huang <kai.huang@intel.com>
Tested-by: Farrah Chen <farrah.chen@intel.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-ID: <20240830043600.127750-11-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2024-09-04 11:02:34 -04:00
Sean Christopherson
0617a769ce KVM: x86: Rename virtualization {en,dis}abling APIs to match common KVM
Rename x86's the per-CPU vendor hooks used to enable virtualization in
hardware to align with the recently renamed arch hooks.

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Kai Huang <kai.huang@intel.com>
Message-ID: <20240830043600.127750-7-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2024-09-04 11:02:33 -04:00
Sean Christopherson
73b42dc69b KVM: x86: Re-split x2APIC ICR into ICR+ICR2 for AMD (x2AVIC)
Re-introduce the "split" x2APIC ICR storage that KVM used prior to Intel's
IPI virtualization support, but only for AMD.  While not stated anywhere
in the APM, despite stating the ICR is a single 64-bit register, AMD CPUs
store the 64-bit ICR as two separate 32-bit values in ICR and ICR2.  When
IPI virtualization (IPIv on Intel, all AVIC flavors on AMD) is enabled,
KVM needs to match CPU behavior as some ICR ICR writes will be handled by
the CPU, not by KVM.

Add a kvm_x86_ops knob to control the underlying format used by the CPU to
store the x2APIC ICR, and tune it to AMD vs. Intel regardless of whether
or not x2AVIC is enabled.  If KVM is handling all ICR writes, the storage
format for x2APIC mode doesn't matter, and having the behavior follow AMD
versus Intel will provide better test coverage and ease debugging.

Fixes: 4d1d7942e3 ("KVM: SVM: Introduce logic to (de)activate x2AVIC mode")
Cc: stable@vger.kernel.org
Cc: Maxim Levitsky <mlevitsk@redhat.com>
Cc: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Link: https://lore.kernel.org/r/20240719235107.3023592-4-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
2024-08-29 16:25:05 -07:00
Sean Christopherson
b848f24bd7 KVM: x86: Rename get_msr_feature() APIs to get_feature_msr()
Rename all APIs related to feature MSRs from get_msr_feature() to
get_feature_msr().  The APIs get "feature MSRs", not "MSR features".
And unlike kvm_{g,s}et_msr_common(), the "feature" adjective doesn't
describe the helper itself.

No functional change intended.

Link: https://lore.kernel.org/r/20240802181935.292540-6-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
2024-08-22 12:06:56 -07:00
Paolo Bonzini
208a352a54 KVM VMX changes for 6.11
- Remove an unnecessary EPT TLB flush when enabling hardware.
 
  - Fix a series of bugs that cause KVM to fail to detect nested pending posted
    interrupts as valid wake eents for a vCPU executing HLT in L2 (with
    HLT-exiting disable by L1).
 
  - Misc cleanups
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Merge tag 'kvm-x86-vmx-6.11' of https://github.com/kvm-x86/linux into HEAD

KVM VMX changes for 6.11

 - Remove an unnecessary EPT TLB flush when enabling hardware.

 - Fix a series of bugs that cause KVM to fail to detect nested pending posted
   interrupts as valid wake eents for a vCPU executing HLT in L2 (with
   HLT-exiting disable by L1).

 - Misc cleanups
2024-07-16 09:56:41 -04:00
Paolo Bonzini
5dcc1e7614 KVM x86 misc changes for 6.11
- Add a global struct to consolidate tracking of host values, e.g. EFER, and
    move "shadow_phys_bits" into the structure as "maxphyaddr".
 
  - Add KVM_CAP_X86_APIC_BUS_CYCLES_NS to allow configuring the effective APIC
    bus frequency, because TDX.
 
  - Print the name of the APICv/AVIC inhibits in the relevant tracepoint.
 
  - Clean up KVM's handling of vendor specific emulation to consistently act on
    "compatible with Intel/AMD", versus checking for a specific vendor.
 
  - Misc cleanups
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Merge tag 'kvm-x86-misc-6.11' of https://github.com/kvm-x86/linux into HEAD

KVM x86 misc changes for 6.11

 - Add a global struct to consolidate tracking of host values, e.g. EFER, and
   move "shadow_phys_bits" into the structure as "maxphyaddr".

 - Add KVM_CAP_X86_APIC_BUS_CYCLES_NS to allow configuring the effective APIC
   bus frequency, because TDX.

 - Print the name of the APICv/AVIC inhibits in the relevant tracepoint.

 - Clean up KVM's handling of vendor specific emulation to consistently act on
   "compatible with Intel/AMD", versus checking for a specific vendor.

 - Misc cleanups
2024-07-16 09:53:05 -04:00
Sean Christopherson
321ef62b0c KVM: nVMX: Fold requested virtual interrupt check into has_nested_events()
Check for a Requested Virtual Interrupt, i.e. a virtual interrupt that is
pending delivery, in vmx_has_nested_events() and drop the one-off
kvm_x86_ops.guest_apic_has_interrupt() hook.

In addition to dropping a superfluous hook, this fixes a bug where KVM
would incorrectly treat virtual interrupts _for L2_ as always enabled due
to kvm_arch_interrupt_allowed(), by way of vmx_interrupt_blocked(),
treating IRQs as enabled if L2 is active and vmcs12 is configured to exit
on IRQs, i.e. KVM would treat a virtual interrupt for L2 as a valid wake
event based on L1's IRQ blocking status.

Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20240607172609.3205077-6-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
2024-06-28 08:59:06 -07:00
Sean Christopherson
8fbb696a8f KVM: x86: Fold kvm_arch_sched_in() into kvm_arch_vcpu_load()
Fold the guts of kvm_arch_sched_in() into kvm_arch_vcpu_load(), keying
off the recently added kvm_vcpu.scheduled_out as appropriate.

Note, there is a very slight functional change, as PLE shrink updates will
now happen after blasting WBINVD, but that is quite uninteresting as the
two operations do not interact in any way.

Acked-by: Kai Huang <kai.huang@intel.com>
Link: https://lore.kernel.org/r/20240522014013.1672962-4-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
2024-06-11 14:18:44 -07:00
Alejandro Jimenez
f992572120 KVM: x86: Keep consistent naming for APICv/AVIC inhibit reasons
Keep kvm_apicv_inhibit enum naming consistent with the current pattern by
renaming the reason/enumerator defined as APICV_INHIBIT_REASON_DISABLE to
APICV_INHIBIT_REASON_DISABLED.

No functional change intended.

Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Alejandro Jimenez <alejandro.j.jimenez@oracle.com>
Link: https://lore.kernel.org/r/20240506225321.3440701-3-alejandro.j.jimenez@oracle.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
2024-06-05 06:18:28 -07:00
Linus Torvalds
f4b0c4b508 ARM:
* Move a lot of state that was previously stored on a per vcpu
   basis into a per-CPU area, because it is only pertinent to the
   host while the vcpu is loaded. This results in better state
   tracking, and a smaller vcpu structure.
 
 * Add full handling of the ERET/ERETAA/ERETAB instructions in
   nested virtualisation. The last two instructions also require
   emulating part of the pointer authentication extension.
   As a result, the trap handling of pointer authentication has
   been greatly simplified.
 
 * Turn the global (and not very scalable) LPI translation cache
   into a per-ITS, scalable cache, making non directly injected
   LPIs much cheaper to make visible to the vcpu.
 
 * A batch of pKVM patches, mostly fixes and cleanups, as the
   upstreaming process seems to be resuming. Fingers crossed!
 
 * Allocate PPIs and SGIs outside of the vcpu structure, allowing
   for smaller EL2 mapping and some flexibility in implementing
   more or less than 32 private IRQs.
 
 * Purge stale mpidr_data if a vcpu is created after the MPIDR
   map has been created.
 
 * Preserve vcpu-specific ID registers across a vcpu reset.
 
 * Various minor cleanups and improvements.
 
 LoongArch:
 
 * Add ParaVirt IPI support.
 
 * Add software breakpoint support.
 
 * Add mmio trace events support.
 
 RISC-V:
 
 * Support guest breakpoints using ebreak
 
 * Introduce per-VCPU mp_state_lock and reset_cntx_lock
 
 * Virtualize SBI PMU snapshot and counter overflow interrupts
 
 * New selftests for SBI PMU and Guest ebreak
 
 * Some preparatory work for both TDX and SNP page fault handling.
   This also cleans up the page fault path, so that the priorities
   of various kinds of fauls (private page, no memory, write
   to read-only slot, etc.) are easier to follow.
 
 x86:
 
 * Minimize amount of time that shadow PTEs remain in the special
   REMOVED_SPTE state.  This is a state where the mmu_lock is held for
   reading but concurrent accesses to the PTE have to spin; shortening
   its use allows other vCPUs to repopulate the zapped region while
   the zapper finishes tearing down the old, defunct page tables.
 
 * Advertise the max mappable GPA in the "guest MAXPHYADDR" CPUID field,
   which is defined by hardware but left for software use.  This lets KVM
   communicate its inability to map GPAs that set bits 51:48 on hosts
   without 5-level nested page tables.  Guest firmware is expected to
   use the information when mapping BARs; this avoids that they end up at
   a legal, but unmappable, GPA.
 
 * Fixed a bug where KVM would not reject accesses to MSR that aren't
   supposed to exist given the vCPU model and/or KVM configuration.
 
 * As usual, a bunch of code cleanups.
 
 x86 (AMD):
 
 * Implement a new and improved API to initialize SEV and SEV-ES VMs, which
   will also be extendable to SEV-SNP.  The new API specifies the desired
   encryption in KVM_CREATE_VM and then separately initializes the VM.
   The new API also allows customizing the desired set of VMSA features;
   the features affect the measurement of the VM's initial state, and
   therefore enabling them cannot be done tout court by the hypervisor.
 
   While at it, the new API includes two bugfixes that couldn't be
   applied to the old one without a flag day in userspace or without
   affecting the initial measurement.  When a SEV-ES VM is created with
   the new VM type, KVM_GET_REGS/KVM_SET_REGS and friends are
   rejected once the VMSA has been encrypted.  Also, the FPU and AVX
   state will be synchronized and encrypted too.
 
 * Support for GHCB version 2 as applicable to SEV-ES guests.  This, once
   more, is only accessible when using the new KVM_SEV_INIT2 flow for
   initialization of SEV-ES VMs.
 
 x86 (Intel):
 
 * An initial bunch of prerequisite patches for Intel TDX were merged.
   They generally don't do anything interesting.  The only somewhat user
   visible change is a new debugging mode that checks that KVM's MMU
   never triggers a #VE virtualization exception in the guest.
 
 * Clear vmcs.EXIT_QUALIFICATION when synthesizing an EPT Misconfig VM-Exit to
   L1, as per the SDM.
 
 Generic:
 
 * Use vfree() instead of kvfree() for allocations that always use vcalloc()
   or __vcalloc().
 
 * Remove .change_pte() MMU notifier - the changes to non-KVM code are
   small and Andrew Morton asked that I also take those through the KVM
   tree.  The callback was only ever implemented by KVM (which was also the
   original user of MMU notifiers) but it had been nonfunctional ever since
   calls to set_pte_at_notify were wrapped with invalidate_range_start
   and invalidate_range_end... in 2012.
 
 Selftests:
 
 * Enhance the demand paging test to allow for better reporting and stressing
   of UFFD performance.
 
 * Convert the steal time test to generate TAP-friendly output.
 
 * Fix a flaky false positive in the xen_shinfo_test due to comparing elapsed
   time across two different clock domains.
 
 * Skip the MONITOR/MWAIT test if the host doesn't actually support MWAIT.
 
 * Avoid unnecessary use of "sudo" in the NX hugepage test wrapper shell
   script, to play nice with running in a minimal userspace environment.
 
 * Allow skipping the RSEQ test's sanity check that the vCPU was able to
   complete a reasonable number of KVM_RUNs, as the assert can fail on a
   completely valid setup.  If the test is run on a large-ish system that is
   otherwise idle, and the test isn't affined to a low-ish number of CPUs, the
   vCPU task can be repeatedly migrated to CPUs that are in deep sleep states,
   which results in the vCPU having very little net runtime before the next
   migration due to high wakeup latencies.
 
 * Define _GNU_SOURCE for all selftests to fix a warning that was introduced by
   a change to kselftest_harness.h late in the 6.9 cycle, and because forcing
   every test to #define _GNU_SOURCE is painful.
 
 * Provide a global pseudo-RNG instance for all tests, so that library code can
   generate random, but determinstic numbers.
 
 * Use the global pRNG to randomly force emulation of select writes from guest
   code on x86, e.g. to help validate KVM's emulation of locked accesses.
 
 * Allocate and initialize x86's GDT, IDT, TSS, segments, and default exception
   handlers at VM creation, instead of forcing tests to manually trigger the
   related setup.
 
 Documentation:
 
 * Fix a goof in the KVM_CREATE_GUEST_MEMFD documentation.
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm

Pull KVM updates from Paolo Bonzini:
 "ARM:

   - Move a lot of state that was previously stored on a per vcpu basis
     into a per-CPU area, because it is only pertinent to the host while
     the vcpu is loaded. This results in better state tracking, and a
     smaller vcpu structure.

   - Add full handling of the ERET/ERETAA/ERETAB instructions in nested
     virtualisation. The last two instructions also require emulating
     part of the pointer authentication extension. As a result, the trap
     handling of pointer authentication has been greatly simplified.

   - Turn the global (and not very scalable) LPI translation cache into
     a per-ITS, scalable cache, making non directly injected LPIs much
     cheaper to make visible to the vcpu.

   - A batch of pKVM patches, mostly fixes and cleanups, as the
     upstreaming process seems to be resuming. Fingers crossed!

   - Allocate PPIs and SGIs outside of the vcpu structure, allowing for
     smaller EL2 mapping and some flexibility in implementing more or
     less than 32 private IRQs.

   - Purge stale mpidr_data if a vcpu is created after the MPIDR map has
     been created.

   - Preserve vcpu-specific ID registers across a vcpu reset.

   - Various minor cleanups and improvements.

  LoongArch:

   - Add ParaVirt IPI support

   - Add software breakpoint support

   - Add mmio trace events support

  RISC-V:

   - Support guest breakpoints using ebreak

   - Introduce per-VCPU mp_state_lock and reset_cntx_lock

   - Virtualize SBI PMU snapshot and counter overflow interrupts

   - New selftests for SBI PMU and Guest ebreak

   - Some preparatory work for both TDX and SNP page fault handling.

     This also cleans up the page fault path, so that the priorities of
     various kinds of fauls (private page, no memory, write to read-only
     slot, etc.) are easier to follow.

  x86:

   - Minimize amount of time that shadow PTEs remain in the special
     REMOVED_SPTE state.

     This is a state where the mmu_lock is held for reading but
     concurrent accesses to the PTE have to spin; shortening its use
     allows other vCPUs to repopulate the zapped region while the zapper
     finishes tearing down the old, defunct page tables.

   - Advertise the max mappable GPA in the "guest MAXPHYADDR" CPUID
     field, which is defined by hardware but left for software use.

     This lets KVM communicate its inability to map GPAs that set bits
     51:48 on hosts without 5-level nested page tables. Guest firmware
     is expected to use the information when mapping BARs; this avoids
     that they end up at a legal, but unmappable, GPA.

   - Fixed a bug where KVM would not reject accesses to MSR that aren't
     supposed to exist given the vCPU model and/or KVM configuration.

   - As usual, a bunch of code cleanups.

  x86 (AMD):

   - Implement a new and improved API to initialize SEV and SEV-ES VMs,
     which will also be extendable to SEV-SNP.

     The new API specifies the desired encryption in KVM_CREATE_VM and
     then separately initializes the VM. The new API also allows
     customizing the desired set of VMSA features; the features affect
     the measurement of the VM's initial state, and therefore enabling
     them cannot be done tout court by the hypervisor.

     While at it, the new API includes two bugfixes that couldn't be
     applied to the old one without a flag day in userspace or without
     affecting the initial measurement. When a SEV-ES VM is created with
     the new VM type, KVM_GET_REGS/KVM_SET_REGS and friends are rejected
     once the VMSA has been encrypted. Also, the FPU and AVX state will
     be synchronized and encrypted too.

   - Support for GHCB version 2 as applicable to SEV-ES guests.

     This, once more, is only accessible when using the new
     KVM_SEV_INIT2 flow for initialization of SEV-ES VMs.

  x86 (Intel):

   - An initial bunch of prerequisite patches for Intel TDX were merged.

     They generally don't do anything interesting. The only somewhat
     user visible change is a new debugging mode that checks that KVM's
     MMU never triggers a #VE virtualization exception in the guest.

   - Clear vmcs.EXIT_QUALIFICATION when synthesizing an EPT Misconfig
     VM-Exit to L1, as per the SDM.

  Generic:

   - Use vfree() instead of kvfree() for allocations that always use
     vcalloc() or __vcalloc().

   - Remove .change_pte() MMU notifier - the changes to non-KVM code are
     small and Andrew Morton asked that I also take those through the
     KVM tree.

     The callback was only ever implemented by KVM (which was also the
     original user of MMU notifiers) but it had been nonfunctional ever
     since calls to set_pte_at_notify were wrapped with
     invalidate_range_start and invalidate_range_end... in 2012.

  Selftests:

   - Enhance the demand paging test to allow for better reporting and
     stressing of UFFD performance.

   - Convert the steal time test to generate TAP-friendly output.

   - Fix a flaky false positive in the xen_shinfo_test due to comparing
     elapsed time across two different clock domains.

   - Skip the MONITOR/MWAIT test if the host doesn't actually support
     MWAIT.

   - Avoid unnecessary use of "sudo" in the NX hugepage test wrapper
     shell script, to play nice with running in a minimal userspace
     environment.

   - Allow skipping the RSEQ test's sanity check that the vCPU was able
     to complete a reasonable number of KVM_RUNs, as the assert can fail
     on a completely valid setup.

     If the test is run on a large-ish system that is otherwise idle,
     and the test isn't affined to a low-ish number of CPUs, the vCPU
     task can be repeatedly migrated to CPUs that are in deep sleep
     states, which results in the vCPU having very little net runtime
     before the next migration due to high wakeup latencies.

   - Define _GNU_SOURCE for all selftests to fix a warning that was
     introduced by a change to kselftest_harness.h late in the 6.9
     cycle, and because forcing every test to #define _GNU_SOURCE is
     painful.

   - Provide a global pseudo-RNG instance for all tests, so that library
     code can generate random, but determinstic numbers.

   - Use the global pRNG to randomly force emulation of select writes
     from guest code on x86, e.g. to help validate KVM's emulation of
     locked accesses.

   - Allocate and initialize x86's GDT, IDT, TSS, segments, and default
     exception handlers at VM creation, instead of forcing tests to
     manually trigger the related setup.

  Documentation:

   - Fix a goof in the KVM_CREATE_GUEST_MEMFD documentation"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (225 commits)
  selftests/kvm: remove dead file
  KVM: selftests: arm64: Test vCPU-scoped feature ID registers
  KVM: selftests: arm64: Test that feature ID regs survive a reset
  KVM: selftests: arm64: Store expected register value in set_id_regs
  KVM: selftests: arm64: Rename helper in set_id_regs to imply VM scope
  KVM: arm64: Only reset vCPU-scoped feature ID regs once
  KVM: arm64: Reset VM feature ID regs from kvm_reset_sys_regs()
  KVM: arm64: Rename is_id_reg() to imply VM scope
  KVM: arm64: Destroy mpidr_data for 'late' vCPU creation
  KVM: arm64: Use hVHE in pKVM by default on CPUs with VHE support
  KVM: arm64: Fix hvhe/nvhe early alias parsing
  KVM: SEV: Allow per-guest configuration of GHCB protocol version
  KVM: SEV: Add GHCB handling for termination requests
  KVM: SEV: Add GHCB handling for Hypervisor Feature Support requests
  KVM: SEV: Add support to handle AP reset MSR protocol
  KVM: x86: Explicitly zero kvm_caps during vendor module load
  KVM: x86: Fully re-initialize supported_mce_cap on vendor module load
  KVM: x86: Fully re-initialize supported_vm_types on vendor module load
  KVM: x86/mmu: Sanity check that __kvm_faultin_pfn() doesn't create noslot pfns
  KVM: x86/mmu: Initialize kvm_page_fault's pfn and hva to error values
  ...
2024-05-15 14:46:43 -07:00
Paolo Bonzini
5f18c642ff KVM: VMX: Move out vmx_x86_ops to 'main.c' to dispatch VMX and TDX
KVM accesses Virtual Machine Control Structure (VMCS) with VMX instructions
to operate on VM.  TDX doesn't allow VMM to operate VMCS directly.
Instead, TDX has its own data structures, and TDX SEAMCALL APIs for VMM to
indirectly operate those data structures.  This means we must have a TDX
version of kvm_x86_ops.

The existing global struct kvm_x86_ops already defines an interface which
can be adapted to TDX, but kvm_x86_ops is a system-wide, not per-VM
structure.  To allow VMX to coexist with TDs, the kvm_x86_ops callbacks
will have wrappers "if (tdx) tdx_op() else vmx_op()" to pick VMX or
TDX at run time.

To split the runtime switch, the VMX implementation, and the TDX
implementation, add main.c, and move out the vmx_x86_ops hooks in
preparation for adding TDX.  Use 'vt' for the naming scheme as a nod to
VT-x and as a concatenation of VmxTdx.

The eventually converted code will look like this:

vmx.c:
  vmx_op() { ... }
  VMX initialization
tdx.c:
  tdx_op() { ... }
  TDX initialization
x86_ops.h:
  vmx_op();
  tdx_op();
main.c:
  static vt_op() { if (tdx) tdx_op() else vmx_op() }
  static struct kvm_x86_ops vt_x86_ops = {
        .op = vt_op,
  initialization functions call both VMX and TDX initialization

Opportunistically, fix the name inconsistency from vmx_create_vcpu() and
vmx_free_vcpu() to vmx_vcpu_create() and vmx_vcpu_free().

Co-developed-by: Xiaoyao Li <xiaoyao.li@intel.com>
Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
Reviewed-by: Binbin Wu <binbin.wu@linux.intel.com>
Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>
Reviewed-by: Yuan Yao <yuan.yao@intel.com>
Message-Id: <e603c317587f933a9d1bee8728c84e4935849c16.1705965634.git.isaku.yamahata@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2024-04-12 04:42:24 -04:00