Commit Graph

339 Commits

Author SHA1 Message Date
Marc Zyngier
ce75916749 KVM: arm64: pkvm: Use a single function to expose all id-regs
Rather than exposing a whole set of helper functions to retrieve
individual ID registers, use the existing decoding tree and expose
a single helper instead.

This allow a number of functions to be made static, and we now
have a single entry point to maintain.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Andrew Jones <drjones@redhat.com>
Reviewed-by: Fuad Tabba <tabba@google.com>
Tested-by: Fuad Tabba <tabba@google.com>
Link: https://lore.kernel.org/r/20211013120346.2926621-3-maz@kernel.org
2021-10-18 16:57:08 +01:00
Marc Zyngier
8a049862c3 KVM: arm64: Fix early exit ptrauth handling
The previous rework of the early exit code to provide an EC-based
decoding tree missed the fact that we have two trap paths for
ptrauth: the instructions (EC_PAC) and the sysregs (EC_SYS64).

Rework the handlers to call the ptrauth handling code on both
paths.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Fuad Tabba <tabba@google.com>
Tested-by: Fuad Tabba <tabba@google.com>
Link: https://lore.kernel.org/r/20211013120346.2926621-2-maz@kernel.org
2021-10-18 16:57:08 +01:00
Fuad Tabba
2a0c343386 KVM: arm64: Initialize trap registers for protected VMs
Protected VMs have more restricted features that need to be
trapped. Moreover, the host should not be trusted to set the
appropriate trapping registers and their values.

Initialize the trapping registers, i.e., hcr_el2, mdcr_el2, and
cptr_el2 at EL2 for protected guests, based on the values of the
guest's feature id registers.

No functional change intended as trap handlers introduced in the
previous patch are still not hooked in to the guest exit
handlers.

Reviewed-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Fuad Tabba <tabba@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20211010145636.1950948-9-tabba@google.com
2021-10-11 14:57:29 +01:00
Fuad Tabba
6c30bfb18d KVM: arm64: Add handlers for protected VM System Registers
Add system register handlers for protected VMs. These cover Sys64
registers (including feature id registers), and debug.

No functional change intended as these are not hooked in yet to
the guest exit handlers introduced earlier. So when trapping is
triggered, the exit handlers let the host handle it, as before.

Reviewed-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Fuad Tabba <tabba@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20211010145636.1950948-8-tabba@google.com
2021-10-11 14:57:29 +01:00
Fuad Tabba
3b1a690eda KVM: arm64: Pass struct kvm to per-EC handlers
We need struct kvm to check for protected VMs to be able to pick
the right handlers for them in subsequent patches.

Signed-off-by: Fuad Tabba <tabba@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20211010145636.1950948-5-tabba@google.com
2021-10-11 14:57:28 +01:00
Marc Zyngier
8fb2046180 KVM: arm64: Move early handlers to per-EC handlers
Simplify the early exception handling by slicing the gigantic decoding
tree into a more manageable set of functions, similar to what we have
in handle_exit.c.

This will also make the structure reusable for pKVM's own early exit
handling.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Fuad Tabba <tabba@google.com>
Link: https://lore.kernel.org/r/20211010145636.1950948-4-tabba@google.com
2021-10-11 14:57:28 +01:00
Marc Zyngier
7dd9b5a157 KVM: arm64: Move __get_fault_info() and co into their own include file
In order to avoid including the whole of the switching helpers
in unrelated files, move the __get_fault_info() and related helpers
into their own include file.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Fuad Tabba <tabba@google.com>
Link: https://lore.kernel.org/r/20211010145636.1950948-2-tabba@google.com
2021-10-11 14:57:27 +01:00
Quentin Perret
1d58a17ef5 KVM: arm64: Fix host stage-2 PGD refcount
The KVM page-table library refcounts the pages of concatenated stage-2
PGDs individually. However, when running KVM in protected mode, the
host's stage-2 PGD is currently managed by EL2 as a single high-order
compound page, which can cause the refcount of the tail pages to reach 0
when they shouldn't, hence corrupting the page-table.

Fix this by introducing a new hyp_split_page() helper in the EL2 page
allocator (matching the kernel's split_page() function), and make use of
it from host_s2_zalloc_pages_exact().

Fixes: 1025c8c0c6 ("KVM: arm64: Wrap the host with a stage 2")
Acked-by: Will Deacon <will@kernel.org>
Suggested-by: Will Deacon <will@kernel.org>
Signed-off-by: Quentin Perret <qperret@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20211005090155.734578-5-qperret@google.com
2021-10-05 13:02:54 +01:00
Marc Zyngier
7c7b363d62 Merge branch kvm-arm64/pkvm-fixed-features-prologue into kvmarm-master/next
* kvm-arm64/pkvm-fixed-features-prologue:
  : Rework a bunch of common infrastructure as a prologue
  : to Fuad Tabba's protected VM fixed feature series.
  KVM: arm64: Upgrade trace_kvm_arm_set_dreg32() to 64bit
  KVM: arm64: Add config register bit definitions
  KVM: arm64: Add feature register flag definitions
  KVM: arm64: Track value of cptr_el2 in struct kvm_vcpu_arch
  KVM: arm64: Keep mdcr_el2's value as set by __init_el2_debug
  KVM: arm64: Restore mdcr_el2 from vcpu
  KVM: arm64: Refactor sys_regs.h,c for nVHE reuse
  KVM: arm64: Fix names of config register fields
  KVM: arm64: MDCR_EL2 is a 64-bit register
  KVM: arm64: Remove trailing whitespace in comment
  KVM: arm64: placeholder to check if VM is protected

Signed-off-by: Marc Zyngier <maz@kernel.org>
2021-08-20 12:23:53 +01:00
Marc Zyngier
deb151a582 Merge branch kvm-arm64/mmu/vmid-cleanups into kvmarm-master/next
* kvm-arm64/mmu/vmid-cleanups:
  : Cleanup the stage-2 configuration by providing a single helper,
  : and tidy up some of the ordering requirements for the VMID
  : allocator.
  KVM: arm64: Upgrade VMID accesses to {READ,WRITE}_ONCE
  KVM: arm64: Unify stage-2 programming behind __load_stage2()
  KVM: arm64: Move kern_hyp_va() usage in __load_guest_stage2() into the callers

Signed-off-by: Marc Zyngier <maz@kernel.org>
2021-08-20 12:23:15 +01:00
Fuad Tabba
1460b4b25f KVM: arm64: Restore mdcr_el2 from vcpu
On deactivating traps, restore the value of mdcr_el2 from the
newly created and preserved host value vcpu context, rather than
directly reading the hardware register.

Up until and including this patch the two values are the same,
i.e., the hardware register and the vcpu one. A future patch will
be changing the value of mdcr_el2 on activating traps, and this
ensures that its value will be restored.

No functional change intended.

Signed-off-by: Fuad Tabba <tabba@google.com>
Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210817081134.2918285-7-tabba@google.com
2021-08-20 11:12:17 +01:00
Marc Zyngier
4efc0ede4f KVM: arm64: Unify stage-2 programming behind __load_stage2()
The protected mode relies on a separate helper to load the
S2 context. Move over to the __load_guest_stage2() helper
instead, and rename it to __load_stage2() to present a unified
interface.

Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Jade Alglave <jade.alglave@arm.com>
Cc: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20210806113109.2475-5-will@kernel.org
2021-08-20 09:11:28 +01:00
Quentin Perret
64a80fb766 KVM: arm64: Make __pkvm_create_mappings static
The __pkvm_create_mappings() function is no longer used outside of
nvhe/mm.c, make it static.

Signed-off-by: Quentin Perret <qperret@google.com>
Reviewed-by: Fuad Tabba <tabba@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210809152448.1810400-22-qperret@google.com
2021-08-11 11:39:52 +01:00
Quentin Perret
66c57edd3b KVM: arm64: Restrict EL2 stage-1 changes in protected mode
The host kernel is currently able to change EL2 stage-1 mappings without
restrictions thanks to the __pkvm_create_mappings() hypercall. But in a
world where the host is no longer part of the TCB, this clearly poses a
problem.

To fix this, introduce a new hypercall to allow the host to share a
physical memory page with the hypervisor, and remove the
__pkvm_create_mappings() variant. The new hypercall implements
ownership and permission checks before allowing the sharing operation,
and it annotates the shared page in the hypervisor stage-1 and host
stage-2 page-tables.

Signed-off-by: Quentin Perret <qperret@google.com>
Reviewed-by: Fuad Tabba <tabba@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210809152448.1810400-21-qperret@google.com
2021-08-11 11:39:52 +01:00
Quentin Perret
f9370010e9 KVM: arm64: Refactor protected nVHE stage-1 locking
Refactor the hypervisor stage-1 locking in nVHE protected mode to expose
a new pkvm_create_mappings_locked() function. This will be used in later
patches to allow walking and changing the hypervisor stage-1 without
releasing the lock.

Signed-off-by: Quentin Perret <qperret@google.com>
Reviewed-by: Fuad Tabba <tabba@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210809152448.1810400-20-qperret@google.com
2021-08-11 11:39:51 +01:00
Quentin Perret
ad0e0139a8 KVM: arm64: Remove __pkvm_mark_hyp
Now that we mark memory owned by the hypervisor in the host stage-2
during __pkvm_init(), we no longer need to rely on the host to
explicitly mark the hyp sections later on.

Remove the __pkvm_mark_hyp() hypercall altogether.

Signed-off-by: Quentin Perret <qperret@google.com>
Reviewed-by: Fuad Tabba <tabba@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210809152448.1810400-19-qperret@google.com
2021-08-11 11:39:51 +01:00
Quentin Perret
e009dce129 KVM: arm64: Introduce addr_is_memory()
Introduce a helper usable in nVHE protected mode to check whether a
physical address is in a RAM region or not.

Signed-off-by: Quentin Perret <qperret@google.com>
Reviewed-by: Fuad Tabba <tabba@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210809152448.1810400-16-qperret@google.com
2021-08-11 11:39:51 +01:00
Quentin Perret
2d77e238ba KVM: arm64: Expose pkvm_hyp_id
Allow references to the hypervisor's owner id from outside
mem_protect.c.

Signed-off-by: Quentin Perret <qperret@google.com>
Reviewed-by: Fuad Tabba <tabba@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210809152448.1810400-15-qperret@google.com
2021-08-11 11:39:51 +01:00
Quentin Perret
39257da0e0 KVM: arm64: Expose host stage-2 manipulation helpers
We will need to manipulate the host stage-2 page-table from outside
mem_protect.c soon. Introduce two functions allowing this, and make
them usable to users of mem_protect.h.

Signed-off-by: Quentin Perret <qperret@google.com>
Reviewed-by: Fuad Tabba <tabba@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210809152448.1810400-14-qperret@google.com
2021-08-11 11:39:50 +01:00
Quentin Perret
ec250a67ea KVM: arm64: Add helpers to tag shared pages in SW bits
We will soon start annotating shared pages in page-tables in nVHE
protected mode. Define all the states in which a page can be (owned,
shared and owned, shared and borrowed), and provide helpers allowing to
convert this into SW bits annotations using the matching prot
attributes.

Reviewed-by: Fuad Tabba <tabba@google.com>
Signed-off-by: Quentin Perret <qperret@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210809152448.1810400-13-qperret@google.com
2021-08-11 11:39:50 +01:00
Quentin Perret
8e049e0daf KVM: arm64: Introduce hyp_assert_lock_held()
Introduce a poor man's lockdep implementation at EL2 which allows to
BUG() whenever a hyp spinlock is not held when it should. Hide this
feature behind a new Kconfig option that targets the EL2 object
specifically, instead of piggy backing on the existing CONFIG_LOCKDEP.
EL2 cannot WARN() cleanly to report locking issues, hence BUG() is the
only option and it is not clear whether we want this widely enabled.
This is most likely going to be useful for local testing until the EL2
WARN() situation has improved.

Signed-off-by: Quentin Perret <qperret@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210809152448.1810400-3-qperret@google.com
2021-08-11 11:39:35 +01:00
Will Deacon
d21292f13f KVM: arm64: Add hyp_spin_is_locked() for basic locking assertions at EL2
Introduce hyp_spin_is_locked() so that functions can easily assert that
a given lock is held (albeit possibly by another CPU!) without having to
drag full lockdep support up to EL2.

Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Quentin Perret <qperret@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210809152448.1810400-2-qperret@google.com
2021-08-11 11:39:35 +01:00
Marc Zyngier
9f03db6673 Merge branch kvm-arm64/mmu/mte into kvmarm-master/next
KVM/arm64 support for MTE, courtesy of Steven Price.
It allows the guest to use memory tagging, and offers
a new userspace API to save/restore the tags.

* kvm-arm64/mmu/mte:
  KVM: arm64: Document MTE capability and ioctl
  KVM: arm64: Add ioctl to fetch/store tags in a guest
  KVM: arm64: Expose KVM_ARM_CAP_MTE
  KVM: arm64: Save/restore MTE registers
  KVM: arm64: Introduce MTE VM feature
  arm64: mte: Sync tags for pages where PTE is untagged

Signed-off-by: Marc Zyngier <maz@kernel.org>
2021-06-22 15:09:34 +01:00
Steven Price
e1f358b504 KVM: arm64: Save/restore MTE registers
Define the new system registers that MTE introduces and context switch
them. The MTE feature is still hidden from the ID register as it isn't
supported in a VM yet.

Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Steven Price <steven.price@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210621111716.37157-4-steven.price@arm.com
2021-06-22 14:08:05 +01:00
Quentin Perret
6929586d8e KVM: arm64: Use less bits for hyp_page refcount
The hyp_page refcount is currently encoded on 4 bytes even though we
never need to count that many objects in a page. Make it 2 bytes to save
some space in the vmemmap.

As overflows are more likely to happen as well, make sure to catch those
with a BUG in the increment function.

Signed-off-by: Quentin Perret <qperret@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210608114518.748712-8-qperret@google.com
2021-06-11 13:24:12 +01:00
Quentin Perret
87ec060673 KVM: arm64: Use less bits for hyp_page order
The hyp_page order is currently encoded on 4 bytes even though it is
guaranteed to be smaller than this. Make it 2 bytes to reduce the hyp
vmemmap overhead.

Signed-off-by: Quentin Perret <qperret@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210608114518.748712-7-qperret@google.com
2021-06-11 13:24:11 +01:00
Quentin Perret
d978b9cfe6 KVM: arm64: Remove hyp_pool pointer from struct hyp_page
Each struct hyp_page currently contains a pointer to a hyp_pool struct
where the page should be freed if its refcount reaches 0. However, this
information can always be inferred from the context in the EL2 code, so
drop the pointer to save a few bytes in the vmemmap.

Signed-off-by: Quentin Perret <qperret@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210608114518.748712-6-qperret@google.com
2021-06-11 13:24:11 +01:00
Quentin Perret
7c350ea39e KVM: arm64: Unify MMIO and mem host stage-2 pools
We currently maintain two separate memory pools for the host stage-2,
one for pages used in the page-table when mapping memory regions, and
the other to map MMIO regions. The former is large enough to map all of
memory with page granularity and the latter can cover an arbitrary
portion of IPA space, but allows to 'recycle' pages.

However, this split makes accounting difficult to manage as pages at
intermediate levels of the page-table may be used to map both memory and
MMIO regions. Simplify the scheme by merging both pools into one. This
means we can now hit the -ENOMEM case in the memory abort path, but
we're still guaranteed forward-progress in the worst case by unmapping
MMIO regions. On the plus side this also means we can usually map a lot
more MMIO space at once if memory ranges happen to be mapped with block
mappings.

Signed-off-by: Quentin Perret <qperret@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210608114518.748712-5-qperret@google.com
2021-06-11 13:24:11 +01:00
Quentin Perret
914cde58a0 KVM: arm64: Remove list_head from hyp_page
The list_head member of struct hyp_page is only needed when the page is
attached to a free-list, which by definition implies the page is free.
As such, nothing prevents us from using the page itself to store the
list_head, hence reducing the size of the vmemmap.

Signed-off-by: Quentin Perret <qperret@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210608114518.748712-4-qperret@google.com
2021-06-11 13:24:11 +01:00
Quentin Perret
6cbf874e51 KVM: arm64: Move hyp_pool locking out of refcount helpers
The hyp_page refcount helpers currently rely on the hyp_pool lock for
serialization. However, this means the refcounts can't be changed from
the buddy allocator core as it already holds the lock, which means pages
have to go through odd transient states.

For example, when a page is freed, its refcount is set to 0, and the
lock is transiently released before the page can be attached to a free
list in the buddy tree. This is currently harmless as the allocator
checks the list node of each page to see if it is available for
allocation or not, but it means the page refcount can't be trusted to
represent the state of the page even if the pool lock is held.

In order to fix this, remove the pool locking from the refcount helpers,
and move all the logic to the buddy allocator. This will simplify the
removal of the list node from struct hyp_page in a later patch.

Signed-off-by: Quentin Perret <qperret@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210608114518.748712-2-qperret@google.com
2021-06-11 13:24:11 +01:00
Marc Zyngier
f5e3068061 KVM: arm64: Move __adjust_pc out of line
In order to make it easy to call __adjust_pc() from the EL1 code
(in the case of nVHE), rename it to __kvm_adjust_pc() and move
it out of line.

No expected functional change.

Reviewed-by: Alexandru Elisei <alexandru.elisei@arm.com>
Reviewed-by: Zenghui Yu <yuzenghui@huawei.com>
Tested-by: Zenghui Yu <yuzenghui@huawei.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Cc: stable@vger.kernel.org # 5.11
2021-05-15 10:27:59 +01:00
Marc Zyngier
5c92a7643b Merge branch 'kvm-arm64/nvhe-panic-info' into kvmarm-master/next
Signed-off-by: Marc Zyngier <maz@kernel.org>
2021-04-13 15:38:03 +01:00
Andrew Scull
aec0fae62e KVM: arm64: Log source when panicking from nVHE hyp
To aid with debugging, add details of the source of a panic from nVHE
hyp. This is done by having nVHE hyp exit to nvhe_hyp_panic_handler()
rather than directly to panic(). The handler will then add the extra
details for debugging before panicking the kernel.

If the panic was due to a BUG(), look up the metadata to log the file
and line, if available, otherwise log an address that can be looked up
in vmlinux. The hyp offset is also logged to allow other hyp VAs to be
converted, similar to how the kernel offset is logged during a panic.

__hyp_panic_string is now inlined since it no longer needs to be
referenced as a symbol and the message is free to diverge between VHE
and nVHE.

The following is an example of the logs generated by a BUG in nVHE hyp.

[   46.754840] kvm [307]: nVHE hyp BUG at: arch/arm64/kvm/hyp/nvhe/switch.c:242!
[   46.755357] kvm [307]: Hyp Offset: 0xfffea6c58e1e0000
[   46.755824] Kernel panic - not syncing: HYP panic:
[   46.755824] PS:400003c9 PC:0000d93a82c705ac ESR:f2000800
[   46.755824] FAR:0000000080080000 HPFAR:0000000000800800 PAR:0000000000000000
[   46.755824] VCPU:0000d93a880d0000
[   46.756960] CPU: 3 PID: 307 Comm: kvm-vcpu-0 Not tainted 5.12.0-rc3-00005-gc572b99cf65b-dirty #133
[   46.757459] Hardware name: QEMU QEMU Virtual Machine, BIOS 0.0.0 02/06/2015
[   46.758366] Call trace:
[   46.758601]  dump_backtrace+0x0/0x1b0
[   46.758856]  show_stack+0x18/0x70
[   46.759057]  dump_stack+0xd0/0x12c
[   46.759236]  panic+0x16c/0x334
[   46.759426]  arm64_kernel_unmapped_at_el0+0x0/0x30
[   46.759661]  kvm_arch_vcpu_ioctl_run+0x134/0x750
[   46.759936]  kvm_vcpu_ioctl+0x2f0/0x970
[   46.760156]  __arm64_sys_ioctl+0xa8/0xec
[   46.760379]  el0_svc_common.constprop.0+0x60/0x120
[   46.760627]  do_el0_svc+0x24/0x90
[   46.760766]  el0_svc+0x2c/0x54
[   46.760915]  el0_sync_handler+0x1a4/0x1b0
[   46.761146]  el0_sync+0x170/0x180
[   46.761889] SMP: stopping secondary CPUs
[   46.762786] Kernel Offset: 0x3e1cd2820000 from 0xffff800010000000
[   46.763142] PHYS_OFFSET: 0xffffa9f680000000
[   46.763359] CPU features: 0x00240022,61806008
[   46.763651] Memory Limit: none
[   46.813867] ---[ end Kernel panic - not syncing: HYP panic:
[   46.813867] PS:400003c9 PC:0000d93a82c705ac ESR:f2000800
[   46.813867] FAR:0000000080080000 HPFAR:0000000000800800 PAR:0000000000000000
[   46.813867] VCPU:0000d93a880d0000 ]---

Signed-off-by: Andrew Scull <ascull@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210318143311.839894-6-ascull@google.com
2021-04-01 09:54:37 +01:00
Quentin Perret
90134ac9ca KVM: arm64: Protect the .hyp sections from the host
When KVM runs in nVHE protected mode, use the host stage 2 to unmap the
hypervisor sections by marking them as owned by the hypervisor itself.
The long-term goal is to ensure the EL2 code can remain robust
regardless of the host's state, so this starts by making sure the host
cannot e.g. write to the .hyp sections directly.

Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Quentin Perret <qperret@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210319100146.1149909-39-qperret@google.com
2021-03-19 12:02:19 +00:00
Quentin Perret
1025c8c0c6 KVM: arm64: Wrap the host with a stage 2
When KVM runs in protected nVHE mode, make use of a stage 2 page-table
to give the hypervisor some control over the host memory accesses. The
host stage 2 is created lazily using large block mappings if possible,
and will default to page mappings in absence of a better solution.

>From this point on, memory accesses from the host to protected memory
regions (e.g. not 'owned' by the host) are fatal and lead to hyp_panic().

Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Quentin Perret <qperret@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210319100146.1149909-36-qperret@google.com
2021-03-19 12:02:18 +00:00
Quentin Perret
04e5de0309 KVM: arm64: Reserve memory for host stage 2
Extend the memory pool allocated for the hypervisor to include enough
pages to map all of memory at page granularity for the host stage 2.
While at it, also reserve some memory for device mappings.

Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Quentin Perret <qperret@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210319100146.1149909-27-qperret@google.com
2021-03-19 12:01:22 +00:00
Quentin Perret
159b859bee KVM: arm64: Refactor __populate_fault_info()
Refactor __populate_fault_info() to introduce __get_fault_info() which
will be used once the host is wrapped in a stage 2.

Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Quentin Perret <qperret@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210319100146.1149909-25-qperret@google.com
2021-03-19 12:01:21 +00:00
Quentin Perret
f320bc742b KVM: arm64: Prepare the creation of s1 mappings at EL2
When memory protection is enabled, the EL2 code needs the ability to
create and manage its own page-table. To do so, introduce a new set of
hypercalls to bootstrap a memory management system at EL2.

This leads to the following boot flow in nVHE Protected mode:

 1. the host allocates memory for the hypervisor very early on, using
    the memblock API;

 2. the host creates a set of stage 1 page-table for EL2, installs the
    EL2 vectors, and issues the __pkvm_init hypercall;

 3. during __pkvm_init, the hypervisor re-creates its stage 1 page-table
    and stores it in the memory pool provided by the host;

 4. the hypervisor then extends its stage 1 mappings to include a
    vmemmap in the EL2 VA space, hence allowing to use the buddy
    allocator introduced in a previous patch;

 5. the hypervisor jumps back in the idmap page, switches from the
    host-provided page-table to the new one, and wraps up its
    initialization by enabling the new allocator, before returning to
    the host.

 6. the host can free the now unused page-table created for EL2, and
    will now need to issue hypercalls to make changes to the EL2 stage 1
    mappings instead of modifying them directly.

Note that for the sake of simplifying the review, this patch focuses on
the hypervisor side of things. In other words, this only implements the
new hypercalls, but does not make use of them from the host yet. The
host-side changes will follow in a subsequent patch.

Credits to Will for __pkvm_init_switch_pgd.

Acked-by: Will Deacon <will@kernel.org>
Co-authored-by: Will Deacon <will@kernel.org>
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Quentin Perret <qperret@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210319100146.1149909-18-qperret@google.com
2021-03-19 12:01:21 +00:00
Quentin Perret
8e17c66249 KVM: arm64: Introduce a Hyp buddy page allocator
When memory protection is enabled, the hyp code will require a basic
form of memory management in order to allocate and free memory pages at
EL2. This is needed for various use-cases, including the creation of hyp
mappings or the allocation of stage 2 page tables.

To address these use-case, introduce a simple memory allocator in the
hyp code. The allocator is designed as a conventional 'buddy allocator',
working with a page granularity. It allows to allocate and free
physically contiguous pages from memory 'pools', with a guaranteed order
alignment in the PA space. Each page in a memory pool is associated
with a struct hyp_page which holds the page's metadata, including its
refcount, as well as its current order, hence mimicking the kernel's
buddy system in the GFP infrastructure. The hyp_page metadata are made
accessible through a hyp_vmemmap, following the concept of
SPARSE_VMEMMAP in the kernel.

Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Quentin Perret <qperret@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210319100146.1149909-13-qperret@google.com
2021-03-19 12:01:20 +00:00
Quentin Perret
e759604087 KVM: arm64: Introduce an early Hyp page allocator
With nVHE, the host currently creates all stage 1 hypervisor mappings at
EL1 during boot, installs them at EL2, and extends them as required
(e.g. when creating a new VM). But in a world where the host is no
longer trusted, it cannot have full control over the code mapped in the
hypervisor.

In preparation for enabling the hypervisor to create its own stage 1
mappings during boot, introduce an early page allocator, with minimal
functionality. This allocator is designed to be used only during early
bootstrap of the hyp code when memory protection is enabled, which will
then switch to using a full-fledged page allocator after init.

Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Quentin Perret <qperret@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210319100146.1149909-11-qperret@google.com
2021-03-19 12:01:20 +00:00
Will Deacon
67c2d32633 arm64: kvm: Add standalone ticket spinlock implementation for use at hyp
We will soon need to synchronise multiple CPUs in the hyp text at EL2.
The qspinlock-based locking used by the host is overkill for this purpose
and relies on the kernel's "percpu" implementation for the MCS nodes.

Implement a simple ticket locking scheme based heavily on the code removed
by commit c11090474d ("arm64: locking: Replace ticket lock implementation
with qspinlock").

Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Quentin Perret <qperret@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210319100146.1149909-4-qperret@google.com
2021-03-19 12:01:19 +00:00
Marc Zyngier
a1baa01f76 Linux 5.12-rc3
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Merge tag 'v5.12-rc3' into kvm-arm64/host-stage2

Linux 5.12-rc3

Signed-off-by: Marc Zyngier <maz@kernel.org>

# gpg: Signature made Sun 14 Mar 2021 21:41:02 GMT
# gpg:                using RSA key ABAF11C65A2970B130ABE3C479BE3E4300411886
# gpg:                issuer "torvalds@linux-foundation.org"
# gpg: Can't check signature: No public key
2021-03-19 12:01:04 +00:00
Marc Zyngier
8c8010d69c KVM: arm64: Save/restore SVE state for nVHE
Implement the SVE save/restore for nVHE, following a similar
logic to that of the VHE implementation:

- the SVE state is switched on trap from EL1 to EL2

- no further changes to ZCR_EL2 occur as long as the guest isn't
  preempted or exit to userspace

- ZCR_EL2 is reset to its default value on the first SVE access from
  the host EL1, and ZCR_EL1 restored to the default guest value in
  vcpu_put()

Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
2021-03-18 14:23:12 +00:00
Marc Zyngier
52029198c1 KVM: arm64: Rework SVE host-save/guest-restore
In order to keep the code readable, move the host-save/guest-restore
sequences in their own functions, with the following changes:
- the hypervisor ZCR is now set from C code
- ZCR_EL2 is always used as the EL2 accessor

This results in some minor assembler macro rework.
No functional change intended.

Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
2021-03-18 13:57:37 +00:00
Marc Zyngier
468f3477ef KVM: arm64: Introduce vcpu_sve_vq() helper
The KVM code contains a number of "sve_vq_from_vl(vcpu->arch.sve_max_vl)"
instances, and we are about to add more.

Introduce vcpu_sve_vq() as a shorthand for this expression.

Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
2021-03-18 11:24:10 +00:00
Marc Zyngier
83857371d4 KVM: arm64: Use {read,write}_sysreg_el1 to access ZCR_EL1
Switch to the unified EL1 accessors for ZCR_EL1, which will make
things easier for nVHE support.

Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
2021-03-18 11:23:48 +00:00
Marc Zyngier
297b8603e3 KVM: arm64: Provide KVM's own save/restore SVE primitives
as we are about to change the way KVM deals with SVE, provide
KVM with its own save/restore SVE primitives.

No functional change intended.

Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
2021-03-18 11:23:14 +00:00
Marc Zyngier
f27647b588 KVM: arm64: Don't access PMSELR_EL0/PMUSERENR_EL0 when no PMU is available
When running under a nesting hypervisor, it isn't guaranteed that
the virtual HW will include a PMU. In which case, let's not try
to access the PMU registers in the world switch, as that'd be
deadly.

Reported-by: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Alexandru Elisei <alexandru.elisei@arm.com>
Link: https://lore.kernel.org/r/20210209114844.3278746-3-maz@kernel.org
Message-Id: <20210305185254.3730990-6-maz@kernel.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-03-06 04:18:40 -05:00
David Brazdil
247bc166e6 KVM: arm64: Remove hyp_symbol_addr
Hyp code used the hyp_symbol_addr helper to force PC-relative addressing
because absolute addressing results in kernel VAs due to the way hyp
code is linked. This is not true anymore, so remove the helper and
update all of its users.

Acked-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: David Brazdil <dbrazdil@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210105180541.65031-9-dbrazdil@google.com
2021-01-23 14:01:00 +00:00
David Brazdil
860a4c3d1e KVM: arm64: Move skip_host_instruction to adjust_pc.h
Move function for skipping host instruction in the host trap handler to
a header file containing analogical helpers for guests.

Signed-off-by: David Brazdil <dbrazdil@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20201208142452.87237-7-dbrazdil@google.com
2020-12-22 10:49:09 +00:00
Marc Zyngier
3a514592b6 Merge remote-tracking branch 'origin/kvm-arm64/psci-relay' into kvmarm-master/next
Signed-off-by: Marc Zyngier <maz@kernel.org>
2020-12-09 10:00:24 +00:00
David Brazdil
eeeee7193d KVM: arm64: Bootstrap PSCI SMC handler in nVHE EL2
Add a handler of PSCI SMCs in nVHE hyp code. The handler is initialized
with the version used by the host's PSCI driver and the function IDs it
was configured with. If the SMC function ID matches one of the
configured PSCI calls (for v0.1) or falls into the PSCI function ID
range (for v0.2+), the SMC is handled by the PSCI handler. For now, all
SMCs return PSCI_RET_NOT_SUPPORTED.

Signed-off-by: David Brazdil <dbrazdil@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20201202184122.26046-17-dbrazdil@google.com
2020-12-04 10:08:34 +00:00
Marc Zyngier
e650b64f1a KVM: arm64: Add basic hooks for injecting exceptions from EL2
Add the basic infrastructure to describe injection of exceptions
into a guest. So far, nothing uses this code path.

Signed-off-by: Marc Zyngier <maz@kernel.org>
2020-11-10 08:34:25 +00:00
Marc Zyngier
defe21f49b KVM: arm64: Move PC rollback on SError to HYP
Instead of handling the "PC rollback on SError during HVC" at EL1 (which
requires disclosing PC to a potentially untrusted kernel), let's move
this fixup to ... fixup_guest_exit(), which is where we do all fixups.

Isn't that neat?

Signed-off-by: Marc Zyngier <maz@kernel.org>
2020-11-10 08:34:25 +00:00
Marc Zyngier
cdb5e02ed1 KVM: arm64: Make kvm_skip_instr() and co private to HYP
In an effort to remove the vcpu PC manipulations from EL1 on nVHE
systems, move kvm_skip_instr() to be HYP-specific. EL1's intent
to increment PC post emulation is now signalled via a flag in the
vcpu structure.

Signed-off-by: Marc Zyngier <maz@kernel.org>
2020-11-10 08:34:24 +00:00
Rob Herring
96d389ca10 arm64: Add workaround for Arm Cortex-A77 erratum 1508412
On Cortex-A77 r0p0 and r1p0, a sequence of a non-cacheable or device load
and a store exclusive or PAR_EL1 read can cause a deadlock.

The workaround requires a DMB SY before and after a PAR_EL1 register
read. In addition, it's possible an interrupt (doing a device read) or
KVM guest exit could be taken between the DMB and PAR read, so we
also need a DMB before returning from interrupt and before returning to
a guest.

A deadlock is still possible with the workaround as KVM guests must also
have the workaround. IOW, a malicious guest can deadlock an affected
systems.

This workaround also depends on a firmware counterpart to enable the h/w
to insert DMB SY after load and store exclusive instructions. See the
errata document SDEN-1152370 v10 [1] for more information.

[1] https://static.docs.arm.com/101992/0010/Arm_Cortex_A77_MP074_Software_Developer_Errata_Notice_v10.pdf

Signed-off-by: Rob Herring <robh@kernel.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Marc Zyngier <maz@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Julien Thierry <julien.thierry.kdev@gmail.com>
Cc: kvmarm@lists.cs.columbia.edu
Link: https://lore.kernel.org/r/20201028182839.166037-2-robh@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
2020-10-29 12:56:01 +00:00
Paolo Bonzini
1b21c8db0e KVM/arm64 updates for Linux 5.10
- New page table code for both hypervisor and guest stage-2
 - Introduction of a new EL2-private host context
 - Allow EL2 to have its own private per-CPU variables
 - Support of PMU event filtering
 - Complete rework of the Spectre mitigation
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Merge tag 'kvmarm-5.10' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD

KVM/arm64 updates for Linux 5.10

- New page table code for both hypervisor and guest stage-2
- Introduction of a new EL2-private host context
- Allow EL2 to have its own private per-CPU variables
- Support of PMU event filtering
- Complete rework of the Spectre mitigation
2020-10-20 08:14:25 -04:00
Marc Zyngier
14ef9d0492 Merge branch 'kvm-arm64/hyp-pcpu' into kvmarm-master/next
Signed-off-by: Marc Zyngier <maz@kernel.org>
2020-09-30 14:05:35 +01:00
Marc Zyngier
816c347f3a Merge remote-tracking branch 'arm64/for-next/ghostbusters' into kvm-arm64/hyp-pcpu
Signed-off-by: Marc Zyngier <maz@kernel.org>
2020-09-30 09:48:30 +01:00
David Brazdil
717cf94adb kvm: arm64: Remove __hyp_this_cpu_read
this_cpu_ptr is meant for use in kernel proper because it selects between
TPIDR_EL1/2 based on nVHE/VHE. __hyp_this_cpu_ptr was used in hyp to always
select TPIDR_EL2. Unify all users behind this_cpu_ptr and friends by
selecting _EL2 register under __KVM_NVHE_HYPERVISOR__. VHE continues
selecting the register using alternatives.

Under CONFIG_DEBUG_PREEMPT, the kernel helpers perform a preemption check
which is omitted by the hyp helpers. Preserve the behavior for nVHE by
overriding the corresponding macros under __KVM_NVHE_HYPERVISOR__. Extend
the checks into VHE hyp code.

Signed-off-by: David Brazdil <dbrazdil@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Acked-by: Andrew Scull <ascull@google.com>
Acked-by: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20200922204910.7265-5-dbrazdil@google.com
2020-09-30 08:33:52 +01:00
Marc Zyngier
29e8910a56 KVM: arm64: Simplify handling of ARCH_WORKAROUND_2
Owing to the fact that the host kernel is always mitigated, we can
drastically simplify the WA2 handling by keeping the mitigation
state ON when entering the guest. This means the guest is either
unaffected or not mitigated.

This results in a nice simplification of the mitigation space,
and the removal of a lot of code that was never really used anyway.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Will Deacon <will@kernel.org>
2020-09-29 16:08:16 +01:00
Will Deacon
9b0955baa4 arm64: Rename ARM64_SSBD to ARM64_SPECTRE_V4
In a similar manner to the renaming of ARM64_HARDEN_BRANCH_PREDICTOR
to ARM64_SPECTRE_V2, rename ARM64_SSBD to ARM64_SPECTRE_V4. This isn't
_entirely_ accurate, as we also need to take into account the interaction
with SSBS, but that will be taken care of in subsequent patches.

Signed-off-by: Will Deacon <will@kernel.org>
2020-09-29 16:08:16 +01:00
Will Deacon
6e5f092784 arm64: Remove Spectre-related CONFIG_* options
The spectre mitigations are too configurable for their own good, leading
to confusing logic trying to figure out when we should mitigate and when
we shouldn't. Although the plethora of command-line options need to stick
around for backwards compatibility, the default-on CONFIG options that
depend on EXPERT can be dropped, as the mitigations only do anything if
the system is vulnerable, a mitigation is available and the command-line
hasn't disabled it.

Remove CONFIG_HARDEN_BRANCH_PREDICTOR and CONFIG_ARM64_SSBD in favour of
enabling this code unconditionally.

Signed-off-by: Will Deacon <will@kernel.org>
2020-09-29 16:08:15 +01:00
Paolo Bonzini
bf3c0e5e71 Merge branch 'x86-seves-for-paolo' of https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip into HEAD 2020-09-22 06:43:17 -04:00
Marc Zyngier
c4ad98e4b7 KVM: arm64: Assume write fault on S1PTW permission fault on instruction fetch
KVM currently assumes that an instruction abort can never be a write.
This is in general true, except when the abort is triggered by
a S1PTW on instruction fetch that tries to update the S1 page tables
(to set AF, for example).

This can happen if the page tables have been paged out and brought
back in without seeing a direct write to them (they are thus marked
read only), and the fault handling code will make the PT executable(!)
instead of writable. The guest gets stuck forever.

In these conditions, the permission fault must be considered as
a write so that the Stage-1 update can take place. This is essentially
the I-side equivalent of the problem fixed by 60e21a0ef5 ("arm64: KVM:
Take S1 walks into account when determining S2 write faults").

Update kvm_is_write_fault() to return true on IABT+S1PTW, and introduce
kvm_vcpu_trap_is_exec_fault() that only return true when no faulting
on a S1 fault. Additionally, kvm_vcpu_dabt_iss1tw() is renamed to
kvm_vcpu_abt_iss1tw(), as the above makes it plain that it isn't
specific to data abort.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Will Deacon <will@kernel.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20200915104218.1284701-2-maz@kernel.org
2020-09-18 18:01:48 +01:00
Andrew Scull
4e3393a969 KVM: arm64: nVHE: Switch to hyp context for EL2
Save and restore the host context when switching to and from hyp. This
gives hyp its own context that the host will not see as a step towards a
full trust boundary between the two.

SP_EL0 and pointer authentication keys are currently shared between the
host and hyp so don't need to be switched yet.

Signed-off-by: Andrew Scull <ascull@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20200915104643.2543892-13-ascull@google.com
2020-09-15 18:39:03 +01:00
Andrew Scull
7db2153047 KVM: arm64: Restore hyp when panicking in guest context
If the guest context is loaded when a panic is triggered, restore the
hyp context so e.g. the shadow call stack works when hyp_panic() is
called and SP_EL0 is valid when the host's panic() is called.

Use the hyp context's __hyp_running_vcpu field to track when hyp
transitions to and from the guest vcpu so the exception handlers know
whether the context needs to be restored.

Signed-off-by: Andrew Scull <ascull@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20200915104643.2543892-11-ascull@google.com
2020-09-15 18:39:02 +01:00
Andrew Scull
b619d9aa8b KVM: arm64: Introduce hyp context
During __guest_enter, save and restore from a new hyp context rather
than the host context. This is preparation for separation of the hyp and
host context in nVHE.

Signed-off-by: Andrew Scull <ascull@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20200915104643.2543892-9-ascull@google.com
2020-09-15 18:39:02 +01:00
Andrew Scull
6a0259ed29 KVM: arm64: Remove hyp_panic arguments
hyp_panic is able to find all the context it needs from within itself so
remove the argument. The __hyp_panic wrapper becomes redundant so is
also removed.

Signed-off-by: Andrew Scull <ascull@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20200915104643.2543892-3-ascull@google.com
2020-09-15 18:39:01 +01:00
Andrew Scull
501a67a25d KVM: arm64: Remove __activate_vm wrapper
The __activate_vm wrapper serves no useful function and has a misleading
name as it simply calls __load_guest_stage2 and does not touch
HCR_EL2.VM so remove it.

Also rename __deactivate_vm to __load_host_stage2 to match naming
pattern.

Signed-off-by: Andrew Scull <ascull@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20200915104643.2543892-2-ascull@google.com
2020-09-15 18:39:01 +01:00
Linus Torvalds
96d454cd2c - Fix kernel build with the integrated LLVM assembler which doesn't
see the -Wa,-march option.
 
 - Fix "make vdso_install" when COMPAT_VDSO is disabled.
 
 - Make KVM more robust if the AT S1E1R instruction triggers an exception
   (architecture corner cases).
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Merge tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux

Pull arm64 fixes from Catalin Marinas:

 - Fix kernel build with the integrated LLVM assembler which doesn't see
   the -Wa,-march option.

 - Fix "make vdso_install" when COMPAT_VDSO is disabled.

 - Make KVM more robust if the AT S1E1R instruction triggers an
   exception (architecture corner cases).

* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
  KVM: arm64: Set HCR_EL2.PTW to prevent AT taking synchronous exception
  KVM: arm64: Survive synchronous exceptions caused by AT instructions
  KVM: arm64: Add kvm_extable for vaxorcism code
  arm64: vdso32: make vdso32 install conditional
  arm64: use a common .arch preamble for inline assembly
2020-08-28 11:37:33 -07:00
James Morse
88a84ccccb KVM: arm64: Survive synchronous exceptions caused by AT instructions
KVM doesn't expect any synchronous exceptions when executing, any such
exception leads to a panic(). AT instructions access the guest page
tables, and can cause a synchronous external abort to be taken.

The arm-arm is unclear on what should happen if the guest has configured
the hardware update of the access-flag, and a memory type in TCR_EL1 that
does not support atomic operations. B2.2.6 "Possible implementation
restrictions on using atomic instructions" from DDI0487F.a lists
synchronous external abort as a possible behaviour of atomic instructions
that target memory that isn't writeback cacheable, but the page table
walker may behave differently.

Make KVM robust to synchronous exceptions caused by AT instructions.
Add a get_user() style helper for AT instructions that returns -EFAULT
if an exception was generated.

While KVM's version of the exception table mixes synchronous and
asynchronous exceptions, only one of these can occur at each location.

Re-enter the guest when the AT instructions take an exception on the
assumption the guest will take the same exception. This isn't guaranteed
to make forward progress, as the AT instructions may always walk the page
tables, but guest execution may use the translation cached in the TLB.

This isn't a problem, as since commit 5dcd0fdbb4 ("KVM: arm64: Defer guest
entry when an asynchronous exception is pending"), KVM will return to the
host to process IRQs allowing the rest of the system to keep running.

Cc: stable@vger.kernel.org # <v5.3: 5dcd0fdbb4 ("KVM: arm64: Defer guest entry when an asynchronous exception is pending")
Signed-off-by: James Morse <james.morse@arm.com>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2020-08-28 15:23:46 +01:00
James Morse
e9ee186bb7 KVM: arm64: Add kvm_extable for vaxorcism code
KVM has a one instruction window where it will allow an SError exception
to be consumed by the hypervisor without treating it as a hypervisor bug.
This is used to consume asynchronous external abort that were caused by
the guest.

As we are about to add another location that survives unexpected exceptions,
generalise this code to make it behave like the host's extable.

KVM's version has to be mapped to EL2 to be accessible on nVHE systems.

The SError vaxorcism code is a one instruction window, so has two entries
in the extable. Because the KVM code is copied for VHE and nVHE, we end up
with four entries, half of which correspond with code that isn't mapped.

Signed-off-by: James Morse <james.morse@arm.com>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2020-08-28 15:23:42 +01:00
Gustavo A. R. Silva
df561f6688 treewide: Use fallthrough pseudo-keyword
Replace the existing /* fall through */ comments and its variants with
the new pseudo-keyword macro fallthrough[1]. Also, remove unnecessary
fall-through markings when it is the case.

[1] https://www.kernel.org/doc/html/v5.7/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through

Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
2020-08-23 17:36:59 -05:00
Marc Zyngier
16314874b1 Merge branch 'kvm-arm64/misc-5.9' into kvmarm-master/next
Signed-off-by: Marc Zyngier <maz@kernel.org>
2020-07-30 16:13:04 +01:00
Marc Zyngier
a394cf6e85 Merge branch 'kvm-arm64/misc-5.9' into kvmarm-master/next-WIP
Signed-off-by: Marc Zyngier <maz@kernel.org>
2020-07-28 16:26:16 +01:00
Marc Zyngier
710f198218 KVM: arm64: Move SPSR_EL1 to the system register array
SPSR_EL1 being a VNCR-capable register with ARMv8.4-NV, move it to
the sysregs array and update the accessors.

Reviewed-by: James Morse <james.morse@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
2020-07-07 09:28:38 +01:00
Marc Zyngier
fd85b66789 KVM: arm64: Disintegrate SPSR array
As we're about to move SPSR_EL1 into the VNCR page, we need to
disassociate it from the rest of the 32bit cruft. Let's break
the array into individual fields.

Reviewed-by: James Morse <james.morse@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
2020-07-07 09:28:38 +01:00
Marc Zyngier
1bded23ea7 KVM: arm64: Move SP_EL1 to the system register array
SP_EL1 being a VNCR-capable register with ARMv8.4-NV, move it to the
system register array and update the accessors.

Reviewed-by: James Morse <james.morse@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
2020-07-07 09:28:38 +01:00
Marc Zyngier
98909e6d1c KVM: arm64: Move ELR_EL1 to the system register array
As ELR-EL1 is a VNCR-capable register with ARMv8.4-NV, let's move it to
the sys_regs array and repaint the accessors. While we're at it, let's
kill the now useless accessors used only on the fault injection path.

Reviewed-by: James Morse <james.morse@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
2020-07-07 09:28:38 +01:00
Marc Zyngier
e47c2055c6 KVM: arm64: Make struct kvm_regs userspace-only
struct kvm_regs is used by userspace to indicate which register gets
accessed by the {GET,SET}_ONE_REG API. But as we're about to refactor
the layout of the in-kernel register structures, we need the kernel to
move away from it.

Let's make kvm_regs userspace only, and let the kernel map it to its own
internal representation.

Reviewed-by: James Morse <james.morse@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
2020-07-07 09:28:38 +01:00
Marc Zyngier
5b78077a00 KVM: arm64: debug: Drop useless vpcu parameter
As part of the ongoing spring cleanup, remove the now useless
vcpu parameter that is passed around (host and guest contexts
give us everything we need).

Signed-off-by: Marc Zyngier <maz@kernel.org>
2020-07-07 09:28:38 +01:00
Marc Zyngier
2c3db77c62 KVM: arm64: pauth: Use ctxt_sys_reg() instead of raw sys_regs access
Now that we have a wrapper for the sysreg accesses, let's use that
consistently.

Signed-off-by: Marc Zyngier <maz@kernel.org>
2020-07-07 09:28:37 +01:00
Marc Zyngier
71071acfd3 KVM: arm64: hyp: Use ctxt_sys_reg/__vcpu_sys_reg instead of raw sys_regs access
Switch the hypervisor code to using ctxt_sys_reg/__vcpu_sys_reg instead
of raw sys_regs accesses. No intended functionnal change.

Signed-off-by: Marc Zyngier <maz@kernel.org>
2020-07-07 09:28:37 +01:00
Christoffer Dall
a0e50aa3f4 KVM: arm64: Factor out stage 2 page table data from struct kvm
As we are about to reuse our stage 2 page table manipulation code for
shadow stage 2 page tables in the context of nested virtualization, we
are going to manage multiple stage 2 page tables for a single VM.

This requires some pretty invasive changes to our data structures,
which moves the vmid and pgd pointers into a separate structure and
change pretty much all of our mmu code to operate on this structure
instead.

The new structure is called struct kvm_s2_mmu.

There is no intended functional change by this patch alone.

Reviewed-by: James Morse <james.morse@arm.com>
Reviewed-by: Alexandru Elisei <alexandru.elisei@arm.com>
[Designed data structure layout in collaboration]
Signed-off-by: Christoffer Dall <christoffer.dall@arm.com>
Co-developed-by: Marc Zyngier <maz@kernel.org>
[maz: Moved the last_vcpu_ran down to the S2 MMU structure as well]
Signed-off-by: Marc Zyngier <maz@kernel.org>
2020-07-07 09:28:37 +01:00
David Brazdil
c50cb04303 KVM: arm64: Remove __hyp_text macro, use build rules instead
With nVHE code now fully separated from the rest of the kernel, the effects of
the __hyp_text macro (which had to be applied on all nVHE code) can be
achieved with build rules instead. The macro used to:
  (a) move code to .hyp.text ELF section, now done by renaming .text using
      `objcopy`, and
  (b) `notrace` and `__noscs` would negate effects of CC_FLAGS_FTRACE and
      CC_FLAGS_SCS, respectivelly, now those flags are  erased from
      KBUILD_CFLAGS (same way as in EFI stub).

Note that by removing __hyp_text from code shared with VHE, all VHE code is now
compiled into .text and without `notrace` and `__noscs`.

Use of '.pushsection .hyp.text' removed from assembly files as this is now also
covered by the build rules.

For MAINTAINERS: if needed to re-run, uses of macro were removed with the
following command. Formatting was fixed up manually.

  find arch/arm64/kvm/hyp -type f -name '*.c' -o -name '*.h' \
       -exec sed -i 's/ __hyp_text//g' {} +

Signed-off-by: David Brazdil <dbrazdil@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20200625131420.71444-15-dbrazdil@google.com
2020-07-05 18:38:45 +01:00
David Brazdil
13aeb9b400 KVM: arm64: Split hyp/sysreg-sr.c to VHE/nVHE
sysreg-sr.c contains KVM's code for saving/restoring system registers, with
some code shared between VHE/nVHE. These common routines are moved to
a header file, VHE-specific code is moved to vhe/sysreg-sr.c and nVHE-specific
code to nvhe/sysreg-sr.c.

Signed-off-by: David Brazdil <dbrazdil@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20200625131420.71444-12-dbrazdil@google.com
2020-07-05 18:38:29 +01:00
David Brazdil
d400c5b202 KVM: arm64: Split hyp/debug-sr.c to VHE/nVHE
debug-sr.c contains KVM's code for context-switching debug registers, with some
code shared between VHE/nVHE. These common routines are moved to a header file,
VHE-specific code is moved to vhe/debug-sr.c and nVHE-specific code to
nvhe/debug-sr.c.

Functions are slightly refactored to move code hidden behind `has_vhe()` checks
to the corresponding .c files.

Signed-off-by: David Brazdil <dbrazdil@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20200625131420.71444-11-dbrazdil@google.com
2020-07-05 18:38:25 +01:00
David Brazdil
09cf57eba3 KVM: arm64: Split hyp/switch.c to VHE/nVHE
switch.c implements context-switching for KVM, with large parts shared between
VHE/nVHE. These common routines are moved to a header file, VHE-specific code
is moved to vhe/switch.c and nVHE-specific code is moved to nvhe/switch.c.

Previously __kvm_vcpu_run needed a different symbol name for VHE/nVHE. This
is cleaned up and the caller in arm.c simplified.

Signed-off-by: David Brazdil <dbrazdil@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20200625131420.71444-10-dbrazdil@google.com
2020-07-05 18:38:21 +01:00