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UPSTREAM: KVM: arm64: Start trapping ID registers for 32 bit guests

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To date KVM has not trapped ID register accesses from AArch32, meaning
that guests get an unconstrained view of what hardware supports. This
can be a serious problem because we try to base the guest's feature
registers on values that are safe system-wide. Furthermore, KVM does not
implement the latest ISA in the PMU and Debug architecture, so we
constrain these fields to supported values.

Since KVM now correctly handles CP15 and CP10 register traps, we no
longer need to clear HCR_EL2.TID3 for 32 bit guests and will instead
emulate reads with their safe values.

Signed-off-by: Oliver Upton <oupton@google.com>
Reviewed-by: Reiji Watanabe <reijiw@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220503060205.2823727-6-oupton@google.com
(cherry picked from commit fd1264c4ca)
Signed-off-by: Will Deacon <willdeacon@google.com>
Bug: 233587962
Bug: 233588291
Change-Id: Ib3e9b7446aee48495c19174b86fc9129dcd792db
This commit is contained in:
Oliver Upton
2022-05-03 06:02:03 +00:00
committed by Will Deacon
parent ec5582946f
commit 331dd85b8c
2 changed files with 2 additions and 8 deletions
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3
arch/arm64/include/asm/kvm_arm.h
View File

@@ -80,11 +80,12 @@
* FMO: Override CPSR.F and enable signaling with VF
* SWIO: Turn set/way invalidates into set/way clean+invalidate
* PTW: Take a stage2 fault if a stage1 walk steps in device memory
* TID3: Trap EL1 reads of group 3 ID registers
*/
#define HCR_GUEST_FLAGS (HCR_TSC | HCR_TSW | HCR_TWE | HCR_TWI | HCR_VM | \
HCR_BSU_IS | HCR_FB | HCR_TACR | \
HCR_AMO | HCR_SWIO | HCR_TIDCP | HCR_RW | HCR_TLOR | \
HCR_FMO | HCR_IMO | HCR_PTW )
HCR_FMO | HCR_IMO | HCR_PTW | HCR_TID3 )
#define HCR_VIRT_EXCP_MASK (HCR_VSE | HCR_VI | HCR_VF)
#define HCR_HOST_NVHE_FLAGS (HCR_RW | HCR_API | HCR_APK | HCR_ATA)
#define HCR_HOST_NVHE_PROTECTED_FLAGS (HCR_HOST_NVHE_FLAGS | HCR_TSC)

7
arch/arm64/include/asm/kvm_emulate.h
View File

@@ -87,13 +87,6 @@ static inline void vcpu_reset_hcr(struct kvm_vcpu *vcpu)
if (vcpu_el1_is_32bit(vcpu))
vcpu->arch.hcr_el2 &= ~HCR_RW;
else
/*
* TID3: trap feature register accesses that we virtualise.
* For now this is conditional, since no AArch32 feature regs
* are currently virtualised.
*/
vcpu->arch.hcr_el2 |= HCR_TID3;
if (cpus_have_const_cap(ARM64_MISMATCHED_CACHE_TYPE) ||
vcpu_el1_is_32bit(vcpu))