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KVM: arm64: nv: Reinject PAC exceptions caused by HCR_EL2.API==0

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In order for a L1 hypervisor to correctly handle PAuth instructions,
it must observe traps caused by a L1 PAuth instruction when
HCR_EL2.API==0. Since we already handle the case for API==1 as
a fixup, only the exception injection case needs to be handled.

Rework the kvm_handle_ptrauth() callback to reinject the trap
in this case. Note that APK==0 is already handled by the exising
triage_sysreg_trap() helper.

Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20240419102935.1935571-11-maz@kernel.org
Signed-off-by: Marc Zyngier <maz@kernel.org>
This commit is contained in:
Marc Zyngier
2024-04-19 11:29:30 +01:00
parent 279946ada1
commit 15db034733
1 changed files with 25 additions and 3 deletions
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28
arch/arm64/kvm/handle_exit.c
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@@ -214,12 +214,34 @@ static int handle_sve(struct kvm_vcpu *vcpu)
} }
/* /*
* Guest usage of a ptrauth instruction (which the guest EL1 did not turn into * Two possibilities to handle a trapping ptrauth instruction:
* a NOP). If we get here, it is that we didn't fixup ptrauth on exit, and all *
* that we can do is give the guest an UNDEF. * - Guest usage of a ptrauth instruction (which the guest EL1 did not
* turn into a NOP). If we get here, it is that we didn't fixup
* ptrauth on exit, and all that we can do is give the guest an
* UNDEF (as the guest isn't supposed to use ptrauth without being
* told it could).
*
* - Running an L2 NV guest while L1 has left HCR_EL2.API==0, and for
* which we reinject the exception into L1. API==1 is handled as a
* fixup so the only way to get here is when API==0.
*
* Anything else is an emulation bug (hence the WARN_ON + UNDEF).
*/ */
static int kvm_handle_ptrauth(struct kvm_vcpu *vcpu) static int kvm_handle_ptrauth(struct kvm_vcpu *vcpu)
{ {
if (!vcpu_has_ptrauth(vcpu)) {
kvm_inject_undefined(vcpu);
return 1;
}
if (vcpu_has_nv(vcpu) && !is_hyp_ctxt(vcpu)) {
kvm_inject_nested_sync(vcpu, kvm_vcpu_get_esr(vcpu));
return 1;
}
/* Really shouldn't be here! */
WARN_ON_ONCE(1);
kvm_inject_undefined(vcpu); kvm_inject_undefined(vcpu);
return 1; return 1;
} }