Commit 15db0347 authored by Marc Zyngier's avatar Marc Zyngier
Browse files

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



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: default avatarOliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20240419102935.1935571-11-maz@kernel.org


Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
parent 279946ad

arch/arm64/kvm/handle_exit.c

+25 −3
Original line number Diff line number Diff line
@@ -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

 * 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.

 * Two possibilities to handle a trapping ptrauth instruction:

 *

 * - 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)

{

	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);

	return 1;

}