Commit a790e338 authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini
Browse files

KVM: SVM: Ignore writes to Remote Read Data on AVIC write traps 



Drop writes to APIC_RRR, a.k.a. Remote Read Data Register, on AVIC
unaccelerated write traps.  The register is read-only and isn't emulated
by KVM.  Sending the register through kvm_apic_write_nodecode() will
result in screaming when x2APIC is enabled due to the unexpected failure
to retrieve the MSR (KVM expects that only "legal" accesses will trap).

Fixes: 4d1d7942 ("KVM: SVM: Introduce logic to (de)activate x2AVIC mode")
Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
Reviewed-by: default avatarMaxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20230106011306.85230-30-seanjc@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent bbfc7aa6

arch/x86/kvm/svm/avic.c

+3 −0
Original line number Diff line number Diff line
@@ -628,6 +628,9 @@ static int avic_unaccel_trap_write(struct kvm_vcpu *vcpu) 
	case APIC_DFR:

		avic_handle_dfr_update(vcpu);

		break;

	case APIC_RRR:

		/* Ignore writes to Read Remote Data, it's read-only. */

		return 1;

	default:

		break;

	}