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[v5,29/33] KVM: SVM: Ignore writes to Remote Read Data on AVIC write traps

Message ID 20230106011306.85230-30-seanjc@google.com (mailing list archive)
State New, archived
Headers show
Series KVM: x86: AVIC and local APIC fixes+cleanups | expand

Commit Message

Sean Christopherson Jan. 6, 2023, 1:13 a.m. UTC 
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: 4d1d7942e36a ("KVM: SVM: Introduce logic to (de)activate x2AVIC mode")
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
---
 arch/x86/kvm/svm/avic.c | 3 +++
 1 file changed, 3 insertions(+)
diff mbox series

Patch

diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c
index 2c6737f72bd4..ff08732469cb 100644
--- a/arch/x86/kvm/svm/avic.c
+++ b/arch/x86/kvm/svm/avic.c
@@ -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;
 	}