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

jira LE-1907
Rebuild_History Non-Buildable kernel-5.14.0-284.30.1.el9_2
commit-author Sean Christopherson <seanjc@google.com>
commit a790e33

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: 4d1d794 ("KVM: SVM: Introduce logic to (de)activate x2AVIC mode")
	Signed-off-by: Sean Christopherson <seanjc@google.com>
	Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20230106011306.85230-30-seanjc@google.com>
	Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
(cherry picked from commit a790e33)
	Signed-off-by: Jonathan Maple <jmaple@ciq.com>

Author: PlaidCat

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;
 	}