KVM: x86: nSVM: always intercept x2apic msrs

As a preparation for x2avic, this patch ensures that x2apic msrs are always intercepted for the nested guest. Reviewed-by: Suravee Suthikulpanit <[email protected]> Tested-by: Suravee Suthikulpanit <[email protected]> Signed-off-by: Maxim Levitsky <[email protected]> Message-Id: <[email protected]> Signed-off-by: Paolo Bonzini <[email protected]>
AOSC-Tracking · Jun 24, 2022 · 7a8f7c1 · 7a8f7c1
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commit 7a8f7c1
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diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
@@ -230,6 +230,11 @@ static bool nested_svm_vmrun_msrpm(struct vcpu_svm *svm)
 			break;
 
 		p      = msrpm_offsets[i];
+
+		/* x2apic msrs are intercepted always for the nested guest */
+		if (is_x2apic_msrpm_offset(p))
+			continue;
+
 		offset = svm->nested.ctl.msrpm_base_pa + (p * 4);
 
 		if (kvm_vcpu_read_guest(&svm->vcpu, offset, &value, 4))

diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
@@ -521,6 +521,15 @@ static inline bool nested_npt_enabled(struct vcpu_svm *svm)
 	return svm->nested.ctl.nested_ctl & SVM_NESTED_CTL_NP_ENABLE;
 }
 
+static inline bool is_x2apic_msrpm_offset(u32 offset)
+{
+	/* 4 msrs per u8, and 4 u8 in u32 */
+	u32 msr = offset * 16;
+
+	return (msr >= APIC_BASE_MSR) &&
+	       (msr < (APIC_BASE_MSR + 0x100));
+}
+
 /* svm.c */
 #define MSR_INVALID				0xffffffffU