[PATCH v6 10/17] KVM: x86: nSVM: always intercept x2apic msrs

Suravee Suthikulpanit
2022-05-19T10:28:57Z

From: Maxim Levitsky <mlevitsk@redhat.com>

As a preparation for x2avic, this patch ensures that x2apic msrs
are always intercepted for the nested guest.

Reviewed-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Tested-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
---
arch/x86/kvm/svm/nested.c | 5 +++++
arch/x86/kvm/svm/svm.h | 9 +++++++++
2 files changed, 14 insertions(+)

diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index f209c1ca540c..b61f8939c210 100644
--- 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
index 16f1d117c98b..7e53474c8834 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -517,6 +517,15 @@ 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

--
2.25.1