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-rw-r--r--arch/x86/kvm/svm/sev.c19
-rw-r--r--arch/x86/kvm/svm/svm.c1
-rw-r--r--arch/x86/kvm/svm/svm.h2
3 files changed, 21 insertions, 1 deletions
diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 4900c078045a..6ee925d66648 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -2972,6 +2972,25 @@ static void sev_es_vcpu_after_set_cpuid(struct vcpu_svm *svm)
set_msr_interception(vcpu, svm->msrpm, MSR_TSC_AUX, v_tsc_aux, v_tsc_aux);
}
+
+ /*
+ * For SEV-ES, accesses to MSR_IA32_XSS should not be intercepted if
+ * the host/guest supports its use.
+ *
+ * guest_can_use() checks a number of requirements on the host/guest to
+ * ensure that MSR_IA32_XSS is available, but it might report true even
+ * if X86_FEATURE_XSAVES isn't configured in the guest to ensure host
+ * MSR_IA32_XSS is always properly restored. For SEV-ES, it is better
+ * to further check that the guest CPUID actually supports
+ * X86_FEATURE_XSAVES so that accesses to MSR_IA32_XSS by misbehaved
+ * guests will still get intercepted and caught in the normal
+ * kvm_emulate_rdmsr()/kvm_emulated_wrmsr() paths.
+ */
+ if (guest_can_use(vcpu, X86_FEATURE_XSAVES) &&
+ guest_cpuid_has(vcpu, X86_FEATURE_XSAVES))
+ set_msr_interception(vcpu, svm->msrpm, MSR_IA32_XSS, 1, 1);
+ else
+ set_msr_interception(vcpu, svm->msrpm, MSR_IA32_XSS, 0, 0);
}
void sev_vcpu_after_set_cpuid(struct vcpu_svm *svm)
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index f3bb30b40876..a8bd4e909a1e 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -103,6 +103,7 @@ static const struct svm_direct_access_msrs {
{ .index = MSR_IA32_LASTBRANCHTOIP, .always = false },
{ .index = MSR_IA32_LASTINTFROMIP, .always = false },
{ .index = MSR_IA32_LASTINTTOIP, .always = false },
+ { .index = MSR_IA32_XSS, .always = false },
{ .index = MSR_EFER, .always = false },
{ .index = MSR_IA32_CR_PAT, .always = false },
{ .index = MSR_AMD64_SEV_ES_GHCB, .always = true },
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index be67ab7fdd10..c409f934c377 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -30,7 +30,7 @@
#define IOPM_SIZE PAGE_SIZE * 3
#define MSRPM_SIZE PAGE_SIZE * 2
-#define MAX_DIRECT_ACCESS_MSRS 46
+#define MAX_DIRECT_ACCESS_MSRS 47
#define MSRPM_OFFSETS 32
extern u32 msrpm_offsets[MSRPM_OFFSETS] __read_mostly;
extern bool npt_enabled;