kvm: x86: mask out XSAVES

This feature is not supported inside KVM guests yet, because we do not emulate
MSR_IA32_XSS.  Mask it out.

Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 10 insertions, 1 deletions

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 20d83217fb1d..a4f5ac46226c 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -320,6 +320,10 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
                 F(ADX) | F(SMAP) | F(AVX512F) | F(AVX512PF) | F(AVX512ER) |
                 F(AVX512CD);
 
+        /* cpuid 0xD.1.eax */
+        const u32 kvm_supported_word10_x86_features =
+                F(XSAVEOPT) | F(XSAVEC) | F(XGETBV1);
+
         /* all calls to cpuid_count() should be made on the same cpu */
         get_cpu();
 
@@ -456,13 +460,18 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
                 entry->eax &= supported;
                 entry->edx &= supported >> 32;
                 entry->flags |= KVM_CPUID_FLAG_SIGNIFCANT_INDEX;
+                if (!supported)
+                        break;
+
                 for (idx = 1, i = 1; idx < 64; ++idx) {
                         u64 mask = ((u64)1 << idx);
                         if (*nent >= maxnent)
                                 goto out;
 
                         do_cpuid_1_ent(&entry[i], function, idx);
-                        if (entry[i].eax == 0 || !(supported & mask))
+                        if (idx == 1)
+                                entry[i].eax &= kvm_supported_word10_x86_features;
+                        else if (entry[i].eax == 0 || !(supported & mask))
                                 continue;
                         entry[i].flags |=
                                KVM_CPUID_FLAG_SIGNIFCANT_INDEX;