KVM: cpuid: mask more bits in leaf 0xd and subleaves

- EAX=0Dh, ECX=1: output registers EBX/ECX/EDX are reserved.

- EAX=0Dh, ECX>1: output register ECX bit 0 is clear for all the CPUID
leaves we support, because variable "supported" comes from XCR0 and not
XSS.  Bits above 0 are reserved, so ECX is overall zero.  Output register
EDX is reserved.

Source: Intel Architecture Instruction Set Extensions Programming
Reference, ref. number 319433-022

Reviewed-by: Radim Krčmář <rkrcmar@redhat.com>
Tested-by: Wanpeng Li <wanpeng.li@linux.intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 2f7bc2d..644bfe8 100644 (file)
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -482,8 +482,14 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
                                        entry[i].ebx =
                                                xstate_required_size(supported,
                                                                     true);
-                       } else if (entry[i].eax == 0 || !(supported & mask))
-                               continue;
+                       } else {
+                               if (entry[i].eax == 0 || !(supported & mask))
+                                       continue;
+                               if (WARN_ON_ONCE(entry[i].ecx & 1))
+                                       continue;
+                       }
+                       entry[i].ecx = 0;
+                       entry[i].edx = 0;
                        entry[i].flags |=
                               KVM_CPUID_FLAG_SIGNIFCANT_INDEX;
                        ++*nent;