[PATCH 6/9] KVM: cpuid: mask more bits in leaf 0xd and subleaves

Paolo Bonzini
2014-12-04T15:57:11Z

- EAX=0Dh, ECX=1: output registers 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>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
arch/x86/kvm/cpuid.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 2f7bc2de9915..644bfe828ce1 100644
--- 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;
--
1.8.3.1