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KVM: VMX: Relax check on unusable segment

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Some userspace (e.g. QEMU 1.1) munge the d and g bits of segment
descriptors, causing us not to recognize them as unusable segments
with emulate_invalid_guest_state=1.  Relax the check by testing for
segment not present (a non-present segment cannot be usable).

Signed-off-by: Avi Kivity <avi@redhat.com>
This commit is contained in:
Avi Kivity 2012-06-07 17:06:10 +03:00
parent 510425ff33
commit f0495f9b99
1 changed files with 1 additions and 3 deletions
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4
arch/x86/kvm/vmx.c
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@ -3198,7 +3198,7 @@ static u32 vmx_segment_access_rights(struct kvm_segment *var)
{
u32 ar;
if (var->unusable)
if (var->unusable || !var->present)
ar = 1 << 16;
else {
ar = var->type & 15;
@ -3210,8 +3210,6 @@ static u32 vmx_segment_access_rights(struct kvm_segment *var)
ar |= (var->db & 1) << 14;
ar |= (var->g & 1) << 15;
}
if (ar == 0) /* a 0 value means unusable */
ar = AR_UNUSABLE_MASK;
return ar;
}