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KVM: fix load_guest_segment_descriptor() to return X86EMUL_*

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This patch fixes load_guest_segment_descriptor() to return
X86EMUL_PROPAGATE_FAULT when it tries to access the descriptor
table beyond the limit of it: suggested by Marcelo.

I have checked current callers of this helper function,
  - kvm_load_segment_descriptor()
  - kvm_task_switch()
and confirmed that this patch will change nothing in the
upper layers if we do not change the handling of this
return value from load_guest_segment_descriptor().

Next step: Although fixing the kvm_task_switch() to handle the
propagated faults properly seems difficult, and maybe not worth
it because TSS is not used commonly these days, we can fix
kvm_load_segment_descriptor(). By doing so, the injected #GP
becomes possible to be handled by the guest. The only problem
for this is how to differentiate this fault from the page faults
generated by kvm_read_guest_virt(). We may have to split this
function to achive this goal.

Signed-off-by: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
This commit is contained in:
Takuya Yoshikawa 2010-02-01 22:11:04 +09:00 committed by Marcelo Tosatti
parent ab9f4ecbb6
commit c125c60732
1 changed files with 1 additions and 1 deletions
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arch/x86/kvm/x86.c
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@ -4663,7 +4663,7 @@ static int load_guest_segment_descriptor(struct kvm_vcpu *vcpu, u16 selector,
if (dtable.limit < index * 8 + 7) {
kvm_queue_exception_e(vcpu, GP_VECTOR, selector & 0xfffc);
return 1;
return X86EMUL_PROPAGATE_FAULT;
}
return kvm_read_guest_virt(dtable.base + index*8, seg_desc, sizeof(*seg_desc), vcpu);
}