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KVM: x86: emulating descriptor load misses long-mode case

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In 64-bit mode a #GP should be delivered to the guest "if the code segment
descriptor pointed to by the selector in the 64-bit gate doesn't have the L-bit
set and the D-bit clear." - Intel SDM "Interrupt 13—General Protection
Exception (#GP)".

This patch fixes the behavior of CS loading emulation code. Although the
comment says that segment loading is not supported in long mode, this function
is executed in long mode, so the fix is necassary.

Signed-off-by: Nadav Amit <namit@cs.technion.ac.il>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Nadav Amit 2014-09-18 22:39:43 +03:00 committed by Paolo Bonzini
parent 77c3913b74
commit 040c8dc8a5
1 changed files with 9 additions and 0 deletions
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9
arch/x86/kvm/emulate.c
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@ -1504,6 +1504,15 @@ static int __load_segment_descriptor(struct x86_emulate_ctxt *ctxt,
if (rpl > cpl || dpl != cpl)
goto exception;
}
/* in long-mode d/b must be clear if l is set */
if (seg_desc.d && seg_desc.l) {
u64 efer = 0;
ctxt->ops->get_msr(ctxt, MSR_EFER, &efer);
if (efer & EFER_LMA)
goto exception;
}
/* CS(RPL) <- CPL */
selector = (selector & 0xfffc) | cpl;
break;