Commit 040c8dc8 authored Sep 18, 2014 by Nadav Amit Committed by Paolo Bonzini Sep 24, 2014

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



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 13â€”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>

parent 77c3913b

arch/x86/kvm/emulate.c

+9 −0

Original line number	Diff line number	Diff line
		@@ -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;

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