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Commit 64a38292 authored by Nadav Amit's avatar Nadav Amit Committed by Paolo Bonzini
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KVM: x86: Emulate should check #UD before #GP 



Intel SDM table 6-2 ("Priority Among Simultaneous Exceptions and Interrupts")
shows that faults from decoding the next instruction got higher priority than
general protection.  Moving the protected-mode check before the CPL check to
avoid wrong exception on vm86 mode.

Signed-off-by: default avatarNadav Amit <namit@cs.technion.ac.il>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent bc397a6c

arch/x86/kvm/emulate.c

+6 −6
Original line number Diff line number Diff line
@@ -4801,6 +4801,12 @@ int x86_emulate_insn(struct x86_emulate_ctxt *ctxt) 
				goto done;

		}



		/* Instruction can only be executed in protected mode */

		if ((ctxt->d & Prot) && ctxt->mode < X86EMUL_MODE_PROT16) {

			rc = emulate_ud(ctxt);

			goto done;

		}



		/* Privileged instruction can be executed only in CPL=0 */

		if ((ctxt->d & Priv) && ops->cpl(ctxt)) {

			if (ctxt->d & PrivUD)
@@ -4810,12 +4816,6 @@ int x86_emulate_insn(struct x86_emulate_ctxt *ctxt) 
			goto done;

		}



		/* Instruction can only be executed in protected mode */

		if ((ctxt->d & Prot) && ctxt->mode < X86EMUL_MODE_PROT16) {

			rc = emulate_ud(ctxt);

			goto done;

		}



		/* Do instruction specific permission checks */

		if (ctxt->d & CheckPerm) {

			rc = ctxt->check_perm(ctxt);