KVM: x86: Emulate should check #UD before #GP (64a38292) · Commits · 戴 / test

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:

Nadav Amit <namit@cs.technion.ac.il> Signed-off-by:

Paolo Bonzini <pbonzini@redhat.com>

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);

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