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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: Nadav Amit <namit@cs.technion.ac.il>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Nadav Amit 2014-12-10 11:19:04 +02:00 committed by Paolo Bonzini
parent bc397a6c91
commit 64a38292ed
1 changed files with 6 additions and 6 deletions
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12
arch/x86/kvm/emulate.c
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@ -4801,6 +4801,12 @@ int x86_emulate_insn(struct x86_emulate_ctxt *ctxt)
goto done; 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 */ /* Privileged instruction can be executed only in CPL=0 */
if ((ctxt->d & Priv) && ops->cpl(ctxt)) { if ((ctxt->d & Priv) && ops->cpl(ctxt)) {
if (ctxt->d & PrivUD) if (ctxt->d & PrivUD)
@ -4810,12 +4816,6 @@ int x86_emulate_insn(struct x86_emulate_ctxt *ctxt)
goto done; 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 */ /* Do instruction specific permission checks */
if (ctxt->d & CheckPerm) { if (ctxt->d & CheckPerm) {
rc = ctxt->check_perm(ctxt); rc = ctxt->check_perm(ctxt);