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 <[email protected]>
---
arch/x86/kvm/emulate.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 5cd5401..0d42aca 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -4803,6 +4803,12 @@ 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)
@@ -4812,12 +4818,6 @@ 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);
--
1.9.1
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