From 64a38292ed5f1e9d1bbc15b591cc3b57ce89473f Mon Sep 17 00:00:00 2001 From: Nadav Amit Date: Wed, 10 Dec 2014 11:19:04 +0200 Subject: [PATCH] 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 Signed-off-by: Paolo Bonzini --- 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 c1e71873e0c..a8fcec6b706 100644 --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -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); -- 2.46.0