KVM: inject #UD if instruction emulation fails and exit to userspace
Do not kill VM when instruction emulation fails. Inject #UD and report
failure to userspace instead. Userspace may choose to reenter guest if
vcpu is in userspace (cpl == 3) in which case guest OS will kill
offending process and continue running.
Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 5989317..a82cfa1 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -3070,7 +3070,7 @@
++vcpu->stat.io_exits;
if (string || in)
- return !(emulate_instruction(vcpu, 0, 0, 0) == EMULATE_DO_MMIO);
+ return emulate_instruction(vcpu, 0, 0, 0) == EMULATE_DONE;
port = exit_qualification >> 16;
size = (exit_qualification & 7) + 1;
@@ -3327,22 +3327,7 @@
static int handle_apic_access(struct kvm_vcpu *vcpu)
{
- unsigned long exit_qualification;
- enum emulation_result er;
- unsigned long offset;
-
- exit_qualification = vmcs_readl(EXIT_QUALIFICATION);
- offset = exit_qualification & 0xffful;
-
- er = emulate_instruction(vcpu, 0, 0, 0);
-
- if (er != EMULATE_DONE) {
- printk(KERN_ERR
- "Fail to handle apic access vmexit! Offset is 0x%lx\n",
- offset);
- return -ENOEXEC;
- }
- return 1;
+ return emulate_instruction(vcpu, 0, 0, 0) == EMULATE_DONE;
}
static int handle_task_switch(struct kvm_vcpu *vcpu)
@@ -3554,13 +3539,8 @@
goto out;
}
- if (err != EMULATE_DONE) {
- vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
- vcpu->run->internal.suberror = KVM_INTERNAL_ERROR_EMULATION;
- vcpu->run->internal.ndata = 0;
- ret = 0;
- goto out;
- }
+ if (err != EMULATE_DONE)
+ return 0;
if (signal_pending(current))
goto out;