lkml.org 
[lkml]   [2017]   [Aug]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Date
SubjectRe: [PATCH v3 2/4] KVM: X86: Fix loss of exception which has not yet injected
2017-08-24 17:35 GMT+08:00 Paolo Bonzini <pbonzini@redhat.com>:
> On 24/08/2017 11:13, Wanpeng Li wrote:
>> 2017-08-24 16:57 GMT+08:00 Paolo Bonzini <pbonzini@redhat.com>:
>>> On 24/08/2017 08:52, Wanpeng Li wrote:
>>>>> @@ -6862,6 +6876,7 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
>>>>> kvm_x86_ops->enable_nmi_window(vcpu);
>>>>> if (kvm_cpu_has_injectable_intr(vcpu) || req_int_win)
>>>>> kvm_x86_ops->enable_irq_window(vcpu);
>>>>> + WARN_ON(vcpu->arch.exception.pending);
>>>>
>>>> This WARN_ON() is suggested during the review of last version,
>>>> however, there are many cases in inject_pending_event() can result in
>>>> return directly w/ vcpu->arch.exception.pending is true. Actually I
>>>> have already catched the warning several times during the testing. I
>>>> think we should remove it when committing.
>>>
>>> No, it's a good thing that it's failing, because it's finding a bug.
>>> There's no such thing as an "exception window", so at the very least it
>>
>> Good point, the code looks good, I will fold it in next version.
>> However, I still can observe the warning.
>
> In patch 4, vmx_check_nested_events must clear vcpu->ex.pending.

It is true, but I can still observe the warning.


diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 6f88a79..4f97c4f 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -10990,6 +10990,8 @@ static int vmx_check_nested_events(struct
kvm_vcpu *vcpu, bool external_intr)
if (vmx->nested.nested_run_pending)
return -EBUSY;

+ vcpu->arch.exception.pending = false;
+ vcpu->arch.exception.injected = true;
nested_vmx_inject_exception_vmexit(vcpu, exit_qual);
return 0;
}
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index b698b2f..77e3031 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -6365,14 +6365,20 @@ static int inject_pending_event(struct
kvm_vcpu *vcpu, bool req_int_win)
return 0;
}

- if (vcpu->arch.nmi_injected) {
- kvm_x86_ops->set_nmi(vcpu);
- return 0;
- }
+ /*
+ * Exceptions must be injected immediately, or the exception
+ * frame will have the address of the NMI or interrupt handler.
+ */
+ if (!vcpu->arch.exception.pending) {
+ if (vcpu->arch.nmi_injected) {
+ kvm_x86_ops->set_nmi(vcpu);
+ return 0;
+ }

- if (vcpu->arch.interrupt.pending) {
- kvm_x86_ops->set_irq(vcpu);
- return 0;
+ if (vcpu->arch.interrupt.pending) {
+ kvm_x86_ops->set_irq(vcpu);
+ return 0;
+ }
}

if (is_guest_mode(vcpu) && kvm_x86_ops->check_nested_events) {
\
 
 \ /
  Last update: 2017-08-24 11:48    [W:0.095 / U:4.376 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site