lkml.org 
[lkml]   [2017]   [Aug]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
SubjectRe: [PATCH v3 2/4] KVM: X86: Fix loss of exception which has not yet injected
From
Date
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
should set req_immediate_exit to true.

Does this help?

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index b698b2f135a2..76d5a192be6c 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) {
Paolo

\
 
 \ /
  Last update: 2017-08-24 10:58    [W:0.127 / U:3.792 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site