Messages in this thread | | | Date | Thu, 3 Jul 2014 13:11:42 +0800 | From | Wanpeng Li <> | Subject | Re: [PATCH] KVM: nVMX: Fix IRQs inject to L2 which belong to L1 since race |
| |
Hi Bandan, On Wed, Jul 02, 2014 at 12:27:59PM -0400, Bandan Das wrote: >Wanpeng Li <wanpeng.li@linux.intel.com> writes: > >> This patch fix bug https://bugzilla.kernel.org/show_bug.cgi?id=72381 >I can also reproduce this easily with Linux as L1 by "slowing it down" >eg. running with ept = 0 > >I suggest changing the subject to - >KVM: nVMX: Fix race that incorrectly injects L1's irq to L2 >
Ok, I will fold this to next version. ;-)
>> If we didn't inject a still-pending event to L1 since nested_run_pending, >> KVM_REQ_EVENT should be requested after the vmexit in order to inject the >> event to L1. However, current log blindly request a KVM_REQ_EVENT even if > >What's current "log" ? Do you mean current "code" ? >
Yeah, it's a typo. I mean "logic".
[...] >Also, I am wondering isn't it enough to just do this to avoid this race ? > > static int vmx_interrupt_allowed(struct kvm_vcpu *vcpu) > { >- return (!to_vmx(vcpu)->nested.nested_run_pending && >+ return (!is_guest_mode(vcpu) && >+ !to_vmx(vcpu)->nested.nested_run_pending && > vmcs_readl(GUEST_RFLAGS) & X86_EFLAGS_IF) && > !(vmcs_read32(GUEST_INTERRUPTIBILITY_INFO) & >
I don't think you fix the root cause of the race, and there are two cases which I concern about your proposal:
- If there is a special L1 which don't ask to exit on external intrs, you will lose the intrs which L0 inject to L2.
- If inject_pending_event fail to inject an intr since the change that you made in vmx_interrupt_allowed, L0 will request an intr window for L2, however, the intr is belong to L1.
Regards, Wanpeng Li
>Thanks, >Bandan
| |