Hi Bandan, On Wed, Jul 02, 2014 at 12:27:59PM -0400, Bandan Das wrote: >Wanpeng Li <wanpeng.li@xxxxxxxxxxxxxxx> 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 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
