Marcelo Tosatti wrote:
> On Fri, Apr 11, 2008 at 03:18:19PM +0300, Avi Kivity wrote:
>
>> kvm_vcpu_kick() can be called from nonatomic contexts, so the vcpu->cpu
>> == cpu check is dangerous (and will warn on preemptible kernels, no?)
>>
>
> Doh, right. How's this.
>
> -----------
>
> KVM: fix kvm_vcpu_kick vs __vcpu_run race
>
> There is a window open between testing of pending IRQ's
> and assignment of guest_mode in __vcpu_run.
>
> Injection of IRQ's can race with __vcpu_run as follows:
>
> CPU0 CPU1
> kvm_x86_ops->run()
> vcpu->guest_mode = 0 SET_IRQ_LINE ioctl
> ..
> kvm_x86_ops->inject_pending_irq
> kvm_cpu_has_interrupt()
>
> apic_test_and_set_irr()
> kvm_vcpu_kick
> if (vcpu->guest_mode)
> send_ipi()
>
> vcpu->guest_mode = 1
>
> So move guest_mode=1 assignment before ->inject_pending_irq, and make
> sure that it won't reorder after it.
>
>
>
Applied, but this
> @@ -3944,11 +3950,13 @@ static void vcpu_kick_intr(void *info)
> void kvm_vcpu_kick(struct kvm_vcpu *vcpu)
> {
> int ipi_pcpu = vcpu->cpu;
> + int cpu = get_cpu();
>
> if (waitqueue_active(&vcpu->wq)) {
> wake_up_interruptible(&vcpu->wq);
> ++vcpu->stat.halt_wakeup;
> }
> - if (vcpu->guest_mode)
> + if (vcpu->guest_mode && vcpu->cpu != cpu)
> smp_call_function_single(ipi_pcpu, vcpu_kick_intr, vcpu, 0, 0);
> + put_cpu();
> }
>
Looks like a no-op now, as vcpu_kick_intr() does nothing and
smp_call_function_single() won't force an exit if vcpu->cpu == cpu, so I
dropped this hunk.
--
error compiling committee.c: too many arguments to function
-------------------------------------------------------------------------
This SF.net email is sponsored by the 2008 JavaOne(SM) Conference
Don't miss this year's exciting event. There's still time to save $100.
Use priority code J8TL2D2.
http://ad.doubleclick.net/clk;198757673;13503038;p?http://java.sun.com/javaone
_______________________________________________
kvm-devel mailing list
kvm-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/kvm-devel
