On 07/10/2012 11:50 AM, Gleb Natapov wrote: > On Mon, Jul 09, 2012 at 08:05:40PM +0300, Avi Kivity wrote: > > It's a write-only bit, set by the timer and cleared by the main loop. > > Remove it. Retain the definition since ppc uses it. > > > > Signed-off-by: Avi Kivity <[email protected]> > > --- > > arch/x86/kvm/timer.c | 8 ++------ > > arch/x86/kvm/x86.c | 1 - > > 2 files changed, 2 insertions(+), 7 deletions(-) > > > > diff --git a/arch/x86/kvm/timer.c b/arch/x86/kvm/timer.c > > index 6b85cc6..c28f838 100644 > > --- a/arch/x86/kvm/timer.c > > +++ b/arch/x86/kvm/timer.c > > @@ -27,14 +27,10 @@ enum hrtimer_restart kvm_timer_fn(struct hrtimer *data) > > /* > > * There is a race window between reading and incrementing, but we do > > * not care about potentially losing timer events in the !reinject > > - * case anyway. Note: KVM_REQ_PENDING_TIMER is implicitly checked > > - * in vcpu_enter_guest. > So what about the part that says "KVM_REQ_PENDING_TIMER is implicitly > checked in vcpu_enter_guest"? This patch drops the check. So now if > timer triggers while vcpu is in userspace it will enter guest mode > without injecting timer interrupt on the next ioctl(KVM_RUN). Or do I > miss something here?
You're right, the bit appears to be write-only, but it isn't. The check inside the critical section for vcpu->requests reads it. I guess we can make the check explicit by doing a 'goto out' if the bit is set. -- I have a truly marvellous patch that fixes the bug which this signature is too narrow to contain. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
