On 01/05/2011 05:48 PM, Avi Kivity wrote: > On 01/05/2011 11:38 AM, Xiao Guangrong wrote: >> We can interrupt the vcpu only when it's running in guest mode >> to reduce IPI. >> >> It looks like only ia64 and x86 need to send IPI to other vcpus, so >> i only add the implementation of 'vcpu->guest_mode' in ia64, but i >> don't know ia64 well, please point out the right way for me if the >> implementation is incorrect >> >> And ia64 is not tested since i don't have ia64 box >> >> Signed-off-by: Xiao Guangrong<[email protected]> >> --- >> arch/ia64/kvm/kvm-ia64.c | 2 ++ >> virt/kvm/kvm_main.c | 3 ++- >> 2 files changed, 4 insertions(+), 1 deletions(-) >> >> diff --git a/arch/ia64/kvm/kvm-ia64.c b/arch/ia64/kvm/kvm-ia64.c >> index 70d224d..15c11b2 100644 >> --- a/arch/ia64/kvm/kvm-ia64.c >> +++ b/arch/ia64/kvm/kvm-ia64.c >> @@ -662,6 +662,7 @@ again: >> goto vcpu_run_fail; >> >> srcu_read_unlock(&vcpu->kvm->srcu, idx); >> + atomic_set(&vcpu->guest_mode, 1); >> kvm_guest_enter(); > > I think it needs an smp_wmb() (technically x86 needs it too, but x86 is > strongly ordered) >
Hi Avi, After read the code of ia64 more carefully, i noticed ia64 doesn't check 'vcpu->requests' before go to guest mode, so it means we no need memory barrier here? right? Certainly, we need an smb_mb between setting vcpu->mode and checking vcpu->request in x86. -- 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
