| Message ID | 20170320105818.20481-9-cdall@linaro.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 20/03/17 10:58, Christoffer Dall wrote: > Now when we do an early init of the static parts of the VGIC data > structures, we can do things like checking if the AP lists are empty > directly without having to explicitly check if the vgic is initialized > and reduce a bit of work in our criticial path. critical > Note: list_empty is a single atomic read (uses READ_ONCE) and can > therefore check if a list is empty or not without the need to take the > spinlock protecting the list. This note might be better placed in patch #2. > > Signed-off-by: Christoffer Dall <cdall@linaro.org> Acked-by: Marc Zyngier <marc.zyngier@arm.com> M.
On Tue, Mar 21, 2017 at 12:08:15PM +0000, Marc Zyngier wrote: > On 20/03/17 10:58, Christoffer Dall wrote: > > Now when we do an early init of the static parts of the VGIC data > > structures, we can do things like checking if the AP lists are empty > > directly without having to explicitly check if the vgic is initialized > > and reduce a bit of work in our criticial path. > > critical > > > Note: list_empty is a single atomic read (uses READ_ONCE) and can > > therefore check if a list is empty or not without the need to take the > > spinlock protecting the list. > > This note might be better placed in patch #2. Agreed. > > > > > Signed-off-by: Christoffer Dall <cdall@linaro.org> > > Acked-by: Marc Zyngier <marc.zyngier@arm.com> > Thanks, -Christoffer
diff --git a/virt/kvm/arm/vgic/vgic.c b/virt/kvm/arm/vgic/vgic.c index f5b3c25..093873e 100644 --- a/virt/kvm/arm/vgic/vgic.c +++ b/virt/kvm/arm/vgic/vgic.c @@ -653,9 +653,6 @@ void kvm_vgic_sync_hwstate(struct kvm_vcpu *vcpu) /* Flush our emulation state into the GIC hardware before entering the guest. */ void kvm_vgic_flush_hwstate(struct kvm_vcpu *vcpu) { - if (unlikely(!vgic_initialized(vcpu->kvm))) - return; - if (list_empty(&vcpu->arch.vgic_cpu.ap_list_head)) return;
Now when we do an early init of the static parts of the VGIC data structures, we can do things like checking if the AP lists are empty directly without having to explicitly check if the vgic is initialized and reduce a bit of work in our criticial path. Note: list_empty is a single atomic read (uses READ_ONCE) and can therefore check if a list is empty or not without the need to take the spinlock protecting the list. Signed-off-by: Christoffer Dall <cdall@linaro.org> --- virt/kvm/arm/vgic/vgic.c | 3 --- 1 file changed, 3 deletions(-)