Re: [PATCH v2 4/4] x86/kvm/hyper-v: avoid open-coding stimer_mark_pending() in kvm_hv_notify_acked_sint()
On Mon, Nov 26, 2018 at 04:47:32PM +0100, Vitaly Kuznetsov wrote: > stimers_pending optimization only helps us to avoid multiple > kvm_make_request() calls. This doesn't happen very often and these > calls are very cheap in the first place, remove open-coded version of > stimer_mark_pending() from kvm_hv_notify_acked_sint(). Frankly speaking, I've yet to see a guest that configures more than one SynIC timer. So it was indeed a bit of overengineering in the first place. > Suggested-by: Paolo Bonzini > Signed-off-by: Vitaly Kuznetsov > --- > arch/x86/kvm/hyperv.c | 12 +++- > 1 file changed, 3 insertions(+), 9 deletions(-) Reviewed-by: Roman Kagan
Re: [PATCH v2 4/4] x86/kvm/hyper-v: avoid open-coding stimer_mark_pending() in kvm_hv_notify_acked_sint()
On Mon, Nov 26, 2018 at 04:47:32PM +0100, Vitaly Kuznetsov wrote: > stimers_pending optimization only helps us to avoid multiple > kvm_make_request() calls. This doesn't happen very often and these > calls are very cheap in the first place, remove open-coded version of > stimer_mark_pending() from kvm_hv_notify_acked_sint(). Frankly speaking, I've yet to see a guest that configures more than one SynIC timer. So it was indeed a bit of overengineering in the first place. > Suggested-by: Paolo Bonzini > Signed-off-by: Vitaly Kuznetsov > --- > arch/x86/kvm/hyperv.c | 12 +++- > 1 file changed, 3 insertions(+), 9 deletions(-) Reviewed-by: Roman Kagan
Re: [PATCH v2 4/4] x86/kvm/hyper-v: avoid open-coding stimer_mark_pending() in kvm_hv_notify_acked_sint()
On 26/11/18 16:47, Vitaly Kuznetsov wrote: > stimers_pending optimization only helps us to avoid multiple > kvm_make_request() calls. This doesn't happen very often and these > calls are very cheap in the first place, remove open-coded version of > stimer_mark_pending() from kvm_hv_notify_acked_sint(). I wouldn't say very cheap, but still relatively cheap compared to a vmexit. Paolo
Re: [PATCH v2 4/4] x86/kvm/hyper-v: avoid open-coding stimer_mark_pending() in kvm_hv_notify_acked_sint()
On 26/11/18 16:47, Vitaly Kuznetsov wrote: > stimers_pending optimization only helps us to avoid multiple > kvm_make_request() calls. This doesn't happen very often and these > calls are very cheap in the first place, remove open-coded version of > stimer_mark_pending() from kvm_hv_notify_acked_sint(). I wouldn't say very cheap, but still relatively cheap compared to a vmexit. Paolo
[PATCH v2 4/4] x86/kvm/hyper-v: avoid open-coding stimer_mark_pending() in kvm_hv_notify_acked_sint()
stimers_pending optimization only helps us to avoid multiple
kvm_make_request() calls. This doesn't happen very often and these
calls are very cheap in the first place, remove open-coded version of
stimer_mark_pending() from kvm_hv_notify_acked_sint().
Suggested-by: Paolo Bonzini
Signed-off-by: Vitaly Kuznetsov
---
arch/x86/kvm/hyperv.c | 12 +++-
1 file changed, 3 insertions(+), 9 deletions(-)
diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index 9533133be566..e6a2a085644a 100644
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -206,7 +206,7 @@ static void kvm_hv_notify_acked_sint(struct kvm_vcpu *vcpu,
u32 sint)
struct kvm_vcpu_hv_synic *synic = vcpu_to_synic(vcpu);
struct kvm_vcpu_hv *hv_vcpu = vcpu_to_hv_vcpu(vcpu);
struct kvm_vcpu_hv_stimer *stimer;
- int gsi, idx, stimers_pending;
+ int gsi, idx;
trace_kvm_hv_notify_acked_sint(vcpu->vcpu_id, sint);
@@ -214,19 +214,13 @@ static void kvm_hv_notify_acked_sint(struct kvm_vcpu
*vcpu, u32 sint)
synic_clear_sint_msg_pending(synic, sint);
/* Try to deliver pending Hyper-V SynIC timers messages */
- stimers_pending = 0;
for (idx = 0; idx < ARRAY_SIZE(hv_vcpu->stimer); idx++) {
stimer = _vcpu->stimer[idx];
if (stimer->msg_pending && stimer->config.enable &&
!stimer->config.direct_mode &&
- stimer->config.sintx == sint) {
- set_bit(stimer->index,
- hv_vcpu->stimer_pending_bitmap);
- stimers_pending++;
- }
+ stimer->config.sintx == sint)
+ stimer_mark_pending(stimer, false);
}
- if (stimers_pending)
- kvm_make_request(KVM_REQ_HV_STIMER, vcpu);
idx = srcu_read_lock(>irq_srcu);
gsi = atomic_read(>sint_to_gsi[sint]);
--
2.19.1
[PATCH v2 4/4] x86/kvm/hyper-v: avoid open-coding stimer_mark_pending() in kvm_hv_notify_acked_sint()
stimers_pending optimization only helps us to avoid multiple
kvm_make_request() calls. This doesn't happen very often and these
calls are very cheap in the first place, remove open-coded version of
stimer_mark_pending() from kvm_hv_notify_acked_sint().
Suggested-by: Paolo Bonzini
Signed-off-by: Vitaly Kuznetsov
---
arch/x86/kvm/hyperv.c | 12 +++-
1 file changed, 3 insertions(+), 9 deletions(-)
diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index 9533133be566..e6a2a085644a 100644
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -206,7 +206,7 @@ static void kvm_hv_notify_acked_sint(struct kvm_vcpu *vcpu,
u32 sint)
struct kvm_vcpu_hv_synic *synic = vcpu_to_synic(vcpu);
struct kvm_vcpu_hv *hv_vcpu = vcpu_to_hv_vcpu(vcpu);
struct kvm_vcpu_hv_stimer *stimer;
- int gsi, idx, stimers_pending;
+ int gsi, idx;
trace_kvm_hv_notify_acked_sint(vcpu->vcpu_id, sint);
@@ -214,19 +214,13 @@ static void kvm_hv_notify_acked_sint(struct kvm_vcpu
*vcpu, u32 sint)
synic_clear_sint_msg_pending(synic, sint);
/* Try to deliver pending Hyper-V SynIC timers messages */
- stimers_pending = 0;
for (idx = 0; idx < ARRAY_SIZE(hv_vcpu->stimer); idx++) {
stimer = _vcpu->stimer[idx];
if (stimer->msg_pending && stimer->config.enable &&
!stimer->config.direct_mode &&
- stimer->config.sintx == sint) {
- set_bit(stimer->index,
- hv_vcpu->stimer_pending_bitmap);
- stimers_pending++;
- }
+ stimer->config.sintx == sint)
+ stimer_mark_pending(stimer, false);
}
- if (stimers_pending)
- kvm_make_request(KVM_REQ_HV_STIMER, vcpu);
idx = srcu_read_lock(>irq_srcu);
gsi = atomic_read(>sint_to_gsi[sint]);
--
2.19.1
