* [PATCH] kvm: x86: remove vmx_vm_has_apicv() outside of hwapic_isr_update()
@ 2014-12-01 9:28 Tiejun Chen
2014-12-01 11:43 ` Paolo Bonzini
0 siblings, 1 reply; 6+ messages in thread
From: Tiejun Chen @ 2014-12-01 9:28 UTC (permalink / raw)
To: pbonzini; +Cc: kvm
In most cases calling hwapic_isr_update(), actually we always
check if kvm_apic_vid_enabled() == 1, and also actually,
kvm_apic_vid_enabled()
-> kvm_x86_ops->vm_has_apicv()
-> vmx_vm_has_apicv() or '0' in svm case
So its unnecessary to recall this inside hwapic_isr_update(), here
just remove vmx_vm_has_apicv() out and follow others.
Signed-off-by: Tiejun Chen <tiejun.chen@intel.com>
---
arch/x86/kvm/lapic.c | 3 ++-
arch/x86/kvm/vmx.c | 3 ---
2 files changed, 2 insertions(+), 4 deletions(-)
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index e0e5642..2ddc426 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -1739,7 +1739,8 @@ void kvm_apic_post_state_restore(struct kvm_vcpu *vcpu,
if (kvm_x86_ops->hwapic_irr_update)
kvm_x86_ops->hwapic_irr_update(vcpu,
apic_find_highest_irr(apic));
- kvm_x86_ops->hwapic_isr_update(vcpu->kvm, apic_find_highest_isr(apic));
+ if (kvm_apic_vid_enabled(vcpu->kvm))
+ kvm_x86_ops->hwapic_isr_update(vcpu->kvm, apic_find_highest_isr(apic));
kvm_make_request(KVM_REQ_EVENT, vcpu);
kvm_rtc_eoi_tracking_restore_one(vcpu);
}
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 6a951d8..f0c16a9 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -7406,9 +7406,6 @@ static void vmx_hwapic_isr_update(struct kvm *kvm, int isr)
u16 status;
u8 old;
- if (!vmx_vm_has_apicv(kvm))
- return;
-
if (isr == -1)
isr = 0;
--
1.9.1
^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: [PATCH] kvm: x86: remove vmx_vm_has_apicv() outside of hwapic_isr_update() 2014-12-01 9:28 [PATCH] kvm: x86: remove vmx_vm_has_apicv() outside of hwapic_isr_update() Tiejun Chen @ 2014-12-01 11:43 ` Paolo Bonzini 2014-12-19 2:32 ` Chen, Tiejun 0 siblings, 1 reply; 6+ messages in thread From: Paolo Bonzini @ 2014-12-01 11:43 UTC (permalink / raw) To: Tiejun Chen; +Cc: kvm On 01/12/2014 10:28, Tiejun Chen wrote: > In most cases calling hwapic_isr_update(), actually we always > check if kvm_apic_vid_enabled() == 1, and also actually, > kvm_apic_vid_enabled() > -> kvm_x86_ops->vm_has_apicv() > -> vmx_vm_has_apicv() or '0' in svm case > > So its unnecessary to recall this inside hwapic_isr_update(), here > just remove vmx_vm_has_apicv() out and follow others. If you want to do this, please NULL out the function pointer instead, as KVM already does for hwapic_irr_update. Paolo > Signed-off-by: Tiejun Chen <tiejun.chen@intel.com> > --- > arch/x86/kvm/lapic.c | 3 ++- > arch/x86/kvm/vmx.c | 3 --- > 2 files changed, 2 insertions(+), 4 deletions(-) > > diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c > index e0e5642..2ddc426 100644 > --- a/arch/x86/kvm/lapic.c > +++ b/arch/x86/kvm/lapic.c > @@ -1739,7 +1739,8 @@ void kvm_apic_post_state_restore(struct kvm_vcpu *vcpu, > if (kvm_x86_ops->hwapic_irr_update) > kvm_x86_ops->hwapic_irr_update(vcpu, > apic_find_highest_irr(apic)); > - kvm_x86_ops->hwapic_isr_update(vcpu->kvm, apic_find_highest_isr(apic)); > + if (kvm_apic_vid_enabled(vcpu->kvm)) > + kvm_x86_ops->hwapic_isr_update(vcpu->kvm, apic_find_highest_isr(apic)); > kvm_make_request(KVM_REQ_EVENT, vcpu); > kvm_rtc_eoi_tracking_restore_one(vcpu); > } > diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c > index 6a951d8..f0c16a9 100644 > --- a/arch/x86/kvm/vmx.c > +++ b/arch/x86/kvm/vmx.c > @@ -7406,9 +7406,6 @@ static void vmx_hwapic_isr_update(struct kvm *kvm, int isr) > u16 status; > u8 old; > > - if (!vmx_vm_has_apicv(kvm)) > - return; > - > if (isr == -1) > isr = 0; > > ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] kvm: x86: remove vmx_vm_has_apicv() outside of hwapic_isr_update() 2014-12-01 11:43 ` Paolo Bonzini @ 2014-12-19 2:32 ` Chen, Tiejun 2014-12-19 11:12 ` Paolo Bonzini 0 siblings, 1 reply; 6+ messages in thread From: Chen, Tiejun @ 2014-12-19 2:32 UTC (permalink / raw) To: Paolo Bonzini; +Cc: kvm On 2014/12/1 19:43, Paolo Bonzini wrote: > > > On 01/12/2014 10:28, Tiejun Chen wrote: >> In most cases calling hwapic_isr_update(), actually we always >> check if kvm_apic_vid_enabled() == 1, and also actually, >> kvm_apic_vid_enabled() >> -> kvm_x86_ops->vm_has_apicv() >> -> vmx_vm_has_apicv() or '0' in svm case >> >> So its unnecessary to recall this inside hwapic_isr_update(), here >> just remove vmx_vm_has_apicv() out and follow others. > > If you want to do this, please NULL out the function pointer instead, as > KVM already does for hwapic_irr_update. Are you saying something below? if (enable_apicv) ... else { kvm_x86_ops->hwapic_irr_update = NULL; But there's a little bit difference to NULL out hwapic_isr_update(), static int vmx_vm_has_apicv(struct kvm *kvm) { return enable_apicv && irqchip_in_kernel(kvm); } Yes, I can do something like this, static __init int hadware_setup(void) { ... if (enable_apicv) { ... if (!irqchip_in_kernel(kvm)) kvm_x86_ops->hwapic_isr_update = NULL; } else { ... kvm_x86_ops->hwapic_isr_update = NULL; But this means we have to revise hadware_setup() to get 'kvm' inside, then rebase other callers to hwapic_isr_update(), is it really good? Here what I will intend to do is trying to reduce some cost (reduplicate check) with a little code, so its may not be worth changing much more. Tiejun > > Paolo > >> Signed-off-by: Tiejun Chen <tiejun.chen@intel.com> >> --- >> arch/x86/kvm/lapic.c | 3 ++- >> arch/x86/kvm/vmx.c | 3 --- >> 2 files changed, 2 insertions(+), 4 deletions(-) >> >> diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c >> index e0e5642..2ddc426 100644 >> --- a/arch/x86/kvm/lapic.c >> +++ b/arch/x86/kvm/lapic.c >> @@ -1739,7 +1739,8 @@ void kvm_apic_post_state_restore(struct kvm_vcpu *vcpu, >> if (kvm_x86_ops->hwapic_irr_update) >> kvm_x86_ops->hwapic_irr_update(vcpu, >> apic_find_highest_irr(apic)); >> - kvm_x86_ops->hwapic_isr_update(vcpu->kvm, apic_find_highest_isr(apic)); >> + if (kvm_apic_vid_enabled(vcpu->kvm)) >> + kvm_x86_ops->hwapic_isr_update(vcpu->kvm, apic_find_highest_isr(apic)); >> kvm_make_request(KVM_REQ_EVENT, vcpu); >> kvm_rtc_eoi_tracking_restore_one(vcpu); >> } >> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c >> index 6a951d8..f0c16a9 100644 >> --- a/arch/x86/kvm/vmx.c >> +++ b/arch/x86/kvm/vmx.c >> @@ -7406,9 +7406,6 @@ static void vmx_hwapic_isr_update(struct kvm *kvm, int isr) >> u16 status; >> u8 old; >> >> - if (!vmx_vm_has_apicv(kvm)) >> - return; >> - >> if (isr == -1) >> isr = 0; >> >> > -- > To unsubscribe from this list: send the line "unsubscribe kvm" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] kvm: x86: remove vmx_vm_has_apicv() outside of hwapic_isr_update() 2014-12-19 2:32 ` Chen, Tiejun @ 2014-12-19 11:12 ` Paolo Bonzini 2014-12-22 9:01 ` Chen, Tiejun 0 siblings, 1 reply; 6+ messages in thread From: Paolo Bonzini @ 2014-12-19 11:12 UTC (permalink / raw) To: Chen, Tiejun; +Cc: kvm On 19/12/2014 03:32, Chen, Tiejun wrote: > > Are you saying something below? > > if (enable_apicv) > ... > else { > kvm_x86_ops->hwapic_irr_update = NULL; Yes. > But this means we have to revise hadware_setup() to get 'kvm' inside, This would not even be possible, since hardware_setup() is only called once. However, for the only caller of hwapic_isr_update (but presumably all of them, as is the case for hwapic_irr_update), you already know that irqchip_in_kernel(kvm) is true. You are in kvm_apic_post_state_restore, which takes a kvm_lapic_state, and no lapic exists if !irqchip_in_kernel(kvm). (Yes, irqchip_in_kernel) is a bit weird and tests pic_irqchip(kvm) instead, but it's the same. It tests pic_irqchip(kvm) only because the LAPIC is per-cpu and irqchip_in_kernel takes a struct kvm). So it's possible to NULL out hwapic_isr_update in hardware_setup. It simply shouldn't happen that you call hwapic_isr_update without the in-kernel irqchip. The kernel knows nothing about ISR/IRR without the in-kernel irqchip. Paolo > then rebase other callers to hwapic_isr_update(), is it really good? ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] kvm: x86: remove vmx_vm_has_apicv() outside of hwapic_isr_update() 2014-12-19 11:12 ` Paolo Bonzini @ 2014-12-22 9:01 ` Chen, Tiejun 2014-12-22 9:33 ` Paolo Bonzini 0 siblings, 1 reply; 6+ messages in thread From: Chen, Tiejun @ 2014-12-22 9:01 UTC (permalink / raw) To: Paolo Bonzini; +Cc: kvm On 2014/12/19 19:12, Paolo Bonzini wrote: > > > On 19/12/2014 03:32, Chen, Tiejun wrote: >> >> Are you saying something below? >> >> if (enable_apicv) >> ... >> else { >> kvm_x86_ops->hwapic_irr_update = NULL; > > Yes. > >> But this means we have to revise hadware_setup() to get 'kvm' inside, > > This would not even be possible, since hardware_setup() is only called once. Yeah. > > However, for the only caller of hwapic_isr_update (but presumably all of > them, as is the case for hwapic_irr_update), you already know that There are two other callers to hwapic_isr_update(), apic_set_isr() and apic_clear_isr(), but I think they still work here. > irqchip_in_kernel(kvm) is true. You are in kvm_apic_post_state_restore, > which takes a kvm_lapic_state, and no lapic exists if > !irqchip_in_kernel(kvm). > > (Yes, irqchip_in_kernel) is a bit weird and tests pic_irqchip(kvm) > instead, but it's the same. It tests pic_irqchip(kvm) only because the > LAPIC is per-cpu and irqchip_in_kernel takes a struct kvm). > > So it's possible to NULL out hwapic_isr_update in hardware_setup. It > simply shouldn't happen that you call hwapic_isr_update without the > in-kernel irqchip. The kernel knows nothing about ISR/IRR without the > in-kernel irqchip. Thanks for your kind elaboration which always benefits me. What about this revision as follows? kvm: x86: vmx: NULL out hwapic_isr_update() in case of !enable_apicv In most cases calling hwapic_isr_update(), we always check if kvm_apic_vid_enabled() == 1, but actually, kvm_apic_vid_enabled() -> kvm_x86_ops->vm_has_apicv() -> vmx_vm_has_apicv() or '0' in svm case -> return enable_apicv && irqchip_in_kernel(kvm) So its a little cost to recall vmx_vm_has_apicv() inside hwapic_isr_update(), here just NULL out hwapic_isr_update() in case of !enable_apicv inside hardware_setup() then make all related stuffs follow this. Note we don't check this under that condition of irqchip_in_kernel() since we should make sure definitely any caller don't work without in-kernel irqchip. Signed-off-by: Tiejun Chen <tiejun.chen@intel.com> --- arch/x86/kvm/lapic.c | 7 ++++--- arch/x86/kvm/vmx.c | 4 +--- 2 files changed, 5 insertions(+), 6 deletions(-) diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c index 4f0c0b9..eb4cd5e 100644 --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -402,7 +402,7 @@ static inline void apic_set_isr(int vec, struct kvm_lapic *apic) * because the processor can modify ISR under the hood. Instead * just set SVI. */ - if (unlikely(kvm_apic_vid_enabled(vcpu->kvm))) + if (unlikely(kvm_x86_ops->hwapic_isr_update)) kvm_x86_ops->hwapic_isr_update(vcpu->kvm, vec); else { ++apic->isr_count; @@ -450,7 +450,7 @@ static inline void apic_clear_isr(int vec, struct kvm_lapic *apic) * on the other hand isr_count and highest_isr_cache are unused * and must be left alone. */ - if (unlikely(kvm_apic_vid_enabled(vcpu->kvm))) + if (unlikely(kvm_x86_ops->hwapic_isr_update)) kvm_x86_ops->hwapic_isr_update(vcpu->kvm, apic_find_highest_isr(apic)); else { @@ -1742,7 +1742,8 @@ void kvm_apic_post_state_restore(struct kvm_vcpu *vcpu, if (kvm_x86_ops->hwapic_irr_update) kvm_x86_ops->hwapic_irr_update(vcpu, apic_find_highest_irr(apic)); - kvm_x86_ops->hwapic_isr_update(vcpu->kvm, apic_find_highest_isr(apic)); + if (kvm_x86_ops->hwapic_isr_update) + kvm_x86_ops->hwapic_isr_update(vcpu->kvm, apic_find_highest_isr(apic)); kvm_make_request(KVM_REQ_EVENT, vcpu); kvm_rtc_eoi_tracking_restore_one(vcpu); } diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 96c84a8..e378dff 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -5895,6 +5895,7 @@ static __init int hardware_setup(void) kvm_x86_ops->update_cr8_intercept = NULL; else { kvm_x86_ops->hwapic_irr_update = NULL; + kvm_x86_ops->hwapic_isr_update = NULL; kvm_x86_ops->deliver_posted_interrupt = NULL; kvm_x86_ops->sync_pir_to_irr = vmx_sync_pir_to_irr_dummy; } @@ -7471,9 +7472,6 @@ static void vmx_hwapic_isr_update(struct kvm *kvm, int isr) u16 status; u8 old; - if (!vmx_vm_has_apicv(kvm)) - return; - if (isr == -1) isr = 0; -- 1.9.1 I can send out as a patch if we have on any objections. Thanks Tiejun ^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH] kvm: x86: remove vmx_vm_has_apicv() outside of hwapic_isr_update() 2014-12-22 9:01 ` Chen, Tiejun @ 2014-12-22 9:33 ` Paolo Bonzini 0 siblings, 0 replies; 6+ messages in thread From: Paolo Bonzini @ 2014-12-22 9:33 UTC (permalink / raw) To: Chen, Tiejun; +Cc: kvm On 22/12/2014 10:01, Chen, Tiejun wrote: > I can send out as a patch if we have on any objections. No problem, I will apply it to kvm/queue. Paolo ^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2014-12-22 9:33 UTC | newest] Thread overview: 6+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2014-12-01 9:28 [PATCH] kvm: x86: remove vmx_vm_has_apicv() outside of hwapic_isr_update() Tiejun Chen 2014-12-01 11:43 ` Paolo Bonzini 2014-12-19 2:32 ` Chen, Tiejun 2014-12-19 11:12 ` Paolo Bonzini 2014-12-22 9:01 ` Chen, Tiejun 2014-12-22 9:33 ` Paolo Bonzini
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