* [PATCH v2 1/5] KVM: LAPIC: Introduce interrupt delivery fastpath
2020-04-23 9:01 [PATCH v2 0/5] KVM: VMX: Tscdeadline timer emulation fastpath Wanpeng Li
@ 2020-04-23 9:01 ` Wanpeng Li
2020-04-23 9:25 ` Paolo Bonzini
2020-04-23 9:01 ` [PATCH v2 2/5] KVM: X86: Introduce need_cancel_enter_guest helper Wanpeng Li
` (3 subsequent siblings)
4 siblings, 1 reply; 19+ messages in thread
From: Wanpeng Li @ 2020-04-23 9:01 UTC (permalink / raw)
To: linux-kernel, kvm
Cc: Paolo Bonzini, Sean Christopherson, Vitaly Kuznetsov, Wanpeng Li,
Jim Mattson, Joerg Roedel, Haiwei Li
From: Wanpeng Li <wanpengli@tencent.com>
Introduce interrupt delivery fastpath, I observe kvm_x86_ops.deliver_posted_interrupt()
has more latency then vmx_sync_pir_to_irr in my case, since it needs to wait
vmentry, after that it can handle external interrupt, ack the notification
vector, read posted-interrupt desciptor etc, it is slower than evaluate and
delivery during vmentry method. For non-APICv, inject directly since we will
not go though inject_pending_event().
Tested-by: Haiwei Li <lihaiwei@tencent.com>
Cc: Haiwei Li <lihaiwei@tencent.com>
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
---
arch/x86/include/asm/kvm_host.h | 1 +
arch/x86/kvm/lapic.c | 32 ++++++++++++++++++++++++++++++++
arch/x86/kvm/svm/avic.c | 5 +++++
arch/x86/kvm/svm/svm.c | 1 +
arch/x86/kvm/svm/svm.h | 1 +
arch/x86/kvm/vmx/vmx.c | 23 +++++++++++++++++------
6 files changed, 57 insertions(+), 6 deletions(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index f26df2c..f809763 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1157,6 +1157,7 @@ struct kvm_x86_ops {
void (*set_apic_access_page_addr)(struct kvm_vcpu *vcpu);
int (*deliver_posted_interrupt)(struct kvm_vcpu *vcpu, int vector);
int (*sync_pir_to_irr)(struct kvm_vcpu *vcpu);
+ bool (*pi_test_and_set_pir_on)(struct kvm_vcpu *vcpu, int vector);
int (*set_tss_addr)(struct kvm *kvm, unsigned int addr);
int (*set_identity_map_addr)(struct kvm *kvm, u64 ident_addr);
int (*get_tdp_level)(struct kvm_vcpu *vcpu);
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 38f7dc9..7703142 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -1259,6 +1259,30 @@ void kvm_apic_send_ipi(struct kvm_lapic *apic, u32 icr_low, u32 icr_high)
kvm_irq_delivery_to_apic(apic->vcpu->kvm, apic, &irq, NULL);
}
+static void fast_deliver_interrupt(struct kvm_lapic *apic, int vector)
+{
+ struct kvm_vcpu *vcpu = apic->vcpu;
+
+ kvm_lapic_clear_vector(vector, apic->regs + APIC_TMR);
+
+ if (vcpu->arch.apicv_active) {
+ if (kvm_x86_ops.pi_test_and_set_pir_on(vcpu, vector))
+ return;
+
+ kvm_x86_ops.sync_pir_to_irr(vcpu);
+ } else {
+ kvm_lapic_set_irr(vector, apic);
+ if (kvm_cpu_has_injectable_intr(vcpu)) {
+ if (kvm_x86_ops.interrupt_allowed(vcpu)) {
+ kvm_queue_interrupt(vcpu,
+ kvm_cpu_get_interrupt(vcpu), false);
+ kvm_x86_ops.set_irq(vcpu);
+ } else
+ kvm_x86_ops.enable_irq_window(vcpu);
+ }
+ }
+}
+
static u32 apic_get_tmcct(struct kvm_lapic *apic)
{
ktime_t remaining, now;
@@ -2351,6 +2375,14 @@ int kvm_apic_local_deliver(struct kvm_lapic *apic, int lvt_type)
return 0;
}
+static void kvm_apic_local_deliver_fast(struct kvm_lapic *apic, int lvt_type)
+{
+ u32 reg = kvm_lapic_get_reg(apic, lvt_type);
+
+ if (kvm_apic_hw_enabled(apic) && !(reg & APIC_LVT_MASKED))
+ fast_deliver_interrupt(apic, reg & APIC_VECTOR_MASK);
+}
+
void kvm_apic_nmi_wd_deliver(struct kvm_vcpu *vcpu)
{
struct kvm_lapic *apic = vcpu->arch.apic;
diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c
index e80daa9..ab9e0fd 100644
--- a/arch/x86/kvm/svm/avic.c
+++ b/arch/x86/kvm/svm/avic.c
@@ -905,6 +905,11 @@ int svm_update_pi_irte(struct kvm *kvm, unsigned int host_irq,
return ret;
}
+bool svm_pi_test_and_set_pir_on(struct kvm_vcpu *vcpu, int vector)
+{
+ return false;
+}
+
bool svm_check_apicv_inhibit_reasons(ulong bit)
{
ulong supported = BIT(APICV_INHIBIT_REASON_DISABLE) |
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index eb95283..fd0cab3 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -4035,6 +4035,7 @@ static struct kvm_x86_ops svm_x86_ops __initdata = {
.deliver_posted_interrupt = svm_deliver_avic_intr,
.dy_apicv_has_pending_interrupt = svm_dy_apicv_has_pending_interrupt,
.update_pi_irte = svm_update_pi_irte,
+ .pi_test_and_set_pir_on = svm_pi_test_and_set_pir_on,
.setup_mce = svm_setup_mce,
.smi_allowed = svm_smi_allowed,
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index ca95204..8a62a8b 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -457,6 +457,7 @@ int svm_update_pi_irte(struct kvm *kvm, unsigned int host_irq,
uint32_t guest_irq, bool set);
void svm_vcpu_blocking(struct kvm_vcpu *vcpu);
void svm_vcpu_unblocking(struct kvm_vcpu *vcpu);
+bool svm_pi_test_and_set_pir_on(struct kvm_vcpu *vcpu, int vector);
/* sev.c */
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 766303b..fd20cb3 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -3883,6 +3883,21 @@ static int vmx_deliver_nested_posted_interrupt(struct kvm_vcpu *vcpu,
}
return -1;
}
+
+static bool vmx_pi_test_and_set_pir_on(struct kvm_vcpu *vcpu, int vector)
+{
+ struct vcpu_vmx *vmx = to_vmx(vcpu);
+
+ if (pi_test_and_set_pir(vector, &vmx->pi_desc))
+ return true;
+
+ /* If a previous notification has sent the IPI, nothing to do. */
+ if (pi_test_and_set_on(&vmx->pi_desc))
+ return true;
+
+ return false;
+}
+
/*
* Send interrupt to vcpu via posted interrupt way.
* 1. If target vcpu is running(non-root mode), send posted interrupt
@@ -3892,7 +3907,6 @@ static int vmx_deliver_nested_posted_interrupt(struct kvm_vcpu *vcpu,
*/
static int vmx_deliver_posted_interrupt(struct kvm_vcpu *vcpu, int vector)
{
- struct vcpu_vmx *vmx = to_vmx(vcpu);
int r;
r = vmx_deliver_nested_posted_interrupt(vcpu, vector);
@@ -3902,11 +3916,7 @@ static int vmx_deliver_posted_interrupt(struct kvm_vcpu *vcpu, int vector)
if (!vcpu->arch.apicv_active)
return -1;
- if (pi_test_and_set_pir(vector, &vmx->pi_desc))
- return 0;
-
- /* If a previous notification has sent the IPI, nothing to do. */
- if (pi_test_and_set_on(&vmx->pi_desc))
+ if (vmx_pi_test_and_set_pir_on(vcpu, vector))
return 0;
if (!kvm_vcpu_trigger_posted_interrupt(vcpu, false))
@@ -7826,6 +7836,7 @@ static struct kvm_x86_ops vmx_x86_ops __initdata = {
.hwapic_isr_update = vmx_hwapic_isr_update,
.guest_apic_has_interrupt = vmx_guest_apic_has_interrupt,
.sync_pir_to_irr = vmx_sync_pir_to_irr,
+ .pi_test_and_set_pir_on = vmx_pi_test_and_set_pir_on,
.deliver_posted_interrupt = vmx_deliver_posted_interrupt,
.dy_apicv_has_pending_interrupt = vmx_dy_apicv_has_pending_interrupt,
--
2.7.4
^ permalink raw reply related [flat|nested] 19+ messages in thread* Re: [PATCH v2 1/5] KVM: LAPIC: Introduce interrupt delivery fastpath
2020-04-23 9:01 ` [PATCH v2 1/5] KVM: LAPIC: Introduce interrupt delivery fastpath Wanpeng Li
@ 2020-04-23 9:25 ` Paolo Bonzini
2020-04-23 9:35 ` Wanpeng Li
0 siblings, 1 reply; 19+ messages in thread
From: Paolo Bonzini @ 2020-04-23 9:25 UTC (permalink / raw)
To: Wanpeng Li, linux-kernel, kvm
Cc: Sean Christopherson, Vitaly Kuznetsov, Wanpeng Li, Jim Mattson,
Joerg Roedel, Haiwei Li
On 23/04/20 11:01, Wanpeng Li wrote:
> +static void fast_deliver_interrupt(struct kvm_lapic *apic, int vector)
> +{
> + struct kvm_vcpu *vcpu = apic->vcpu;
> +
> + kvm_lapic_clear_vector(vector, apic->regs + APIC_TMR);
> +
> + if (vcpu->arch.apicv_active) {
> + if (kvm_x86_ops.pi_test_and_set_pir_on(vcpu, vector))
> + return;
> +
> + kvm_x86_ops.sync_pir_to_irr(vcpu);
> + } else {
> + kvm_lapic_set_irr(vector, apic);
> + if (kvm_cpu_has_injectable_intr(vcpu)) {
> + if (kvm_x86_ops.interrupt_allowed(vcpu)) {
> + kvm_queue_interrupt(vcpu,
> + kvm_cpu_get_interrupt(vcpu), false);
> + kvm_x86_ops.set_irq(vcpu);
> + } else
> + kvm_x86_ops.enable_irq_window(vcpu);
> + }
> + }
> +}
> +
Ok, got it now. The problem is that deliver_posted_interrupt goes through
if (!kvm_vcpu_trigger_posted_interrupt(vcpu, false))
kvm_vcpu_kick(vcpu);
Would it help to make the above
if (vcpu != kvm_get_running_vcpu() &&
!kvm_vcpu_trigger_posted_interrupt(vcpu, false))
kvm_vcpu_kick(vcpu);
? If that is enough for the APICv case, it's good enough.
Paolo
^ permalink raw reply [flat|nested] 19+ messages in thread* Re: [PATCH v2 1/5] KVM: LAPIC: Introduce interrupt delivery fastpath
2020-04-23 9:25 ` Paolo Bonzini
@ 2020-04-23 9:35 ` Wanpeng Li
2020-04-23 9:39 ` Paolo Bonzini
0 siblings, 1 reply; 19+ messages in thread
From: Wanpeng Li @ 2020-04-23 9:35 UTC (permalink / raw)
To: Paolo Bonzini
Cc: LKML, kvm, Sean Christopherson, Vitaly Kuznetsov, Wanpeng Li,
Jim Mattson, Joerg Roedel, Haiwei Li
On Thu, 23 Apr 2020 at 17:25, Paolo Bonzini <pbonzini@redhat.com> wrote:
>
> On 23/04/20 11:01, Wanpeng Li wrote:
> > +static void fast_deliver_interrupt(struct kvm_lapic *apic, int vector)
> > +{
> > + struct kvm_vcpu *vcpu = apic->vcpu;
> > +
> > + kvm_lapic_clear_vector(vector, apic->regs + APIC_TMR);
> > +
> > + if (vcpu->arch.apicv_active) {
> > + if (kvm_x86_ops.pi_test_and_set_pir_on(vcpu, vector))
> > + return;
> > +
> > + kvm_x86_ops.sync_pir_to_irr(vcpu);
> > + } else {
> > + kvm_lapic_set_irr(vector, apic);
> > + if (kvm_cpu_has_injectable_intr(vcpu)) {
> > + if (kvm_x86_ops.interrupt_allowed(vcpu)) {
> > + kvm_queue_interrupt(vcpu,
> > + kvm_cpu_get_interrupt(vcpu), false);
> > + kvm_x86_ops.set_irq(vcpu);
> > + } else
> > + kvm_x86_ops.enable_irq_window(vcpu);
> > + }
> > + }
> > +}
> > +
>
> Ok, got it now. The problem is that deliver_posted_interrupt goes through
>
> if (!kvm_vcpu_trigger_posted_interrupt(vcpu, false))
> kvm_vcpu_kick(vcpu);
>
> Would it help to make the above
>
> if (vcpu != kvm_get_running_vcpu() &&
> !kvm_vcpu_trigger_posted_interrupt(vcpu, false))
> kvm_vcpu_kick(vcpu);
>
> ? If that is enough for the APICv case, it's good enough.
We will not exit from vmx_vcpu_run to vcpu_enter_guest, so it will not
help, right?
Wanpeng
^ permalink raw reply [flat|nested] 19+ messages in thread* Re: [PATCH v2 1/5] KVM: LAPIC: Introduce interrupt delivery fastpath
2020-04-23 9:35 ` Wanpeng Li
@ 2020-04-23 9:39 ` Paolo Bonzini
2020-04-23 9:44 ` Wanpeng Li
0 siblings, 1 reply; 19+ messages in thread
From: Paolo Bonzini @ 2020-04-23 9:39 UTC (permalink / raw)
To: Wanpeng Li
Cc: LKML, kvm, Sean Christopherson, Vitaly Kuznetsov, Wanpeng Li,
Jim Mattson, Joerg Roedel, Haiwei Li
On 23/04/20 11:35, Wanpeng Li wrote:
>> Ok, got it now. The problem is that deliver_posted_interrupt goes through
>>
>> if (!kvm_vcpu_trigger_posted_interrupt(vcpu, false))
>> kvm_vcpu_kick(vcpu);
>>
>> Would it help to make the above
>>
>> if (vcpu != kvm_get_running_vcpu() &&
>> !kvm_vcpu_trigger_posted_interrupt(vcpu, false))
>> kvm_vcpu_kick(vcpu);
>>
>> ? If that is enough for the APICv case, it's good enough.
> We will not exit from vmx_vcpu_run to vcpu_enter_guest, so it will not
> help, right?
Oh indeed---the call to sync_pir_to_irr is in vcpu_enter_guest. You can
add it to patch 3 right before "goto cont_run", since AMD does not need it.
Paolo
^ permalink raw reply [flat|nested] 19+ messages in thread
* Re: [PATCH v2 1/5] KVM: LAPIC: Introduce interrupt delivery fastpath
2020-04-23 9:39 ` Paolo Bonzini
@ 2020-04-23 9:44 ` Wanpeng Li
2020-04-23 9:52 ` Paolo Bonzini
0 siblings, 1 reply; 19+ messages in thread
From: Wanpeng Li @ 2020-04-23 9:44 UTC (permalink / raw)
To: Paolo Bonzini
Cc: LKML, kvm, Sean Christopherson, Vitaly Kuznetsov, Wanpeng Li,
Jim Mattson, Joerg Roedel, Haiwei Li
On Thu, 23 Apr 2020 at 17:41, Paolo Bonzini <pbonzini@redhat.com> wrote:
>
> On 23/04/20 11:35, Wanpeng Li wrote:
> >> Ok, got it now. The problem is that deliver_posted_interrupt goes through
> >>
> >> if (!kvm_vcpu_trigger_posted_interrupt(vcpu, false))
> >> kvm_vcpu_kick(vcpu);
> >>
> >> Would it help to make the above
> >>
> >> if (vcpu != kvm_get_running_vcpu() &&
> >> !kvm_vcpu_trigger_posted_interrupt(vcpu, false))
> >> kvm_vcpu_kick(vcpu);
> >>
> >> ? If that is enough for the APICv case, it's good enough.
> > We will not exit from vmx_vcpu_run to vcpu_enter_guest, so it will not
> > help, right?
>
> Oh indeed---the call to sync_pir_to_irr is in vcpu_enter_guest. You can
> add it to patch 3 right before "goto cont_run", since AMD does not need it.
Just move kvm_x86_ops.sync_pir_to_irr(vcpu)? How about the set pir/on
part for APICv and non-APICv part in fast_deliver_interrupt()?
Wanpeng
^ permalink raw reply [flat|nested] 19+ messages in thread* Re: [PATCH v2 1/5] KVM: LAPIC: Introduce interrupt delivery fastpath
2020-04-23 9:44 ` Wanpeng Li
@ 2020-04-23 9:52 ` Paolo Bonzini
0 siblings, 0 replies; 19+ messages in thread
From: Paolo Bonzini @ 2020-04-23 9:52 UTC (permalink / raw)
To: Wanpeng Li
Cc: LKML, kvm, Sean Christopherson, Vitaly Kuznetsov, Wanpeng Li,
Jim Mattson, Joerg Roedel, Haiwei Li
On 23/04/20 11:44, Wanpeng Li wrote:
>>>> Would it help to make the above
>>>>
>>>> if (vcpu != kvm_get_running_vcpu() &&
>>>> !kvm_vcpu_trigger_posted_interrupt(vcpu, false))
>>>> kvm_vcpu_kick(vcpu);
>>>>
>>>> ? If that is enough for the APICv case, it's good enough.
>>>
>>> We will not exit from vmx_vcpu_run to vcpu_enter_guest, so it will not
>>> help, right?
>>
>> Oh indeed---the call to sync_pir_to_irr is in vcpu_enter_guest. You can
>> add it to patch 3 right before "goto cont_run", since AMD does not need it.
>
> Just move kvm_x86_ops.sync_pir_to_irr(vcpu)? How about the set pir/on
> part for APICv and non-APICv part in fast_deliver_interrupt()?
That should be handled by deliver_posted_interrupt with no performance
penalty, if you add "vcpu != kvm_get_running_vcpu()" before it calls
kvm_vcpu_trigger_posted_interrupt.
Paolo
^ permalink raw reply [flat|nested] 19+ messages in thread
* [PATCH v2 2/5] KVM: X86: Introduce need_cancel_enter_guest helper
2020-04-23 9:01 [PATCH v2 0/5] KVM: VMX: Tscdeadline timer emulation fastpath Wanpeng Li
2020-04-23 9:01 ` [PATCH v2 1/5] KVM: LAPIC: Introduce interrupt delivery fastpath Wanpeng Li
@ 2020-04-23 9:01 ` Wanpeng Li
2020-04-23 9:01 ` [PATCH v2 3/5] KVM: VMX: Introduce generic fastpath handler Wanpeng Li
` (2 subsequent siblings)
4 siblings, 0 replies; 19+ messages in thread
From: Wanpeng Li @ 2020-04-23 9:01 UTC (permalink / raw)
To: linux-kernel, kvm
Cc: Paolo Bonzini, Sean Christopherson, Vitaly Kuznetsov, Wanpeng Li,
Jim Mattson, Joerg Roedel, Haiwei Li
From: Wanpeng Li <wanpengli@tencent.com>
Introduce need_cancel_enter_guest() helper, it will be used by later patches.
Tested-by: Haiwei Li <lihaiwei@tencent.com>
Cc: Haiwei Li <lihaiwei@tencent.com>
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
---
arch/x86/kvm/x86.c | 10 ++++++++--
arch/x86/kvm/x86.h | 1 +
2 files changed, 9 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 59958ce..4561104 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1581,6 +1581,13 @@ int kvm_emulate_wrmsr(struct kvm_vcpu *vcpu)
}
EXPORT_SYMBOL_GPL(kvm_emulate_wrmsr);
+bool kvm_need_cancel_enter_guest(struct kvm_vcpu *vcpu)
+{
+ return (vcpu->mode == EXITING_GUEST_MODE || kvm_request_pending(vcpu)
+ || need_resched() || signal_pending(current));
+}
+EXPORT_SYMBOL_GPL(kvm_need_cancel_enter_guest);
+
/*
* The fast path for frequent and performance sensitive wrmsr emulation,
* i.e. the sending of IPI, sending IPI early in the VM-Exit flow reduces
@@ -8373,8 +8380,7 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
if (kvm_lapic_enabled(vcpu) && vcpu->arch.apicv_active)
kvm_x86_ops.sync_pir_to_irr(vcpu);
- if (vcpu->mode == EXITING_GUEST_MODE || kvm_request_pending(vcpu)
- || need_resched() || signal_pending(current)) {
+ if (kvm_need_cancel_enter_guest(vcpu)) {
vcpu->mode = OUTSIDE_GUEST_MODE;
smp_wmb();
local_irq_enable();
diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
index 7b5ed8e..1906e7e 100644
--- a/arch/x86/kvm/x86.h
+++ b/arch/x86/kvm/x86.h
@@ -364,5 +364,6 @@ static inline bool kvm_dr7_valid(u64 data)
void kvm_load_guest_xsave_state(struct kvm_vcpu *vcpu);
void kvm_load_host_xsave_state(struct kvm_vcpu *vcpu);
u64 kvm_spec_ctrl_valid_bits(struct kvm_vcpu *vcpu);
+bool kvm_need_cancel_enter_guest(struct kvm_vcpu *vcpu);
#endif
--
2.7.4
^ permalink raw reply related [flat|nested] 19+ messages in thread* [PATCH v2 3/5] KVM: VMX: Introduce generic fastpath handler
2020-04-23 9:01 [PATCH v2 0/5] KVM: VMX: Tscdeadline timer emulation fastpath Wanpeng Li
2020-04-23 9:01 ` [PATCH v2 1/5] KVM: LAPIC: Introduce interrupt delivery fastpath Wanpeng Li
2020-04-23 9:01 ` [PATCH v2 2/5] KVM: X86: Introduce need_cancel_enter_guest helper Wanpeng Li
@ 2020-04-23 9:01 ` Wanpeng Li
2020-04-23 9:01 ` [PATCH v2 4/5] KVM: X86: TSCDEADLINE MSR emulation fastpath Wanpeng Li
2020-04-23 9:01 ` [PATCH v2 5/5] KVM: VMX: Handle preemption timer fastpath Wanpeng Li
4 siblings, 0 replies; 19+ messages in thread
From: Wanpeng Li @ 2020-04-23 9:01 UTC (permalink / raw)
To: linux-kernel, kvm
Cc: Paolo Bonzini, Sean Christopherson, Vitaly Kuznetsov, Wanpeng Li,
Jim Mattson, Joerg Roedel, Haiwei Li
From: Wanpeng Li <wanpengli@tencent.com>
Introduce generic fastpath handler to handle MSR fastpath, VMX-preemption
timer fastpath etc.
Tested-by: Haiwei Li <lihaiwei@tencent.com>
Cc: Haiwei Li <lihaiwei@tencent.com>
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
---
arch/x86/include/asm/kvm_host.h | 1 +
arch/x86/kvm/vmx/vmx.c | 24 +++++++++++++++++++-----
2 files changed, 20 insertions(+), 5 deletions(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index f809763..bcddf93 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -188,6 +188,7 @@ enum {
enum exit_fastpath_completion {
EXIT_FASTPATH_NONE,
EXIT_FASTPATH_SKIP_EMUL_INS,
+ EXIT_FASTPATH_CONT_RUN,
};
struct x86_emulate_ctxt;
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index fd20cb3..2613e58 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -6569,6 +6569,20 @@ void vmx_update_host_rsp(struct vcpu_vmx *vmx, unsigned long host_rsp)
}
}
+static enum exit_fastpath_completion vmx_exit_handlers_fastpath(struct kvm_vcpu *vcpu)
+{
+ if (!is_guest_mode(vcpu)) {
+ switch (to_vmx(vcpu)->exit_reason) {
+ case EXIT_REASON_MSR_WRITE:
+ return handle_fastpath_set_msr_irqoff(vcpu);
+ default:
+ return EXIT_FASTPATH_NONE;
+ }
+ }
+
+ return EXIT_FASTPATH_NONE;
+}
+
bool __vmx_vcpu_run(struct vcpu_vmx *vmx, unsigned long *regs, bool launched);
static enum exit_fastpath_completion vmx_vcpu_run(struct kvm_vcpu *vcpu)
@@ -6577,6 +6591,7 @@ static enum exit_fastpath_completion vmx_vcpu_run(struct kvm_vcpu *vcpu)
struct vcpu_vmx *vmx = to_vmx(vcpu);
unsigned long cr3, cr4;
+cont_run:
/* Record the guest's net vcpu time for enforced NMI injections. */
if (unlikely(!enable_vnmi &&
vmx->loaded_vmcs->soft_vnmi_blocked))
@@ -6743,17 +6758,16 @@ static enum exit_fastpath_completion vmx_vcpu_run(struct kvm_vcpu *vcpu)
if (unlikely(vmx->exit_reason & VMX_EXIT_REASONS_FAILED_VMENTRY))
return EXIT_FASTPATH_NONE;
- if (!is_guest_mode(vcpu) && vmx->exit_reason == EXIT_REASON_MSR_WRITE)
- exit_fastpath = handle_fastpath_set_msr_irqoff(vcpu);
- else
- exit_fastpath = EXIT_FASTPATH_NONE;
-
vmx->loaded_vmcs->launched = 1;
vmx->idt_vectoring_info = vmcs_read32(IDT_VECTORING_INFO_FIELD);
vmx_recover_nmi_blocking(vmx);
vmx_complete_interrupts(vmx);
+ exit_fastpath = vmx_exit_handlers_fastpath(vcpu);
+ if (exit_fastpath == EXIT_FASTPATH_CONT_RUN)
+ goto cont_run;
+
return exit_fastpath;
}
--
2.7.4
^ permalink raw reply related [flat|nested] 19+ messages in thread* [PATCH v2 4/5] KVM: X86: TSCDEADLINE MSR emulation fastpath
2020-04-23 9:01 [PATCH v2 0/5] KVM: VMX: Tscdeadline timer emulation fastpath Wanpeng Li
` (2 preceding siblings ...)
2020-04-23 9:01 ` [PATCH v2 3/5] KVM: VMX: Introduce generic fastpath handler Wanpeng Li
@ 2020-04-23 9:01 ` Wanpeng Li
2020-04-23 9:37 ` Paolo Bonzini
2020-04-23 9:01 ` [PATCH v2 5/5] KVM: VMX: Handle preemption timer fastpath Wanpeng Li
4 siblings, 1 reply; 19+ messages in thread
From: Wanpeng Li @ 2020-04-23 9:01 UTC (permalink / raw)
To: linux-kernel, kvm
Cc: Paolo Bonzini, Sean Christopherson, Vitaly Kuznetsov, Wanpeng Li,
Jim Mattson, Joerg Roedel, Haiwei Li
From: Wanpeng Li <wanpengli@tencent.com>
This patch implements tscdealine msr emulation fastpath, after wrmsr
tscdeadline vmexit, handle it as soon as possible and vmentry immediately
without checking various kvm stuff when possible.
Tested-by: Haiwei Li <lihaiwei@tencent.com>
Cc: Haiwei Li <lihaiwei@tencent.com>
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
---
arch/x86/kvm/lapic.c | 47 ++++++++++++++++++++++++++++++++++++++++++++---
arch/x86/kvm/lapic.h | 1 +
arch/x86/kvm/x86.c | 32 ++++++++++++++++++++++++++------
3 files changed, 71 insertions(+), 9 deletions(-)
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 7703142..d652bd9 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -1898,6 +1898,8 @@ void kvm_lapic_expired_hv_timer(struct kvm_vcpu *vcpu)
}
EXPORT_SYMBOL_GPL(kvm_lapic_expired_hv_timer);
+static void kvm_inject_apic_timer_irqs_fast(struct kvm_vcpu *vcpu);
+
void kvm_lapic_switch_to_hv_timer(struct kvm_vcpu *vcpu)
{
restart_apic_timer(vcpu->arch.apic);
@@ -2189,17 +2191,48 @@ u64 kvm_get_lapic_tscdeadline_msr(struct kvm_vcpu *vcpu)
return apic->lapic_timer.tscdeadline;
}
-void kvm_set_lapic_tscdeadline_msr(struct kvm_vcpu *vcpu, u64 data)
+static int __kvm_set_lapic_tscdeadline_msr(struct kvm_vcpu *vcpu, u64 data)
{
struct kvm_lapic *apic = vcpu->arch.apic;
if (!lapic_in_kernel(vcpu) || apic_lvtt_oneshot(apic) ||
apic_lvtt_period(apic))
- return;
+ return 0;
hrtimer_cancel(&apic->lapic_timer.timer);
apic->lapic_timer.tscdeadline = data;
- start_apic_timer(apic);
+
+ return 1;
+}
+
+void kvm_set_lapic_tscdeadline_msr(struct kvm_vcpu *vcpu, u64 data)
+{
+ if (__kvm_set_lapic_tscdeadline_msr(vcpu, data))
+ start_apic_timer(vcpu->arch.apic);
+}
+
+static int tscdeadline_expired_timer_fast(struct kvm_vcpu *vcpu)
+{
+ if (kvm_check_request(KVM_REQ_PENDING_TIMER, vcpu)) {
+ kvm_clear_request(KVM_REQ_PENDING_TIMER, vcpu);
+ kvm_inject_apic_timer_irqs_fast(vcpu);
+ atomic_set(&vcpu->arch.apic->lapic_timer.pending, 0);
+ }
+
+ return 0;
+}
+
+int kvm_set_lapic_tscdeadline_msr_fast(struct kvm_vcpu *vcpu, u64 data)
+{
+ struct kvm_lapic *apic = vcpu->arch.apic;
+
+ if (__kvm_set_lapic_tscdeadline_msr(vcpu, data)) {
+ atomic_set(&apic->lapic_timer.pending, 0);
+ if (start_hv_timer(apic))
+ return tscdeadline_expired_timer_fast(vcpu);
+ }
+
+ return 1;
}
void kvm_lapic_set_tpr(struct kvm_vcpu *vcpu, unsigned long cr8)
@@ -2492,6 +2525,14 @@ void kvm_inject_apic_timer_irqs(struct kvm_vcpu *vcpu)
}
}
+static void kvm_inject_apic_timer_irqs_fast(struct kvm_vcpu *vcpu)
+{
+ struct kvm_lapic *apic = vcpu->arch.apic;
+
+ kvm_apic_local_deliver_fast(apic, APIC_LVTT);
+ apic->lapic_timer.tscdeadline = 0;
+}
+
int kvm_get_apic_interrupt(struct kvm_vcpu *vcpu)
{
int vector = kvm_apic_has_interrupt(vcpu);
diff --git a/arch/x86/kvm/lapic.h b/arch/x86/kvm/lapic.h
index 7f15f9e..5ef1364 100644
--- a/arch/x86/kvm/lapic.h
+++ b/arch/x86/kvm/lapic.h
@@ -251,6 +251,7 @@ void kvm_lapic_expired_hv_timer(struct kvm_vcpu *vcpu);
bool kvm_lapic_hv_timer_in_use(struct kvm_vcpu *vcpu);
void kvm_lapic_restart_hv_timer(struct kvm_vcpu *vcpu);
bool kvm_can_post_timer_interrupt(struct kvm_vcpu *vcpu);
+int kvm_set_lapic_tscdeadline_msr_fast(struct kvm_vcpu *vcpu, u64 data);
static inline enum lapic_mode kvm_apic_mode(u64 apic_base)
{
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 4561104..112f1c4 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1616,27 +1616,47 @@ static int handle_fastpath_set_x2apic_icr_irqoff(struct kvm_vcpu *vcpu, u64 data
return 1;
}
+static int handle_fastpath_set_tscdeadline(struct kvm_vcpu *vcpu, u64 data)
+{
+ if (!kvm_x86_ops.set_hv_timer ||
+ kvm_mwait_in_guest(vcpu->kvm) ||
+ kvm_can_post_timer_interrupt(vcpu))
+ return 1;
+
+ return kvm_set_lapic_tscdeadline_msr_fast(vcpu, data);
+}
+
enum exit_fastpath_completion handle_fastpath_set_msr_irqoff(struct kvm_vcpu *vcpu)
{
u32 msr = kvm_rcx_read(vcpu);
u64 data;
- int ret = 0;
+ int ret = EXIT_FASTPATH_NONE;
switch (msr) {
case APIC_BASE_MSR + (APIC_ICR >> 4):
data = kvm_read_edx_eax(vcpu);
- ret = handle_fastpath_set_x2apic_icr_irqoff(vcpu, data);
+ if (!handle_fastpath_set_x2apic_icr_irqoff(vcpu, data))
+ ret = EXIT_FASTPATH_SKIP_EMUL_INS;
+ break;
+ case MSR_IA32_TSCDEADLINE:
+ if (!(kvm_need_cancel_enter_guest(vcpu) ||
+ kvm_event_needs_reinjection(vcpu))) {
+ data = kvm_read_edx_eax(vcpu);
+ if (!handle_fastpath_set_tscdeadline(vcpu, data))
+ ret = EXIT_FASTPATH_CONT_RUN;
+ }
break;
default:
- return EXIT_FASTPATH_NONE;
+ ret = EXIT_FASTPATH_NONE;
}
- if (!ret) {
+ if (ret != EXIT_FASTPATH_NONE) {
trace_kvm_msr_write(msr, data);
- return EXIT_FASTPATH_SKIP_EMUL_INS;
+ if (ret == EXIT_FASTPATH_CONT_RUN)
+ kvm_skip_emulated_instruction(vcpu);
}
- return EXIT_FASTPATH_NONE;
+ return ret;
}
EXPORT_SYMBOL_GPL(handle_fastpath_set_msr_irqoff);
--
2.7.4
^ permalink raw reply related [flat|nested] 19+ messages in thread* Re: [PATCH v2 4/5] KVM: X86: TSCDEADLINE MSR emulation fastpath
2020-04-23 9:01 ` [PATCH v2 4/5] KVM: X86: TSCDEADLINE MSR emulation fastpath Wanpeng Li
@ 2020-04-23 9:37 ` Paolo Bonzini
2020-04-23 9:54 ` Wanpeng Li
0 siblings, 1 reply; 19+ messages in thread
From: Paolo Bonzini @ 2020-04-23 9:37 UTC (permalink / raw)
To: Wanpeng Li, linux-kernel, kvm
Cc: Sean Christopherson, Vitaly Kuznetsov, Wanpeng Li, Jim Mattson,
Joerg Roedel, Haiwei Li
On 23/04/20 11:01, Wanpeng Li wrote:
> +
> +void kvm_set_lapic_tscdeadline_msr(struct kvm_vcpu *vcpu, u64 data)
> +{
> + if (__kvm_set_lapic_tscdeadline_msr(vcpu, data))
> + start_apic_timer(vcpu->arch.apic);
> +}
> +
> +int kvm_set_lapic_tscdeadline_msr_fast(struct kvm_vcpu *vcpu, u64 data)
> +{
> + struct kvm_lapic *apic = vcpu->arch.apic;
> +
> + if (__kvm_set_lapic_tscdeadline_msr(vcpu, data)) {
> + atomic_set(&apic->lapic_timer.pending, 0);
> + if (start_hv_timer(apic))
> + return tscdeadline_expired_timer_fast(vcpu);
> + }
> +
> + return 1;
> }
>
> +static int tscdeadline_expired_timer_fast(struct kvm_vcpu *vcpu)
> +{
> + if (kvm_check_request(KVM_REQ_PENDING_TIMER, vcpu)) {
> + kvm_clear_request(KVM_REQ_PENDING_TIMER, vcpu);
> + kvm_inject_apic_timer_irqs_fast(vcpu);
> + atomic_set(&vcpu->arch.apic->lapic_timer.pending, 0);
> + }
> +
> + return 0;
> +}
This could also be handled in apic_timer_expired. For example you can
add an argument from_timer_fn and do
if (!from_timer_fn) {
WARN_ON(kvm_get_running_vcpu() != vcpu);
kvm_inject_apic_timer_irqs_fast(vcpu);
return;
}
if (kvm_use_posted_timer_interrupt(apic->vcpu)) {
...
}
atomic_inc(&apic->lapic_timer.pending);
kvm_set_pending_timer(vcpu);
and then you don't need kvm_set_lapic_tscdeadline_msr_fast and
everything else. Anyway thanks, this is already much better.
Paoo
^ permalink raw reply [flat|nested] 19+ messages in thread* Re: [PATCH v2 4/5] KVM: X86: TSCDEADLINE MSR emulation fastpath
2020-04-23 9:37 ` Paolo Bonzini
@ 2020-04-23 9:54 ` Wanpeng Li
2020-04-23 10:28 ` Paolo Bonzini
0 siblings, 1 reply; 19+ messages in thread
From: Wanpeng Li @ 2020-04-23 9:54 UTC (permalink / raw)
To: Paolo Bonzini
Cc: LKML, kvm, Sean Christopherson, Vitaly Kuznetsov, Wanpeng Li,
Jim Mattson, Joerg Roedel, Haiwei Li
On Thu, 23 Apr 2020 at 17:39, Paolo Bonzini <pbonzini@redhat.com> wrote:
>
> On 23/04/20 11:01, Wanpeng Li wrote:
> > +
> > +void kvm_set_lapic_tscdeadline_msr(struct kvm_vcpu *vcpu, u64 data)
> > +{
> > + if (__kvm_set_lapic_tscdeadline_msr(vcpu, data))
> > + start_apic_timer(vcpu->arch.apic);
> > +}
> > +
> > +int kvm_set_lapic_tscdeadline_msr_fast(struct kvm_vcpu *vcpu, u64 data)
> > +{
> > + struct kvm_lapic *apic = vcpu->arch.apic;
> > +
> > + if (__kvm_set_lapic_tscdeadline_msr(vcpu, data)) {
> > + atomic_set(&apic->lapic_timer.pending, 0);
> > + if (start_hv_timer(apic))
> > + return tscdeadline_expired_timer_fast(vcpu);
> > + }
> > +
> > + return 1;
> > }
> >
> > +static int tscdeadline_expired_timer_fast(struct kvm_vcpu *vcpu)
> > +{
> > + if (kvm_check_request(KVM_REQ_PENDING_TIMER, vcpu)) {
> > + kvm_clear_request(KVM_REQ_PENDING_TIMER, vcpu);
> > + kvm_inject_apic_timer_irqs_fast(vcpu);
> > + atomic_set(&vcpu->arch.apic->lapic_timer.pending, 0);
> > + }
> > +
> > + return 0;
> > +}
>
> This could also be handled in apic_timer_expired. For example you can
> add an argument from_timer_fn and do
>
> if (!from_timer_fn) {
> WARN_ON(kvm_get_running_vcpu() != vcpu);
> kvm_inject_apic_timer_irqs_fast(vcpu);
> return;
> }
>
> if (kvm_use_posted_timer_interrupt(apic->vcpu)) {
> ...
> }
> atomic_inc(&apic->lapic_timer.pending);
> kvm_set_pending_timer(vcpu);
>
> and then you don't need kvm_set_lapic_tscdeadline_msr_fast and
I guess you mean don't need tscdeadline_expired_timer_fast().
Wanpeng
^ permalink raw reply [flat|nested] 19+ messages in thread* Re: [PATCH v2 4/5] KVM: X86: TSCDEADLINE MSR emulation fastpath
2020-04-23 9:54 ` Wanpeng Li
@ 2020-04-23 10:28 ` Paolo Bonzini
0 siblings, 0 replies; 19+ messages in thread
From: Paolo Bonzini @ 2020-04-23 10:28 UTC (permalink / raw)
To: Wanpeng Li
Cc: LKML, kvm, Sean Christopherson, Vitaly Kuznetsov, Wanpeng Li,
Jim Mattson, Joerg Roedel, Haiwei Li
On 23/04/20 11:54, Wanpeng Li wrote:
>> and then you don't need kvm_set_lapic_tscdeadline_msr_fast and
>
> I guess you mean don't need tscdeadline_expired_timer_fast().
Both.
Paolo
^ permalink raw reply [flat|nested] 19+ messages in thread
* [PATCH v2 5/5] KVM: VMX: Handle preemption timer fastpath
2020-04-23 9:01 [PATCH v2 0/5] KVM: VMX: Tscdeadline timer emulation fastpath Wanpeng Li
` (3 preceding siblings ...)
2020-04-23 9:01 ` [PATCH v2 4/5] KVM: X86: TSCDEADLINE MSR emulation fastpath Wanpeng Li
@ 2020-04-23 9:01 ` Wanpeng Li
2020-04-23 9:40 ` Paolo Bonzini
2020-04-26 7:38 ` kbuild test robot
4 siblings, 2 replies; 19+ messages in thread
From: Wanpeng Li @ 2020-04-23 9:01 UTC (permalink / raw)
To: linux-kernel, kvm
Cc: Paolo Bonzini, Sean Christopherson, Vitaly Kuznetsov, Wanpeng Li,
Jim Mattson, Joerg Roedel, Haiwei Li
From: Wanpeng Li <wanpengli@tencent.com>
This patch implements handle preemption timer fastpath, after timer fire
due to VMX-preemption timer counts down to zero, handle it as soon as
possible and vmentry immediately without checking various kvm stuff when
possible.
Testing on SKX Server.
cyclictest in guest(w/o mwait exposed, adaptive advance lapic timer is default -1):
5632.75ns -> 4559.25ns, 19%
kvm-unit-test/vmexit.flat:
w/o APICv, w/o advance timer:
tscdeadline_immed: 4780.75 -> 3851 19.4%
tscdeadline: 7474 -> 6528.5 12.7%
w/o APICv, w/ adaptive advance timer default -1:
tscdeadline_immed: 4845.75 -> 3930.5 18.9%
tscdeadline: 6048 -> 5871.75 3%
w/ APICv, w/o avanced timer:
tscdeadline_immed: 2919 -> 2467.75 15.5%
tscdeadline: 5661.75 -> 5188.25 8.4%
w/ APICv, w/ adaptive advance timer default -1:
tscdeadline_immed: 3018.5 -> 2561 15.2%
tscdeadline: 4663.75 -> 4537 2.7%
Tested-by: Haiwei Li <lihaiwei@tencent.com>
Cc: Haiwei Li <lihaiwei@tencent.com>
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
---
arch/x86/kvm/lapic.c | 19 +++++++++++++++++++
arch/x86/kvm/lapic.h | 1 +
arch/x86/kvm/vmx/vmx.c | 22 ++++++++++++++++++++++
3 files changed, 42 insertions(+)
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index d652bd9..2741931 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -1899,6 +1899,25 @@ void kvm_lapic_expired_hv_timer(struct kvm_vcpu *vcpu)
EXPORT_SYMBOL_GPL(kvm_lapic_expired_hv_timer);
static void kvm_inject_apic_timer_irqs_fast(struct kvm_vcpu *vcpu);
+bool kvm_lapic_expired_hv_timer_fast(struct kvm_vcpu *vcpu)
+{
+ struct kvm_lapic *apic = vcpu->arch.apic;
+ struct kvm_timer *ktimer = &apic->lapic_timer;
+
+ if (!apic_lvtt_tscdeadline(apic) ||
+ !ktimer->hv_timer_in_use ||
+ atomic_read(&ktimer->pending))
+ return 0;
+
+ WARN_ON(swait_active(&vcpu->wq));
+ cancel_hv_timer(apic);
+
+ ktimer->expired_tscdeadline = ktimer->tscdeadline;
+ kvm_inject_apic_timer_irqs_fast(vcpu);
+
+ return 1;
+}
+EXPORT_SYMBOL_GPL(kvm_lapic_expired_hv_timer_fast);
void kvm_lapic_switch_to_hv_timer(struct kvm_vcpu *vcpu)
{
diff --git a/arch/x86/kvm/lapic.h b/arch/x86/kvm/lapic.h
index 5ef1364..1b5abd8 100644
--- a/arch/x86/kvm/lapic.h
+++ b/arch/x86/kvm/lapic.h
@@ -252,6 +252,7 @@ bool kvm_lapic_hv_timer_in_use(struct kvm_vcpu *vcpu);
void kvm_lapic_restart_hv_timer(struct kvm_vcpu *vcpu);
bool kvm_can_post_timer_interrupt(struct kvm_vcpu *vcpu);
int kvm_set_lapic_tscdeadline_msr_fast(struct kvm_vcpu *vcpu, u64 data);
+bool kvm_lapic_expired_hv_timer_fast(struct kvm_vcpu *vcpu);
static inline enum lapic_mode kvm_apic_mode(u64 apic_base)
{
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 2613e58..527d1c1 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -6569,12 +6569,34 @@ void vmx_update_host_rsp(struct vcpu_vmx *vmx, unsigned long host_rsp)
}
}
+static void vmx_cancel_hv_timer(struct kvm_vcpu *vcpu);
+
+static enum exit_fastpath_completion handle_fastpath_preemption_timer(struct kvm_vcpu *vcpu)
+{
+ struct vcpu_vmx *vmx = to_vmx(vcpu);
+
+ if (kvm_need_cancel_enter_guest(vcpu) ||
+ kvm_event_needs_reinjection(vcpu))
+ return EXIT_FASTPATH_NONE;
+
+ if (!vmx->req_immediate_exit &&
+ !unlikely(vmx->loaded_vmcs->hv_timer_soft_disabled) &&
+ kvm_lapic_expired_hv_timer_fast(vcpu)) {
+ trace_kvm_exit(EXIT_REASON_PREEMPTION_TIMER, vcpu, KVM_ISA_VMX);
+ return EXIT_FASTPATH_CONT_RUN;
+ }
+
+ return EXIT_FASTPATH_NONE;
+}
+
static enum exit_fastpath_completion vmx_exit_handlers_fastpath(struct kvm_vcpu *vcpu)
{
if (!is_guest_mode(vcpu)) {
switch (to_vmx(vcpu)->exit_reason) {
case EXIT_REASON_MSR_WRITE:
return handle_fastpath_set_msr_irqoff(vcpu);
+ case EXIT_REASON_PREEMPTION_TIMER:
+ return handle_fastpath_preemption_timer(vcpu);
default:
return EXIT_FASTPATH_NONE;
}
--
2.7.4
^ permalink raw reply related [flat|nested] 19+ messages in thread* Re: [PATCH v2 5/5] KVM: VMX: Handle preemption timer fastpath
2020-04-23 9:01 ` [PATCH v2 5/5] KVM: VMX: Handle preemption timer fastpath Wanpeng Li
@ 2020-04-23 9:40 ` Paolo Bonzini
2020-04-23 9:56 ` Wanpeng Li
2020-04-26 7:38 ` kbuild test robot
1 sibling, 1 reply; 19+ messages in thread
From: Paolo Bonzini @ 2020-04-23 9:40 UTC (permalink / raw)
To: Wanpeng Li, linux-kernel, kvm
Cc: Sean Christopherson, Vitaly Kuznetsov, Wanpeng Li, Jim Mattson,
Joerg Roedel, Haiwei Li
On 23/04/20 11:01, Wanpeng Li wrote:
> +bool kvm_lapic_expired_hv_timer_fast(struct kvm_vcpu *vcpu)
> +{
> + struct kvm_lapic *apic = vcpu->arch.apic;
> + struct kvm_timer *ktimer = &apic->lapic_timer;
> +
> + if (!apic_lvtt_tscdeadline(apic) ||
> + !ktimer->hv_timer_in_use ||
> + atomic_read(&ktimer->pending))
> + return 0;
> +
> + WARN_ON(swait_active(&vcpu->wq));
> + cancel_hv_timer(apic);
> +
> + ktimer->expired_tscdeadline = ktimer->tscdeadline;
> + kvm_inject_apic_timer_irqs_fast(vcpu);
> +
> + return 1;
> +}
> +EXPORT_SYMBOL_GPL(kvm_lapic_expired_hv_timer_fast);
Please re-evaluate if this is needed (or which parts are needed) after
cleaning up patch 4. Anyway again---this is already better, I don't
like the duplicated code but at least I can understand what's going on.
Paolo
^ permalink raw reply [flat|nested] 19+ messages in thread* Re: [PATCH v2 5/5] KVM: VMX: Handle preemption timer fastpath
2020-04-23 9:40 ` Paolo Bonzini
@ 2020-04-23 9:56 ` Wanpeng Li
2020-04-23 10:29 ` Paolo Bonzini
0 siblings, 1 reply; 19+ messages in thread
From: Wanpeng Li @ 2020-04-23 9:56 UTC (permalink / raw)
To: Paolo Bonzini
Cc: LKML, kvm, Sean Christopherson, Vitaly Kuznetsov, Wanpeng Li,
Jim Mattson, Joerg Roedel, Haiwei Li
On Thu, 23 Apr 2020 at 17:40, Paolo Bonzini <pbonzini@redhat.com> wrote:
>
> On 23/04/20 11:01, Wanpeng Li wrote:
> > +bool kvm_lapic_expired_hv_timer_fast(struct kvm_vcpu *vcpu)
> > +{
> > + struct kvm_lapic *apic = vcpu->arch.apic;
> > + struct kvm_timer *ktimer = &apic->lapic_timer;
> > +
> > + if (!apic_lvtt_tscdeadline(apic) ||
> > + !ktimer->hv_timer_in_use ||
> > + atomic_read(&ktimer->pending))
> > + return 0;
> > +
> > + WARN_ON(swait_active(&vcpu->wq));
> > + cancel_hv_timer(apic);
> > +
> > + ktimer->expired_tscdeadline = ktimer->tscdeadline;
> > + kvm_inject_apic_timer_irqs_fast(vcpu);
> > +
> > + return 1;
> > +}
> > +EXPORT_SYMBOL_GPL(kvm_lapic_expired_hv_timer_fast);
>
> Please re-evaluate if this is needed (or which parts are needed) after
> cleaning up patch 4. Anyway again---this is already better, I don't
> like the duplicated code but at least I can understand what's going on.
Except the apic_lvtt_tscdeadline(apic) check, others are duplicated,
what do you think about apic_lvtt_tscdeadline(apic) check?
Wanpeng
^ permalink raw reply [flat|nested] 19+ messages in thread* Re: [PATCH v2 5/5] KVM: VMX: Handle preemption timer fastpath
2020-04-23 9:56 ` Wanpeng Li
@ 2020-04-23 10:29 ` Paolo Bonzini
2020-04-24 6:38 ` Wanpeng Li
0 siblings, 1 reply; 19+ messages in thread
From: Paolo Bonzini @ 2020-04-23 10:29 UTC (permalink / raw)
To: Wanpeng Li
Cc: LKML, kvm, Sean Christopherson, Vitaly Kuznetsov, Wanpeng Li,
Jim Mattson, Joerg Roedel, Haiwei Li
On 23/04/20 11:56, Wanpeng Li wrote:
>> Please re-evaluate if this is needed (or which parts are needed) after
>> cleaning up patch 4. Anyway again---this is already better, I don't
>> like the duplicated code but at least I can understand what's going on.
> Except the apic_lvtt_tscdeadline(apic) check, others are duplicated,
> what do you think about apic_lvtt_tscdeadline(apic) check?
We have to take a look again after you clean up patch 4. My hope is to
reuse the slowpath code as much as possible, by introducing some
optimizations here and there.
Paolo
^ permalink raw reply [flat|nested] 19+ messages in thread
* Re: [PATCH v2 5/5] KVM: VMX: Handle preemption timer fastpath
2020-04-23 10:29 ` Paolo Bonzini
@ 2020-04-24 6:38 ` Wanpeng Li
0 siblings, 0 replies; 19+ messages in thread
From: Wanpeng Li @ 2020-04-24 6:38 UTC (permalink / raw)
To: Paolo Bonzini
Cc: LKML, kvm, Sean Christopherson, Vitaly Kuznetsov, Wanpeng Li,
Jim Mattson, Joerg Roedel, Haiwei Li
On Thu, 23 Apr 2020 at 18:29, Paolo Bonzini <pbonzini@redhat.com> wrote:
>
> On 23/04/20 11:56, Wanpeng Li wrote:
> >> Please re-evaluate if this is needed (or which parts are needed) after
> >> cleaning up patch 4. Anyway again---this is already better, I don't
> >> like the duplicated code but at least I can understand what's going on.
> > Except the apic_lvtt_tscdeadline(apic) check, others are duplicated,
> > what do you think about apic_lvtt_tscdeadline(apic) check?
>
> We have to take a look again after you clean up patch 4. My hope is to
> reuse the slowpath code as much as possible, by introducing some
> optimizations here and there.
I found we are not need to move the if (vcpu->arch.apicv_active) from
__apic_accept_irq() to a separate function if I understand you
correctly. Please see patch v3 3/5. In addition, I observe
kvm-unit-tests #UD etc if check need_cancel_enter_guest() after the
generic fastpath handler, I didn't dig too much, just move it before
the generic fastpath handler for safe in patch v3 2/5.
Wanpeng
^ permalink raw reply [flat|nested] 19+ messages in thread
* Re: [PATCH v2 5/5] KVM: VMX: Handle preemption timer fastpath
2020-04-23 9:01 ` [PATCH v2 5/5] KVM: VMX: Handle preemption timer fastpath Wanpeng Li
2020-04-23 9:40 ` Paolo Bonzini
@ 2020-04-26 7:38 ` kbuild test robot
1 sibling, 0 replies; 19+ messages in thread
From: kbuild test robot @ 2020-04-26 7:38 UTC (permalink / raw)
To: Wanpeng Li, linux-kernel, kvm
Cc: kbuild-all, Paolo Bonzini, Sean Christopherson, Vitaly Kuznetsov,
Wanpeng Li, Jim Mattson, Joerg Roedel, Haiwei Li
[-- Attachment #1: Type: text/plain, Size: 1480 bytes --]
Hi Wanpeng,
I love your patch! Yet something to improve:
[auto build test ERROR on kvm/linux-next]
[also build test ERROR on next-20200424]
[cannot apply to tip/auto-latest linus/master linux/master v5.7-rc2]
[if your patch is applied to the wrong git tree, please drop us a note to help
improve the system. BTW, we also suggest to use '--base' option to specify the
base tree in git format-patch, please see https://stackoverflow.com/a/37406982]
url: https://github.com/0day-ci/linux/commits/Wanpeng-Li/KVM-VMX-Tscdeadline-timer-emulation-fastpath/20200426-132300
base: https://git.kernel.org/pub/scm/virt/kvm/kvm.git linux-next
config: i386-randconfig-d001-20200426 (attached as .config)
compiler: gcc-7 (Ubuntu 7.5.0-6ubuntu2) 7.5.0
reproduce:
# save the attached .config to linux build tree
make ARCH=i386
If you fix the issue, kindly add following tag as appropriate
Reported-by: kbuild test robot <lkp@intel.com>
All errors (new ones prefixed by >>):
>> arch/x86/kvm/vmx/vmx.c:6572:13: error: 'vmx_cancel_hv_timer' declared 'static' but never defined [-Werror=unused-function]
static void vmx_cancel_hv_timer(struct kvm_vcpu *vcpu);
^~~~~~~~~~~~~~~~~~~
cc1: all warnings being treated as errors
vim +6572 arch/x86/kvm/vmx/vmx.c
6571
> 6572 static void vmx_cancel_hv_timer(struct kvm_vcpu *vcpu);
6573
---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
[-- Attachment #2: .config.gz --]
[-- Type: application/gzip, Size: 36316 bytes --]
^ permalink raw reply [flat|nested] 19+ messages in thread