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Date: Mon, 30 Nov 2020 12:28:47 +0000
From: Marc Zyngier <maz@...nel.org>
To: Shenming Lu <lushenming@...wei.com>
Cc: Thomas Gleixner <tglx@...utronix.de>, linux-kernel@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.cs.columbia.edu,
kvm@...r.kernel.org, James Morse <james.morse@....com>,
Julien Thierry <julien.thierry.kdev@...il.com>,
Suzuki K Poulose <suzuki.poulose@....com>,
Catalin Marinas <catalin.marinas@....com>,
Will Deacon <will@...nel.org>,
Eric Auger <eric.auger@...hat.com>,
Christoffer Dall <christoffer.dall@....com>,
wanghaibin.wang@...wei.com, yuzenghui@...wei.com
Subject: Re: [PATCH v2 2/2] KVM: arm64: Delay the execution of the polling on
the GICR_VPENDBASER.Dirty bit
On 2020-11-30 12:12, Shenming Lu wrote:
> On 2020/11/30 19:22, Marc Zyngier wrote:
>> On 2020-11-28 14:18, Shenming Lu wrote:
>>> In order to further reduce the impact of the wait delay of the
>>> VPT analysis, we can delay the execution of the polling on the
>>> GICR_VPENDBASER.Dirty bit (call it from kvm_vgic_flush_hwstate()
>>> corresponding to vPE resident), let the GIC and the CPU work in
>>> parallel on the entry path.
>>>
>>> Signed-off-by: Shenming Lu <lushenming@...wei.com>
>>> ---
>>> arch/arm64/kvm/vgic/vgic-v4.c | 16 ++++++++++++++++
>>> arch/arm64/kvm/vgic/vgic.c | 3 +++
>>> drivers/irqchip/irq-gic-v3-its.c | 16 ++++++++++++----
>>> drivers/irqchip/irq-gic-v4.c | 11 +++++++++++
>>> include/kvm/arm_vgic.h | 3 +++
>>> include/linux/irqchip/arm-gic-v4.h | 4 ++++
>>> 6 files changed, 49 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/arch/arm64/kvm/vgic/vgic-v4.c
>>> b/arch/arm64/kvm/vgic/vgic-v4.c
>>> index b5fa73c9fd35..b0da74809187 100644
>>> --- a/arch/arm64/kvm/vgic/vgic-v4.c
>>> +++ b/arch/arm64/kvm/vgic/vgic-v4.c
>>> @@ -353,6 +353,22 @@ int vgic_v4_load(struct kvm_vcpu *vcpu)
>>> return err;
>>> }
>>>
>>> +void vgic_v4_commit(struct kvm_vcpu *vcpu)
>>> +{
>>> + struct its_vpe *vpe = &vcpu->arch.vgic_cpu.vgic_v3.its_vpe;
>>> +
>>> + /*
>>> + * No need to wait for the vPE to be ready across a shallow
>>> guest
>>> + * exit, as only a vcpu_put will invalidate it.
>>> + */
>>> + if (vpe->vpe_ready)
>>> + return;
>>> +
>>> + its_commit_vpe(vpe);
>>> +
>>> + vpe->vpe_ready = true;
>>
>> This should be written as:
>>
>> if (!ready)
>> commit();
>>
>> and ready being driven by the commit() call itself.
>>
>>> +}
>>> +
>>> static struct vgic_its *vgic_get_its(struct kvm *kvm,
>>> struct kvm_kernel_irq_routing_entry *irq_entry)
>>> {
>>> diff --git a/arch/arm64/kvm/vgic/vgic.c b/arch/arm64/kvm/vgic/vgic.c
>>> index c3643b7f101b..1c597c9885fa 100644
>>> --- a/arch/arm64/kvm/vgic/vgic.c
>>> +++ b/arch/arm64/kvm/vgic/vgic.c
>>> @@ -915,6 +915,9 @@ void kvm_vgic_flush_hwstate(struct kvm_vcpu
>>> *vcpu)
>>>
>>> if (can_access_vgic_from_kernel())
>>> vgic_restore_state(vcpu);
>>> +
>>> + if (vgic_supports_direct_msis(vcpu->kvm))
>>> + vgic_v4_commit(vcpu);
>>> }
>>>
>>> void kvm_vgic_load(struct kvm_vcpu *vcpu)
>>> diff --git a/drivers/irqchip/irq-gic-v3-its.c
>>> b/drivers/irqchip/irq-gic-v3-its.c
>>> index 22f427135c6b..f30aba14933e 100644
>>> --- a/drivers/irqchip/irq-gic-v3-its.c
>>> +++ b/drivers/irqchip/irq-gic-v3-its.c
>>> @@ -3842,8 +3842,6 @@ static void its_vpe_schedule(struct its_vpe
>>> *vpe)
>>> val |= vpe->idai ? GICR_VPENDBASER_IDAI : 0;
>>> val |= GICR_VPENDBASER_Valid;
>>> gicr_write_vpendbaser(val, vlpi_base + GICR_VPENDBASER);
>>> -
>>> - its_wait_vpt_parse_complete();
>>> }
>>>
>>> static void its_vpe_deschedule(struct its_vpe *vpe)
>>> @@ -3855,6 +3853,8 @@ static void its_vpe_deschedule(struct its_vpe
>>> *vpe)
>>>
>>> vpe->idai = !!(val & GICR_VPENDBASER_IDAI);
>>> vpe->pending_last = !!(val & GICR_VPENDBASER_PendingLast);
>>> +
>>> + vpe->vpe_ready = false;
>>
>> This should be set from the its_make_vpe_non_resident() call.
>>
>>> }
>>>
>>> static void its_vpe_invall(struct its_vpe *vpe)
>>> @@ -3891,6 +3891,10 @@ static int its_vpe_set_vcpu_affinity(struct
>>> irq_data *d, void *vcpu_info)
>>> its_vpe_deschedule(vpe);
>>> return 0;
>>>
>>> + case COMMIT_VPE:
>>> + its_wait_vpt_parse_complete();
>>> + return 0;
>>> +
>>> case INVALL_VPE:
>>> its_vpe_invall(vpe);
>>> return 0;
>>> @@ -4052,8 +4056,6 @@ static void its_vpe_4_1_schedule(struct its_vpe
>>> *vpe,
>>> val |= FIELD_PREP(GICR_VPENDBASER_4_1_VPEID, vpe->vpe_id);
>>>
>>> gicr_write_vpendbaser(val, vlpi_base + GICR_VPENDBASER);
>>> -
>>> - its_wait_vpt_parse_complete();
>>> }
>>>
>>> static void its_vpe_4_1_deschedule(struct its_vpe *vpe,
>>> @@ -4091,6 +4093,8 @@ static void its_vpe_4_1_deschedule(struct
>>> its_vpe *vpe,
>>> GICR_VPENDBASER_PendingLast);
>>> vpe->pending_last = true;
>>> }
>>> +
>>> + vpe->vpe_ready = false;
>>> }
>>>
>>> static void its_vpe_4_1_invall(struct its_vpe *vpe)
>>> @@ -4128,6 +4132,10 @@ static int
>>> its_vpe_4_1_set_vcpu_affinity(struct
>>> irq_data *d, void *vcpu_info)
>>> its_vpe_4_1_deschedule(vpe, info);
>>> return 0;
>>>
>>> + case COMMIT_VPE:
>>> + its_wait_vpt_parse_complete();
>>> + return 0;
>>> +
>>> case INVALL_VPE:
>>> its_vpe_4_1_invall(vpe);
>>> return 0;
>>> diff --git a/drivers/irqchip/irq-gic-v4.c
>>> b/drivers/irqchip/irq-gic-v4.c
>>> index 0c18714ae13e..6cea71a4e68b 100644
>>> --- a/drivers/irqchip/irq-gic-v4.c
>>> +++ b/drivers/irqchip/irq-gic-v4.c
>>> @@ -258,6 +258,17 @@ int its_make_vpe_resident(struct its_vpe *vpe,
>>> bool g0en, bool g1en)
>>> return ret;
>>> }
>>>
>>> +int its_commit_vpe(struct its_vpe *vpe)
>>> +{
>>> + struct its_cmd_info info = {
>>> + .cmd_type = COMMIT_VPE,
>>> + };
>>> +
>>> + WARN_ON(preemptible());
>>> +
>>> + return its_send_vpe_cmd(vpe, &info);
>>> +}
>>> +
>>> int its_invall_vpe(struct its_vpe *vpe)
>>> {
>>> struct its_cmd_info info = {
>>> diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h
>>> index a8d8fdcd3723..f2170df6cf7c 100644
>>> --- a/include/kvm/arm_vgic.h
>>> +++ b/include/kvm/arm_vgic.h
>>> @@ -401,7 +401,10 @@ int kvm_vgic_v4_set_forwarding(struct kvm *kvm,
>>> int irq,
>>> int kvm_vgic_v4_unset_forwarding(struct kvm *kvm, int irq,
>>> struct kvm_kernel_irq_routing_entry *irq_entry);
>>>
>>> +void vgic_v4_commit(struct kvm_vcpu *vcpu);
>>> +
>>> int vgic_v4_load(struct kvm_vcpu *vcpu);
>>> +
>>
>> Spurious new lines.
>>
>>> int vgic_v4_put(struct kvm_vcpu *vcpu, bool need_db);
>>>
>>> #endif /* __KVM_ARM_VGIC_H */
>>> diff --git a/include/linux/irqchip/arm-gic-v4.h
>>> b/include/linux/irqchip/arm-gic-v4.h
>>> index 6976b8331b60..936d88e482a9 100644
>>> --- a/include/linux/irqchip/arm-gic-v4.h
>>> +++ b/include/linux/irqchip/arm-gic-v4.h
>>> @@ -75,6 +75,8 @@ struct its_vpe {
>>> u16 vpe_id;
>>> /* Pending VLPIs on schedule out? */
>>> bool pending_last;
>>> + /* VPT parse complete */
>>> + bool vpe_ready;
>>> };
>>>
>>> /*
>>> @@ -104,6 +106,7 @@ enum its_vcpu_info_cmd_type {
>>> PROP_UPDATE_AND_INV_VLPI,
>>> SCHEDULE_VPE,
>>> DESCHEDULE_VPE,
>>> + COMMIT_VPE,
>>> INVALL_VPE,
>>> PROP_UPDATE_VSGI,
>>> };
>>> @@ -129,6 +132,7 @@ int its_alloc_vcpu_irqs(struct its_vm *vm);
>>> void its_free_vcpu_irqs(struct its_vm *vm);
>>> int its_make_vpe_resident(struct its_vpe *vpe, bool g0en, bool
>>> g1en);
>>> int its_make_vpe_non_resident(struct its_vpe *vpe, bool db);
>>> +int its_commit_vpe(struct its_vpe *vpe);
>>> int its_invall_vpe(struct its_vpe *vpe);
>>> int its_map_vlpi(int irq, struct its_vlpi_map *map);
>>> int its_get_vlpi(int irq, struct its_vlpi_map *map);
>>
>> In order to speed up the respin round-trip, I've taken the liberty
>> to refactor this patch myself. Please have a look at [1] and let
>> me know if you're OK with it.
>
> I have looked at it and am OK.
>
> By the way, will the first patch (set the delay_us to 1) be picked up
> together?
I'll route it via the irqchip tree.
Thanks,
M.
--
Jazz is not dead. It just smells funny...
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