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Message-ID: <b2387410a28f9c5d9ece45e12feead94@kernel.org>
Date: Mon, 30 Nov 2020 11:22:56 +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 2020-11-28 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.
Thanks,
M.
[1]
https://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git/commit/?h=kvm-arm64/misc-5.11&id=57e3cebd022fbc035dcf190ac789fd2ffc747f5b
--
Jazz is not dead. It just smells funny...
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