Re: [PATCH v2 2/2] KVM: arm64: Delay the execution of the polling on the GICR_VPENDBASER.Dirty bit
From: Marc Zyngier
Date: Mon Nov 30 2020 - 06:23:42 EST
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@xxxxxxxxxx>
---
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...