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KVM: arm64: Delay the polling of the GICR_VPENDBASER.Dirty bit

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In order to reduce the impact of the VPT parsing happening on the GIC,
we can split the vcpu reseidency in two phases:

- programming GICR_VPENDBASER: this still happens in vcpu_load()
- checking for the VPT parsing to be complete: this can happen
  on vcpu entry (in kvm_vgic_flush_hwstate())

This allows the GIC and the CPU to work in parallel, rewmoving some
of the entry overhead.

Suggested-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Shenming Lu <lushenming@huawei.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20201128141857.983-3-lushenming@huawei.com
This commit is contained in:
Shenming Lu 2020-11-28 22:18:57 +08:00 committed by Marc Zyngier
parent bf118a5cb7
commit 57e3cebd02
6 changed files with 47 additions and 4 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

12
arch/arm64/kvm/vgic/vgic-v4.c
View file

@ -353,6 +353,18 @@ 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->ready)
its_commit_vpe(vpe);
}
static struct vgic_its *vgic_get_its(struct kvm *kvm,
struct kvm_kernel_irq_routing_entry *irq_entry)
{

3
arch/arm64/kvm/vgic/vgic.c
View file

@ -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)

12
drivers/irqchip/irq-gic-v3-its.c
View file

@ -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)
@ -3891,6 +3889,10 @@ 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 +4054,6 @@ 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,
@ -4128,6 +4128,10 @@ 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;

19
drivers/irqchip/irq-gic-v4.c
View file

@ -232,6 +232,8 @@ int its_make_vpe_non_resident(struct its_vpe *vpe, bool db)
if (!ret)
vpe->resident = false;
vpe->ready = false;
return ret;
}
@ -258,6 +260,23 @@ 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,
};
int ret;
WARN_ON(preemptible());
ret = its_send_vpe_cmd(vpe, &info);
if (!ret)
vpe->ready = true;
return ret;
}
int its_invall_vpe(struct its_vpe *vpe)
{
struct its_cmd_info info = {

1
include/kvm/arm_vgic.h
View file

@ -402,6 +402,7 @@ int kvm_vgic_v4_unset_forwarding(struct kvm *kvm, int irq,
struct kvm_kernel_irq_routing_entry *irq_entry);
int vgic_v4_load(struct kvm_vcpu *vcpu);
void vgic_v4_commit(struct kvm_vcpu *vcpu);
int vgic_v4_put(struct kvm_vcpu *vcpu, bool need_db);
#endif /* __KVM_ARM_VGIC_H */

4
include/linux/irqchip/arm-gic-v4.h
View file

@ -39,6 +39,8 @@ struct its_vpe {
irq_hw_number_t vpe_db_lpi;
/* VPE resident */
bool resident;
/* VPT parse complete */
bool ready;
union {
/* GICv4.0 implementations */
struct {
@ -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);