Commit 8e01d9a3 authored by Marc Zyngier's avatar Marc Zyngier
Browse files

KVM: arm64: vgic-v4: Move the GICv4 residency flow to be driven by vcpu_load/put 



When the VHE code was reworked, a lot of the vgic stuff was moved around,
but the GICv4 residency code did stay untouched, meaning that we come
in and out of residency on each flush/sync, which is obviously suboptimal.

To address this, let's move things around a bit:

- Residency entry (flush) moves to vcpu_load
- Residency exit (sync) moves to vcpu_put
- On blocking (entry to WFI), we "put"
- On unblocking (exit from WFI), we "load"

Because these can nest (load/block/put/load/unblock/put, for example),
we now have per-VPE tracking of the residency state.

Additionally, vgic_v4_put gains a "need doorbell" parameter, which only
gets set to true when blocking because of a WFI. This allows a finer
control of the doorbell, which now also gets disabled as soon as
it gets signaled.

Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20191027144234.8395-2-maz@kernel.org
parent 5c401308

drivers/irqchip/irq-gic-v4.c

+6 −1
Original line number Diff line number Diff line
@@ -141,12 +141,17 @@ static int its_send_vpe_cmd(struct its_vpe *vpe, struct its_cmd_info *info) 
int its_schedule_vpe(struct its_vpe *vpe, bool on)

{

	struct its_cmd_info info;

	int ret;



	WARN_ON(preemptible());



	info.cmd_type = on ? SCHEDULE_VPE : DESCHEDULE_VPE;



	return its_send_vpe_cmd(vpe, &info);

	ret = its_send_vpe_cmd(vpe, &info);

	if (!ret)

		vpe->resident = on;



	return ret;

}



int its_invall_vpe(struct its_vpe *vpe)

include/kvm/arm_vgic.h

+2 −2
Original line number Diff line number Diff line
@@ -396,7 +396,7 @@ 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 kvm_vgic_v4_enable_doorbell(struct kvm_vcpu *vcpu);

void kvm_vgic_v4_disable_doorbell(struct kvm_vcpu *vcpu);

int vgic_v4_load(struct kvm_vcpu *vcpu);

int vgic_v4_put(struct kvm_vcpu *vcpu, bool need_db);



#endif /* __KVM_ARM_VGIC_H */

include/linux/irqchip/arm-gic-v4.h

+2 −0
Original line number Diff line number Diff line
@@ -35,6 +35,8 @@ struct its_vpe { 
	/* Doorbell interrupt */

	int			irq;

	irq_hw_number_t		vpe_db_lpi;

	/* VPE resident */

	bool			resident;

	/* VPE proxy mapping */

	int			vpe_proxy_event;

	/*

virt/kvm/arm/arm.c

+8 −4
Original line number Diff line number Diff line
@@ -322,20 +322,24 @@ void kvm_arch_vcpu_blocking(struct kvm_vcpu *vcpu) 
	/*

	 * If we're about to block (most likely because we've just hit a

	 * WFI), we need to sync back the state of the GIC CPU interface

	 * so that we have the lastest PMR and group enables. This ensures

	 * so that we have the latest PMR and group enables. This ensures

	 * that kvm_arch_vcpu_runnable has up-to-date data to decide

	 * whether we have pending interrupts.

	 *

	 * For the same reason, we want to tell GICv4 that we need

	 * doorbells to be signalled, should an interrupt become pending.

	 */

	preempt_disable();

	kvm_vgic_vmcr_sync(vcpu);

	vgic_v4_put(vcpu, true);

	preempt_enable();



	kvm_vgic_v4_enable_doorbell(vcpu);

}



void kvm_arch_vcpu_unblocking(struct kvm_vcpu *vcpu)

{

	kvm_vgic_v4_disable_doorbell(vcpu);

	preempt_disable();

	vgic_v4_load(vcpu);

	preempt_enable();

}



int kvm_arch_vcpu_init(struct kvm_vcpu *vcpu)

virt/kvm/arm/vgic/vgic-v3.c

+4 −0
Original line number Diff line number Diff line
@@ -664,6 +664,8 @@ void vgic_v3_load(struct kvm_vcpu *vcpu) 


	if (has_vhe())

		__vgic_v3_activate_traps(vcpu);



	WARN_ON(vgic_v4_load(vcpu));

}



void vgic_v3_vmcr_sync(struct kvm_vcpu *vcpu)
@@ -676,6 +678,8 @@ void vgic_v3_vmcr_sync(struct kvm_vcpu *vcpu) 


void vgic_v3_put(struct kvm_vcpu *vcpu)

{

	WARN_ON(vgic_v4_put(vcpu, false));



	vgic_v3_vmcr_sync(vcpu);



	kvm_call_hyp(__vgic_v3_save_aprs, vcpu);

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