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: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20191027144234.8395-2-maz@kernel.org

diff --git a/drivers/irqchip/irq-gic-v4.c b/drivers/irqchip/irq-gic-v4.c
index 563e87e..4596992 100644 (file)
--- a/drivers/irqchip/irq-gic-v4.c
+++ b/drivers/irqchip/irq-gic-v4.c
@@ -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)

diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h
index af4f09c..4dc58d7 100644 (file)
--- a/include/kvm/arm_vgic.h
+++ b/include/kvm/arm_vgic.h
@@ -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 */

diff --git a/include/linux/irqchip/arm-gic-v4.h b/include/linux/irqchip/arm-gic-v4.h
index e6b1557..ab1396a 100644 (file)
--- a/include/linux/irqchip/arm-gic-v4.h
+++ b/include/linux/irqchip/arm-gic-v4.h
@@ -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;
        /*

diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c
index 86c6aa1..bd2afcf 100644 (file)
--- a/virt/kvm/arm/arm.c
+++ b/virt/kvm/arm/arm.c
@@ -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)

diff --git a/virt/kvm/arm/vgic/vgic-v3.c b/virt/kvm/arm/vgic/vgic-v3.c
index 8d69f00..48307a9 100644 (file)
--- a/virt/kvm/arm/vgic/vgic-v3.c
+++ b/virt/kvm/arm/vgic/vgic-v3.c
@@ -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);

diff --git a/virt/kvm/arm/vgic/vgic-v4.c b/virt/kvm/arm/vgic/vgic-v4.c
index 477af6a..7e1f320 100644 (file)
--- a/virt/kvm/arm/vgic/vgic-v4.c
+++ b/virt/kvm/arm/vgic/vgic-v4.c
@@ -85,6 +85,10 @@ static irqreturn_t vgic_v4_doorbell_handler(int irq, void *info)
 {
        struct kvm_vcpu *vcpu = info;
 
+       /* We got the message, no need to fire again */
+       if (!irqd_irq_disabled(&irq_to_desc(irq)->irq_data))
+               disable_irq_nosync(irq);
+
        vcpu->arch.vgic_cpu.vgic_v3.its_vpe.pending_last = true;
        kvm_make_request(KVM_REQ_IRQ_PENDING, vcpu);
        kvm_vcpu_kick(vcpu);
@@ -192,20 +196,30 @@ void vgic_v4_teardown(struct kvm *kvm)
        its_vm->vpes = NULL;
 }
 
-int vgic_v4_sync_hwstate(struct kvm_vcpu *vcpu)
+int vgic_v4_put(struct kvm_vcpu *vcpu, bool need_db)
 {
-       if (!vgic_supports_direct_msis(vcpu->kvm))
+       struct its_vpe *vpe = &vcpu->arch.vgic_cpu.vgic_v3.its_vpe;
+       struct irq_desc *desc = irq_to_desc(vpe->irq);
+
+       if (!vgic_supports_direct_msis(vcpu->kvm) || !vpe->resident)
                return 0;
 
-       return its_schedule_vpe(&vcpu->arch.vgic_cpu.vgic_v3.its_vpe, false);
+       /*
+        * If blocking, a doorbell is required. Undo the nested
+        * disable_irq() calls...
+        */
+       while (need_db && irqd_irq_disabled(&desc->irq_data))
+               enable_irq(vpe->irq);
+
+       return its_schedule_vpe(vpe, false);
 }
 
-int vgic_v4_flush_hwstate(struct kvm_vcpu *vcpu)
+int vgic_v4_load(struct kvm_vcpu *vcpu)
 {
-       int irq = vcpu->arch.vgic_cpu.vgic_v3.its_vpe.irq;
+       struct its_vpe *vpe = &vcpu->arch.vgic_cpu.vgic_v3.its_vpe;
        int err;
 
-       if (!vgic_supports_direct_msis(vcpu->kvm))
+       if (!vgic_supports_direct_msis(vcpu->kvm) || vpe->resident)
                return 0;
 
        /*
@@ -214,11 +228,14 @@ int vgic_v4_flush_hwstate(struct kvm_vcpu *vcpu)
         * doc in drivers/irqchip/irq-gic-v4.c to understand how this
         * turns into a VMOVP command at the ITS level.
         */
-       err = irq_set_affinity(irq, cpumask_of(smp_processor_id()));
+       err = irq_set_affinity(vpe->irq, cpumask_of(smp_processor_id()));
        if (err)
                return err;
 
-       err = its_schedule_vpe(&vcpu->arch.vgic_cpu.vgic_v3.its_vpe, true);
+       /* Disabled the doorbell, as we're about to enter the guest */
+       disable_irq_nosync(vpe->irq);
+
+       err = its_schedule_vpe(vpe, true);
        if (err)
                return err;
 
@@ -226,9 +243,7 @@ int vgic_v4_flush_hwstate(struct kvm_vcpu *vcpu)
         * Now that the VPE is resident, let's get rid of a potential
         * doorbell interrupt that would still be pending.
         */
-       err = irq_set_irqchip_state(irq, IRQCHIP_STATE_PENDING, false);
-
-       return err;
+       return irq_set_irqchip_state(vpe->irq, IRQCHIP_STATE_PENDING, false);
 }
 
 static struct vgic_its *vgic_get_its(struct kvm *kvm,
@@ -335,21 +350,3 @@ out:
        mutex_unlock(&its->its_lock);
        return ret;
 }
-
-void kvm_vgic_v4_enable_doorbell(struct kvm_vcpu *vcpu)
-{
-       if (vgic_supports_direct_msis(vcpu->kvm)) {
-               int irq = vcpu->arch.vgic_cpu.vgic_v3.its_vpe.irq;
-               if (irq)
-                       enable_irq(irq);
-       }
-}
-
-void kvm_vgic_v4_disable_doorbell(struct kvm_vcpu *vcpu)
-{
-       if (vgic_supports_direct_msis(vcpu->kvm)) {
-               int irq = vcpu->arch.vgic_cpu.vgic_v3.its_vpe.irq;
-               if (irq)
-                       disable_irq(irq);
-       }
-}

diff --git a/virt/kvm/arm/vgic/vgic.c b/virt/kvm/arm/vgic/vgic.c
index 45a870c..99b02ca 100644 (file)
--- a/virt/kvm/arm/vgic/vgic.c
+++ b/virt/kvm/arm/vgic/vgic.c
@@ -857,8 +857,6 @@ void kvm_vgic_sync_hwstate(struct kvm_vcpu *vcpu)
 {
        struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
 
-       WARN_ON(vgic_v4_sync_hwstate(vcpu));
-
        /* An empty ap_list_head implies used_lrs == 0 */
        if (list_empty(&vcpu->arch.vgic_cpu.ap_list_head))
                return;
@@ -882,8 +880,6 @@ static inline void vgic_restore_state(struct kvm_vcpu *vcpu)
 /* Flush our emulation state into the GIC hardware before entering the guest. */
 void kvm_vgic_flush_hwstate(struct kvm_vcpu *vcpu)
 {
-       WARN_ON(vgic_v4_flush_hwstate(vcpu));
-
        /*
         * If there are no virtual interrupts active or pending for this
         * VCPU, then there is no work to do and we can bail out without

diff --git a/virt/kvm/arm/vgic/vgic.h b/virt/kvm/arm/vgic/vgic.h
index 83066a8..c7fefd6 100644 (file)
--- a/virt/kvm/arm/vgic/vgic.h
+++ b/virt/kvm/arm/vgic/vgic.h
@@ -316,7 +316,5 @@ void vgic_its_invalidate_cache(struct kvm *kvm);
 bool vgic_supports_direct_msis(struct kvm *kvm);
 int vgic_v4_init(struct kvm *kvm);
 void vgic_v4_teardown(struct kvm *kvm);
-int vgic_v4_sync_hwstate(struct kvm_vcpu *vcpu);
-int vgic_v4_flush_hwstate(struct kvm_vcpu *vcpu);
 
 #endif