From 9103617df202d74e5c65f8af84a9aa727f812a06 Mon Sep 17 00:00:00 2001 From: Christoffer Dall Date: Tue, 25 Aug 2015 22:50:57 +0200 Subject: [PATCH] arm/arm64: KVM: vgic: Factor out level irq processing on guest exit Currently vgic_process_maintenance() processes dealing with a completed level-triggered interrupt directly, but we are soon going to reuse this logic for level-triggered mapped interrupts with the HW bit set, so move this logic into a separate static function. Probably the most scary part of this commit is convincing yourself that the current flow is safe compared to the old one. In the following I try to list the changes and why they are harmless: Move vgic_irq_clear_queued after kvm_notify_acked_irq: Harmless because the only potential effect of clearing the queued flag wrt. kvm_set_irq is that vgic_update_irq_pending does not set the pending bit on the emulated CPU interface or in the pending_on_cpu bitmask if the function is called with level=1. However, the point of kvm_notify_acked_irq is to call kvm_set_irq with level=0, and we set the queued flag again in __kvm_vgic_sync_hwstate later on if the level is stil high. Move vgic_set_lr before kvm_notify_acked_irq: Also, harmless because the LR are cpu-local operations and kvm_notify_acked only affects the dist Move vgic_dist_irq_clear_soft_pend after kvm_notify_acked_irq: Also harmless, because now we check the level state in the clear_soft_pend function and lower the pending bits if the level is low. Reviewed-by: Eric Auger Reviewed-by: Marc Zyngier Signed-off-by: Christoffer Dall --- virt/kvm/arm/vgic.c | 94 +++++++++++++++++++++++++++------------------ 1 file changed, 56 insertions(+), 38 deletions(-) diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c index 66c66165e712..367a180fb5ac 100644 --- a/virt/kvm/arm/vgic.c +++ b/virt/kvm/arm/vgic.c @@ -107,6 +107,7 @@ static struct vgic_lr vgic_get_lr(const struct kvm_vcpu *vcpu, int lr); static void vgic_set_lr(struct kvm_vcpu *vcpu, int lr, struct vgic_lr lr_desc); static struct irq_phys_map *vgic_irq_map_search(struct kvm_vcpu *vcpu, int virt_irq); +static int compute_pending_for_cpu(struct kvm_vcpu *vcpu); static const struct vgic_ops *vgic_ops; static const struct vgic_params *vgic; @@ -357,6 +358,11 @@ static void vgic_dist_irq_clear_soft_pend(struct kvm_vcpu *vcpu, int irq) struct vgic_dist *dist = &vcpu->kvm->arch.vgic; vgic_bitmap_set_irq_val(&dist->irq_soft_pend, vcpu->vcpu_id, irq, 0); + if (!vgic_dist_irq_get_level(vcpu, irq)) { + vgic_dist_irq_clear_pending(vcpu, irq); + if (!compute_pending_for_cpu(vcpu)) + clear_bit(vcpu->vcpu_id, dist->irq_pending_on_cpu); + } } static int vgic_dist_irq_is_pending(struct kvm_vcpu *vcpu, int irq) @@ -1338,12 +1344,56 @@ epilog: } } +static int process_level_irq(struct kvm_vcpu *vcpu, int lr, struct vgic_lr vlr) +{ + int level_pending = 0; + + vlr.state = 0; + vlr.hwirq = 0; + vgic_set_lr(vcpu, lr, vlr); + + /* + * If the IRQ was EOIed (called from vgic_process_maintenance) or it + * went from active to non-active (called from vgic_sync_hwirq) it was + * also ACKed and we we therefore assume we can clear the soft pending + * state (should it had been set) for this interrupt. + * + * Note: if the IRQ soft pending state was set after the IRQ was + * acked, it actually shouldn't be cleared, but we have no way of + * knowing that unless we start trapping ACKs when the soft-pending + * state is set. + */ + vgic_dist_irq_clear_soft_pend(vcpu, vlr.irq); + + /* + * Tell the gic to start sampling the line of this interrupt again. + */ + vgic_irq_clear_queued(vcpu, vlr.irq); + + /* Any additional pending interrupt? */ + if (vgic_dist_irq_get_level(vcpu, vlr.irq)) { + vgic_cpu_irq_set(vcpu, vlr.irq); + level_pending = 1; + } else { + vgic_dist_irq_clear_pending(vcpu, vlr.irq); + vgic_cpu_irq_clear(vcpu, vlr.irq); + } + + /* + * Despite being EOIed, the LR may not have + * been marked as empty. + */ + vgic_sync_lr_elrsr(vcpu, lr, vlr); + + return level_pending; +} + static bool vgic_process_maintenance(struct kvm_vcpu *vcpu) { u32 status = vgic_get_interrupt_status(vcpu); struct vgic_dist *dist = &vcpu->kvm->arch.vgic; - bool level_pending = false; struct kvm *kvm = vcpu->kvm; + int level_pending = 0; kvm_debug("STATUS = %08x\n", status); @@ -1358,54 +1408,22 @@ static bool vgic_process_maintenance(struct kvm_vcpu *vcpu) for_each_set_bit(lr, eisr_ptr, vgic->nr_lr) { struct vgic_lr vlr = vgic_get_lr(vcpu, lr); - WARN_ON(vgic_irq_is_edge(vcpu, vlr.irq)); - spin_lock(&dist->lock); - vgic_irq_clear_queued(vcpu, vlr.irq); + WARN_ON(vgic_irq_is_edge(vcpu, vlr.irq)); WARN_ON(vlr.state & LR_STATE_MASK); - vlr.state = 0; - vgic_set_lr(vcpu, lr, vlr); - /* - * If the IRQ was EOIed it was also ACKed and we we - * therefore assume we can clear the soft pending - * state (should it had been set) for this interrupt. - * - * Note: if the IRQ soft pending state was set after - * the IRQ was acked, it actually shouldn't be - * cleared, but we have no way of knowing that unless - * we start trapping ACKs when the soft-pending state - * is set. - */ - vgic_dist_irq_clear_soft_pend(vcpu, vlr.irq); /* * kvm_notify_acked_irq calls kvm_set_irq() - * to reset the IRQ level. Need to release the - * lock for kvm_set_irq to grab it. + * to reset the IRQ level, which grabs the dist->lock + * so we call this before taking the dist->lock. */ - spin_unlock(&dist->lock); - kvm_notify_acked_irq(kvm, 0, vlr.irq - VGIC_NR_PRIVATE_IRQS); - spin_lock(&dist->lock); - - /* Any additional pending interrupt? */ - if (vgic_dist_irq_get_level(vcpu, vlr.irq)) { - vgic_cpu_irq_set(vcpu, vlr.irq); - level_pending = true; - } else { - vgic_dist_irq_clear_pending(vcpu, vlr.irq); - vgic_cpu_irq_clear(vcpu, vlr.irq); - } + spin_lock(&dist->lock); + level_pending |= process_level_irq(vcpu, lr, vlr); spin_unlock(&dist->lock); - - /* - * Despite being EOIed, the LR may not have - * been marked as empty. - */ - vgic_sync_lr_elrsr(vcpu, lr, vlr); } } -- 2.20.1