From 3802411d01880c4283426d22653e011159b1c947 Mon Sep 17 00:00:00 2001 From: Andre Przywara Date: Fri, 15 Jul 2016 12:43:33 +0100 Subject: [PATCH] KVM: arm64: vgic-its: Connect LPIs to the VGIC emulation LPIs are dynamically created (mapped) at guest runtime and their actual number can be quite high, but is mostly assigned using a very sparse allocation scheme. So arrays are not an ideal data structure to hold the information. We use a spin-lock protected linked list to hold all mapped LPIs, represented by their struct vgic_irq. This lock is grouped between the ap_list_lock and the vgic_irq lock in our locking order. Also we store a pointer to that struct vgic_irq in our struct its_itte, so we can easily access it. Eventually we call our new vgic_get_lpi() from vgic_get_irq(), so the VGIC code gets transparently access to LPIs. Signed-off-by: Andre Przywara Reviewed-by: Marc Zyngier Tested-by: Eric Auger Signed-off-by: Marc Zyngier --- include/kvm/arm_vgic.h | 6 ++++ virt/kvm/arm/vgic/vgic-init.c | 3 ++ virt/kvm/arm/vgic/vgic-its.c | 5 +++ virt/kvm/arm/vgic/vgic-v3.c | 2 ++ virt/kvm/arm/vgic/vgic.c | 63 +++++++++++++++++++++++++++++++---- 5 files changed, 73 insertions(+), 6 deletions(-) diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h index 61867492d361..a6ca326055cf 100644 --- a/include/kvm/arm_vgic.h +++ b/include/kvm/arm_vgic.h @@ -77,6 +77,7 @@ enum vgic_irq_config { struct vgic_irq { spinlock_t irq_lock; /* Protects the content of the struct */ + struct list_head lpi_list; /* Used to link all LPIs together */ struct list_head ap_list; struct kvm_vcpu *vcpu; /* SGIs and PPIs: The VCPU @@ -193,6 +194,11 @@ struct vgic_dist { * GICv3 spec: 6.1.2 "LPI Configuration tables" */ u64 propbaser; + + /* Protects the lpi_list and the count value below. */ + spinlock_t lpi_list_lock; + struct list_head lpi_list_head; + int lpi_list_count; }; struct vgic_v2_cpu_if { diff --git a/virt/kvm/arm/vgic/vgic-init.c b/virt/kvm/arm/vgic/vgic-init.c index ac3c1a5f7bf4..535e713704f0 100644 --- a/virt/kvm/arm/vgic/vgic-init.c +++ b/virt/kvm/arm/vgic/vgic-init.c @@ -157,6 +157,9 @@ static int kvm_vgic_dist_init(struct kvm *kvm, unsigned int nr_spis) struct kvm_vcpu *vcpu0 = kvm_get_vcpu(kvm, 0); int i; + INIT_LIST_HEAD(&dist->lpi_list_head); + spin_lock_init(&dist->lpi_list_lock); + dist->spis = kcalloc(nr_spis, sizeof(struct vgic_irq), GFP_KERNEL); if (!dist->spis) return -ENOMEM; diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c index 11cfe2f12c6c..14f91ff487cc 100644 --- a/virt/kvm/arm/vgic/vgic-its.c +++ b/virt/kvm/arm/vgic/vgic-its.c @@ -56,6 +56,7 @@ struct its_collection { struct its_itte { struct list_head itte_list; + struct vgic_irq *irq; struct its_collection *collection; u32 lpi; u32 event_id; @@ -148,6 +149,10 @@ static unsigned long vgic_mmio_read_its_idregs(struct kvm *kvm, static void its_free_itte(struct kvm *kvm, struct its_itte *itte) { list_del(&itte->itte_list); + + /* This put matches the get in vgic_add_lpi. */ + vgic_put_irq(kvm, itte->irq); + kfree(itte); } diff --git a/virt/kvm/arm/vgic/vgic-v3.c b/virt/kvm/arm/vgic/vgic-v3.c index 6f8f31f910e7..0506543df38a 100644 --- a/virt/kvm/arm/vgic/vgic-v3.c +++ b/virt/kvm/arm/vgic/vgic-v3.c @@ -81,6 +81,8 @@ void vgic_v3_fold_lr_state(struct kvm_vcpu *vcpu) else intid = val & GICH_LR_VIRTUALID; irq = vgic_get_irq(vcpu->kvm, vcpu, intid); + if (!irq) /* An LPI could have been unmapped. */ + continue; spin_lock(&irq->irq_lock); diff --git a/virt/kvm/arm/vgic/vgic.c b/virt/kvm/arm/vgic/vgic.c index d3ba1b4227e7..53299fc93c15 100644 --- a/virt/kvm/arm/vgic/vgic.c +++ b/virt/kvm/arm/vgic/vgic.c @@ -36,7 +36,8 @@ struct vgic_global __section(.hyp.text) kvm_vgic_global_state; * its->cmd_lock (mutex) * its->its_lock (mutex) * vgic_cpu->ap_list_lock - * vgic_irq->irq_lock + * kvm->lpi_list_lock + * vgic_irq->irq_lock * * If you need to take multiple locks, always take the upper lock first, * then the lower ones, e.g. first take the its_lock, then the irq_lock. @@ -51,6 +52,41 @@ struct vgic_global __section(.hyp.text) kvm_vgic_global_state; * spin_lock(vcpuY->arch.vgic_cpu.ap_list_lock); */ +/* + * Iterate over the VM's list of mapped LPIs to find the one with a + * matching interrupt ID and return a reference to the IRQ structure. + */ +static struct vgic_irq *vgic_get_lpi(struct kvm *kvm, u32 intid) +{ + struct vgic_dist *dist = &kvm->arch.vgic; + struct vgic_irq *irq = NULL; + + spin_lock(&dist->lpi_list_lock); + + list_for_each_entry(irq, &dist->lpi_list_head, lpi_list) { + if (irq->intid != intid) + continue; + + /* + * This increases the refcount, the caller is expected to + * call vgic_put_irq() later once it's finished with the IRQ. + */ + kref_get(&irq->refcount); + goto out_unlock; + } + irq = NULL; + +out_unlock: + spin_unlock(&dist->lpi_list_lock); + + return irq; +} + +/* + * This looks up the virtual interrupt ID to get the corresponding + * struct vgic_irq. It also increases the refcount, so any caller is expected + * to call vgic_put_irq() once it's finished with this IRQ. + */ struct vgic_irq *vgic_get_irq(struct kvm *kvm, struct kvm_vcpu *vcpu, u32 intid) { @@ -62,9 +98,9 @@ struct vgic_irq *vgic_get_irq(struct kvm *kvm, struct kvm_vcpu *vcpu, if (intid <= VGIC_MAX_SPI) return &kvm->arch.vgic.spis[intid - VGIC_NR_PRIVATE_IRQS]; - /* LPIs are not yet covered */ + /* LPIs */ if (intid >= VGIC_MIN_LPI) - return NULL; + return vgic_get_lpi(kvm, intid); WARN(1, "Looking up struct vgic_irq for reserved INTID"); return NULL; @@ -78,18 +114,33 @@ static void vgic_get_irq_kref(struct vgic_irq *irq) kref_get(&irq->refcount); } -/* The refcount should never drop to 0 at the moment. */ +/* + * We can't do anything in here, because we lack the kvm pointer to + * lock and remove the item from the lpi_list. So we keep this function + * empty and use the return value of kref_put() to trigger the freeing. + */ static void vgic_irq_release(struct kref *ref) { - WARN_ON(1); } void vgic_put_irq(struct kvm *kvm, struct vgic_irq *irq) { + struct vgic_dist *dist; + if (irq->intid < VGIC_MIN_LPI) return; - kref_put(&irq->refcount, vgic_irq_release); + if (!kref_put(&irq->refcount, vgic_irq_release)) + return; + + dist = &kvm->arch.vgic; + + spin_lock(&dist->lpi_list_lock); + list_del(&irq->lpi_list); + dist->lpi_list_count--; + spin_unlock(&dist->lpi_list_lock); + + kfree(irq); } /** -- 2.20.1