[PATCH v3 06/11] KVM: arm/arm64: vgic: Allow dynamic mapping of physical/virtual interrupts
Christoffer Dall
christoffer.dall at linaro.org
Tue Aug 4 06:04:57 PDT 2015
On Fri, Jul 24, 2015 at 04:55:04PM +0100, Marc Zyngier wrote:
> In order to be able to feed physical interrupts to a guest, we need
> to be able to establish the virtual-physical mapping between the two
> worlds.
>
> The mappings are kept in a set of RCU lists, indexed by virtual interrupts.
>
> Signed-off-by: Marc Zyngier <marc.zyngier at arm.com>
> ---
> arch/arm/kvm/arm.c | 2 +
> include/kvm/arm_vgic.h | 26 +++++++
> virt/kvm/arm/vgic.c | 189 ++++++++++++++++++++++++++++++++++++++++++++++++-
> 3 files changed, 216 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
> index f1bf418..ce404a5 100644
> --- a/arch/arm/kvm/arm.c
> +++ b/arch/arm/kvm/arm.c
> @@ -125,6 +125,7 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
> if (ret)
> goto out_free_stage2_pgd;
>
> + kvm_vgic_early_init(kvm);
> kvm_timer_init(kvm);
>
> /* Mark the initial VMID generation invalid */
> @@ -249,6 +250,7 @@ out:
>
> void kvm_arch_vcpu_postcreate(struct kvm_vcpu *vcpu)
> {
> + kvm_vgic_vcpu_early_init(vcpu);
> }
>
> void kvm_arch_vcpu_free(struct kvm_vcpu *vcpu)
> diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h
> index a881e39..68212a1 100644
> --- a/include/kvm/arm_vgic.h
> +++ b/include/kvm/arm_vgic.h
> @@ -159,6 +159,20 @@ struct vgic_io_device {
> struct kvm_io_device dev;
> };
>
> +struct irq_phys_map {
> + u32 virt_irq;
> + u32 phys_irq;
> + u32 irq;
> + bool deleted;
> + bool active;
> +};
> +
> +struct irq_phys_map_entry {
> + struct list_head entry;
> + struct rcu_head rcu;
> + struct irq_phys_map map;
> +};
> +
> struct vgic_dist {
> spinlock_t lock;
> bool in_kernel;
> @@ -256,6 +270,10 @@ struct vgic_dist {
> struct vgic_vm_ops vm_ops;
> struct vgic_io_device dist_iodev;
> struct vgic_io_device *redist_iodevs;
> +
> + /* Virtual irq to hwirq mapping */
> + spinlock_t irq_phys_map_lock;
> + struct list_head irq_phys_map_list;
> };
>
> struct vgic_v2_cpu_if {
> @@ -307,6 +325,9 @@ struct vgic_cpu {
> struct vgic_v2_cpu_if vgic_v2;
> struct vgic_v3_cpu_if vgic_v3;
> };
> +
> + /* Protected by the distributor's irq_phys_map_lock */
> + struct list_head irq_phys_map_list;
> };
>
> #define LR_EMPTY 0xff
> @@ -321,8 +342,10 @@ int kvm_vgic_addr(struct kvm *kvm, unsigned long type, u64 *addr, bool write);
> int kvm_vgic_hyp_init(void);
> int kvm_vgic_map_resources(struct kvm *kvm);
> int kvm_vgic_get_max_vcpus(void);
> +void kvm_vgic_early_init(struct kvm *kvm);
> int kvm_vgic_create(struct kvm *kvm, u32 type);
> void kvm_vgic_destroy(struct kvm *kvm);
> +void kvm_vgic_vcpu_early_init(struct kvm_vcpu *vcpu);
> void kvm_vgic_vcpu_destroy(struct kvm_vcpu *vcpu);
> void kvm_vgic_flush_hwstate(struct kvm_vcpu *vcpu);
> void kvm_vgic_sync_hwstate(struct kvm_vcpu *vcpu);
> @@ -331,6 +354,9 @@ int kvm_vgic_inject_irq(struct kvm *kvm, int cpuid, unsigned int irq_num,
> void vgic_v3_dispatch_sgi(struct kvm_vcpu *vcpu, u64 reg);
> int kvm_vgic_vcpu_pending_irq(struct kvm_vcpu *vcpu);
> int kvm_vgic_vcpu_active_irq(struct kvm_vcpu *vcpu);
> +struct irq_phys_map *kvm_vgic_map_phys_irq(struct kvm_vcpu *vcpu,
> + int virt_irq, int irq);
> +int kvm_vgic_unmap_phys_irq(struct kvm_vcpu *vcpu, struct irq_phys_map *map);
>
> #define irqchip_in_kernel(k) (!!((k)->arch.vgic.in_kernel))
> #define vgic_initialized(k) (!!((k)->arch.vgic.nr_cpus))
> diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c
> index 5bd1695..c74d929 100644
> --- a/virt/kvm/arm/vgic.c
> +++ b/virt/kvm/arm/vgic.c
> @@ -24,6 +24,7 @@
> #include <linux/of.h>
> #include <linux/of_address.h>
> #include <linux/of_irq.h>
> +#include <linux/rculist.h>
> #include <linux/uaccess.h>
>
> #include <asm/kvm_emulate.h>
> @@ -82,6 +83,8 @@ static void vgic_retire_disabled_irqs(struct kvm_vcpu *vcpu);
> static void vgic_retire_lr(int lr_nr, int irq, struct kvm_vcpu *vcpu);
> 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 const struct vgic_ops *vgic_ops;
> static const struct vgic_params *vgic;
> @@ -1583,6 +1586,166 @@ static irqreturn_t vgic_maintenance_handler(int irq, void *data)
> return IRQ_HANDLED;
> }
>
> +static struct list_head *vgic_get_irq_phys_map_list(struct kvm_vcpu *vcpu,
> + int virt_irq)
> +{
> + if (virt_irq < VGIC_NR_PRIVATE_IRQS)
> + return &vcpu->arch.vgic_cpu.irq_phys_map_list;
> + else
> + return &vcpu->kvm->arch.vgic.irq_phys_map_list;
> +}
> +
> +/**
> + * kvm_vgic_map_phys_irq - map a virtual IRQ to a physical IRQ
> + * @vcpu: The VCPU pointer
> + * @virt_irq: The virtual irq number
> + * @irq: The Linux IRQ number
> + *
> + * Establish a mapping between a guest visible irq (@virt_irq) and a
> + * Linux irq (@irq). On injection, @virt_irq will be associated with
> + * the physical interrupt represented by @irq.
> + *
> + * Returns a valid pointer on success, and an error pointer otherwise
> + */
> +struct irq_phys_map *kvm_vgic_map_phys_irq(struct kvm_vcpu *vcpu,
> + int virt_irq, int irq)
> +{
> + struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
> + struct list_head *root = vgic_get_irq_phys_map_list(vcpu, virt_irq);
> + struct irq_phys_map *map;
> + struct irq_phys_map_entry *entry;
> + struct irq_desc *desc;
> + struct irq_data *data;
> + int phys_irq;
> +
> + desc = irq_to_desc(irq);
> + if (!desc) {
> + kvm_err("kvm_vgic_map_phys_irq: no interrupt descriptor\n");
super over-ridiculous nit:
if you respin you could consider "%s: no...", __FUNC__
> + return ERR_PTR(-EINVAL);
> + }
> +
> + data = irq_desc_get_irq_data(desc);
> + while (data->parent_data)
> + data = data->parent_data;
> +
> + phys_irq = data->hwirq;
> +
> + /* Create a new mapping */
> + entry = kzalloc(sizeof(*entry), GFP_KERNEL);
> + if (!entry)
> + return ERR_PTR(-ENOMEM);
> +
> + spin_lock(&dist->irq_phys_map_lock);
> +
> + /* Try to match an existing mapping */
> + map = vgic_irq_map_search(vcpu, virt_irq);
> + if (map) {
> + /* Make sure this mapping matches */
why do we need to check that it matches? Is it ever allowed to have
multiple mappings of a virtual interrupt?
> + if (map->phys_irq != phys_irq ||
> + map->irq != irq)
> + map = ERR_PTR(-EINVAL);
> +
> + goto out;
why is this a valid situation? Shouldn't you return -EEXIST or
something instead? (that would also simplify the error-checking free
routine below).
If you want it to be valid to map the same virq to irq multiple times
(to free the caller from some bookkeeping, I presume?) then that should
be part of the function documentation, and I think we should add a
"found existing mapping" comment above the goto out statement.
> + }
> +
> + map = &entry->map;
> + map->virt_irq = virt_irq;
> + map->phys_irq = phys_irq;
> + map->irq = irq;
> +
> + list_add_tail_rcu(&entry->entry, root);
> +
> +out:
> + spin_unlock(&dist->irq_phys_map_lock);
> + /* If we've found a hit in the existing list, free the useless
> + * entry */
> + if (IS_ERR(map) || map != &entry->map)
> + kfree(entry);
> + return map;
> +}
> +
> +static struct irq_phys_map *vgic_irq_map_search(struct kvm_vcpu *vcpu,
> + int virt_irq)
> +{
> + struct list_head *root = vgic_get_irq_phys_map_list(vcpu, virt_irq);
> + struct irq_phys_map_entry *entry;
> + struct irq_phys_map *map;
> +
> + rcu_read_lock();
> +
> + list_for_each_entry_rcu(entry, root, entry) {
> + map = &entry->map;
> + if (map->virt_irq == virt_irq && !map->deleted) {
> + rcu_read_unlock();
> + return map;
> + }
> + }
> +
> + rcu_read_unlock();
> +
> + return NULL;
> +}
> +
> +static void vgic_free_phys_irq_map_rcu(struct rcu_head *rcu)
> +{
> + struct irq_phys_map_entry *entry;
> +
> + entry = container_of(rcu, struct irq_phys_map_entry, rcu);
> + kfree(entry);
> +}
> +
> +/**
> + * kvm_vgic_unmap_phys_irq - Remove a virtual to physical IRQ mapping
> + * @vcpu: The VCPU pointer
> + * @map: The pointer to a mapping obtained through kvm_vgic_map_phys_irq
> + *
> + * Remove an existing mapping between virtual and physical interrupts.
> + */
> +int kvm_vgic_unmap_phys_irq(struct kvm_vcpu *vcpu, struct irq_phys_map *map)
> +{
> + struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
> + struct irq_phys_map_entry *entry;
> + struct list_head *root;
> +
> + if (!map)
> + return -EINVAL;
> +
> + root = vgic_get_irq_phys_map_list(vcpu, map->virt_irq);
> +
> + spin_lock(&dist->irq_phys_map_lock);
> +
> + list_for_each_entry(entry, root, entry) {
> + if (&entry->map == map && !map->deleted) {
> + map->deleted = true;
why do you need the 'deleted' flag? You now search the list only after
holding the lock, so the race I pointed out before doesn't exist
anymore. Is there an additional issue that the deleted flag is taking
care of?
> + list_del_rcu(&entry->entry);
> + call_rcu(&entry->rcu, vgic_free_phys_irq_map_rcu);
> + break;
> + }
> + }
> +
> + spin_unlock(&dist->irq_phys_map_lock);
> +
> + return 0;
> +}
> +
> +static void vgic_destroy_irq_phys_map(struct kvm *kvm, struct list_head *root)
> +{
> + struct vgic_dist *dist = &kvm->arch.vgic;
> + struct irq_phys_map_entry *entry;
> +
> + spin_lock(&dist->irq_phys_map_lock);
> +
> + list_for_each_entry(entry, root, entry) {
> + if (!entry->map.deleted) {
> + entry->map.deleted = true;
> + list_del_rcu(&entry->entry);
> + call_rcu(&entry->rcu, vgic_free_phys_irq_map_rcu);
> + }
> + }
> +
> + spin_unlock(&dist->irq_phys_map_lock);
> +}
> +
> void kvm_vgic_vcpu_destroy(struct kvm_vcpu *vcpu)
> {
> struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
> @@ -1591,6 +1754,7 @@ void kvm_vgic_vcpu_destroy(struct kvm_vcpu *vcpu)
> kfree(vgic_cpu->active_shared);
> kfree(vgic_cpu->pend_act_shared);
> kfree(vgic_cpu->vgic_irq_lr_map);
> + vgic_destroy_irq_phys_map(vcpu->kvm, &vgic_cpu->irq_phys_map_list);
> vgic_cpu->pending_shared = NULL;
> vgic_cpu->active_shared = NULL;
> vgic_cpu->pend_act_shared = NULL;
> @@ -1628,6 +1792,17 @@ static int vgic_vcpu_init_maps(struct kvm_vcpu *vcpu, int nr_irqs)
> }
>
> /**
> + * kvm_vgic_vcpu_early_init - Earliest possible per-vcpu vgic init stage
earliest possible... oh how I love the vgic code.
If you have the energy and context to write a comment in the beginning
of this file describing the init flow, I think that would be useful...
> + *
> + * No memory allocation should be performed here, only static init.
> + */
> +void kvm_vgic_vcpu_early_init(struct kvm_vcpu *vcpu)
> +{
> + struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
> + INIT_LIST_HEAD(&vgic_cpu->irq_phys_map_list);
> +}
> +
> +/**
> * kvm_vgic_get_max_vcpus - Get the maximum number of VCPUs allowed by HW
> *
> * The host's GIC naturally limits the maximum amount of VCPUs a guest
> @@ -1664,6 +1839,7 @@ void kvm_vgic_destroy(struct kvm *kvm)
> kfree(dist->irq_spi_target);
> kfree(dist->irq_pending_on_cpu);
> kfree(dist->irq_active_on_cpu);
> + vgic_destroy_irq_phys_map(kvm, &dist->irq_phys_map_list);
> dist->irq_sgi_sources = NULL;
> dist->irq_spi_cpu = NULL;
> dist->irq_spi_target = NULL;
> @@ -1787,6 +1963,18 @@ static int init_vgic_model(struct kvm *kvm, int type)
> return 0;
> }
>
> +/**
> + * kvm_vgic_early_init - Earliest possible vgic initialization stage
> + *
> + * No memory allocation should be performed here, only static init.
> + */
> +void kvm_vgic_early_init(struct kvm *kvm)
> +{
> + spin_lock_init(&kvm->arch.vgic.lock);
so here we're initializing the data structures even before the vgic is
created, right? So therefore it's safe to move the vgic.lock init up
here?
> + spin_lock_init(&kvm->arch.vgic.irq_phys_map_lock);
> + INIT_LIST_HEAD(&kvm->arch.vgic.irq_phys_map_list);
> +}
> +
> int kvm_vgic_create(struct kvm *kvm, u32 type)
> {
> int i, vcpu_lock_idx = -1, ret;
> @@ -1832,7 +2020,6 @@ int kvm_vgic_create(struct kvm *kvm, u32 type)
> if (ret)
> goto out_unlock;
>
> - spin_lock_init(&kvm->arch.vgic.lock);
> kvm->arch.vgic.in_kernel = true;
> kvm->arch.vgic.vgic_model = type;
> kvm->arch.vgic.vctrl_base = vgic->vctrl_base;
> --
> 2.1.4
>
Thanks,
-Christoffer
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