KVM: Add resampling irqfds for level triggered interrupts (7a84428a) · Commits · 戴 / test

Documentation/virtual/kvm/api.txt

+13 −0

Original line number	Diff line number	Diff line
		@@ -1950,6 +1950,19 @@ the guest using the specified gsi pin. The irqfd is removed using
		the KVM_IRQFD_FLAG_DEASSIGN flag, specifying both kvm_irqfd.fd
		and kvm_irqfd.gsi.

		With KVM_CAP_IRQFD_RESAMPLE, KVM_IRQFD supports a de-assert and notify
		mechanism allowing emulation of level-triggered, irqfd-based
		interrupts. When KVM_IRQFD_FLAG_RESAMPLE is set the user must pass an
		additional eventfd in the kvm_irqfd.resamplefd field. When operating
		in resample mode, posting of an interrupt through kvm_irq.fd asserts
		the specified gsi in the irqchip. When the irqchip is resampled, such
		as from an EOI, the gsi is de-asserted and the user is notifed via
		kvm_irqfd.resamplefd. It is the user's responsibility to re-queue
		the interrupt if the device making use of it still requires service.
		Note that closing the resamplefd is not sufficient to disable the
		irqfd. The KVM_IRQFD_FLAG_RESAMPLE is only necessary on assignment
		and need not be specified with KVM_IRQFD_FLAG_DEASSIGN.

		4.76 KVM_PPC_ALLOCATE_HTAB

		Capability: KVM_CAP_PPC_ALLOC_HTAB

arch/x86/kvm/x86.c

+4 −0

Original line number	Diff line number	Diff line
		@@ -2176,6 +2176,7 @@ int kvm_dev_ioctl_check_extension(long ext)
		case KVM_CAP_PCI_2_3:
		case KVM_CAP_KVMCLOCK_CTRL:
		case KVM_CAP_READONLY_MEM:
		case KVM_CAP_IRQFD_RESAMPLE:
		r = 1;
		break;
		case KVM_CAP_COALESCED_MMIO:
		@@ -6268,6 +6269,9 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)

		/* Reserve bit 0 of irq_sources_bitmap for userspace irq source */
		set_bit(KVM_USERSPACE_IRQ_SOURCE_ID, &kvm->arch.irq_sources_bitmap);
		/* Reserve bit 1 of irq_sources_bitmap for irqfd-resampler */
		set_bit(KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID,
		&kvm->arch.irq_sources_bitmap);

		raw_spin_lock_init(&kvm->arch.tsc_write_lock);
		mutex_init(&kvm->arch.apic_map_lock);

include/linux/kvm.h

+11 −1

Original line number	Diff line number	Diff line
		@@ -625,6 +625,7 @@ struct kvm_ppc_smmu_info {
		#ifdef __KVM_HAVE_READONLY_MEM
		#define KVM_CAP_READONLY_MEM 81
		#endif
		#define KVM_CAP_IRQFD_RESAMPLE 82

		#ifdef KVM_CAP_IRQ_ROUTING

		@@ -690,12 +691,21 @@ struct kvm_xen_hvm_config {
		#endif

		#define KVM_IRQFD_FLAG_DEASSIGN (1 << 0)
		/*
		* Available with KVM_CAP_IRQFD_RESAMPLE
		*
		* KVM_IRQFD_FLAG_RESAMPLE indicates resamplefd is valid and specifies
		* the irqfd to operate in resampling mode for level triggered interrupt
		* emlation. See Documentation/virtual/kvm/api.txt.
		*/
		#define KVM_IRQFD_FLAG_RESAMPLE (1 << 1)

		struct kvm_irqfd {
		__u32 fd;
		__u32 gsi;
		__u32 flags;
		__u8 pad[20];
		__u32 resamplefd;
		__u8 pad[16];
		};

		struct kvm_clock_data {

include/linux/kvm_host.h

+4 −1

Original line number	Diff line number	Diff line
		@@ -120,6 +120,7 @@ static inline bool is_error_page(struct page *page)
		#define KVM_REQ_PMI 17

		#define KVM_USERSPACE_IRQ_SOURCE_ID 0
		#define KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID 1

		struct kvm;
		struct kvm_vcpu;
		@@ -343,6 +344,8 @@ struct kvm {
		struct {
		spinlock_t lock;
		struct list_head items;
		struct list_head resampler_list;
		struct mutex resampler_lock;
		} irqfds;
		struct list_head ioeventfds;
		#endif

virt/kvm/eventfd.c

+146 −4

Original line number	Diff line number	Diff line
		@@ -43,6 +43,31 @@
		* --------------------------------------------------------------------
		*/

		/*
		* Resampling irqfds are a special variety of irqfds used to emulate
		* level triggered interrupts. The interrupt is asserted on eventfd
		* trigger. On acknowledgement through the irq ack notifier, the
		* interrupt is de-asserted and userspace is notified through the
		* resamplefd. All resamplers on the same gsi are de-asserted
		* together, so we don't need to track the state of each individual
		* user. We can also therefore share the same irq source ID.
		*/
		struct _irqfd_resampler {
		struct kvm *kvm;
		/*
		* List of resampling struct _irqfd objects sharing this gsi.
		* RCU list modified under kvm->irqfds.resampler_lock
		*/
		struct list_head list;
		struct kvm_irq_ack_notifier notifier;
		/*
		* Entry in list of kvm->irqfd.resampler_list. Use for sharing
		* resamplers among irqfds on the same gsi.
		* Accessed and modified under kvm->irqfds.resampler_lock
		*/
		struct list_head link;
		};

		struct _irqfd {
		/* Used for MSI fast-path */
		struct kvm *kvm;
		@@ -52,6 +77,12 @@ struct _irqfd {
		/* Used for level IRQ fast-path */
		int gsi;
		struct work_struct inject;
		/* The resampler used by this irqfd (resampler-only) */
		struct _irqfd_resampler *resampler;
		/* Eventfd notified on resample (resampler-only) */
		struct eventfd_ctx *resamplefd;
		/* Entry in list of irqfds for a resampler (resampler-only) */
		struct list_head resampler_link;
		/* Used for setup/shutdown */
		struct eventfd_ctx *eventfd;
		struct list_head list;
		@@ -67,8 +98,58 @@ irqfd_inject(struct work_struct *work)
		struct _irqfd *irqfd = container_of(work, struct _irqfd, inject);
		struct kvm *kvm = irqfd->kvm;

		if (!irqfd->resampler) {
		kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID, irqfd->gsi, 1);
		kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID, irqfd->gsi, 0);
		} else
		kvm_set_irq(kvm, KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID,
		irqfd->gsi, 1);
		}

		/*
		* Since resampler irqfds share an IRQ source ID, we de-assert once
		* then notify all of the resampler irqfds using this GSI. We can't
		* do multiple de-asserts or we risk racing with incoming re-asserts.
		*/
		static void
		irqfd_resampler_ack(struct kvm_irq_ack_notifier *kian)
		{
		struct _irqfd_resampler *resampler;
		struct _irqfd *irqfd;

		resampler = container_of(kian, struct _irqfd_resampler, notifier);

		kvm_set_irq(resampler->kvm, KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID,
		resampler->notifier.gsi, 0);

		rcu_read_lock();

		list_for_each_entry_rcu(irqfd, &resampler->list, resampler_link)
		eventfd_signal(irqfd->resamplefd, 1);

		rcu_read_unlock();
		}

		static void
		irqfd_resampler_shutdown(struct _irqfd *irqfd)
		{
		struct _irqfd_resampler *resampler = irqfd->resampler;
		struct kvm *kvm = resampler->kvm;

		mutex_lock(&kvm->irqfds.resampler_lock);

		list_del_rcu(&irqfd->resampler_link);
		synchronize_rcu();

		if (list_empty(&resampler->list)) {
		list_del(&resampler->link);
		kvm_unregister_irq_ack_notifier(kvm, &resampler->notifier);
		kvm_set_irq(kvm, KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID,
		resampler->notifier.gsi, 0);
		kfree(resampler);
		}

		mutex_unlock(&kvm->irqfds.resampler_lock);
		}

		/*
		@@ -92,6 +173,11 @@ irqfd_shutdown(struct work_struct *work)
		*/
		flush_work_sync(&irqfd->inject);

		if (irqfd->resampler) {
		irqfd_resampler_shutdown(irqfd);
		eventfd_ctx_put(irqfd->resamplefd);
		}

		/*
		* It is now safe to release the object's resources
		*/
		@@ -203,7 +289,7 @@ kvm_irqfd_assign(struct kvm kvm, struct kvm_irqfd args)
		struct kvm_irq_routing_table *irq_rt;
		struct _irqfd irqfd, tmp;
		struct file *file = NULL;
		struct eventfd_ctx *eventfd = NULL;
		struct eventfd_ctx eventfd = NULL, resamplefd = NULL;
		int ret;
		unsigned int events;

		@@ -231,6 +317,54 @@ kvm_irqfd_assign(struct kvm kvm, struct kvm_irqfd args)

		irqfd->eventfd = eventfd;

		if (args->flags & KVM_IRQFD_FLAG_RESAMPLE) {
		struct _irqfd_resampler *resampler;

		resamplefd = eventfd_ctx_fdget(args->resamplefd);
		if (IS_ERR(resamplefd)) {
		ret = PTR_ERR(resamplefd);
		goto fail;
		}

		irqfd->resamplefd = resamplefd;
		INIT_LIST_HEAD(&irqfd->resampler_link);

		mutex_lock(&kvm->irqfds.resampler_lock);

		list_for_each_entry(resampler,
		&kvm->irqfds.resampler_list, list) {
		if (resampler->notifier.gsi == irqfd->gsi) {
		irqfd->resampler = resampler;
		break;
		}
		}

		if (!irqfd->resampler) {
		resampler = kzalloc(sizeof(*resampler), GFP_KERNEL);
		if (!resampler) {
		ret = -ENOMEM;
		mutex_unlock(&kvm->irqfds.resampler_lock);
		goto fail;
		}

		resampler->kvm = kvm;
		INIT_LIST_HEAD(&resampler->list);
		resampler->notifier.gsi = irqfd->gsi;
		resampler->notifier.irq_acked = irqfd_resampler_ack;
		INIT_LIST_HEAD(&resampler->link);

		list_add(&resampler->link, &kvm->irqfds.resampler_list);
		kvm_register_irq_ack_notifier(kvm,
		&resampler->notifier);
		irqfd->resampler = resampler;
		}

		list_add_rcu(&irqfd->resampler_link, &irqfd->resampler->list);
		synchronize_rcu();

		mutex_unlock(&kvm->irqfds.resampler_lock);
		}

		/*
		* Install our own custom wake-up handling so we are notified via
		* a callback whenever someone signals the underlying eventfd
		@@ -276,6 +410,12 @@ kvm_irqfd_assign(struct kvm kvm, struct kvm_irqfd args)
		return 0;

		fail:
		if (irqfd->resampler)
		irqfd_resampler_shutdown(irqfd);

		if (resamplefd && !IS_ERR(resamplefd))
		eventfd_ctx_put(resamplefd);

		if (eventfd && !IS_ERR(eventfd))
		eventfd_ctx_put(eventfd);

		@@ -291,6 +431,8 @@ kvm_eventfd_init(struct kvm *kvm)
		{
		spin_lock_init(&kvm->irqfds.lock);
		INIT_LIST_HEAD(&kvm->irqfds.items);
		INIT_LIST_HEAD(&kvm->irqfds.resampler_list);
		mutex_init(&kvm->irqfds.resampler_lock);
		INIT_LIST_HEAD(&kvm->ioeventfds);
		}

		@@ -340,7 +482,7 @@ kvm_irqfd_deassign(struct kvm kvm, struct kvm_irqfd args)
		int
		kvm_irqfd(struct kvm kvm, struct kvm_irqfd args)
		{
		if (args->flags & ~KVM_IRQFD_FLAG_DEASSIGN)
		if (args->flags & ~(KVM_IRQFD_FLAG_DEASSIGN \| KVM_IRQFD_FLAG_RESAMPLE))
		return -EINVAL;

		if (args->flags & KVM_IRQFD_FLAG_DEASSIGN)

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