[PATCH v8 3/6] kvm: Add IRQ source ID option to KVM_IRQFD

[Alex Williamson <alex.williamson@redhat.com>]

This allows specifying an IRQ source ID to be used when injecting an
interrupt.  When not specified KVM_USERSPACE_IRQ_SOURCE_ID is used.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
---

 Documentation/virtual/kvm/api.txt |    5 +++++
 arch/x86/kvm/x86.c                |    1 +
 include/linux/kvm.h               |    6 +++++-
 virt/kvm/eventfd.c                |   14 ++++++++++----
 4 files changed, 21 insertions(+), 5 deletions(-)

diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
index 062cfd5..46f4b4d 100644
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -1946,6 +1946,11 @@ 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.
 
+When KVM_CAP_IRQFD_IRQ_SOURCE_ID is available, KVM_IRQFD supports the
+KVM_IRQFD_FLAG_IRQ_SOURCE_ID which can be used to specify an IRQ
+source ID (see KVM_IRQ_SOURCE_ID) to be used for the guest interrupt.
+This flag has no effect on deassignment.
+
 4.76 KVM_PPC_ALLOCATE_HTAB
 
 Capability: KVM_CAP_PPC_ALLOC_HTAB
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 75e743e..946c5bd 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2174,6 +2174,7 @@ int kvm_dev_ioctl_check_extension(long ext)
 	case KVM_CAP_GET_TSC_KHZ:
 	case KVM_CAP_PCI_2_3:
 	case KVM_CAP_KVMCLOCK_CTRL:
+	case KVM_CAP_IRQFD_IRQ_SOURCE_ID:
 		r = 1;
 		break;
 	case KVM_CAP_COALESCED_MMIO:
diff --git a/include/linux/kvm.h b/include/linux/kvm.h
index 67b6b49..deda8a9 100644
--- a/include/linux/kvm.h
+++ b/include/linux/kvm.h
@@ -619,6 +619,7 @@ struct kvm_ppc_smmu_info {
 #define KVM_CAP_S390_COW 79
 #define KVM_CAP_PPC_ALLOC_HTAB 80
 #define KVM_CAP_NR_IRQ_SOURCE_ID 81
+#define KVM_CAP_IRQFD_IRQ_SOURCE_ID 82
 
 #ifdef KVM_CAP_IRQ_ROUTING
 
@@ -684,12 +685,15 @@ struct kvm_xen_hvm_config {
 #endif
 
 #define KVM_IRQFD_FLAG_DEASSIGN (1 << 0)
+/* Available with KVM_CAP_IRQFD_IRQ_SOURCE_ID */
+#define KVM_IRQFD_FLAG_IRQ_SOURCE_ID (1 << 1)
 
 struct kvm_irqfd {
 	__u32 fd;
 	__u32 gsi;
 	__u32 flags;
-	__u8  pad[20];
+	__u32 irq_source_id;
+	__u8  pad[16];
 };
 
 #define KVM_IRQ_SOURCE_ID_FLAG_DEASSIGN (1 << 0)
diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c
index 7d7e2aa..30150f1 100644
--- a/virt/kvm/eventfd.c
+++ b/virt/kvm/eventfd.c
@@ -51,6 +51,7 @@ struct _irqfd {
 	struct kvm_kernel_irq_routing_entry __rcu *irq_entry;
 	/* Used for level IRQ fast-path */
 	int gsi;
+	int irq_source_id;
 	struct work_struct inject;
 	/* Used for setup/shutdown */
 	struct eventfd_ctx *eventfd;
@@ -67,8 +68,8 @@ irqfd_inject(struct work_struct *work)
 	struct _irqfd *irqfd = container_of(work, struct _irqfd, inject);
 	struct kvm *kvm = irqfd->kvm;
 
-	kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID, irqfd->gsi, 1);
-	kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID, irqfd->gsi, 0);
+	kvm_set_irq(kvm, irqfd->irq_source_id, irqfd->gsi, 1);
+	kvm_set_irq(kvm, irqfd->irq_source_id, irqfd->gsi, 0);
 }
 
 /*
@@ -138,7 +139,7 @@ irqfd_wakeup(wait_queue_t *wait, unsigned mode, int sync, void *key)
 		irq = rcu_dereference(irqfd->irq_entry);
 		/* An event has been signaled, inject an interrupt */
 		if (irq)
-			kvm_set_msi(irq, kvm, KVM_USERSPACE_IRQ_SOURCE_ID, 1);
+			kvm_set_msi(irq, kvm, irqfd->irq_source_id, 1);
 		else
 			schedule_work(&irqfd->inject);
 		rcu_read_unlock();
@@ -213,6 +214,10 @@ kvm_irqfd_assign(struct kvm *kvm, struct kvm_irqfd *args)
 
 	irqfd->kvm = kvm;
 	irqfd->gsi = args->gsi;
+	if (args->flags & KVM_IRQFD_FLAG_IRQ_SOURCE_ID)
+		irqfd->irq_source_id = args->irq_source_id;
+	else
+		irqfd->irq_source_id = KVM_USERSPACE_IRQ_SOURCE_ID;
 	INIT_LIST_HEAD(&irqfd->list);
 	INIT_WORK(&irqfd->inject, irqfd_inject);
 	INIT_WORK(&irqfd->shutdown, irqfd_shutdown);
@@ -340,7 +345,8 @@ 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_IRQ_SOURCE_ID))
 		return -EINVAL;
 
 	if (args->flags & KVM_IRQFD_FLAG_DEASSIGN)