linux-kernel - [PATCH v2 8/8] irqbypass: Require producers to pass in Linux IRQ number during registration

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Message-ID: <20250516230734.2564775-9-seanjc@google.com>
Date: Fri, 16 May 2025 16:07:34 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Sean Christopherson <seanjc@...gle.com>, Paolo Bonzini <pbonzini@...hat.com>, 
	"Michael S. Tsirkin" <mst@...hat.com>, Jason Wang <jasowang@...hat.com>, 
	Alex Williamson <alex.williamson@...hat.com>
Cc: kvm@...r.kernel.org, virtualization@...ts.linux.dev, 
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Kevin Tian <kevin.tian@...el.com>, Oliver Upton <oliver.upton@...ux.dev>, 
	David Matlack <dmatlack@...gle.com>, Like Xu <like.xu.linux@...il.com>, 
	Binbin Wu <binbin.wu@...ux.intel.com>, Yong He <alexyonghe@...cent.com>
Subject: [PATCH v2 8/8] irqbypass: Require producers to pass in Linux IRQ
 number during registration

Pass in the Linux IRQ associated with an IRQ bypass producer instead of
relying on the caller to set the field prior to registration, as there's
no benefit to relying on callers to do the right thing.

Take care to set producer->irq before __connect(), as KVM expects the IRQ
to be valid as soon as a connection is possible.

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 drivers/vfio/pci/vfio_pci_intrs.c | 3 +--
 drivers/vhost/vdpa.c              | 4 ++--
 include/linux/irqbypass.h         | 2 +-
 virt/lib/irqbypass.c              | 5 ++++-
 4 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/drivers/vfio/pci/vfio_pci_intrs.c b/drivers/vfio/pci/vfio_pci_intrs.c
index d87fe116762a..123298a4dc8f 100644
--- a/drivers/vfio/pci/vfio_pci_intrs.c
+++ b/drivers/vfio/pci/vfio_pci_intrs.c
@@ -505,8 +505,7 @@ static int vfio_msi_set_vector_signal(struct vfio_pci_core_device *vdev,
 	if (ret)
 		goto out_put_eventfd_ctx;
 
-	ctx->producer.irq = irq;
-	ret = irq_bypass_register_producer(&ctx->producer, trigger);
+	ret = irq_bypass_register_producer(&ctx->producer, trigger, irq);
 	if (unlikely(ret)) {
 		dev_info(&pdev->dev,
 		"irq bypass producer (eventfd %p) registration fails: %d\n",
diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
index 7b265ffda697..af1e1fdfd9ed 100644
--- a/drivers/vhost/vdpa.c
+++ b/drivers/vhost/vdpa.c
@@ -212,8 +212,8 @@ static void vhost_vdpa_setup_vq_irq(struct vhost_vdpa *v, u16 qid)
 	if (!vq->call_ctx.ctx)
 		return;
 
-	vq->call_ctx.producer.irq = irq;
-	ret = irq_bypass_register_producer(&vq->call_ctx.producer, vq->call_ctx.ctx);
+	ret = irq_bypass_register_producer(&vq->call_ctx.producer,
+					   vq->call_ctx.ctx, irq);
 	if (unlikely(ret))
 		dev_info(&v->dev, "vq %u, irq bypass producer (eventfd %p) registration fails, ret =  %d\n",
 			 qid, vq->call_ctx.ctx, ret);
diff --git a/include/linux/irqbypass.h b/include/linux/irqbypass.h
index cd64fcaa88fe..ede1fa938152 100644
--- a/include/linux/irqbypass.h
+++ b/include/linux/irqbypass.h
@@ -84,7 +84,7 @@ struct irq_bypass_consumer {
 };
 
 int irq_bypass_register_producer(struct irq_bypass_producer *producer,
-				 struct eventfd_ctx *eventfd);
+				 struct eventfd_ctx *eventfd, int irq);
 void irq_bypass_unregister_producer(struct irq_bypass_producer *producer);
 int irq_bypass_register_consumer(struct irq_bypass_consumer *consumer,
 				 struct eventfd_ctx *eventfd);
diff --git a/virt/lib/irqbypass.c b/virt/lib/irqbypass.c
index ea888b9203d2..62c160200be9 100644
--- a/virt/lib/irqbypass.c
+++ b/virt/lib/irqbypass.c
@@ -85,12 +85,13 @@ static void __disconnect(struct irq_bypass_producer *prod,
  * irq_bypass_register_producer - register IRQ bypass producer
  * @producer: pointer to producer structure
  * @eventfd: pointer to the eventfd context associated with the producer
+ * @irq: Linux IRQ number of the underlying producer device
  *
  * Add the provided IRQ producer to the set of producers and connect with the
  * consumer with a matching eventfd, if one exists.
  */
 int irq_bypass_register_producer(struct irq_bypass_producer *producer,
-				 struct eventfd_ctx *eventfd)
+				 struct eventfd_ctx *eventfd, int irq)
 {
 	unsigned long index = (unsigned long)eventfd;
 	struct irq_bypass_consumer *consumer;
@@ -99,6 +100,8 @@ int irq_bypass_register_producer(struct irq_bypass_producer *producer,
 	if (WARN_ON_ONCE(producer->eventfd))
 		return -EINVAL;
 
+	producer->irq = irq;
+
 	guard(mutex)(&lock);
 
 	ret = xa_insert(&producers, index, producer, GFP_KERNEL);
-- 
2.49.0.1112.g889b7c5bd8-goog