virtio/vhost: Factor notify_vq_gsi()

All vhost devices should perform the same operations when initializing
the IRQFD. Move it to virtio/vhost.c

This fixes vsock, which didn't go through the irq__add_irqfd() helper
and couldn't be used on systems that require GSI translation (GICv2m).

Also correct notify_vq_gsi() in net.c, to check which virtqueue is being
configured. Since vhost only manages the data queues, we shouldn't try
to setup GSI routing for the control queue. This hasn't been a problem
so far because the Linux guest doesn't use IRQs for the control queue.

Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Link: https://lore.kernel.org/r/20230606130426.978945-5-jean-philippe@linaro.org
Signed-off-by: Will Deacon <will@kernel.org>

5 files changed, 53 insertions, 63 deletions

diff --git a/include/kvm/virtio.h b/include/kvm/virtio.h
index 6912875e..a2f8355a 100644
--- a/include/kvm/virtio.h
+++ b/include/kvm/virtio.h
@@ -77,6 +77,10 @@ struct virt_queue {
 	u16		endian;
 	bool		use_event_idx;
 	bool		enabled;
+
+	/* vhost IRQ handling */
+	int		gsi;
+	int		irqfd;
 };
 
 /*
@@ -263,6 +267,10 @@ void virtio_vhost_set_vring(struct kvm *kvm, int vhost_fd, u32 index,
 			    struct virt_queue *queue);
 void virtio_vhost_set_vring_kick(struct kvm *kvm, int vhost_fd,
 				 u32 index, int event_fd);
+void virtio_vhost_set_vring_call(struct kvm *kvm, int vhost_fd, u32 index,
+				 u32 gsi, struct virt_queue *queue);
+void virtio_vhost_reset_vring(struct kvm *kvm, int vhost_fd, u32 index,
+			      struct virt_queue *queue);
 
 int virtio_transport_parser(const struct option *opt, const char *arg, int unset);
 
diff --git a/virtio/net.c b/virtio/net.c
index c0871163..3e1aedf7 100644
--- a/virtio/net.c
+++ b/virtio/net.c
@@ -4,12 +4,12 @@
 #include "kvm/mutex.h"
 #include "kvm/util.h"
 #include "kvm/kvm.h"
-#include "kvm/irq.h"
 #include "kvm/uip.h"
 #include "kvm/guest_compat.h"
 #include "kvm/iovec.h"
 #include "kvm/strbuf.h"
 
+#include <linux/list.h>
 #include <linux/vhost.h>
 #include <linux/virtio_net.h>
 #include <linux/if_tun.h>
@@ -25,7 +25,6 @@
 #include <sys/ioctl.h>
 #include <sys/types.h>
 #include <sys/wait.h>
-#include <sys/eventfd.h>
 
 #define VIRTIO_NET_QUEUE_SIZE		256
 #define VIRTIO_NET_NUM_QUEUES		8
@@ -44,8 +43,6 @@ struct net_dev_queue {
 	pthread_t			thread;
 	struct mutex			lock;
 	pthread_cond_t			cond;
-	int				gsi;
-	int				irqfd;
 };
 
 struct net_dev {
@@ -647,11 +644,7 @@ static void exit_vq(struct kvm *kvm, void *dev, u32 vq)
 	struct net_dev *ndev = dev;
 	struct net_dev_queue *queue = &ndev->queues[vq];
 
-	if (!is_ctrl_vq(ndev, vq) && queue->gsi) {
-		irq__del_irqfd(kvm, queue->gsi, queue->irqfd);
-		close(queue->irqfd);
-		queue->gsi = queue->irqfd = 0;
-	}
+	virtio_vhost_reset_vring(kvm, ndev->vhost_fd, vq, &queue->vq);
 
 	/*
 	 * TODO: vhost reset owner. It's the only way to cleanly stop vhost, but
@@ -675,27 +668,12 @@ static void notify_vq_gsi(struct kvm *kvm, void *dev, u32 vq, u32 gsi)
 {
 	struct net_dev *ndev = dev;
 	struct net_dev_queue *queue = &ndev->queues[vq];
-	struct vhost_vring_file file;
-	int r;
 
-	if (ndev->vhost_fd == 0)
+	if (ndev->vhost_fd == 0 || is_ctrl_vq(ndev, vq))
 		return;
 
-	file = (struct vhost_vring_file) {
-		.index	= vq,
-		.fd	= eventfd(0, 0),
-	};
-
-	r = irq__add_irqfd(kvm, gsi, file.fd, -1);
-	if (r < 0)
-		die_perror("KVM_IRQFD failed");
-
-	queue->irqfd = file.fd;
-	queue->gsi = gsi;
-
-	r = ioctl(ndev->vhost_fd, VHOST_SET_VRING_CALL, &file);
-	if (r < 0)
-		die_perror("VHOST_SET_VRING_CALL failed");
+	virtio_vhost_set_vring_call(kvm, ndev->vhost_fd, vq, gsi,
+				    &queue->vq);
 }
 
 static void notify_vq_eventfd(struct kvm *kvm, void *dev, u32 vq, u32 efd)
diff --git a/virtio/scsi.c b/virtio/scsi.c
index ebddec36..708fb23a 100644
--- a/virtio/scsi.c
+++ b/virtio/scsi.c
@@ -90,25 +90,14 @@ static int init_vq(struct kvm *kvm, void *dev, u32 vq)
 
 static void notify_vq_gsi(struct kvm *kvm, void *dev, u32 vq, u32 gsi)
 {
-	struct vhost_vring_file file;
 	struct scsi_dev *sdev = dev;
 	int r;
 
 	if (sdev->vhost_fd == 0)
 		return;
 
-	file = (struct vhost_vring_file) {
-		.index	= vq,
-		.fd	= eventfd(0, 0),
-	};
-
-	r = irq__add_irqfd(kvm, gsi, file.fd, -1);
-	if (r < 0)
-		die_perror("KVM_IRQFD failed");
-
-	r = ioctl(sdev->vhost_fd, VHOST_SET_VRING_CALL, &file);
-	if (r < 0)
-		die_perror("VHOST_SET_VRING_CALL failed");
+	virtio_vhost_set_vring_call(kvm, sdev->vhost_fd, vq, gsi,
+				    &sdev->vqs[vq]);
 
 	if (vq > 0)
 		return;
diff --git a/virtio/vhost.c b/virtio/vhost.c
index 3acfd30a..cd83645c 100644
--- a/virtio/vhost.c
+++ b/virtio/vhost.c
@@ -1,9 +1,12 @@
+#include "kvm/irq.h"
 #include "kvm/virtio.h"
 
 #include <linux/kvm.h>
 #include <linux/vhost.h>
 #include <linux/list.h>
 
+#include <sys/eventfd.h>
+
 void virtio_vhost_init(struct kvm *kvm, int vhost_fd)
 {
 	struct kvm_mem_bank *bank;
@@ -79,3 +82,35 @@ void virtio_vhost_set_vring_kick(struct kvm *kvm, int vhost_fd,
 	if (r < 0)
 		die_perror("VHOST_SET_VRING_KICK failed");
 }
+
+void virtio_vhost_set_vring_call(struct kvm *kvm, int vhost_fd, u32 index,
+				 u32 gsi, struct virt_queue *queue)
+{
+	int r;
+	struct vhost_vring_file file = {
+		.index	= index,
+		.fd	= eventfd(0, 0),
+	};
+
+	r = irq__add_irqfd(kvm, gsi, file.fd, -1);
+	if (r < 0)
+		die_perror("KVM_IRQFD failed");
+
+	r = ioctl(vhost_fd, VHOST_SET_VRING_CALL, &file);
+	if (r < 0)
+		die_perror("VHOST_SET_VRING_CALL failed");
+
+	queue->irqfd = file.fd;
+	queue->gsi = gsi;
+}
+
+void virtio_vhost_reset_vring(struct kvm *kvm, int vhost_fd, u32 index,
+			      struct virt_queue *queue)
+
+{
+	if (queue->gsi) {
+		irq__del_irqfd(kvm, queue->gsi, queue->irqfd);
+		close(queue->irqfd);
+		queue->gsi = queue->irqfd = 0;
+	}
+}
diff --git a/virtio/vsock.c b/virtio/vsock.c
index 0ada9e09..559fbaba 100644
--- a/virtio/vsock.c
+++ b/virtio/vsock.c
@@ -131,33 +131,13 @@ static int set_size_vq(struct kvm *kvm, void *dev, u32 vq, int size)
 
 static void notify_vq_gsi(struct kvm *kvm, void *dev, u32 vq, u32 gsi)
 {
-	struct vhost_vring_file file;
 	struct vsock_dev *vdev = dev;
-	struct kvm_irqfd irq;
-	int r;
-
-	if (vdev->vhost_fd == -1)
-		return;
 
-	if (is_event_vq(vq))
+	if (vdev->vhost_fd == -1 || is_event_vq(vq))
 		return;
 
-	irq = (struct kvm_irqfd) {
-		.gsi	= gsi,
-		.fd	= eventfd(0, 0),
-	};
-	file = (struct vhost_vring_file) {
-		.index	= vq,
-		.fd	= irq.fd,
-	};
-
-	r = ioctl(kvm->vm_fd, KVM_IRQFD, &irq);
-	if (r < 0)
-		die_perror("KVM_IRQFD failed");
-
-	r = ioctl(vdev->vhost_fd, VHOST_SET_VRING_CALL, &file);
-	if (r < 0)
-		die_perror("VHOST_SET_VRING_CALL failed");
+	virtio_vhost_set_vring_call(kvm, vdev->vhost_fd, vq, gsi,
+				    &vdev->vqs[vq]);
 }
 
 static unsigned int get_vq_count(struct kvm *kvm, void *dev)