[PATCH 3/3] tap: add die() on vhost error

["Eugenio Pérez" <eperezma@redhat.com>]

In case the kernel needs to signal an error.

Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
---
 epoll_type.h |  2 ++
 passt.c      |  4 ++++
 passt.h      |  1 +
 tap.c        | 16 ++++++++++++++++
 4 files changed, 23 insertions(+)

diff --git a/epoll_type.h b/epoll_type.h
index 6284c79..6b320db 100644
--- a/epoll_type.h
+++ b/epoll_type.h
@@ -46,6 +46,8 @@ enum epoll_type {
 	EPOLL_TYPE_REPAIR,
 	/* vhost-kernel call socket */
 	EPOLL_TYPE_VHOST_CALL,
+	/* vhost-kernel error socket */
+	EPOLL_TYPE_VHOST_ERROR,

 	EPOLL_NUM_TYPES,
 };
diff --git a/passt.c b/passt.c
index 19c5d5f..2779e0b 100644
--- a/passt.c
+++ b/passt.c
@@ -80,6 +80,7 @@ char *epoll_type_str[] = {
 	[EPOLL_TYPE_REPAIR_LISTEN]	= "TCP_REPAIR helper listening socket",
 	[EPOLL_TYPE_REPAIR]		= "TCP_REPAIR helper socket",
 	[EPOLL_TYPE_VHOST_CALL]		= "vhost-kernel call socket",
+	[EPOLL_TYPE_VHOST_ERROR]	= "vhost-kernel error socket",
 };
 static_assert(ARRAY_SIZE(epoll_type_str) == EPOLL_NUM_TYPES,
 	      "epoll_type_str[] doesn't match enum epoll_type");
@@ -361,6 +362,9 @@ loop:
 		case EPOLL_TYPE_VHOST_CALL:
 			vhost_call_cb(&c, ref, &now);
 			break;
+		case EPOLL_TYPE_VHOST_ERROR:
+			die("Error on vhost-kernel socket");
+			break;
 		default:
 			/* Can't happen */
 			ASSERT(0);
diff --git a/passt.h b/passt.h
index eb5aa03..9e42f3b 100644
--- a/passt.h
+++ b/passt.h
@@ -307,6 +307,7 @@ struct ctx {

 		int kick_fd;
 		int call_fd;
+		int err_fd;
 	} vq[2];

 	int no_dns;
diff --git a/tap.c b/tap.c
index fbe83aa..b02d3da 100644
--- a/tap.c
+++ b/tap.c
@@ -1552,6 +1552,22 @@ static int tap_ns_tun(void *arg)
 		if (rc < 0)
 			die_perror("Failed to add call eventfd to epoll");
 		c->vq[i].call_fd = file.fd;
+
+		file.fd = eventfd(0, EFD_NONBLOCK | EFD_CLOEXEC);
+		if (file.fd < 0)
+			die_perror("Failed to create error eventfd");
+
+		rc = ioctl(vhost_fd, VHOST_SET_VRING_ERR, &file);
+		if (rc < 0)
+			die_perror(
+				"VHOST_SET_VRING_ERR ioctl on /dev/vhost-net failed");
+
+		ref.type = EPOLL_TYPE_VHOST_ERROR, ref.fd = file.fd;
+		ev.data.u64 = ref.u64;
+		rc = epoll_ctl(c->epollfd, EPOLL_CTL_ADD, ref.fd, &ev);
+		if (rc < 0)
+			die_perror("Failed to add error eventfd to epoll");
+		c->vq[i].err_fd = file.fd;
 	}

 	/* 1:1 translation */
--
2.49.0