[v2,5/5] vhost: enhance virtqueue access lock asserts

Message ID 20231205094536.2816720-5-david.marchand@redhat.com (mailing list archive)
State Superseded
Delegated to: Maxime Coquelin
Headers
Series [v2,1/5] vhost: fix virtqueue access check in datapath |

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Commit Message

David Marchand Dec. 5, 2023, 9:45 a.m. UTC
  A simple comment in vhost_user_msg_handler() is not that robust.

Add a lock_all_qps property to message handlers so that their
implementation can add a build check and assert a vq is locked.

Signed-off-by: David Marchand <david.marchand@redhat.com>
Acked-by: Eelco Chaudron <echaudro@redhat.com>
Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>
---
Changes since v1:
- moved this patch as the last of the series,

---
 lib/vhost/vhost_user.c | 114 +++++++++++++++++++----------------------
 1 file changed, 53 insertions(+), 61 deletions(-)
  

Comments

Thomas Monjalon Feb. 19, 2024, 10:52 a.m. UTC | #1
05/12/2023 10:45, David Marchand:
> +#define VHOST_USER_ASSERT_LOCK(dev, vq, id) do { \
> +	RTE_BUILD_BUG_ON(!vhost_message_handlers[id].lock_all_qps); \
> +	vq_assert_lock(dev, vq); \
> +} while (0)

Since "eal: enhance compile-time checks using C11 assert",
it is not allowed to have non-constant check in RTE_BUILD_BUG_ON:

lib/vhost/vhost_user.c:413:25: note: in expansion of macro 'VHOST_USER_ASSERT_LOCK'
lib/vhost/vhost_user.c: In function 'vhost_user_set_vring_addr':
lib/eal/include/rte_common.h:518:56: error: expression in static assertion is not constant
  #define RTE_BUILD_BUG_ON(condition) do { static_assert(!(condition), #condition); } while (0)

I suppose we can make this check at compile-time with few adjustments.
For -rc1, I am dropping this patch.
  
David Marchand Feb. 26, 2024, 3:46 p.m. UTC | #2
On Mon, Feb 19, 2024 at 11:52 AM Thomas Monjalon <thomas@monjalon.net> wrote:
>
> 05/12/2023 10:45, David Marchand:
> > +#define VHOST_USER_ASSERT_LOCK(dev, vq, id) do { \
> > +     RTE_BUILD_BUG_ON(!vhost_message_handlers[id].lock_all_qps); \
> > +     vq_assert_lock(dev, vq); \
> > +} while (0)
>
> Since "eal: enhance compile-time checks using C11 assert",
> it is not allowed to have non-constant check in RTE_BUILD_BUG_ON:
>
> lib/vhost/vhost_user.c:413:25: note: in expansion of macro 'VHOST_USER_ASSERT_LOCK'
> lib/vhost/vhost_user.c: In function 'vhost_user_set_vring_addr':
> lib/eal/include/rte_common.h:518:56: error: expression in static assertion is not constant
>   #define RTE_BUILD_BUG_ON(condition) do { static_assert(!(condition), #condition); } while (0)
>
> I suppose we can make this check at compile-time with few adjustments.
> For -rc1, I am dropping this patch.

Iiuc, an array content is not constant (from a compiler pov) unless
the elements are integers.

I suspect there is some gcc-specific implementation that could work,
since with the previous implementation of RTE_BUILD_BUG_ON, this check
was working with both gcc and clang...
But I could not find how to.

I have an alternate solution using enums with the existing macros..
I'll post a new revision.
  

Patch

diff --git a/lib/vhost/vhost_user.c b/lib/vhost/vhost_user.c
index 651ea5854b..e8020ccfd3 100644
--- a/lib/vhost/vhost_user.c
+++ b/lib/vhost/vhost_user.c
@@ -56,14 +56,24 @@ 
 #define INFLIGHT_ALIGNMENT	64
 #define INFLIGHT_VERSION	0x1
 
-typedef struct vhost_message_handler {
+typedef const struct vhost_message_handler {
 	const char *description;
 	int (*callback)(struct virtio_net **pdev, struct vhu_msg_context *ctx,
 		int main_fd);
 	bool accepts_fd;
+	bool lock_all_qps;
 } vhost_message_handler_t;
 static vhost_message_handler_t vhost_message_handlers[];
 
+/* vhost_user_msg_handler() locks all qps based on a handler's lock_all_qps.
+ * Later, a handler may need to ensure the vq has been locked (for example,
+ * when calling lock annotated helpers).
+ */
+#define VHOST_USER_ASSERT_LOCK(dev, vq, id) do { \
+	RTE_BUILD_BUG_ON(!vhost_message_handlers[id].lock_all_qps); \
+	vq_assert_lock(dev, vq); \
+} while (0)
+
 static int send_vhost_reply(struct virtio_net *dev, int sockfd, struct vhu_msg_context *ctx);
 static int read_vhost_message(struct virtio_net *dev, int sockfd, struct vhu_msg_context *ctx);
 
@@ -400,7 +410,7 @@  vhost_user_set_features(struct virtio_net **pdev,
 			cleanup_vq(vq, 1);
 			cleanup_vq_inflight(dev, vq);
 			/* vhost_user_lock_all_queue_pairs locked all qps */
-			vq_assert_lock(dev, vq);
+			VHOST_USER_ASSERT_LOCK(dev, vq, VHOST_USER_SET_FEATURES);
 			rte_rwlock_write_unlock(&vq->access_lock);
 			free_vq(dev, vq);
 		}
@@ -927,7 +937,7 @@  vhost_user_set_vring_addr(struct virtio_net **pdev,
 	vq = dev->virtqueue[ctx->msg.payload.addr.index];
 
 	/* vhost_user_lock_all_queue_pairs locked all qps */
-	vq_assert_lock(dev, vq);
+	VHOST_USER_ASSERT_LOCK(dev, vq, VHOST_USER_SET_VRING_ADDR);
 
 	access_ok = vq->access_ok;
 
@@ -1442,7 +1452,7 @@  vhost_user_set_mem_table(struct virtio_net **pdev,
 
 		if (vq->desc || vq->avail || vq->used) {
 			/* vhost_user_lock_all_queue_pairs locked all qps */
-			vq_assert_lock(dev, vq);
+			VHOST_USER_ASSERT_LOCK(dev, vq, VHOST_USER_SET_MEM_TABLE);
 
 			/*
 			 * If the memory table got updated, the ring addresses
@@ -2234,7 +2244,7 @@  vhost_user_set_vring_enable(struct virtio_net **pdev,
 	vq = dev->virtqueue[index];
 	if (!(dev->flags & VIRTIO_DEV_VDPA_CONFIGURED)) {
 		/* vhost_user_lock_all_queue_pairs locked all qps */
-		vq_assert_lock(dev, vq);
+		VHOST_USER_ASSERT_LOCK(dev, vq, VHOST_USER_SET_VRING_ENABLE);
 		if (enable && vq->async && vq->async->pkts_inflight_n) {
 			VHOST_LOG_CONFIG(dev->ifname, ERR,
 				"failed to enable vring. Inflight packets must be completed first\n");
@@ -2839,41 +2849,43 @@  vhost_user_set_status(struct virtio_net **pdev,
 }
 
 #define VHOST_MESSAGE_HANDLERS \
-VHOST_MESSAGE_HANDLER(VHOST_USER_NONE, NULL, false) \
-VHOST_MESSAGE_HANDLER(VHOST_USER_GET_FEATURES, vhost_user_get_features, false) \
-VHOST_MESSAGE_HANDLER(VHOST_USER_SET_FEATURES, vhost_user_set_features, false) \
-VHOST_MESSAGE_HANDLER(VHOST_USER_SET_OWNER, vhost_user_set_owner, false) \
-VHOST_MESSAGE_HANDLER(VHOST_USER_RESET_OWNER, vhost_user_reset_owner, false) \
-VHOST_MESSAGE_HANDLER(VHOST_USER_SET_MEM_TABLE, vhost_user_set_mem_table, true) \
-VHOST_MESSAGE_HANDLER(VHOST_USER_SET_LOG_BASE, vhost_user_set_log_base, true) \
-VHOST_MESSAGE_HANDLER(VHOST_USER_SET_LOG_FD, vhost_user_set_log_fd, true) \
-VHOST_MESSAGE_HANDLER(VHOST_USER_SET_VRING_NUM, vhost_user_set_vring_num, false) \
-VHOST_MESSAGE_HANDLER(VHOST_USER_SET_VRING_ADDR, vhost_user_set_vring_addr, false) \
-VHOST_MESSAGE_HANDLER(VHOST_USER_SET_VRING_BASE, vhost_user_set_vring_base, false) \
-VHOST_MESSAGE_HANDLER(VHOST_USER_GET_VRING_BASE, vhost_user_get_vring_base, false) \
-VHOST_MESSAGE_HANDLER(VHOST_USER_SET_VRING_KICK, vhost_user_set_vring_kick, true) \
-VHOST_MESSAGE_HANDLER(VHOST_USER_SET_VRING_CALL, vhost_user_set_vring_call, true) \
-VHOST_MESSAGE_HANDLER(VHOST_USER_SET_VRING_ERR, vhost_user_set_vring_err, true) \
-VHOST_MESSAGE_HANDLER(VHOST_USER_GET_PROTOCOL_FEATURES, vhost_user_get_protocol_features, false) \
-VHOST_MESSAGE_HANDLER(VHOST_USER_SET_PROTOCOL_FEATURES, vhost_user_set_protocol_features, false) \
-VHOST_MESSAGE_HANDLER(VHOST_USER_GET_QUEUE_NUM, vhost_user_get_queue_num, false) \
-VHOST_MESSAGE_HANDLER(VHOST_USER_SET_VRING_ENABLE, vhost_user_set_vring_enable, false) \
-VHOST_MESSAGE_HANDLER(VHOST_USER_SEND_RARP, vhost_user_send_rarp, false) \
-VHOST_MESSAGE_HANDLER(VHOST_USER_NET_SET_MTU, vhost_user_net_set_mtu, false) \
-VHOST_MESSAGE_HANDLER(VHOST_USER_SET_BACKEND_REQ_FD, vhost_user_set_req_fd, true) \
-VHOST_MESSAGE_HANDLER(VHOST_USER_IOTLB_MSG, vhost_user_iotlb_msg, false) \
-VHOST_MESSAGE_HANDLER(VHOST_USER_GET_CONFIG, vhost_user_get_config, false) \
-VHOST_MESSAGE_HANDLER(VHOST_USER_SET_CONFIG, vhost_user_set_config, false) \
-VHOST_MESSAGE_HANDLER(VHOST_USER_POSTCOPY_ADVISE, vhost_user_set_postcopy_advise, false) \
-VHOST_MESSAGE_HANDLER(VHOST_USER_POSTCOPY_LISTEN, vhost_user_set_postcopy_listen, false) \
-VHOST_MESSAGE_HANDLER(VHOST_USER_POSTCOPY_END, vhost_user_postcopy_end, false) \
-VHOST_MESSAGE_HANDLER(VHOST_USER_GET_INFLIGHT_FD, vhost_user_get_inflight_fd, false) \
-VHOST_MESSAGE_HANDLER(VHOST_USER_SET_INFLIGHT_FD, vhost_user_set_inflight_fd, true) \
-VHOST_MESSAGE_HANDLER(VHOST_USER_SET_STATUS, vhost_user_set_status, false) \
-VHOST_MESSAGE_HANDLER(VHOST_USER_GET_STATUS, vhost_user_get_status, false)
-
-#define VHOST_MESSAGE_HANDLER(id, handler, accepts_fd) \
-	[id] = { #id, handler, accepts_fd },
+VHOST_MESSAGE_HANDLER(VHOST_USER_NONE, NULL, false, false) \
+VHOST_MESSAGE_HANDLER(VHOST_USER_GET_FEATURES, vhost_user_get_features, false, false) \
+VHOST_MESSAGE_HANDLER(VHOST_USER_SET_FEATURES, vhost_user_set_features, false, true) \
+VHOST_MESSAGE_HANDLER(VHOST_USER_SET_OWNER, vhost_user_set_owner, false, true) \
+VHOST_MESSAGE_HANDLER(VHOST_USER_RESET_OWNER, vhost_user_reset_owner, false, false) \
+VHOST_MESSAGE_HANDLER(VHOST_USER_SET_MEM_TABLE, vhost_user_set_mem_table, true, true) \
+VHOST_MESSAGE_HANDLER(VHOST_USER_SET_LOG_BASE, vhost_user_set_log_base, true, true) \
+VHOST_MESSAGE_HANDLER(VHOST_USER_SET_LOG_FD, vhost_user_set_log_fd, true, true) \
+VHOST_MESSAGE_HANDLER(VHOST_USER_SET_VRING_NUM, vhost_user_set_vring_num, false, true) \
+VHOST_MESSAGE_HANDLER(VHOST_USER_SET_VRING_ADDR, vhost_user_set_vring_addr, false, true) \
+VHOST_MESSAGE_HANDLER(VHOST_USER_SET_VRING_BASE, vhost_user_set_vring_base, false, true) \
+VHOST_MESSAGE_HANDLER(VHOST_USER_GET_VRING_BASE, vhost_user_get_vring_base, false, false) \
+VHOST_MESSAGE_HANDLER(VHOST_USER_SET_VRING_KICK, vhost_user_set_vring_kick, true, true) \
+VHOST_MESSAGE_HANDLER(VHOST_USER_SET_VRING_CALL, vhost_user_set_vring_call, true, true) \
+VHOST_MESSAGE_HANDLER(VHOST_USER_SET_VRING_ERR, vhost_user_set_vring_err, true, true) \
+VHOST_MESSAGE_HANDLER(VHOST_USER_GET_PROTOCOL_FEATURES, vhost_user_get_protocol_features, \
+	false, false) \
+VHOST_MESSAGE_HANDLER(VHOST_USER_SET_PROTOCOL_FEATURES, vhost_user_set_protocol_features, \
+	false, true) \
+VHOST_MESSAGE_HANDLER(VHOST_USER_GET_QUEUE_NUM, vhost_user_get_queue_num, false, false) \
+VHOST_MESSAGE_HANDLER(VHOST_USER_SET_VRING_ENABLE, vhost_user_set_vring_enable, false, true) \
+VHOST_MESSAGE_HANDLER(VHOST_USER_SEND_RARP, vhost_user_send_rarp, false, true) \
+VHOST_MESSAGE_HANDLER(VHOST_USER_NET_SET_MTU, vhost_user_net_set_mtu, false, true) \
+VHOST_MESSAGE_HANDLER(VHOST_USER_SET_BACKEND_REQ_FD, vhost_user_set_req_fd, true, true) \
+VHOST_MESSAGE_HANDLER(VHOST_USER_IOTLB_MSG, vhost_user_iotlb_msg, false, false) \
+VHOST_MESSAGE_HANDLER(VHOST_USER_GET_CONFIG, vhost_user_get_config, false, false) \
+VHOST_MESSAGE_HANDLER(VHOST_USER_SET_CONFIG, vhost_user_set_config, false, false) \
+VHOST_MESSAGE_HANDLER(VHOST_USER_POSTCOPY_ADVISE, vhost_user_set_postcopy_advise, false, false) \
+VHOST_MESSAGE_HANDLER(VHOST_USER_POSTCOPY_LISTEN, vhost_user_set_postcopy_listen, false, false) \
+VHOST_MESSAGE_HANDLER(VHOST_USER_POSTCOPY_END, vhost_user_postcopy_end, false, false) \
+VHOST_MESSAGE_HANDLER(VHOST_USER_GET_INFLIGHT_FD, vhost_user_get_inflight_fd, false, false) \
+VHOST_MESSAGE_HANDLER(VHOST_USER_SET_INFLIGHT_FD, vhost_user_set_inflight_fd, true, false) \
+VHOST_MESSAGE_HANDLER(VHOST_USER_SET_STATUS, vhost_user_set_status, false, false) \
+VHOST_MESSAGE_HANDLER(VHOST_USER_GET_STATUS, vhost_user_get_status, false, false)
+
+#define VHOST_MESSAGE_HANDLER(id, handler, accepts_fd, lock_all_qps) \
+	[id] = { #id, handler, accepts_fd, lock_all_qps },
 static vhost_message_handler_t vhost_message_handlers[] = {
 	VHOST_MESSAGE_HANDLERS
 };
@@ -3141,31 +3153,11 @@  vhost_user_msg_handler(int vid, int fd)
 	 * inactive, so it is safe. Otherwise taking the access_lock
 	 * would cause a dead lock.
 	 */
-	switch (request) {
-	case VHOST_USER_SET_FEATURES:
-	case VHOST_USER_SET_PROTOCOL_FEATURES:
-	case VHOST_USER_SET_OWNER:
-	case VHOST_USER_SET_MEM_TABLE:
-	case VHOST_USER_SET_LOG_BASE:
-	case VHOST_USER_SET_LOG_FD:
-	case VHOST_USER_SET_VRING_NUM:
-	case VHOST_USER_SET_VRING_ADDR:
-	case VHOST_USER_SET_VRING_BASE:
-	case VHOST_USER_SET_VRING_KICK:
-	case VHOST_USER_SET_VRING_CALL:
-	case VHOST_USER_SET_VRING_ERR:
-	case VHOST_USER_SET_VRING_ENABLE:
-	case VHOST_USER_SEND_RARP:
-	case VHOST_USER_NET_SET_MTU:
-	case VHOST_USER_SET_BACKEND_REQ_FD:
+	if (msg_handler->lock_all_qps) {
 		if (!(dev->flags & VIRTIO_DEV_VDPA_CONFIGURED)) {
 			vhost_user_lock_all_queue_pairs(dev);
 			unlock_required = 1;
 		}
-		break;
-	default:
-		break;
-
 	}
 
 	handled = false;