[PATCH hci-8.1 v4 2/5] vhost-blk: reject num-queues above VHOST_BLK_MAX_QUEUES

[Alexander Ivanov <alexander.ivanov@virtuozzo.com>]

Only the automatic num-queues value is capped at VHOST_BLK_MAX_QUEUES,
an explicit one is taken as is. The kernel vhost-blk device has that
many virtqueues and rejects any vq beyond them, so realize fails with
an error that does not point at num-queues:

  qemu-system-x86_64: vhost_set_vring_call failed: No buffer space available (105)
  qemu-system-x86_64: vhost-blk: vhost initialization failed: No buffer space available

Check num-queues against the limit up front instead.

https://virtuozzo.atlassian.net/browse/VSTOR-107537

Fixes: 0ff3cb5ff28f ("block: add vhost-blk backend")
Signed-off-by: Alexander Ivanov <alexander.ivanov@virtuozzo.com>
Reviewed-by: Andrey Drobyshev <andrey.drobyshev@virtuozzo.com>
---
 hw/block/vhost-blk.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/hw/block/vhost-blk.c b/hw/block/vhost-blk.c
index abddff02c6d..8a015d54fa7 100644
--- a/hw/block/vhost-blk.c
+++ b/hw/block/vhost-blk.c
@@ -598,8 +598,9 @@ static void vhost_blk_device_realize(DeviceState *dev, Error **errp)
                                VHOST_BLK_MAX_QUEUES);
     }
 
-    if (!conf->num_queues) {
-        error_setg(errp, "vhost-blk: num-queues property must be larger than 0");
+    if (!conf->num_queues || conf->num_queues > VHOST_BLK_MAX_QUEUES) {
+        error_setg(errp, "vhost-blk: invalid num-queues property (%" PRIu16 "), "
+                   "must be 1-%d", conf->num_queues, VHOST_BLK_MAX_QUEUES);
         return;
     }
 
-- 
2.53.0