File vhost-user-blk-Check-that-num-queues-is-.patch of Package qemu

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File vhost-user-blk-Check-that-num-queues-is-.patch of Package qemu (Revision 2975b97c32dbb241385a7c129d80aa3d)

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From: Kevin Wolf <kwolf@redhat.com>
Date: Thu, 29 Apr 2021 19:13:16 +0200
Subject: vhost-user-blk: Check that num-queues is supported by backend

Git-commit: c90bd505a3e8210c23d69fecab9ee6f56ec4a161

Creating a device with a number of queues that isn't supported by the
backend is pointless, the device won't work properly and the error
messages are rather confusing.

Just fail to create the device if num-queues is higher than what the
backend supports.

Since the relationship between num-queues and the number of virtqueues
depends on the specific device, this is an additional value that needs
to be initialised by the device. For convenience, allow leaving it 0 if
the check should be skipped. This makes sense for vhost-user-net where
separate vhost devices are used for the queues and custom initialisation
code is needed to perform the check.

Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1935031
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Raphael Norwitz <raphael.norwitz@nutanix.com>
Message-Id: <20210429171316.162022-7-kwolf@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Jose R. Ziviani <jziviani@suse.de>
---
 hw/block/vhost-user-blk.c | 1 +
 hw/virtio/vhost-user.c    | 5 +++++
 include/hw/virtio/vhost.h | 2 ++
 3 files changed, 8 insertions(+)

diff --git a/hw/block/vhost-user-blk.c b/hw/block/vhost-user-blk.c
index 738e8498b4a1d650047f7190c435..ceb6bdde71e57640677a48425148 100644
--- a/hw/block/vhost-user-blk.c
+++ b/hw/block/vhost-user-blk.c
@@ -324,6 +324,7 @@ static int vhost_user_blk_connect(DeviceState *dev)
     }
     s->connected = true;
 
+    s->dev.num_queues = s->num_queues;
     s->dev.nvqs = s->num_queues;
     s->dev.vqs = s->vhost_vqs;
     s->dev.vq_index = 0;
diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
index ded0c10453095830e24b6e53e8f8..ee57abe04526f6c55d983cb0254c 100644
--- a/hw/virtio/vhost-user.c
+++ b/hw/virtio/vhost-user.c
@@ -1909,6 +1909,11 @@ static int vhost_user_backend_init(struct vhost_dev *dev, void *opaque)
                 return err;
             }
         }
+        if (dev->num_queues && dev->max_queues < dev->num_queues) {
+            error_report("The maximum number of queues supported by the "
+                         "backend is %" PRIu64, dev->max_queues);
+            return -EINVAL;
+        }
 
         if (virtio_has_feature(features, VIRTIO_F_IOMMU_PLATFORM) &&
                 !(virtio_has_feature(dev->protocol_features,
diff --git a/include/hw/virtio/vhost.h b/include/hw/virtio/vhost.h
index 4a8bc75415f6bba597c195e10a47..21a9a52088dd01838099046587fd 100644
--- a/include/hw/virtio/vhost.h
+++ b/include/hw/virtio/vhost.h
@@ -74,6 +74,8 @@ struct vhost_dev {
     int nvqs;
     /* the first virtqueue which would be used by this vhost dev */
     int vq_index;
+    /* if non-zero, minimum required value for max_queues */
+    int num_queues;
     uint64_t features;
     uint64_t acked_features;
     uint64_t backend_features;

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File vhost-user-blk-Check-that-num-queues-is-.patch of Package qemu (Revision 2975b97c32dbb241385a7c129d80aa3d)

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