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libvhost-user: support many virtqueues

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Currently libvhost-user is hardcoded to at most 8 virtqueues.  The
device backend should decide the number of virtqueues, not
libvhost-user.  This is important for multiqueue device backends where
the guest driver needs an accurate number of virtqueues.

This change breaks libvhost-user and libvhost-user-glib API stability.
There is no stability guarantee yet, so make this change now and update
all in-tree library users.

This patch touches up vhost-user-blk, vhost-user-gpu, vhost-user-input,
vhost-user-scsi, and vhost-user-bridge.  If the device has a fixed
number of queues that exact number is used.  Otherwise the previous
default of 8 virtqueues is used.

vu_init() and vug_init() can now fail if malloc() returns NULL.  I
considered aborting with an error in libvhost-user but it should be safe
to instantiate new vhost-user instances at runtime without risk of
terminating the process.  Therefore callers need to handle the vu_init()
failure now.

vhost-user-blk and vhost-user-scsi duplicate virtqueue index checks that
are already performed by libvhost-user.  This code would need to be
modified to use max_queues but remove it completely instead since it's
redundant.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20190626074815.19994-3-stefanha@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Stefan Hajnoczi 2019-06-26 08:48:13 +01:00 • committed by Michael S. Tsirkin
parent db68f4ff06
commit 6f5fd83788
9 changed files with 105 additions and 51 deletions
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11
contrib/vhost-user-input/main.c
View file

@ -17,6 +17,10 @@
#include "standard-headers/linux/virtio_input.h"
#include "qapi/error.h"
enum {
VHOST_USER_INPUT_MAX_QUEUES = 2,
};
typedef struct virtio_input_event virtio_input_event;
typedef struct virtio_input_config virtio_input_config;
@ -384,7 +388,12 @@ main(int argc, char *argv[])
g_printerr("Invalid vhost-user socket.\n");
exit(EXIT_FAILURE);
}
vug_init(&vi.dev, fd, vi_panic, &vuiface);
if (!vug_init(&vi.dev, VHOST_USER_INPUT_MAX_QUEUES, fd, vi_panic,
&vuiface)) {
g_printerr("Failed to initialize libvhost-user-glib.\n");
exit(EXIT_FAILURE);
}
loop = g_main_loop_new(NULL, FALSE);
g_main_loop_run(loop);