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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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10
contrib/libvhost-user/libvhost-user.h
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@ -25,7 +25,6 @@
#define VHOST_USER_F_PROTOCOL_FEATURES 30
#define VHOST_LOG_PAGE 4096
#define VHOST_MAX_NR_VIRTQUEUE 8
#define VIRTQUEUE_MAX_SIZE 1024
#define VHOST_MEMORY_MAX_NREGIONS 8
@ -353,7 +352,7 @@ struct VuDev {
int sock;
uint32_t nregions;
VuDevRegion regions[VHOST_MEMORY_MAX_NREGIONS];
VuVirtq vq[VHOST_MAX_NR_VIRTQUEUE];
VuVirtq *vq;
VuDevInflightInfo inflight_info;
int log_call_fd;
int slave_fd;
@ -362,6 +361,7 @@ struct VuDev {
uint64_t features;
uint64_t protocol_features;
bool broken;
uint16_t max_queues;
/* @set_watch: add or update the given fd to the watch set,
* call cb when condition is met */
@ -391,6 +391,7 @@ typedef struct VuVirtqElement {
/**
* vu_init:
* @dev: a VuDev context
* @max_queues: maximum number of virtqueues
* @socket: the socket connected to vhost-user master
* @panic: a panic callback
* @set_watch: a set_watch callback
@ -398,8 +399,11 @@ typedef struct VuVirtqElement {
* @iface: a VuDevIface structure with vhost-user device callbacks
*
* Intializes a VuDev vhost-user context.
*
* Returns: true on success, false on failure.
**/
void vu_init(VuDev *dev,
bool vu_init(VuDev *dev,
uint16_t max_queues,
int socket,
vu_panic_cb panic,
vu_set_watch_cb set_watch,