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vhost: add vhost_has_free_slot() interface

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it will allow for other parts of QEMU check if it's safe
to map memory region during hotplug/runtime.
That way hotplug path will have a chance to cancel
hotplug operation instead of crashing in vhost_commit().

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Igor Mammedov 2015-10-06 10:37:27 +02:00 • committed by Michael S. Tsirkin
parent 052bd52fa9
commit 2ce68e4cf5
7 changed files with 57 additions and 0 deletions
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19
hw/virtio/vhost-backend.c
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@ -11,6 +11,7 @@
#include "hw/virtio/vhost.h"
#include "hw/virtio/vhost-backend.h"
#include "qemu/error-report.h"
#include "linux/vhost.h"
#include <sys/ioctl.h>
@ -49,12 +50,30 @@ static int vhost_kernel_get_vq_index(struct vhost_dev *dev, int idx)
return idx - dev->vq_index;
}
static int vhost_kernel_memslots_limit(struct vhost_dev *dev)
{
int limit = 64;
char *s;
if (g_file_get_contents("/sys/module/vhost/parameters/max_mem_regions",
&s, NULL, NULL)) {
uint64_t val = g_ascii_strtoull(s, NULL, 10);
if (!((val == G_MAXUINT64 || !val) && errno)) {
return val;
}
error_report("ignoring invalid max_mem_regions value in vhost module:"
" %s", s);
}
return limit;
}
static const VhostOps kernel_ops = {
.backend_type = VHOST_BACKEND_TYPE_KERNEL,
.vhost_call = vhost_kernel_call,
.vhost_backend_init = vhost_kernel_init,
.vhost_backend_cleanup = vhost_kernel_cleanup,
.vhost_backend_get_vq_index = vhost_kernel_get_vq_index,
.vhost_backend_memslots_limit = vhost_kernel_memslots_limit,
};
int vhost_set_backend_type(struct vhost_dev *dev, VhostBackendType backend_type)