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libvhost-user: Claim support for postcopy 

Tell QEMU we understand the protocol features needed for postcopy.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Dr. David Alan Gilbert 2018-03-12 17:21:23 +00:00 committed by Michael S. Tsirkin
parent 29d8fa7f73
commit 4275cd99c6
1 changed files with 33 additions and 0 deletions
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33
contrib/libvhost-user/libvhost-user.c
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@ -185,6 +185,35 @@ vmsg_close_fds(VhostUserMsg *vmsg)
}
}
/* A test to see if we have userfault available */
static bool
have_userfault(void)
{
#if defined(__linux__) && defined(__NR_userfaultfd) &&\
defined(UFFD_FEATURE_MISSING_SHMEM) &&\
defined(UFFD_FEATURE_MISSING_HUGETLBFS)
/* Now test the kernel we're running on really has the features */
int ufd = syscall(__NR_userfaultfd, O_CLOEXEC | O_NONBLOCK);
struct uffdio_api api_struct;
if (ufd < 0) {
return false;
}
api_struct.api = UFFD_API;
api_struct.features = UFFD_FEATURE_MISSING_SHMEM |
UFFD_FEATURE_MISSING_HUGETLBFS;
if (ioctl(ufd, UFFDIO_API, &api_struct)) {
close(ufd);
return false;
}
close(ufd);
return true;
#else
return false;
#endif
}
static bool
vu_message_read(VuDev *dev, int conn_fd, VhostUserMsg *vmsg)
{
@ -939,6 +968,10 @@ vu_get_protocol_features_exec(VuDev *dev, VhostUserMsg *vmsg)
uint64_t features = 1ULL << VHOST_USER_PROTOCOL_F_LOG_SHMFD |
1ULL << VHOST_USER_PROTOCOL_F_SLAVE_REQ;
if (have_userfault()) {
features |= 1ULL << VHOST_USER_PROTOCOL_F_PAGEFAULT;
}
if (dev->iface->get_protocol_features) {
features |= dev->iface->get_protocol_features(dev);
}