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authorDr. David Alan Gilbert <dgilbert@redhat.com>2018-03-12 17:21:23 +0000
committerMichael S. Tsirkin <mst@redhat.com>2018-03-20 16:40:37 +0200
commit4275cd99c64224a35ab105ec475602ed210c1285 (patch)
tree1f22842613db57c16a60d9b0ee5b280bab50a761 /contrib/libvhost-user
parent29d8fa7f734ec4c55135e85e2d25d1650c8c5985 (diff)
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>
Diffstat (limited to 'contrib/libvhost-user')
-rw-r--r--contrib/libvhost-user/libvhost-user.c33
1 files changed, 33 insertions, 0 deletions
diff --git a/contrib/libvhost-user/libvhost-user.c b/contrib/libvhost-user/libvhost-user.c
index 504ff5ea59..beeed0c43f 100644
--- a/contrib/libvhost-user/libvhost-user.c
+++ b/contrib/libvhost-user/libvhost-user.c
@@ -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);
}