From 4275cd99c64224a35ab105ec475602ed210c1285 Mon Sep 17 00:00:00 2001 From: "Dr. David Alan Gilbert" Date: Mon, 12 Mar 2018 17:21:23 +0000 Subject: libvhost-user: Claim support for postcopy MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Tell QEMU we understand the protocol features needed for postcopy. Signed-off-by: Dr. David Alan Gilbert Reviewed-by: Marc-André Lureau Reviewed-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin --- contrib/libvhost-user/libvhost-user.c | 33 +++++++++++++++++++++++++++++++++ 1 file changed, 33 insertions(+) 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); } -- cgit v1.2.1