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libvhost-user: Open userfaultfd

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Open a userfaultfd (on a postcopy_advise) and send it back in
the reply to the qemu for it to monitor.

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 17:21:03 +00:00 committed by Michael S. Tsirkin
parent d6e47717b0
commit 2a84ffc0be
2 changed files with 43 additions and 2 deletions
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42
contrib/libvhost-user/libvhost-user.c
View File

@ -26,9 +26,20 @@
#include <sys/socket.h>
#include <sys/eventfd.h>
#include <sys/mman.h>
#include "qemu/compiler.h"
#if defined(__linux__)
#include <sys/syscall.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <linux/vhost.h>
#include "qemu/compiler.h"
#ifdef __NR_userfaultfd
#include <linux/userfaultfd.h>
#endif
#endif
#include "qemu/atomic.h"
#include "libvhost-user.h"
@ -888,8 +899,35 @@ vu_set_config(VuDev *dev, VhostUserMsg *vmsg)
static bool
vu_set_postcopy_advise(VuDev *dev, VhostUserMsg *vmsg)
{
/* TODO: Open ufd, pass it back in the request */
dev->postcopy_ufd = -1;
#ifdef UFFDIO_API
struct uffdio_api api_struct;
dev->postcopy_ufd = syscall(__NR_userfaultfd, O_CLOEXEC | O_NONBLOCK);
vmsg->size = 0;
#endif
if (dev->postcopy_ufd == -1) {
vu_panic(dev, "Userfaultfd not available: %s", strerror(errno));
goto out;
}
#ifdef UFFDIO_API
api_struct.api = UFFD_API;
api_struct.features = 0;
if (ioctl(dev->postcopy_ufd, UFFDIO_API, &api_struct)) {
vu_panic(dev, "Failed UFFDIO_API: %s", strerror(errno));
close(dev->postcopy_ufd);
dev->postcopy_ufd = -1;
goto out;
}
/* TODO: Stash feature flags somewhere */
#endif
out:
/* Return a ufd to the QEMU */
vmsg->fd_num = 1;
vmsg->fds[0] = dev->postcopy_ufd;
return true; /* = send a reply */
}

3
contrib/libvhost-user/libvhost-user.h
View File

@ -282,6 +282,9 @@ struct VuDev {
* re-initialize */
vu_panic_cb panic;
const VuDevIface *iface;
/* Postcopy data */
int postcopy_ufd;
};
typedef struct VuVirtqElement {