* Marc-André Lureau (marcandre.lur...@gmail.com) wrote:
> I would rather use libvhost-user: message prefix (same for similar
> libvhost-user patches)
Done.
> On Thu, Aug 24, 2017 at 12:27 PM, Dr. David Alan Gilbert (git)
> <dgilb...@redhat.com> wrote:
> > From: "Dr. David Alan Gilbert" <dgilb...@redhat.com>
> >
> > 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 <dgilb...@redhat.com>
> > ---
> > contrib/libvhost-user/libvhost-user.c | 26 +++++++++++++++++++++++---
> > contrib/libvhost-user/libvhost-user.h | 3 +++
> > 2 files changed, 26 insertions(+), 3 deletions(-)
> >
> > diff --git a/contrib/libvhost-user/libvhost-user.c
> > b/contrib/libvhost-user/libvhost-user.c
> > index 47884c0a15..f9b5b12b28 100644
> > --- a/contrib/libvhost-user/libvhost-user.c
> > +++ b/contrib/libvhost-user/libvhost-user.c
> > @@ -15,6 +15,7 @@
> >
> > #include <qemu/osdep.h>
> > #include <sys/eventfd.h>
> > +#include <sys/syscall.h>
> > #include <linux/vhost.h>
> >
> > #include "qemu/atomic.h"
> > @@ -773,11 +774,30 @@ vu_set_vring_enable_exec(VuDev *dev, VhostUserMsg
> > *vmsg)
> > static bool
> > vu_set_postcopy_advise(VuDev *dev, VhostUserMsg *vmsg)
> > {
> > - /* TODO: Open ufd, pass it back in the request
> > - * TODO: Add addresses
> > - */
> > + struct uffdio_api api_struct;
> > +
> > + dev->postcopy_ufd = syscall(__NR_userfaultfd, O_CLOEXEC | O_NONBLOCK);
>
> This will likely fail to compile on !Linux, could you add some
> appropriate #ifdef?
Note that we already #include <linux/vhost.h> so this file only builds
on Linux anyway before I came along, however I'll add some ifdef's for
my new code.
Dave
> > + /* TODO: Add addresses */
> > vmsg->payload.u64 = 0xcafe;
> > vmsg->size = sizeof(vmsg->payload.u64);
> > +
> > + if (dev->postcopy_ufd == -1) {
> > + vu_panic(dev, "Userfaultfd not available: %s", strerror(errno));
> > + goto out;
> > + }
> > + 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 */
> > +out:
> > + /* Return a ufd to the QEMU */
> > + vmsg->fd_num = 1;
> > + vmsg->fds[0] = dev->postcopy_ufd;
> > return true; /* = send a reply */
> > }
> >
> > diff --git a/contrib/libvhost-user/libvhost-user.h
> > b/contrib/libvhost-user/libvhost-user.h
> > index 3987ce643d..3e8efdd919 100644
> > --- a/contrib/libvhost-user/libvhost-user.h
> > +++ b/contrib/libvhost-user/libvhost-user.h
> > @@ -234,6 +234,9 @@ struct VuDev {
> > * re-initialize */
> > vu_panic_cb panic;
> > const VuDevIface *iface;
> > +
> > + /* Postcopy data */
> > + int postcopy_ufd;
> > };
> >
> > typedef struct VuVirtqElement {
> > --
> > 2.13.5
> >
> >
>
>
>
> --
> Marc-André Lureau
--
Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK
