From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:41158) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1daPrU-0001nD-Pv for qemu-devel@nongnu.org; Wed, 26 Jul 2017 13:12:41 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1daPrR-0006iH-K7 for qemu-devel@nongnu.org; Wed, 26 Jul 2017 13:12:40 -0400 Received: from mx1.redhat.com ([209.132.183.28]:46924) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1daPrR-0006hp-BS for qemu-devel@nongnu.org; Wed, 26 Jul 2017 13:12:37 -0400 Date: Wed, 26 Jul 2017 18:12:22 +0100 From: "Dr. David Alan Gilbert" Message-ID: <20170726171221.GB8648@work-vm> References: <20170628190047.26159-1-dgilbert@redhat.com> <20170628190047.26159-11-dgilbert@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Subject: Re: [Qemu-devel] [RFC 10/29] vhub: Open userfaultfd List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Maxime Coquelin Cc: qemu-devel@nongnu.org, a.perevalov@samsung.com, marcandre.lureau@redhat.com, mst@redhat.com, quintela@redhat.com, peterx@redhat.com, lvivier@redhat.com, aarcange@redhat.com * Maxime Coquelin (maxime.coquelin@redhat.com) wrote: > > > On 06/28/2017 09:00 PM, Dr. David Alan Gilbert (git) wrote: > > From: "Dr. David Alan Gilbert" > > > > 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 > > --- > > contrib/libvhost-user/libvhost-user.c | 24 +++++++++++++++++++++--- > > contrib/libvhost-user/libvhost-user.h | 3 +++ > > 2 files changed, 24 insertions(+), 3 deletions(-) > > > > diff --git a/contrib/libvhost-user/libvhost-user.c b/contrib/libvhost-user/libvhost-user.c > > index e3a32755cf..62e97f6b84 100644 > > --- a/contrib/libvhost-user/libvhost-user.c > > +++ b/contrib/libvhost-user/libvhost-user.c > > @@ -15,6 +15,7 @@ > > #include > > #include > > +#include > > #include > > #include "qemu/atomic.h" > > @@ -774,11 +775,28 @@ 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); > > + /* 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)); > > + return false; > > I think we may want to reply something even in case of error. > > Indeed, if something goes wrong on backend side, Qemu will remain > blocked waiting for the reply. Fixed. > > + } > > + 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); > > + return false; > Ditto Fixed. Thanks, Dave > > + } > > + /* TODO: Stash feature flags somewhere */ > > + /* 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 8bb35582ea..3e65a962da 100644 > > --- a/contrib/libvhost-user/libvhost-user.h > > +++ b/contrib/libvhost-user/libvhost-user.h > > @@ -231,6 +231,9 @@ struct VuDev { > > * re-initialize */ > > vu_panic_cb panic; > > const VuDevIface *iface; > > + > > + /* Postcopy data */ > > + int postcopy_ufd; > > }; > > typedef struct VuVirtqElement { > > -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK