From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:53567) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZIJgL-0004xb-MO for qemu-devel@nongnu.org; Thu, 23 Jul 2015 12:49:18 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZIJgI-0003wJ-5d for qemu-devel@nongnu.org; Thu, 23 Jul 2015 12:49:17 -0400 Received: from mx6-phx2.redhat.com ([209.132.183.39]:45198) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZIJgH-0003vw-UA for qemu-devel@nongnu.org; Thu, 23 Jul 2015 12:49:14 -0400 Date: Thu, 23 Jul 2015 11:36:37 -0400 (EDT) From: =?utf-8?Q?Marc-Andr=C3=A9?= Lureau Message-ID: <1860078353.3420583.1437665797290.JavaMail.zimbra@redhat.com> In-Reply-To: <20150723182723-mutt-send-email-mst@redhat.com> References: <1437615403-13554-1-git-send-email-marcandre.lureau@redhat.com> <1437615403-13554-7-git-send-email-marcandre.lureau@redhat.com> <20150723182723-mutt-send-email-mst@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [PATCH RFC 6/6] vhost-user: document migration log List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Michael S. Tsirkin" Cc: haifeng lin , =?utf-8?Q?Marc-Andr=C3=A9?= Lureau , pbonzini@redhat.com, qemu-devel@nongnu.org, thibaut collet Hi ----- Original Message ----- > On Thu, Jul 23, 2015 at 03:36:43AM +0200, Marc-Andr=C3=A9 Lureau wrote: > > Signed-off-by: Marc-Andr=C3=A9 Lureau >=20 > for some reason I didn't get 5/6. >=20 strange: http://lists.nongnu.org/archive/html/qemu-devel/2015-07/msg04640.h= tml > > --- > > docs/specs/vhost-user.txt | 40 +++++++++++++++++++++++++++++++++++++++= + > > 1 file changed, 40 insertions(+) > >=20 > > diff --git a/docs/specs/vhost-user.txt b/docs/specs/vhost-user.txt > > index 0062baa..c2d2e2a 100644 > > --- a/docs/specs/vhost-user.txt > > +++ b/docs/specs/vhost-user.txt > > @@ -120,6 +120,7 @@ There are several messages that the master sends wi= th > > file descriptors passed > > in the ancillary data: > > =20 > > * VHOST_SET_MEM_TABLE > > + * VHOST_SET_LOG_BASE (if VHOST_USER_PROTOCOL_F_LOG_SHMFD) > > * VHOST_SET_LOG_FD > > * VHOST_SET_VRING_KICK > > * VHOST_SET_VRING_CALL > > @@ -135,6 +136,11 @@ As older slaves don't support negotiating protocol > > features, > > a feature bit was dedicated for this purpose: > > #define VHOST_USER_F_PROTOCOL_FEATURES 30 > > =20 > > +Protocol features > > +----------------- > > + > > +#define VHOST_USER_PROTOCOL_F_LOG_SHMFD 0 > > + > > Message types > > ------------- > > =20 > > @@ -301,3 +307,37 @@ Message types > > Bits (0-7) of the payload contain the vring index. Bit 8 is the > > invalid FD flag. This flag is set when there is no file descript= or > > in the ancillary data. > > + > > +Migration > > +--------- > > + > > +During live migration, the master may need to track the modifications > > +the slave makes to the memory mapped regions. The client should mark > > +the dirty pages in a log. Once it complies to this logging, it may > > +declare VHOST_F_LOG_ALL has a vhost feature. > > + > > +All the modifications to memory pointed by vring "descriptor" should > > +be marked. Modifications to "used" vring should be marked if > > +VHOST_VRING_F_LOG is part of ring's features. >=20 > It's device's features I think. Hmm, it's part of both, not sure why: see vhost_virtqueue_set_addr() and vh= ost_dev_set_features() Not sure it's correct in device features, it doesn't seem to be check in ke= rnel vhost.c either. There is also some dead definitions like VHOST_MEMORY_F_LOG there >=20 > > + > > +Dirty pages are of size: > > +#define VHOST_LOG_PAGE 0x1000 > > + > > +The log memory fd is provided in the ancillary data of > > +VHOST_USER_SET_LOG_BASE message when the slave has > > +VHOST_USER_PROTOCOL_F_LOG_SHMFD protocol feature. > > + > > +The size of the log may be computed by using all the known guest > > +addresses. The log covers from address 0 to the maximum of guest > > +regions. In pseudo-code, to mark page at "addr" as dirty: > > + > > +page =3D addr / VHOST_LOG_PAGE > > +log[page / 8] |=3D 1 << page % 8 >=20 > Pls note it must be done atomically. ok >=20 >=20 > > + > > +VHOST_USER_SET_LOG_FD is an optional message with an eventfd in > > +ancillary data, it may be used to inform the master that the log has > > +been modified. > > + > > +Once the source has finished migration, VHOST_USER_RESET_OWNER message > > +will be sent by the source. No further update must be done before the > > +destination takes over with new regions & rings. > > -- > > 2.4.3 >=20