From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Mon, 25 Sep 2023 16:48:52 -0400 From: Stefan Hajnoczi Message-ID: <20230925204852.GG323580@fedora> References: <20230915102531.55894-1-hreitz@redhat.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="K/zCvWGQCDPOsVDG" Content-Disposition: inline In-Reply-To: <20230915102531.55894-1-hreitz@redhat.com> Subject: Re: [Virtio-fs] [PATCH v3 0/5] vhost-user: Back-end state migration List-Id: Development discussions about virtio-fs List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Hanna Czenczek Cc: qemu-devel@nongnu.org, virtio-fs@redhat.com, "Michael S . Tsirkin" , Eugenio =?iso-8859-1?Q?P=E9rez?= , German Maglione --K/zCvWGQCDPOsVDG Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Fri, Sep 15, 2023 at 12:25:25PM +0200, Hanna Czenczek wrote: > RFC: > https://lists.nongnu.org/archive/html/qemu-devel/2023-03/msg04263.html >=20 > v1: > https://lists.nongnu.org/archive/html/qemu-devel/2023-04/msg01575.html >=20 > v2: > https://lists.nongnu.org/archive/html/qemu-devel/2023-07/msg02604.html >=20 > Hi, >=20 > I=E2=80=99ve decided not to work on vhost-user SUSPEND/RESUME for now =E2= =80=93 it is > not technically required for virtio-fs migration, which is the actual > priority for me now. While we do want to have SUSPEND/RESUME at some > point, the only practically existing reason for it is to be able to > implement vhost-level resetting in virtiofsd, but that is not related to > migration. QEMU sends VHOST_USER_SET_STATUS 0 in vhost_dev_stop(). Are you assuming that virtiofs back-ends do not reset the device upon receiving this message? > So one of the changes in v3 is that it no longer depends on the > vhost-user SUSPEND/RESUME series, and describes the migration protocol > without the device being suspended at any point, but merely that the > vrings are stopped. >=20 > Other changes include: >=20 > - Patch 1: > - Rephrased a lot > - Added a description for the VHOST_USER_SET_DEVICE_STATE_FD > parameters > - Renamed VHOST_USER_PROTOCOL_F_MIGRATORY_STATE to > VHOST_USER_PROTOCOL_F_DEVICE_STATE > - enum variants changed in value due to dropping the SUSPEND/RESUME > dependency >=20 > - Patch 2: > - Pulled in, was a stand-alone patch before > - Dropped a sentence about ring state before feature negotiations, as > the rings are not to be used during that period anyway > - Bit of rephrasing >=20 > - Patch 3: > - Renamed =E2=80=9Cmigratory state=E2=80=9D to =E2=80=9Cdevice state=E2= =80=9D > - enum variants changed in value due to dropping the SUSPEND/RESUME > dependency >=20 > - Patch 4: > - Changed `f` to @f (referencing parameter =E2=80=9Cf=E2=80=9D) in comm= ents > - Use g_autofree for the transfer buffer > - Note SUSPEND state as a future feature, not currently existing > - Wrap read() and write() in RETRY_ON_EINTR() >=20 > - Patch 5: > - Renamed =E2=80=9Cmigratory state=E2=80=9D to =E2=80=9Cdevice state=E2= =80=9D > - (kept R-b still) >=20 >=20 > Hanna Czenczek (5): > vhost-user.rst: Migrating back-end-internal state > vhost-user.rst: Clarify enabling/disabling vrings > vhost-user: Interface for migration state transfer > vhost: Add high-level state save/load functions > vhost-user-fs: Implement internal migration >=20 > docs/interop/vhost-user.rst | 188 ++++++++++++++++++++++- > include/hw/virtio/vhost-backend.h | 24 +++ > include/hw/virtio/vhost.h | 114 ++++++++++++++ > hw/virtio/vhost-user-fs.c | 101 ++++++++++++- > hw/virtio/vhost-user.c | 148 ++++++++++++++++++ > hw/virtio/vhost.c | 241 ++++++++++++++++++++++++++++++ > 6 files changed, 810 insertions(+), 6 deletions(-) >=20 > --=20 > 2.41.0 >=20 --K/zCvWGQCDPOsVDG Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEhpWov9P5fNqsNXdanKSrs4Grc8gFAmUR8jMACgkQnKSrs4Gr c8jKKwf8C5etjvYMEZYDYIJGeOPOVSRiR04zFVZS+/VEolLYYRW0lUzWinu1wjhF PuPo+jaMNKTbuj/MAFiAhx6agRzKu/M57M1kQxjECSWHYYkKD0CkEz3xOQe0hvVu hP3MDse57FlX3whkKNnUSE1aTBcwj4l7pMXLljUpM+UwkzjqlnbZq8DI7XdUe2jG sTp9hYhA0h03V4ACXjd9Ov90QZWWRoOB1BvAawe4PClVdgaQQWM6DiPAsi8ELH6T 9Vyo403dpuek4UvySNWLe7yBDlCT0wv48oXo2NNttzHcJ3G2TfxiFQFma3KlX0Od nlW5mEYBk8qwOgxXKjQU+dFjvRxKKg== =qDLO -----END PGP SIGNATURE----- --K/zCvWGQCDPOsVDG--