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| author | Cornelia Huck <cohuck@redhat.com> | 2021-02-16 12:18:30 +0100 |
|---|---|---|
| committer | Cornelia Huck <cohuck@redhat.com> | 2021-03-04 11:23:35 +0100 |
| commit | 151fcdfd628a396845b275831e920ddbc10a9f18 (patch) | |
| tree | a15d33dd0acced19628020de036bfb54da123f4c | |
| parent | 403af209db8c030ed1e000640cd3cd80c6882883 (diff) | |
| download | qemu-151fcdfd628a396845b275831e920ddbc10a9f18.zip qemu-151fcdfd628a396845b275831e920ddbc10a9f18.tar.gz qemu-151fcdfd628a396845b275831e920ddbc10a9f18.tar.bz2 | |
virtio-ccw: commands on revision-less devices
The virtio standard specifies that any non-transitional device must
reject commands prior to revision setting (which we do). Devices
that are transitional need to assume revision 0 (legacy) if the
driver sends a non-revision-setting command first in order to
support legacy drivers. We neglected to do the latter.
Fortunately, nearly everything worked as intended anyway; the only
problem was not properly rejecting revision setting after some other
command had been issued. Easy to fix by setting revision to 0 if
we see a non-revision command on a legacy-capable revision-less
device.
Found by code inspection, not observed in the wild.
Signed-off-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Halil Pasic <pasic@linux.ibm.com>
Message-Id: <20210216111830.1087847-1-cohuck@redhat.com>
| -rw-r--r-- | hw/s390x/virtio-ccw.c | 21 |
1 files changed, 14 insertions, 7 deletions
diff --git a/hw/s390x/virtio-ccw.c b/hw/s390x/virtio-ccw.c index 4582e94..06c0605 100644 --- a/hw/s390x/virtio-ccw.c +++ b/hw/s390x/virtio-ccw.c @@ -327,13 +327,20 @@ static int virtio_ccw_cb(SubchDev *sch, CCW1 ccw) ccw.cmd_code); check_len = !((ccw.flags & CCW_FLAG_SLI) && !(ccw.flags & CCW_FLAG_DC)); - if (dev->force_revision_1 && dev->revision < 0 && - ccw.cmd_code != CCW_CMD_SET_VIRTIO_REV) { - /* - * virtio-1 drivers must start with negotiating to a revision >= 1, - * so post a command reject for all other commands - */ - return -ENOSYS; + if (dev->revision < 0 && ccw.cmd_code != CCW_CMD_SET_VIRTIO_REV) { + if (dev->force_revision_1) { + /* + * virtio-1 drivers must start with negotiating to a revision >= 1, + * so post a command reject for all other commands + */ + return -ENOSYS; + } else { + /* + * If the driver issues any command that is not SET_VIRTIO_REV, + * we'll have to operate the device in legacy mode. + */ + dev->revision = 0; + } } /* Look at the command. */ |