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authorCornelia Huck <cohuck@redhat.com>2021-02-16 12:06:45 +0100
committerVasily Gorbik <gor@linux.ibm.com>2021-02-24 00:31:23 +0100
commit182f709c5cff683e6732d04c78e328de0532284f (patch)
tree1fbc0bf02e0b17e8e4eae2c89102dbdbaed29f6a /drivers/s390/virtio
parent55f03123f60985815e57cc9d1b29dea48e32e709 (diff)
virtio/s390: implement virtio-ccw revision 2 correctly
CCW_CMD_READ_STATUS was introduced with revision 2 of virtio-ccw, and drivers should only rely on it being implemented when they negotiated at least that revision with the device. However, virtio_ccw_get_status() issued READ_STATUS for any device operating at least at revision 1. If the device accepts READ_STATUS regardless of the negotiated revision (which some implementations like QEMU do, even though the spec currently does not allow it), everything works as intended. While a device rejecting the command should also be handled gracefully, we will not be able to see any changes the device makes to the status, such as setting NEEDS_RESET or setting the status to zero after a completed reset. We negotiated the revision to at most 1, as we never bumped the maximum revision; let's do that now and properly send READ_STATUS only if we are operating at least at revision 2. Cc: stable@vger.kernel.org Fixes: 7d3ce5ab9430 ("virtio/s390: support READ_STATUS command for virtio-ccw") Reviewed-by: Halil Pasic <pasic@linux.ibm.com> Signed-off-by: Cornelia Huck <cohuck@redhat.com> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com> Link: https://lore.kernel.org/r/20210216110645.1087321-1-cohuck@redhat.com Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Diffstat (limited to 'drivers/s390/virtio')
-rw-r--r--drivers/s390/virtio/virtio_ccw.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/s390/virtio/virtio_ccw.c b/drivers/s390/virtio/virtio_ccw.c
index 5730572b52cd..54e686dca6de 100644
--- a/drivers/s390/virtio/virtio_ccw.c
+++ b/drivers/s390/virtio/virtio_ccw.c
@@ -117,7 +117,7 @@ struct virtio_rev_info {
};
/* the highest virtio-ccw revision we support */
-#define VIRTIO_CCW_REV_MAX 1
+#define VIRTIO_CCW_REV_MAX 2
struct virtio_ccw_vq_info {
struct virtqueue *vq;
@@ -952,7 +952,7 @@ static u8 virtio_ccw_get_status(struct virtio_device *vdev)
u8 old_status = vcdev->dma_area->status;
struct ccw1 *ccw;
- if (vcdev->revision < 1)
+ if (vcdev->revision < 2)
return vcdev->dma_area->status;
ccw = ccw_device_dma_zalloc(vcdev->cdev, sizeof(*ccw));