* [PATCH v2] virtio/s390: implement virtio-ccw revision 2 correctly
@ 2021-02-16 11:06 Cornelia Huck
2021-02-19 16:38 ` Cornelia Huck
0 siblings, 1 reply; 3+ messages in thread
From: Cornelia Huck @ 2021-02-16 11:06 UTC (permalink / raw)
To: Halil Pasic
Cc: Pierre Morel, linux-s390, virtualization, kvm, Cornelia Huck, stable
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>
---
v1->v2:
tweak patch description and cc:stable
---
drivers/s390/virtio/virtio_ccw.c | 4 ++--
1 file 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));
--
2.26.2
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH v2] virtio/s390: implement virtio-ccw revision 2 correctly
2021-02-16 11:06 [PATCH v2] virtio/s390: implement virtio-ccw revision 2 correctly Cornelia Huck
@ 2021-02-19 16:38 ` Cornelia Huck
2021-02-19 19:00 ` Vasily Gorbik
0 siblings, 1 reply; 3+ messages in thread
From: Cornelia Huck @ 2021-02-19 16:38 UTC (permalink / raw)
To: Heiko Carstens, Vasily Gorbik, Christian Borntraeger
Cc: Halil Pasic, Pierre Morel, linux-s390, virtualization, kvm, stable
I was thinking of queuing this, but maybe it is quicker to pick it into
the s390 tree directly and save us the extra pull request dance?
Especially as this is a stable-worthy bugfix.
On Tue, 16 Feb 2021 12:06:45 +0100
Cornelia Huck <cohuck@redhat.com> wrote:
> 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>
> ---
>
> v1->v2:
> tweak patch description and cc:stable
>
> ---
> drivers/s390/virtio/virtio_ccw.c | 4 ++--
> 1 file 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));
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH v2] virtio/s390: implement virtio-ccw revision 2 correctly
2021-02-19 16:38 ` Cornelia Huck
@ 2021-02-19 19:00 ` Vasily Gorbik
0 siblings, 0 replies; 3+ messages in thread
From: Vasily Gorbik @ 2021-02-19 19:00 UTC (permalink / raw)
To: Cornelia Huck
Cc: Heiko Carstens, Christian Borntraeger, Halil Pasic, Pierre Morel,
linux-s390, virtualization, kvm, stable
On Fri, Feb 19, 2021 at 05:38:28PM +0100, Cornelia Huck wrote:
> I was thinking of queuing this, but maybe it is quicker to pick it into
> the s390 tree directly and save us the extra pull request dance?
> Especially as this is a stable-worthy bugfix.
Yes, sure. I'll pick it up. Thanks.
^ permalink raw reply [flat|nested] 3+ messages in thread
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2021-02-16 11:06 [PATCH v2] virtio/s390: implement virtio-ccw revision 2 correctly Cornelia Huck
2021-02-19 16:38 ` Cornelia Huck
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