linux-kernel - [PATCH 1/1] s390/virtio_ccw: fix config change notifications

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Message-Id: <20240611214716.1002781-1-pasic@linux.ibm.com>
Date: Tue, 11 Jun 2024 23:47:16 +0200
From: Halil Pasic <pasic@...ux.ibm.com>
To: Cornelia Huck <cohuck@...hat.com>, Halil Pasic <pasic@...ux.ibm.com>,
        Eric Farman <farman@...ux.ibm.com>, Heiko Carstens <hca@...ux.ibm.com>,
        Vasily Gorbik <gor@...ux.ibm.com>,
        Alexander Gordeev <agordeev@...ux.ibm.com>,
        Christian Borntraeger <borntraeger@...ux.ibm.com>,
        Sven Schnelle <svens@...ux.ibm.com>, linux-s390@...r.kernel.org,
        virtualization@...ts.linux.dev, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc: Boqiao Fu <bfu@...hat.com>, Sebastian Mitterle <smitterl@...hat.com>
Subject: [PATCH 1/1] s390/virtio_ccw: fix config change notifications

Commit e3e9bda38e6d ("s390/virtio_ccw: use DMA handle from DMA API")
broke configuration change notifications for virtio-ccw by putting the
DMA address of *indicatorp directly into ccw->cda disregarding the fact
that if !!(vcdev->is_thinint) then the function
virtio_ccw_register_adapter_ind() will overwrite that ccw->cda value
with the address of the virtio_thinint_area so it can actually set up
the adapter interrupts via CCW_CMD_SET_IND_ADAPTER.  Thus we end up
pointing to the wrong object for both CCW_CMD_SET_IND if setting up the
adapter interrupts fails, and for CCW_CMD_SET_CONF_IND regardless
whether it succeeds or fails.

To fix this, let us save away the dma address of *indicatorp in a local
variable, and copy it to ccw->cda after the "vcdev->is_thinint" branch.

Reported-by: Boqiao Fu <bfu@...hat.com>
Reported-by: Sebastian Mitterle <smitterl@...hat.com>
Fixes: e3e9bda38e6d ("s390/virtio_ccw: use DMA handle from DMA API")
Signed-off-by: Halil Pasic <pasic@...ux.ibm.com>
---
I know that checkpatch.pl complains about a missing 'Closes' tag.
Unfortunately I don't have an appropriate URL at hand. @Sebastian,
@Boqiao: do you have any suggetions?
---
 drivers/s390/virtio/virtio_ccw.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/s390/virtio/virtio_ccw.c b/drivers/s390/virtio/virtio_ccw.c
index d7569f395559..d6491fc84e8c 100644
--- a/drivers/s390/virtio/virtio_ccw.c
+++ b/drivers/s390/virtio/virtio_ccw.c
@@ -698,6 +698,7 @@ static int virtio_ccw_find_vqs(struct virtio_device *vdev, unsigned nvqs,
 	dma64_t *indicatorp = NULL;
 	int ret, i, queue_idx = 0;
 	struct ccw1 *ccw;
+	dma32_t indicatorp_dma = 0;
 
 	ccw = ccw_device_dma_zalloc(vcdev->cdev, sizeof(*ccw), NULL);
 	if (!ccw)
@@ -725,7 +726,7 @@ static int virtio_ccw_find_vqs(struct virtio_device *vdev, unsigned nvqs,
 	*/
 	indicatorp = ccw_device_dma_zalloc(vcdev->cdev,
 					   sizeof(*indicatorp),
-					   &ccw->cda);
+					   &indicatorp_dma);
 	if (!indicatorp)
 		goto out;
 	*indicatorp = indicators_dma(vcdev);
@@ -735,6 +736,7 @@ static int virtio_ccw_find_vqs(struct virtio_device *vdev, unsigned nvqs,
 			/* no error, just fall back to legacy interrupts */
 			vcdev->is_thinint = false;
 	}
+	ccw->cda = indicatorp_dma;
 	if (!vcdev->is_thinint) {
 		/* Register queue indicators with host. */
 		*indicators(vcdev) = 0;

base-commit: 83a7eefedc9b56fe7bfeff13b6c7356688ffa670
-- 
2.40.1