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vfio: ccw: validate the count field of a ccw before pinning

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If the count field of a ccw is zero, there is no need to
try to pin page(s) for it. Let's check the count value
before starting pinning operations.

Reviewed-by: Pierre Morel <pmorel@linux.vnet.ibm.com>
Signed-off-by: Dong Jia Shi <bjsdjshi@linux.vnet.ibm.com>
Message-Id: <20171011023822.42948-3-bjsdjshi@linux.vnet.ibm.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>
This commit is contained in:
Dong Jia Shi 2017-10-11 04:38:22 +02:00 committed by Cornelia Huck
parent 688c29533f
commit 4cebc5d6a6
1 changed files with 17 additions and 1 deletions
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18
drivers/s390/cio/vfio_ccw_cp.c
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@ -105,7 +105,10 @@ static int pfn_array_alloc_pin(struct pfn_array *pa, struct device *mdev,
{
int ret = 0;
if (!len || pa->pa_nr)
if (!len)
return 0;
if (pa->pa_nr)
return -EINVAL;
pa->pa_iova = iova;
@ -501,6 +504,16 @@ static int ccwchain_fetch_direct(struct ccwchain *chain,
ccw = chain->ch_ccw + idx;
if (!ccw->count) {
/*
* We just want the translation result of any direct ccw
* to be an IDA ccw, so let's add the IDA flag for it.
* Although the flag will be ignored by firmware.
*/
ccw->flags |= CCW_FLAG_IDA;
return 0;
}
/*
* Pin data page(s) in memory.
* The number of pages actually is the count of the idaws which will be
@ -541,6 +554,9 @@ static int ccwchain_fetch_idal(struct ccwchain *chain,
ccw = chain->ch_ccw + idx;
if (!ccw->count)
return 0;
/* Calculate size of idaws. */
ret = copy_from_iova(cp->mdev, &idaw_iova, ccw->cda, sizeof(idaw_iova));
if (ret)