From: Dong Jia Shi Date: Wed, 11 Oct 2017 02:38:21 +0000 (+0200) Subject: vfio: ccw: bypass bad idaw address when fetching IDAL ccws X-Git-Tag: v4.15-rc1~166^2~37^2~1 X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=688c29533ffc969773bc860d07d3a5f1995f5878;p=linux.git vfio: ccw: bypass bad idaw address when fetching IDAL ccws We currently return the same error code (-EFAULT) to indicate two different error cases: 1. a bug in vfio-ccw implementation has been found. 2. a buggy channel program has been detected. This brings difficulty for userland program (specifically Qemu) to handle. Let's use -EFAULT to only indicate the first case. For the second case, we simply hand over the ccws to lower level for further handling. Notice: Once a bad idaw address is detected, the current behavior is to suppress the ssch. With this fix, the channel program will be accepted, and part of the channel program (the part ahead of the bad idaw) could possibly be executed by the device before I/O conclusion. Suggested-by: Halil Pasic Reviewed-by: Pierre Morel Signed-off-by: Dong Jia Shi Message-Id: <20171011023822.42948-2-bjsdjshi@linux.vnet.ibm.com> Signed-off-by: Cornelia Huck --- diff --git a/drivers/s390/cio/vfio_ccw_cp.c b/drivers/s390/cio/vfio_ccw_cp.c index 5ccfdc80d0ec..722f8b8c7273 100644 --- a/drivers/s390/cio/vfio_ccw_cp.c +++ b/drivers/s390/cio/vfio_ccw_cp.c @@ -569,10 +569,6 @@ static int ccwchain_fetch_idal(struct ccwchain *chain, for (i = 0; i < idaw_nr; i++) { idaw_iova = *(idaws + i); - if (IS_ERR_VALUE(idaw_iova)) { - ret = -EFAULT; - goto out_free_idaws; - } ret = pfn_array_alloc_pin(pat->pat_pa + i, cp->mdev, idaw_iova, 1);