On 02/20/2019 10:28 AM, Cornelia Huck wrote:
On Wed, 20 Feb 2019 14:22:24 +0100
Halil Pasic <pasic@xxxxxxxxxxxxx> wrote:
On Wed, 20 Feb 2019 13:44:46 +0100
Cornelia Huck <cohuck@xxxxxxxxxx> wrote:
On Wed, 20 Feb 2019 06:29:38 -0500
Eric Farman <farman@xxxxxxxxxxxxx> wrote:
On 02/20/2019 04:48 AM, Cornelia Huck wrote:
On Tue, 19 Feb 2019 21:49:07 -0500
Eric Farman <farman@xxxxxxxxxxxxx> wrote:
Hi Connie, Farhan,
On 02/04/2019 12:06 PM, Cornelia Huck wrote:
From: Farhan Ali <alifm@xxxxxxxxxxxxx>
When trying to calculate the length of a ccw chain, we assume
there are ccws after a TIC. This can lead to overcounting and
copying garbage data from guest memory.
Signed-off-by: Farhan Ali <alifm@xxxxxxxxxxxxx>
Message-Id: <d63748c1f1b03147bcbf401596638627a5e35ef7.1548082107.git.alifm@xxxxxxxxxxxxx>
Reviewed-by: Halil Pasic <pasic@xxxxxxxxxxxxx>
Signed-off-by: Cornelia Huck <cohuck@xxxxxxxxxx>
---
drivers/s390/cio/vfio_ccw_cp.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/s390/cio/vfio_ccw_cp.c b/drivers/s390/cio/vfio_ccw_cp.c
index 70a006ba4d05..ba08fe137c2e 100644
--- a/drivers/s390/cio/vfio_ccw_cp.c
+++ b/drivers/s390/cio/vfio_ccw_cp.c
@@ -392,7 +392,7 @@ static int ccwchain_calc_length(u64 iova, struct channel_program *cp)
return -EOPNOTSUPP;
}
- if ((!ccw_is_chain(ccw)) && (!ccw_is_tic(ccw)))
+ if (!ccw_is_chain(ccw))
OK, this function now returns the length of the chain excluding the
last tic.
I'm confused. I read this like the length includes the tic, but not the
ccw? after the tic. Or am I wrong?
break;
ccw++;
Now, cp_init will not copy the last tic to the chain. When it then
looks for tics in that new chain, it won't find any, and stop copying.
Eric also said the TIC is included but the subsequent READ gets 'dropped'
from (SEEK + SIDE + TIC + READ).
Then I'm out of ideas. Are we sure the channel program is correct?
We shouldn't assume that I read things correctly. :) I have not looked
at Jason's patches, and was going by what I saw being referenced in
ccwchain_fetch_{one|tic} with or without this patch.
Now that I've got the morning meetings out of the way, I'll spend some
time sorting out whether we're dropping a read or a tic.
