[RFC PATCH v1 4/5] vfio-ccw: Factor out the ccw0-to-ccw1 transition

Eric Farman
2019-06-18T20:24:02Z

This is a really useful function, but it's buried in the
copy_ccw_from_iova() routine so that ccwchain_calc_length()
can just work with Format-1 CCWs while doing its counting.
But it means we're translating a full 2K of "CCWs" to Format-1,
when in reality there's probably far fewer in that space.

Let's factor it out, so maybe we can do something with it later.

Signed-off-by: Eric Farman <farman@linux.ibm.com>
---
drivers/s390/cio/vfio_ccw_cp.c | 48 ++++++++++++++++++----------------
1 file changed, 25 insertions(+), 23 deletions(-)

diff --git a/drivers/s390/cio/vfio_ccw_cp.c b/drivers/s390/cio/vfio_ccw_cp.c
index a55f8d110920..9a8bf06281e0 100644
--- a/drivers/s390/cio/vfio_ccw_cp.c
+++ b/drivers/s390/cio/vfio_ccw_cp.c
@@ -161,6 +161,27 @@ static inline void pfn_array_idal_create_words(
idaws[0] += pa->pa_iova & (PAGE_SIZE - 1);
}

+void convert_ccw0_to_ccw1(struct ccw1 *source, unsigned long len)
+{
+ struct ccw0 ccw0;
+ struct ccw1 *pccw1 = source;
+ int i;
+
+ for (i = 0; i < len; i++) {
+ ccw0 = *(struct ccw0 *)pccw1;
+ if ((pccw1->cmd_code & 0x0f) == CCW_CMD_TIC) {
+ pccw1->cmd_code = CCW_CMD_TIC;
+ pccw1->flags = 0;
+ pccw1->count = 0;
+ } else {
+ pccw1->cmd_code = ccw0.cmd_code;
+ pccw1->flags = ccw0.flags;
+ pccw1->count = ccw0.count;
+ }
+ pccw1->cda = ccw0.cda;
+ pccw1++;
+ }
+}

/*
* Within the domain (@mdev), copy @n bytes from a guest physical
@@ -211,32 +232,9 @@ static long copy_ccw_from_iova(struct channel_program *cp,
struct ccw1 *to, u64 iova,
unsigned long len)
{
- struct ccw0 ccw0;
- struct ccw1 *pccw1;
int ret;
- int i;

ret = copy_from_iova(cp->mdev, to, iova, len * sizeof(struct ccw1));
- if (ret)
- return ret;
-
- if (!cp->orb.cmd.fmt) {
- pccw1 = to;
- for (i = 0; i < len; i++) {
- ccw0 = *(struct ccw0 *)pccw1;
- if ((pccw1->cmd_code & 0x0f) == CCW_CMD_TIC) {
- pccw1->cmd_code = CCW_CMD_TIC;
- pccw1->flags = 0;
- pccw1->count = 0;
- } else {
- pccw1->cmd_code = ccw0.cmd_code;
- pccw1->flags = ccw0.flags;
- pccw1->count = ccw0.count;
- }
- pccw1->cda = ccw0.cda;
- pccw1++;
- }
- }

return ret;
}
@@ -441,6 +439,10 @@ static int ccwchain_handle_ccw(u32 cda, struct channel_program *cp)
if (len)
return len;

+ /* Convert any Format-0 CCWs to Format-1 */
+ if (!cp->orb.cmd.fmt)
+ convert_ccw0_to_ccw1(cp->guest_cp, len);
+
/* Count the CCWs in the current chain */
len = ccwchain_calc_length(cda, cp);
if (len < 0)
--
2.17.1