[PATCH v2 9/9] s390/cio: Combine direct and indirect CCW paths

Eric Farman
2019-06-06T20:28:41Z

With both the direct-addressed and indirect-addressed CCW paths
simplified to this point, the amount of shared code between them is
(hopefully) more easily visible. Move the processing of IDA-specific
bits into the direct-addressed path, and add some useful commentary of
what the individual pieces are doing. This allows us to remove the
entire ccwchain_fetch_idal() routine and maintain a single function
for any non-TIC CCW.

Signed-off-by: Eric Farman <farman@linux.ibm.com>
---
drivers/s390/cio/vfio_ccw_cp.c | 115 +++++++++++----------------------
1 file changed, 39 insertions(+), 76 deletions(-)

diff --git a/drivers/s390/cio/vfio_ccw_cp.c b/drivers/s390/cio/vfio_ccw_cp.c
index 8205d0b527fc..90d86e1354c1 100644
--- a/drivers/s390/cio/vfio_ccw_cp.c
+++ b/drivers/s390/cio/vfio_ccw_cp.c
@@ -534,10 +534,12 @@ static int ccwchain_fetch_direct(struct ccwchain *chain,
{
struct ccw1 *ccw;
struct pfn_array *pa;
+ u64 iova;
unsigned long *idaws;
int ret;
int bytes = 1;
- int idaw_nr;
+ int idaw_nr, idal_len;
+ int i;

ccw = chain->ch_ccw + idx;

@@ -545,7 +547,17 @@ static int ccwchain_fetch_direct(struct ccwchain *chain,
bytes = ccw->count;

/* Calculate size of IDAL */
- idaw_nr = idal_nr_words((void *)(u64)ccw->cda, bytes);
+ if (ccw_is_idal(ccw)) {
+ /* Read first IDAW to see if it's 4K-aligned or not. */
+ /* All subsequent IDAws will be 4K-aligned. */
+ ret = copy_from_iova(cp->mdev, &iova, ccw->cda, sizeof(iova));
+ if (ret)
+ return ret;
+ } else {
+ iova = ccw->cda;
+ }
+ idaw_nr = idal_nr_words((void *)iova, bytes);
+ idal_len = idaw_nr * sizeof(*idaws);

/* Allocate an IDAL from host storage */
idaws = kcalloc(idaw_nr, sizeof(*idaws), GFP_DMA | GFP_KERNEL);
@@ -555,15 +567,36 @@ static int ccwchain_fetch_direct(struct ccwchain *chain,
}

/*
- * Pin data page(s) in memory.
- * The number of pages actually is the count of the idaws which will be
- * needed when translating a direct ccw to a idal ccw.
+ * Allocate an array of pfn's for pages to pin/translate.
+ * The number of pages is actually the count of the idaws
+ * required for the data transfer, since we only only support
+ * 4K IDAWs today.
*/
pa = chain->ch_pa + idx;
- ret = pfn_array_alloc(pa, ccw->cda, bytes);
+ ret = pfn_array_alloc(pa, iova, bytes);
if (ret < 0)
goto out_free_idaws;

+ if (ccw_is_idal(ccw)) {
+ /* Copy guest IDAL into host IDAL */
+ ret = copy_from_iova(cp->mdev, idaws, ccw->cda, idal_len);
+ if (ret)
+ goto out_unpin;
+
+ /*
+ * Copy guest IDAWs into pfn_array, in case the memory they
+ * occupy is not contiguous.
+ */
+ for (i = 0; i < idaw_nr; i++)
+ pa->pa_iova_pfn[i] = idaws[i] >> PAGE_SHIFT;
+ } else {
+ /*
+ * No action is required here; the iova addresses in pfn_array
+ * were initialized sequentially in pfn_array_alloc() beginning
+ * with the contents of ccw->cda.
+ */
+ }
+
if (ccw_does_data_transfer(ccw)) {
ret = pfn_array_pin(pa, cp->mdev);
if (ret < 0)
@@ -589,73 +622,6 @@ static int ccwchain_fetch_direct(struct ccwchain *chain,
return ret;
}

-static int ccwchain_fetch_idal(struct ccwchain *chain,
- int idx,
- struct channel_program *cp)
-{
- struct ccw1 *ccw;
- struct pfn_array *pa;
- unsigned long *idaws;
- u64 idaw_iova;
- unsigned int idaw_nr, idaw_len;
- int i, ret;
- int bytes = 1;
-
- ccw = chain->ch_ccw + idx;
-
- if (ccw->count)
- bytes = ccw->count;
-
- /* Calculate size of idaws. */
- ret = copy_from_iova(cp->mdev, &idaw_iova, ccw->cda, sizeof(idaw_iova));
- if (ret)
- return ret;
- idaw_nr = idal_nr_words((void *)(idaw_iova), bytes);
- idaw_len = idaw_nr * sizeof(*idaws);
-
- /* Pin data page(s) in memory. */
- pa = chain->ch_pa + idx;
- ret = pfn_array_alloc(pa, idaw_iova, bytes);
- if (ret)
- goto out_init;
-
- /* Translate idal ccw to use new allocated idaws. */
- idaws = kzalloc(idaw_len, GFP_DMA | GFP_KERNEL);
- if (!idaws) {
- ret = -ENOMEM;
- goto out_unpin;
- }
-
- ret = copy_from_iova(cp->mdev, idaws, ccw->cda, idaw_len);
- if (ret)
- goto out_free_idaws;
-
- ccw->cda = virt_to_phys(idaws);
-
- for (i = 0; i < idaw_nr; i++)
- pa->pa_iova_pfn[i] = idaws[i] >> PAGE_SHIFT;
-
- if (ccw_does_data_transfer(ccw)) {
- ret = pfn_array_pin(pa, cp->mdev);
- if (ret < 0)
- goto out_free_idaws;
- } else {
- pa->pa_nr = 0;
- }
-
- pfn_array_idal_create_words(pa, idaws);
-
- return 0;
-
-out_free_idaws:
- kfree(idaws);
-out_unpin:
- pfn_array_unpin_free(pa, cp->mdev);
-out_init:
- ccw->cda = 0;
- return ret;
-}
-
/*
* Fetch one ccw.
* To reduce memory copy, we'll pin the cda page in memory,
@@ -671,9 +637,6 @@ static int ccwchain_fetch_one(struct ccwchain *chain,
if (ccw_is_tic(ccw))
return ccwchain_fetch_tic(chain, idx, cp);

- if (ccw_is_idal(ccw))
- return ccwchain_fetch_idal(chain, idx, cp);
-
return ccwchain_fetch_direct(chain, idx, cp);
}

--
2.17.1