s390/cio: Combine direct and indirect CCW paths

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>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Message-Id: <20190606202831.44135-10-farman@linux.ibm.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>

diff --git a/drivers/s390/cio/vfio_ccw_cp.c b/drivers/s390/cio/vfio_ccw_cp.c
index 8205d0b..90d86e1 100644 (file)
--- 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 @@ out_init:
        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);
 }