RDMA/siw: Convert siw_tx_hdt() to kmap_local_page()

kmap() is being deprecated and will break uses of device dax after PKS
protection is introduced.[1]

The use of kmap() in siw_tx_hdt() is all thread local therefore
kmap_local_page() is a sufficient replacement and will work with pgmap
protected pages when those are implemented.

siw_tx_hdt() tracks pages used in a page_array.  It uses that array to
unmap pages which were mapped on function exit.  Not all entries in the
array are mapped and this is tracked in kmap_mask.

kunmap_local() takes a mapped address rather than a page.  Alter
siw_unmap_pages() to take the iov array to reuse the iov_base address of
each mapping.  Use PAGE_MASK to get the proper address for kunmap_local().

kmap_local_page() mappings are tracked in a stack and must be unmapped in
the opposite order they were mapped in.  Because segments are mapped into
the page array in increasing index order, modify siw_unmap_pages() to
unmap pages in decreasing order.

Use kmap_local_page() instead of kmap() to map pages in the page_array.

[1] https://lore.kernel.org/lkml/20201009195033.3208459-59-ira.weiny@intel.com/

Link: https://lore.kernel.org/r/20210624174814.2822896-1-ira.weiny@intel.com
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Bernard Metzler <bmt@zurich.ibm.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

diff --git a/drivers/infiniband/sw/siw/siw_qp_tx.c b/drivers/infiniband/sw/siw/siw_qp_tx.c
index db68a10..1f4e602 100644 (file)
--- a/drivers/infiniband/sw/siw/siw_qp_tx.c
+++ b/drivers/infiniband/sw/siw/siw_qp_tx.c
@@ -396,13 +396,20 @@ static int siw_0copy_tx(struct socket *s, struct page **page,
 
 #define MAX_TRAILER (MPA_CRC_SIZE + 4)
 
-static void siw_unmap_pages(struct page **pp, unsigned long kmap_mask)
+static void siw_unmap_pages(struct kvec *iov, unsigned long kmap_mask, int len)
 {
-       while (kmap_mask) {
-               if (kmap_mask & BIT(0))
-                       kunmap(*pp);
-               pp++;
-               kmap_mask >>= 1;
+       int i;
+
+       /*
+        * Work backwards through the array to honor the kmap_local_page()
+        * ordering requirements.
+        */
+       for (i = (len-1); i >= 0; i--) {
+               if (kmap_mask & BIT(i)) {
+                       unsigned long addr = (unsigned long)iov[i].iov_base;
+
+                       kunmap_local((void *)(addr & PAGE_MASK));
+               }
        }
 }
 
@@ -498,7 +505,7 @@ static int siw_tx_hdt(struct siw_iwarp_tx *c_tx, struct socket *s)
                                        p = siw_get_upage(mem->umem,
                                                          sge->laddr + sge_off);
                                if (unlikely(!p)) {
-                                       siw_unmap_pages(page_array, kmap_mask);
+                                       siw_unmap_pages(iov, kmap_mask, seg);
                                        wqe->processed -= c_tx->bytes_unsent;
                                        rv = -EFAULT;
                                        goto done_crc;
@@ -506,11 +513,12 @@ static int siw_tx_hdt(struct siw_iwarp_tx *c_tx, struct socket *s)
                                page_array[seg] = p;
 
                                if (!c_tx->use_sendpage) {
-                                       iov[seg].iov_base = kmap(p) + fp_off;
-                                       iov[seg].iov_len = plen;
+                                       void *kaddr = kmap_local_page(p);
 
                                        /* Remember for later kunmap() */
                                        kmap_mask |= BIT(seg);
+                                       iov[seg].iov_base = kaddr + fp_off;
+                                       iov[seg].iov_len = plen;
 
                                        if (do_crc)
                                                crypto_shash_update(
@@ -542,7 +550,7 @@ static int siw_tx_hdt(struct siw_iwarp_tx *c_tx, struct socket *s)
 
                        if (++seg > (int)MAX_ARRAY) {
                                siw_dbg_qp(tx_qp(c_tx), "to many fragments\n");
-                               siw_unmap_pages(page_array, kmap_mask);
+                               siw_unmap_pages(iov, kmap_mask, seg-1);
                                wqe->processed -= c_tx->bytes_unsent;
                                rv = -EMSGSIZE;
                                goto done_crc;
@@ -593,7 +601,7 @@ sge_done:
        } else {
                rv = kernel_sendmsg(s, &msg, iov, seg + 1,
                                    hdr_len + data_len + trl_len);
-               siw_unmap_pages(page_array, kmap_mask);
+               siw_unmap_pages(iov, kmap_mask, seg);
        }
        if (rv < (int)hdr_len) {
                /* Not even complete hdr pushed or negative rv */