IB/mthca: Fix access to MTT and MPT tables on non-cache-coherent CPUs

We allocate the MTT table with alloc_pages() and then do pci_map_sg(),
so we must call pci_dma_sync_sg() after the CPU writes to the MTT
table.  This works since the device will never write MTTs on mem-free
HCAs, once we get rid of the use of the WRITE_MTT firmware command.
This change is needed to make that work, and is an improvement for
now, since it gives FMRs a chance at working.

For MPTs, both the device and CPU might write there, so we must
allocate DMA coherent memory for these.

Signed-off-by: Michael S. Tsirkin <mst@mellanox.co.il>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

1 files changed, 98 insertions, 29 deletions

diff --git a/drivers/infiniband/hw/mthca/mthca_memfree.c b/drivers/infiniband/hw/mthca/mthca_memfree.c
index 6b19645d946..0b9d053a599 100644
--- a/drivers/infiniband/hw/mthca/mthca_memfree.c
+++ b/drivers/infiniband/hw/mthca/mthca_memfree.c
@@ -35,6 +35,9 @@
  */
 
 #include <linux/mm.h>
+#include <linux/scatterlist.h>
+
+#include <asm/page.h>
 
 #include "mthca_memfree.h"
 #include "mthca_dev.h"
@@ -58,22 +61,42 @@ struct mthca_user_db_table {
         }                page[0];
 };
 
-void mthca_free_icm(struct mthca_dev *dev, struct mthca_icm *icm)
+static void mthca_free_icm_pages(struct mthca_dev *dev, struct mthca_icm_chunk *chunk)
+{
+        int i;
+
+        if (chunk->nsg > 0)
+                pci_unmap_sg(dev->pdev, chunk->mem, chunk->npages,
+                             PCI_DMA_BIDIRECTIONAL);
+
+        for (i = 0; i < chunk->npages; ++i)
+                __free_pages(chunk->mem[i].page,
+                             get_order(chunk->mem[i].length));
+}
+
+static void mthca_free_icm_coherent(struct mthca_dev *dev, struct mthca_icm_chunk *chunk)
 {
-        struct mthca_icm_chunk *chunk, *tmp;
         int i;
 
+        for (i = 0; i < chunk->npages; ++i) {
+                dma_free_coherent(&dev->pdev->dev, chunk->mem[i].length,
+                                  lowmem_page_address(chunk->mem[i].page),
+                                  sg_dma_address(&chunk->mem[i]));
+        }
+}
+
+void mthca_free_icm(struct mthca_dev *dev, struct mthca_icm *icm, int coherent)
+{
+        struct mthca_icm_chunk *chunk, *tmp;
+
         if (!icm)
                 return;
 
         list_for_each_entry_safe(chunk, tmp, &icm->chunk_list, list) {
-                if (chunk->nsg > 0)
-                        pci_unmap_sg(dev->pdev, chunk->mem, chunk->npages,
-                                     PCI_DMA_BIDIRECTIONAL);
-
-                for (i = 0; i < chunk->npages; ++i)
-                        __free_pages(chunk->mem[i].page,
-                                     get_order(chunk->mem[i].length));
+                if (coherent)
+                        mthca_free_icm_coherent(dev, chunk);
+                else
+                        mthca_free_icm_pages(dev, chunk);
 
                 kfree(chunk);
         }
@@ -81,12 +104,41 @@ void mthca_free_icm(struct mthca_dev *dev, struct mthca_icm *icm)
         kfree(icm);
 }
 
+static int mthca_alloc_icm_pages(struct scatterlist *mem, int order, gfp_t gfp_mask)
+{
+        mem->page = alloc_pages(gfp_mask, order);
+        if (!mem->page)
+                return -ENOMEM;
+
+        mem->length = PAGE_SIZE << order;
+        mem->offset = 0;
+        return 0;
+}
+
+static int mthca_alloc_icm_coherent(struct device *dev, struct scatterlist *mem,
+                                    int order, gfp_t gfp_mask)
+{
+        void *buf = dma_alloc_coherent(dev, PAGE_SIZE << order, &sg_dma_address(mem),
+                                       gfp_mask);
+        if (!buf)
+                return -ENOMEM;
+
+        sg_set_buf(mem, buf, PAGE_SIZE << order);
+        BUG_ON(mem->offset);
+        sg_dma_len(mem) = PAGE_SIZE << order;
+        return 0;
+}
+
 struct mthca_icm *mthca_alloc_icm(struct mthca_dev *dev, int npages,
-                                  gfp_t gfp_mask)
+                                  gfp_t gfp_mask, int coherent)
 {
         struct mthca_icm *icm;
         struct mthca_icm_chunk *chunk = NULL;
         int cur_order;
+        int ret;
+
+        /* We use sg_set_buf for coherent allocs, which assumes low memory */
+        BUG_ON(coherent && (gfp_mask & __GFP_HIGHMEM));
 
         icm = kmalloc(sizeof *icm, gfp_mask & ~(__GFP_HIGHMEM | __GFP_NOWARN));
         if (!icm)
@@ -112,21 +164,28 @@ struct mthca_icm *mthca_alloc_icm(struct mthca_dev *dev, int npages,
                 while (1 << cur_order > npages)
                         --cur_order;
 
-                chunk->mem[chunk->npages].page = alloc_pages(gfp_mask, cur_order);
-                if (chunk->mem[chunk->npages].page) {
-                        chunk->mem[chunk->npages].length = PAGE_SIZE << cur_order;
-                        chunk->mem[chunk->npages].offset = 0;
+                if (coherent)
+                        ret = mthca_alloc_icm_coherent(&dev->pdev->dev,
+                                                       &chunk->mem[chunk->npages],
+                                                       cur_order, gfp_mask);
+                else
+                        ret = mthca_alloc_icm_pages(&chunk->mem[chunk->npages],
+                                                    cur_order, gfp_mask);
 
-                        if (++chunk->npages == MTHCA_ICM_CHUNK_LEN) {
+                if (!ret) {
+                        ++chunk->npages;
+
+                        if (!coherent && chunk->npages == MTHCA_ICM_CHUNK_LEN) {
                                 chunk->nsg = pci_map_sg(dev->pdev, chunk->mem,
                                                         chunk->npages,
                                                         PCI_DMA_BIDIRECTIONAL);
 
                                 if (chunk->nsg <= 0)
                                         goto fail;
+                        }
 
+                        if (chunk->npages == MTHCA_ICM_CHUNK_LEN)
                                 chunk = NULL;
-                        }
 
                         npages -= 1 << cur_order;
                 } else {
@@ -136,7 +195,7 @@ struct mthca_icm *mthca_alloc_icm(struct mthca_dev *dev, int npages,
                 }
         }
 
-        if (chunk) {
+        if (!coherent && chunk) {
                 chunk->nsg = pci_map_sg(dev->pdev, chunk->mem,
                                         chunk->npages,
                                         PCI_DMA_BIDIRECTIONAL);
@@ -148,7 +207,7 @@ struct mthca_icm *mthca_alloc_icm(struct mthca_dev *dev, int npages,
         return icm;
 
 fail:
-        mthca_free_icm(dev, icm);
+        mthca_free_icm(dev, icm, coherent);
         return NULL;
 }
 
@@ -167,7 +226,7 @@ int mthca_table_get(struct mthca_dev *dev, struct mthca_icm_table *table, int ob
 
         table->icm[i] = mthca_alloc_icm(dev, MTHCA_TABLE_CHUNK_SIZE >> PAGE_SHIFT,
                                         (table->lowmem ? GFP_KERNEL : GFP_HIGHUSER) |
-                                        __GFP_NOWARN);
+                                        __GFP_NOWARN, table->coherent);
         if (!table->icm[i]) {
                 ret = -ENOMEM;
                 goto out;
@@ -175,7 +234,7 @@ int mthca_table_get(struct mthca_dev *dev, struct mthca_icm_table *table, int ob
 
         if (mthca_MAP_ICM(dev, table->icm[i], table->virt + i * MTHCA_TABLE_CHUNK_SIZE,
                           &status) || status) {
-                mthca_free_icm(dev, table->icm[i]);
+                mthca_free_icm(dev, table->icm[i], table->coherent);
                 table->icm[i] = NULL;
                 ret = -ENOMEM;
                 goto out;
@@ -204,16 +263,16 @@ void mthca_table_put(struct mthca_dev *dev, struct mthca_icm_table *table, int o
                 mthca_UNMAP_ICM(dev, table->virt + i * MTHCA_TABLE_CHUNK_SIZE,
                                 MTHCA_TABLE_CHUNK_SIZE / MTHCA_ICM_PAGE_SIZE,
                                 &status);
-                mthca_free_icm(dev, table->icm[i]);
+                mthca_free_icm(dev, table->icm[i], table->coherent);
                 table->icm[i] = NULL;
         }
 
         mutex_unlock(&table->mutex);
 }
 
-void *mthca_table_find(struct mthca_icm_table *table, int obj)
+void *mthca_table_find(struct mthca_icm_table *table, int obj, dma_addr_t *dma_handle)
 {
-        int idx, offset, i;
+        int idx, offset, dma_offset, i;
         struct mthca_icm_chunk *chunk;
         struct mthca_icm *icm;
         struct page *page = NULL;
@@ -225,13 +284,22 @@ void *mthca_table_find(struct mthca_icm_table *table, int obj)
 
         idx = (obj & (table->num_obj - 1)) * table->obj_size;
         icm = table->icm[idx / MTHCA_TABLE_CHUNK_SIZE];
-        offset = idx % MTHCA_TABLE_CHUNK_SIZE;
+        dma_offset = offset = idx % MTHCA_TABLE_CHUNK_SIZE;
 
         if (!icm)
                 goto out;
 
         list_for_each_entry(chunk, &icm->chunk_list, list) {
                 for (i = 0; i < chunk->npages; ++i) {
+                        if (dma_handle && dma_offset >= 0) {
+                                if (sg_dma_len(&chunk->mem[i]) > dma_offset)
+                                        *dma_handle = sg_dma_address(&chunk->mem[i]) +
+                                                dma_offset;
+                                dma_offset -= sg_dma_len(&chunk->mem[i]);
+                        }
+                        /* DMA mapping can merge pages but not split them,
+                         * so if we found the page, dma_handle has already
+                         * been assigned to. */
                         if (chunk->mem[i].length > offset) {
                                 page = chunk->mem[i].page;
                                 goto out;
@@ -283,7 +351,7 @@ void mthca_table_put_range(struct mthca_dev *dev, struct mthca_icm_table *table,
 struct mthca_icm_table *mthca_alloc_icm_table(struct mthca_dev *dev,
                                               u64 virt, int obj_size,
                                               int nobj, int reserved,
-                                              int use_lowmem)
+                                              int use_lowmem, int use_coherent)
 {
         struct mthca_icm_table *table;
         int num_icm;
@@ -302,6 +370,7 @@ struct mthca_icm_table *mthca_alloc_icm_table(struct mthca_dev *dev,
         table->num_obj  = nobj;
         table->obj_size = obj_size;
         table->lowmem   = use_lowmem;
+        table->coherent = use_coherent;
         mutex_init(&table->mutex);
 
         for (i = 0; i < num_icm; ++i)
@@ -314,12 +383,12 @@ struct mthca_icm_table *mthca_alloc_icm_table(struct mthca_dev *dev,
 
                 table->icm[i] = mthca_alloc_icm(dev, chunk_size >> PAGE_SHIFT,
                                                 (use_lowmem ? GFP_KERNEL : GFP_HIGHUSER) |
-                                                __GFP_NOWARN);
+                                                __GFP_NOWARN, use_coherent);
                 if (!table->icm[i])
                         goto err;
                 if (mthca_MAP_ICM(dev, table->icm[i], virt + i * MTHCA_TABLE_CHUNK_SIZE,
                                   &status) || status) {
-                        mthca_free_icm(dev, table->icm[i]);
+                        mthca_free_icm(dev, table->icm[i], table->coherent);
                         table->icm[i] = NULL;
                         goto err;
                 }
@@ -339,7 +408,7 @@ err:
                         mthca_UNMAP_ICM(dev, virt + i * MTHCA_TABLE_CHUNK_SIZE,
                                         MTHCA_TABLE_CHUNK_SIZE / MTHCA_ICM_PAGE_SIZE,
                                         &status);
-                        mthca_free_icm(dev, table->icm[i]);
+                        mthca_free_icm(dev, table->icm[i], table->coherent);
                 }
 
         kfree(table);
@@ -357,7 +426,7 @@ void mthca_free_icm_table(struct mthca_dev *dev, struct mthca_icm_table *table)
                         mthca_UNMAP_ICM(dev, table->virt + i * MTHCA_TABLE_CHUNK_SIZE,
                                         MTHCA_TABLE_CHUNK_SIZE / MTHCA_ICM_PAGE_SIZE,
                                         &status);
-                        mthca_free_icm(dev, table->icm[i]);
+                        mthca_free_icm(dev, table->icm[i], table->coherent);
                 }
 
         kfree(table);