[POWERPC] Use 4kB iommu pages even on 64kB-page systems

The 10Gigabit ethernet device drivers appear to be able to chew
up all 256MB of TCE mappings on pSeries systems, as evidenced by
numerous error messages:

 iommu_alloc failed, tbl c0000000010d5c48 vaddr c0000000d875eff0 npages 1

Some experimentation indicates that this is essentially because
one 1500 byte ethernet MTU gets mapped as a 64K DMA region when
the large 64K pages are enabled. Thus, it doesn't take much to
exhaust all of the available DMA mappings for a high-speed card.

This patch changes the iommu allocator to work with its own
unique, distinct page size. Although the patch is long, its
actually quite simple: it just #defines a distinct IOMMU_PAGE_SIZE
and then uses this in all the places that matter.

As a side effect, it also dramatically improves network performance
on platforms with H-calls on iommu translation inserts/removes (since
we no longer call it 16 times for a 1500 bytes packet when the iommu HW
is still 4k).

In the future, we might want to make the IOMMU_PAGE_SIZE a variable
in the iommu_table instance, thus allowing support for different HW
page sizes in the iommu itself.

Signed-off-by: Linas Vepstas <linas@austin.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Acked-by: Olof Johansson <olof@lixom.net>
Acked-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>

6 files changed, 58 insertions, 78 deletions

diff --git a/arch/powerpc/kernel/iommu.c b/arch/powerpc/kernel/iommu.c
index f88a2a675d90..ba6b7256084b 100644
--- a/arch/powerpc/kernel/iommu.c
+++ b/arch/powerpc/kernel/iommu.c
@@ -47,6 +47,17 @@ static int novmerge = 0;
 static int novmerge = 1;
 #endif
 
+static inline unsigned long iommu_num_pages(unsigned long vaddr,
+                                            unsigned long slen)
+{
+        unsigned long npages;
+
+        npages = IOMMU_PAGE_ALIGN(vaddr + slen) - (vaddr & IOMMU_PAGE_MASK);
+        npages >>= IOMMU_PAGE_SHIFT;
+
+        return npages;
+}
+
 static int __init setup_iommu(char *str)
 {
         if (!strcmp(str, "novmerge"))
@@ -178,10 +189,10 @@ static dma_addr_t iommu_alloc(struct iommu_table *tbl, void *page,
         }
 
         entry += tbl->it_offset;        /* Offset into real TCE table */
-        ret = entry << PAGE_SHIFT;      /* Set the return dma address */
+        ret = entry << IOMMU_PAGE_SHIFT;        /* Set the return dma address */
 
         /* Put the TCEs in the HW table */
-        ppc_md.tce_build(tbl, entry, npages, (unsigned long)page & PAGE_MASK,
+        ppc_md.tce_build(tbl, entry, npages, (unsigned long)page & IOMMU_PAGE_MASK,
                          direction);
 
 
@@ -203,7 +214,7 @@ static void __iommu_free(struct iommu_table *tbl, dma_addr_t dma_addr,
         unsigned long entry, free_entry;
         unsigned long i;
 
-        entry = dma_addr >> PAGE_SHIFT;
+        entry = dma_addr >> IOMMU_PAGE_SHIFT;
         free_entry = entry - tbl->it_offset;
 
         if (((free_entry + npages) > tbl->it_size) ||
@@ -270,7 +281,7 @@ int iommu_map_sg(struct device *dev, struct iommu_table *tbl,
         /* Init first segment length for backout at failure */
         outs->dma_length = 0;
 
-        DBG("mapping %d elements:\n", nelems);
+        DBG("sg mapping %d elements:\n", nelems);
 
         spin_lock_irqsave(&(tbl->it_lock), flags);
 
@@ -285,9 +296,8 @@ int iommu_map_sg(struct device *dev, struct iommu_table *tbl,
                 }
                 /* Allocate iommu entries for that segment */
                 vaddr = (unsigned long)page_address(s->page) + s->offset;
-                npages = PAGE_ALIGN(vaddr + slen) - (vaddr & PAGE_MASK);
-                npages >>= PAGE_SHIFT;
-                entry = iommu_range_alloc(tbl, npages, &handle, mask >> PAGE_SHIFT, 0);
+                npages = iommu_num_pages(vaddr, slen);
+                entry = iommu_range_alloc(tbl, npages, &handle, mask >> IOMMU_PAGE_SHIFT, 0);
 
                 DBG("  - vaddr: %lx, size: %lx\n", vaddr, slen);
 
@@ -301,14 +311,14 @@ int iommu_map_sg(struct device *dev, struct iommu_table *tbl,
 
                 /* Convert entry to a dma_addr_t */
                 entry += tbl->it_offset;
-                dma_addr = entry << PAGE_SHIFT;
-                dma_addr |= s->offset;
+                dma_addr = entry << IOMMU_PAGE_SHIFT;
+                dma_addr |= (s->offset & ~IOMMU_PAGE_MASK);
 
-                DBG("  - %lx pages, entry: %lx, dma_addr: %lx\n",
+                DBG("  - %lu pages, entry: %lx, dma_addr: %lx\n",
                             npages, entry, dma_addr);
 
                 /* Insert into HW table */
-                ppc_md.tce_build(tbl, entry, npages, vaddr & PAGE_MASK, direction);
+                ppc_md.tce_build(tbl, entry, npages, vaddr & IOMMU_PAGE_MASK, direction);
 
                 /* If we are in an open segment, try merging */
                 if (segstart != s) {
@@ -323,7 +333,7 @@ int iommu_map_sg(struct device *dev, struct iommu_table *tbl,
                                 DBG("    can't merge, new segment.\n");
                         } else {
                                 outs->dma_length += s->length;
-                                DBG("    merged, new len: %lx\n", outs->dma_length);
+                                DBG("    merged, new len: %ux\n", outs->dma_length);
                         }
                 }
 
@@ -367,9 +377,8 @@ int iommu_map_sg(struct device *dev, struct iommu_table *tbl,
                 if (s->dma_length != 0) {
                         unsigned long vaddr, npages;
 
-                        vaddr = s->dma_address & PAGE_MASK;
-                        npages = (PAGE_ALIGN(s->dma_address + s->dma_length) - vaddr)
-                                >> PAGE_SHIFT;
+                        vaddr = s->dma_address & IOMMU_PAGE_MASK;
+                        npages = iommu_num_pages(s->dma_address, s->dma_length);
                         __iommu_free(tbl, vaddr, npages);
                         s->dma_address = DMA_ERROR_CODE;
                         s->dma_length = 0;
@@ -398,8 +407,7 @@ void iommu_unmap_sg(struct iommu_table *tbl, struct scatterlist *sglist,
 
                 if (sglist->dma_length == 0)
                         break;
-                npages = (PAGE_ALIGN(dma_handle + sglist->dma_length)
-                          - (dma_handle & PAGE_MASK)) >> PAGE_SHIFT;
+                npages = iommu_num_pages(dma_handle,sglist->dma_length);
                 __iommu_free(tbl, dma_handle, npages);
                 sglist++;
         }
@@ -532,12 +540,11 @@ dma_addr_t iommu_map_single(struct iommu_table *tbl, void *vaddr,
         BUG_ON(direction == DMA_NONE);
 
         uaddr = (unsigned long)vaddr;
-        npages = PAGE_ALIGN(uaddr + size) - (uaddr & PAGE_MASK);
-        npages >>= PAGE_SHIFT;
+        npages = iommu_num_pages(uaddr, size);
 
         if (tbl) {
                 dma_handle = iommu_alloc(tbl, vaddr, npages, direction,
-                                         mask >> PAGE_SHIFT, 0);
+                                         mask >> IOMMU_PAGE_SHIFT, 0);
                 if (dma_handle == DMA_ERROR_CODE) {
                         if (printk_ratelimit())  {
                                 printk(KERN_INFO "iommu_alloc failed, "
@@ -545,7 +552,7 @@ dma_addr_t iommu_map_single(struct iommu_table *tbl, void *vaddr,
                                                 tbl, vaddr, npages);
                         }
                 } else
-                        dma_handle |= (uaddr & ~PAGE_MASK);
+                        dma_handle |= (uaddr & ~IOMMU_PAGE_MASK);
         }
 
         return dma_handle;
@@ -554,11 +561,14 @@ dma_addr_t iommu_map_single(struct iommu_table *tbl, void *vaddr,
 void iommu_unmap_single(struct iommu_table *tbl, dma_addr_t dma_handle,
                 size_t size, enum dma_data_direction direction)
 {
+        unsigned int npages;
+
         BUG_ON(direction == DMA_NONE);
 
-        if (tbl)
-                iommu_free(tbl, dma_handle, (PAGE_ALIGN(dma_handle + size) -
-                                        (dma_handle & PAGE_MASK)) >> PAGE_SHIFT);
+        if (tbl) {
+                npages = iommu_num_pages(dma_handle, size);
+                iommu_free(tbl, dma_handle, npages);
+        }
 }
 
 /* Allocates a contiguous real buffer and creates mappings over it.
@@ -570,11 +580,11 @@ void *iommu_alloc_coherent(struct iommu_table *tbl, size_t size,
 {
         void *ret = NULL;
         dma_addr_t mapping;
-        unsigned int npages, order;
+        unsigned int order;
+        unsigned int nio_pages, io_order;
         struct page *page;
 
         size = PAGE_ALIGN(size);
-        npages = size >> PAGE_SHIFT;
         order = get_order(size);
 
         /*
@@ -598,8 +608,10 @@ void *iommu_alloc_coherent(struct iommu_table *tbl, size_t size,
         memset(ret, 0, size);
 
         /* Set up tces to cover the allocated range */
-        mapping = iommu_alloc(tbl, ret, npages, DMA_BIDIRECTIONAL,
-                              mask >> PAGE_SHIFT, order);
+        nio_pages = size >> IOMMU_PAGE_SHIFT;
+        io_order = get_iommu_order(size);
+        mapping = iommu_alloc(tbl, ret, nio_pages, DMA_BIDIRECTIONAL,
+                              mask >> IOMMU_PAGE_SHIFT, io_order);
         if (mapping == DMA_ERROR_CODE) {
                 free_pages((unsigned long)ret, order);
                 return NULL;
@@ -611,12 +623,13 @@ void *iommu_alloc_coherent(struct iommu_table *tbl, size_t size,
 void iommu_free_coherent(struct iommu_table *tbl, size_t size,
                          void *vaddr, dma_addr_t dma_handle)
 {
-        unsigned int npages;
-
         if (tbl) {
+                unsigned int nio_pages;
+
+                size = PAGE_ALIGN(size);
+                nio_pages = size >> IOMMU_PAGE_SHIFT;
+                iommu_free(tbl, dma_handle, nio_pages);
                 size = PAGE_ALIGN(size);
-                npages = size >> PAGE_SHIFT;
-                iommu_free(tbl, dma_handle, npages);
                 free_pages((unsigned long)vaddr, get_order(size));
         }
 }
diff --git a/arch/powerpc/kernel/vio.c b/arch/powerpc/kernel/vio.c
index cb87e71eec66..ed007878d1bf 100644
--- a/arch/powerpc/kernel/vio.c
+++ b/arch/powerpc/kernel/vio.c
@@ -92,9 +92,9 @@ static struct iommu_table *vio_build_iommu_table(struct vio_dev *dev)
                                 &tbl->it_index, &offset, &size);
 
                 /* TCE table size - measured in tce entries */
-                tbl->it_size = size >> PAGE_SHIFT;
+                tbl->it_size = size >> IOMMU_PAGE_SHIFT;
                 /* offset for VIO should always be 0 */
-                tbl->it_offset = offset >> PAGE_SHIFT;
+                tbl->it_offset = offset >> IOMMU_PAGE_SHIFT;
                 tbl->it_busno = 0;
                 tbl->it_type = TCE_VB;
 
diff --git a/arch/powerpc/platforms/iseries/iommu.c b/arch/powerpc/platforms/iseries/iommu.c
index f4cbbcf8773a..218817d13c5c 100644
--- a/arch/powerpc/platforms/iseries/iommu.c
+++ b/arch/powerpc/platforms/iseries/iommu.c
@@ -43,9 +43,6 @@ static void tce_build_iSeries(struct iommu_table *tbl, long index, long npages,
         u64 rc;
         u64 tce, rpn;
 
-        index <<= TCE_PAGE_FACTOR;
-        npages <<= TCE_PAGE_FACTOR;
-
         while (npages--) {
                 rpn = virt_to_abs(uaddr) >> TCE_SHIFT;
                 tce = (rpn & TCE_RPN_MASK) << TCE_RPN_SHIFT;
@@ -75,9 +72,6 @@ static void tce_free_iSeries(struct iommu_table *tbl, long index, long npages)
 {
         u64 rc;
 
-        npages <<= TCE_PAGE_FACTOR;
-        index <<= TCE_PAGE_FACTOR;
-
         while (npages--) {
                 rc = HvCallXm_setTce((u64)tbl->it_index, (u64)index, 0);
                 if (rc)
@@ -136,10 +130,9 @@ void iommu_table_getparms_iSeries(unsigned long busno,
                 panic("PCI_DMA: parms->size is zero, parms is 0x%p", parms);
 
         /* itc_size is in pages worth of table, it_size is in # of entries */
-        tbl->it_size = ((parms->itc_size * TCE_PAGE_SIZE) /
-                        TCE_ENTRY_SIZE) >> TCE_PAGE_FACTOR;
+        tbl->it_size = (parms->itc_size * TCE_PAGE_SIZE) / TCE_ENTRY_SIZE;
         tbl->it_busno = parms->itc_busno;
-        tbl->it_offset = parms->itc_offset >> TCE_PAGE_FACTOR;
+        tbl->it_offset = parms->itc_offset;
         tbl->it_index = parms->itc_index;
         tbl->it_blocksize = 1;
         tbl->it_type = virtbus ? TCE_VB : TCE_PCI;
diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c
index d24ba547e53f..556c279a789d 100644
--- a/arch/powerpc/platforms/pseries/iommu.c
+++ b/arch/powerpc/platforms/pseries/iommu.c
@@ -57,9 +57,6 @@ static void tce_build_pSeries(struct iommu_table *tbl, long index,
         u64 *tcep;
         u64 rpn;
 
-        index <<= TCE_PAGE_FACTOR;
-        npages <<= TCE_PAGE_FACTOR;
-
         proto_tce = TCE_PCI_READ; // Read allowed
 
         if (direction != DMA_TO_DEVICE)
@@ -82,9 +79,6 @@ static void tce_free_pSeries(struct iommu_table *tbl, long index, long npages)
 {
         u64 *tcep;
 
-        npages <<= TCE_PAGE_FACTOR;
-        index <<= TCE_PAGE_FACTOR;
-
         tcep = ((u64 *)tbl->it_base) + index;
 
         while (npages--)
@@ -95,7 +89,6 @@ static unsigned long tce_get_pseries(struct iommu_table *tbl, long index)
 {
         u64 *tcep;
 
-        index <<= TCE_PAGE_FACTOR;
         tcep = ((u64 *)tbl->it_base) + index;
 
         return *tcep;
@@ -109,9 +102,6 @@ static void tce_build_pSeriesLP(struct iommu_table *tbl, long tcenum,
         u64 proto_tce, tce;
         u64 rpn;
 
-        tcenum <<= TCE_PAGE_FACTOR;
-        npages <<= TCE_PAGE_FACTOR;
-
         rpn = (virt_to_abs(uaddr)) >> TCE_SHIFT;
         proto_tce = TCE_PCI_READ;
         if (direction != DMA_TO_DEVICE)
@@ -146,7 +136,7 @@ static void tce_buildmulti_pSeriesLP(struct iommu_table *tbl, long tcenum,
         u64 rpn;
         long l, limit;
 
-        if (TCE_PAGE_FACTOR == 0 && npages == 1)
+        if (npages == 1)
                 return tce_build_pSeriesLP(tbl, tcenum, npages, uaddr,
                                            direction);
 
@@ -164,9 +154,6 @@ static void tce_buildmulti_pSeriesLP(struct iommu_table *tbl, long tcenum,
                 __get_cpu_var(tce_page) = tcep;
         }
 
-        tcenum <<= TCE_PAGE_FACTOR;
-        npages <<= TCE_PAGE_FACTOR;
-
         rpn = (virt_to_abs(uaddr)) >> TCE_SHIFT;
         proto_tce = TCE_PCI_READ;
         if (direction != DMA_TO_DEVICE)
@@ -207,9 +194,6 @@ static void tce_free_pSeriesLP(struct iommu_table *tbl, long tcenum, long npages
 {
         u64 rc;
 
-        tcenum <<= TCE_PAGE_FACTOR;
-        npages <<= TCE_PAGE_FACTOR;
-
         while (npages--) {
                 rc = plpar_tce_put((u64)tbl->it_index, (u64)tcenum << 12, 0);
 
@@ -229,9 +213,6 @@ static void tce_freemulti_pSeriesLP(struct iommu_table *tbl, long tcenum, long n
 {
         u64 rc;
 
-        tcenum <<= TCE_PAGE_FACTOR;
-        npages <<= TCE_PAGE_FACTOR;
-
         rc = plpar_tce_stuff((u64)tbl->it_index, (u64)tcenum << 12, 0, npages);
 
         if (rc && printk_ratelimit()) {
@@ -248,7 +229,6 @@ static unsigned long tce_get_pSeriesLP(struct iommu_table *tbl, long tcenum)
         u64 rc;
         unsigned long tce_ret;
 
-        tcenum <<= TCE_PAGE_FACTOR;
         rc = plpar_tce_get((u64)tbl->it_index, (u64)tcenum << 12, &tce_ret);
 
         if (rc && printk_ratelimit()) {
@@ -289,7 +269,7 @@ static void iommu_table_setparms(struct pci_controller *phb,
         tbl->it_busno = phb->bus->number;
 
         /* Units of tce entries */
-        tbl->it_offset = phb->dma_window_base_cur >> PAGE_SHIFT;
+        tbl->it_offset = phb->dma_window_base_cur >> IOMMU_PAGE_SHIFT;
 
         /* Test if we are going over 2GB of DMA space */
         if (phb->dma_window_base_cur + phb->dma_window_size > 0x80000000ul) {
@@ -300,7 +280,7 @@ static void iommu_table_setparms(struct pci_controller *phb,
         phb->dma_window_base_cur += phb->dma_window_size;
 
         /* Set the tce table size - measured in entries */
-        tbl->it_size = phb->dma_window_size >> PAGE_SHIFT;
+        tbl->it_size = phb->dma_window_size >> IOMMU_PAGE_SHIFT;
 
         tbl->it_index = 0;
         tbl->it_blocksize = 16;
@@ -325,8 +305,8 @@ static void iommu_table_setparms_lpar(struct pci_controller *phb,
         tbl->it_base   = 0;
         tbl->it_blocksize  = 16;
         tbl->it_type = TCE_PCI;
-        tbl->it_offset = offset >> PAGE_SHIFT;
-        tbl->it_size = size >> PAGE_SHIFT;
+        tbl->it_offset = offset >> IOMMU_PAGE_SHIFT;
+        tbl->it_size = size >> IOMMU_PAGE_SHIFT;
 }
 
 static void iommu_bus_setup_pSeries(struct pci_bus *bus)
@@ -522,8 +502,6 @@ static void iommu_dev_setup_pSeriesLP(struct pci_dev *dev)
         const void *dma_window = NULL;
         struct pci_dn *pci;
 
-        DBG("iommu_dev_setup_pSeriesLP, dev %p (%s)\n", dev, pci_name(dev));
-
         /* dev setup for LPAR is a little tricky, since the device tree might
          * contain the dma-window properties per-device and not neccesarily
          * for the bus. So we need to search upwards in the tree until we
@@ -532,6 +510,9 @@ static void iommu_dev_setup_pSeriesLP(struct pci_dev *dev)
          */
         dn = pci_device_to_OF_node(dev);
 
+        DBG("iommu_dev_setup_pSeriesLP, dev %p (%s) %s\n",
+             dev, pci_name(dev), dn->full_name);
+
         for (pdn = dn; pdn && PCI_DN(pdn) && !PCI_DN(pdn)->iommu_table;
              pdn = pdn->parent) {
                 dma_window = get_property(pdn, "ibm,dma-window", NULL);
diff --git a/arch/powerpc/sysdev/dart.h b/arch/powerpc/sysdev/dart.h
index 1c8817c4835e..ff202edb0591 100644
--- a/arch/powerpc/sysdev/dart.h
+++ b/arch/powerpc/sysdev/dart.h
@@ -72,7 +72,6 @@
 
 #define DART_PAGE_SHIFT         12
 #define DART_PAGE_SIZE          (1 << DART_PAGE_SHIFT)
-#define DART_PAGE_FACTOR        (PAGE_SHIFT - DART_PAGE_SHIFT)
 
 
 #endif /* _POWERPC_SYSDEV_DART_H */
diff --git a/arch/powerpc/sysdev/dart_iommu.c b/arch/powerpc/sysdev/dart_iommu.c
index 03b4477dd7f0..572b7846cc77 100644
--- a/arch/powerpc/sysdev/dart_iommu.c
+++ b/arch/powerpc/sysdev/dart_iommu.c
@@ -156,9 +156,6 @@ static void dart_build(struct iommu_table *tbl, long index,
 
         DBG("dart: build at: %lx, %lx, addr: %x\n", index, npages, uaddr);
 
-        index <<= DART_PAGE_FACTOR;
-        npages <<= DART_PAGE_FACTOR;
-
         dp = ((unsigned int*)tbl->it_base) + index;
 
         /* On U3, all memory is contigous, so we can move this
@@ -199,9 +196,6 @@ static void dart_free(struct iommu_table *tbl, long index, long npages)
 
         DBG("dart: free at: %lx, %lx\n", index, npages);
 
-        index <<= DART_PAGE_FACTOR;
-        npages <<= DART_PAGE_FACTOR;
-
         dp  = ((unsigned int *)tbl->it_base) + index;
 
         while (npages--)
@@ -281,7 +275,7 @@ static void iommu_table_dart_setup(void)
         iommu_table_dart.it_busno = 0;
         iommu_table_dart.it_offset = 0;
         /* it_size is in number of entries */
-        iommu_table_dart.it_size = (dart_tablesize / sizeof(u32)) >> DART_PAGE_FACTOR;
+        iommu_table_dart.it_size = dart_tablesize / sizeof(u32);
 
         /* Initialize the common IOMMU code */
         iommu_table_dart.it_base = (unsigned long)dart_vbase;