[PATCH 3/3] POWERPC: convert the IOMMU to use iova

From: FUJITA Tomonori
Date: Fri Nov 02 2007 - 13:08:42 EST

This converts the PPC64 IOMMU to use iova for free area management.

TODO: we might need to modify iova to use the tricks like avoiding
cacheline bouncing. Performance tests are necessary.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@xxxxxxxxxxxxx>
---
arch/powerpc/kernel/iommu.c | 169 ++++++--------------------------
arch/powerpc/platforms/Kconfig.cputype | 1 +
arch/powerpc/platforms/cell/iommu.c | 3 +-
arch/powerpc/sysdev/dart_iommu.c | 4 +-
include/asm-powerpc/iommu.h | 6 +-
5 files changed, 36 insertions(+), 147 deletions(-)

diff --git a/arch/powerpc/kernel/iommu.c b/arch/powerpc/kernel/iommu.c
index 2d0c9ef..34dcfd3 100644
--- a/arch/powerpc/kernel/iommu.c
+++ b/arch/powerpc/kernel/iommu.c
@@ -31,6 +31,7 @@
#include <linux/string.h>
#include <linux/dma-mapping.h>
#include <linux/bitops.h>
+#include <linux/iova.h>
#include <asm/io.h>
#include <asm/prom.h>
#include <asm/iommu.h>
@@ -82,106 +83,18 @@ __setup("protect4gb=", setup_protect4gb);
__setup("iommu=", setup_iommu);

static unsigned long iommu_range_alloc(struct iommu_table *tbl,
- unsigned long npages,
- unsigned long *handle,
- unsigned long mask,
- unsigned int align_order)
-{
- unsigned long n, end, i, start;
- unsigned long limit;
- int largealloc = npages > 15;
- int pass = 0;
- unsigned long align_mask;
-
- align_mask = 0xffffffffffffffffl >> (64 - align_order);
-
- /* This allocator was derived from x86_64's bit string search */
-
- /* Sanity check */
- if (unlikely(npages == 0)) {
- if (printk_ratelimit())
- WARN_ON(1);
- return DMA_ERROR_CODE;
- }
-
- if (handle && *handle)
- start = *handle;
- else
- start = largealloc ? tbl->it_largehint : tbl->it_hint;
-
- /* Use only half of the table for small allocs (15 pages or less) */
- limit = largealloc ? tbl->it_size : tbl->it_halfpoint;
-
- if (largealloc && start < tbl->it_halfpoint)
- start = tbl->it_halfpoint;
-
- /* The case below can happen if we have a small segment appended
- * to a large, or when the previous alloc was at the very end of
- * the available space. If so, go back to the initial start.
- */
- if (start >= limit)
- start = largealloc ? tbl->it_largehint : tbl->it_hint;
-
- again:
-
- if (limit + tbl->it_offset > mask) {
- limit = mask - tbl->it_offset + 1;
- /* If we're constrained on address range, first try
- * at the masked hint to avoid O(n) search complexity,
- * but on second pass, start at 0.
- */
- if ((start & mask) >= limit || pass > 0)
- start = 0;
- else
- start &= mask;
- }
-
- n = find_next_zero_bit(tbl->it_map, limit, start);
-
- /* Align allocation */
- n = (n + align_mask) & ~align_mask;
-
- end = n + npages;
-
- if (unlikely(end >= limit)) {
- if (likely(pass < 2)) {
- /* First failure, just rescan the half of the table.
- * Second failure, rescan the other half of the table.
- */
- start = (largealloc ^ pass) ? tbl->it_halfpoint : 0;
- limit = pass ? tbl->it_size : limit;
- pass++;
- goto again;
- } else {
- /* Third failure, give up */
- return DMA_ERROR_CODE;
- }
- }
-
- for (i = n; i < end; i++)
- if (test_bit(i, tbl->it_map)) {
- start = i+1;
- goto again;
- }
-
- for (i = n; i < end; i++)
- __set_bit(i, tbl->it_map);
-
- /* Bump the hint to a new block for small allocs. */
- if (largealloc) {
- /* Don't bump to new block to avoid fragmentation */
- tbl->it_largehint = end;
- } else {
- /* Overflow will be taken care of at the next allocation */
- tbl->it_hint = (end + tbl->it_blocksize - 1) &
- ~(tbl->it_blocksize - 1);
- }
+ unsigned long npages,
+ unsigned long mask,
+ unsigned int align_order)
+{
+ unsigned long end;
+ struct iova *iova;

- /* Update handle for SG allocations */
- if (handle)
- *handle = end;
+ end = min_t(unsigned long, DMA_32BIT_MASK >> IOMMU_PAGE_SHIFT,
+ tbl->it_size - 1);
+ iova = alloc_iova(&tbl->iovad, npages, end, 1);

- return n;
+ return iova ? iova->pfn_lo : DMA_ERROR_CODE;
}

static dma_addr_t iommu_alloc(struct iommu_table *tbl, void *page,
@@ -193,7 +106,7 @@ static dma_addr_t iommu_alloc(struct iommu_table *tbl, void *page,

spin_lock_irqsave(&(tbl->it_lock), flags);

- entry = iommu_range_alloc(tbl, npages, NULL, mask, align_order);
+ entry = iommu_range_alloc(tbl, npages, mask, align_order);

if (unlikely(entry == DMA_ERROR_CODE)) {
spin_unlock_irqrestore(&(tbl->it_lock), flags);
@@ -224,7 +137,6 @@ static void __iommu_free(struct iommu_table *tbl, dma_addr_t dma_addr,
unsigned int npages)
{
unsigned long entry, free_entry;
- unsigned long i;

entry = dma_addr >> IOMMU_PAGE_SHIFT;
free_entry = entry - tbl->it_offset;
@@ -246,9 +158,8 @@ static void __iommu_free(struct iommu_table *tbl, dma_addr_t dma_addr,
}

ppc_md.tce_free(tbl, entry, npages);
-
- for (i = 0; i < npages; i++)
- __clear_bit(free_entry+i, tbl->it_map);
+
+ free_iova(&tbl->iovad, free_entry);
}

static void iommu_free(struct iommu_table *tbl, dma_addr_t dma_addr,
@@ -309,7 +220,7 @@ int iommu_map_sg(struct iommu_table *tbl, struct scatterlist *sglist,
/* Allocate iommu entries for that segment */
vaddr = (unsigned long) sg_virt(s);
npages = iommu_num_pages(vaddr, slen);
- entry = iommu_range_alloc(tbl, npages, &handle, mask >> IOMMU_PAGE_SHIFT, 0);
+ entry = iommu_range_alloc(tbl, npages, mask >> IOMMU_PAGE_SHIFT, 0);

DBG(" - vaddr: %lx, size: %lx\n", vaddr, slen);

@@ -439,34 +350,28 @@ void iommu_unmap_sg(struct iommu_table *tbl, struct scatterlist *sglist,
spin_unlock_irqrestore(&(tbl->it_lock), flags);
}

+static struct kmem_cache *iova_cachep;
+
/*
* Build a iommu_table structure. This contains a bit map which
* is used to manage allocation of the tce space.
*/
struct iommu_table *iommu_init_table(struct iommu_table *tbl, int nid)
{
- unsigned long sz;
unsigned long start_index, end_index;
unsigned long entries_per_4g;
unsigned long index;
static int welcomed = 0;
- struct page *page;
-
- /* Set aside 1/4 of the table for large allocations. */
- tbl->it_halfpoint = tbl->it_size * 3 / 4;

- /* number of bytes needed for the bitmap */
- sz = (tbl->it_size + 7) >> 3;
-
- page = alloc_pages_node(nid, GFP_ATOMIC, get_order(sz));
- if (!page)
- panic("iommu_init_table: Can't allocate %ld bytes\n", sz);
- tbl->it_map = page_address(page);
- memset(tbl->it_map, 0, sz);
+ if (!iova_cachep) {
+ iova_cachep = KMEM_CACHE(iova, 0);
+ if (!iova_cachep)
+ return NULL;
+ }

- tbl->it_hint = 0;
- tbl->it_largehint = tbl->it_halfpoint;
spin_lock_init(&tbl->it_lock);
+ init_iova_domain(&tbl->iovad, DMA_32BIT_MASK >> IOMMU_PAGE_SHIFT,
+ iova_cachep);

#ifdef CONFIG_CRASH_DUMP
if (ppc_md.tce_get) {
@@ -482,7 +387,7 @@ struct iommu_table *iommu_init_table(struct iommu_table *tbl, int nid)
* Freed TCE entry contains 0x7fffffffffffffff on JS20
*/
if (tceval && (tceval != 0x7fffffffffffffffUL)) {
- __set_bit(index, tbl->it_map);
+ free_iova(&tbl->iovad, index);
tcecount++;
}
}
@@ -492,7 +397,7 @@ struct iommu_table *iommu_init_table(struct iommu_table *tbl, int nid)
KDUMP_MIN_TCE_ENTRIES);
for (index = tbl->it_size - KDUMP_MIN_TCE_ENTRIES;
index < tbl->it_size; index++)
- __clear_bit(index, tbl->it_map);
+ free_iova(&tbl->iovad, index);
}
}
#else
@@ -514,7 +419,7 @@ struct iommu_table *iommu_init_table(struct iommu_table *tbl, int nid)
end_index = tbl->it_size;

for (index = start_index; index < end_index - 1; index += entries_per_4g)
- __set_bit(index, tbl->it_map);
+ free_iova(&tbl->iovad, index);
}

if (!welcomed) {
@@ -530,31 +435,15 @@ void iommu_free_table(struct device_node *dn)
{
struct pci_dn *pdn = dn->data;
struct iommu_table *tbl = pdn->iommu_table;
- unsigned long bitmap_sz, i;
- unsigned int order;

- if (!tbl || !tbl->it_map) {
+ if (!tbl) {
printk(KERN_ERR "%s: expected TCE map for %s\n", __FUNCTION__,
dn->full_name);
return;
}

/* verify that table contains no entries */
- /* it_size is in entries, and we're examining 64 at a time */
- for (i = 0; i < (tbl->it_size/64); i++) {
- if (tbl->it_map[i] != 0) {
- printk(KERN_WARNING "%s: Unexpected TCEs for %s\n",
- __FUNCTION__, dn->full_name);
- break;
- }
- }
-
- /* calculate bitmap size in bytes */
- bitmap_sz = (tbl->it_size + 7) / 8;
-
- /* free bitmap */
- order = get_order(bitmap_sz);
- free_pages((unsigned long) tbl->it_map, order);
+ put_iova_domain(&tbl->iovad);

/* free table */
kfree(tbl);
diff --git a/arch/powerpc/platforms/Kconfig.cputype b/arch/powerpc/platforms/Kconfig.cputype
index 99684ea..22483e5 100644
--- a/arch/powerpc/platforms/Kconfig.cputype
+++ b/arch/powerpc/platforms/Kconfig.cputype
@@ -1,6 +1,7 @@
config PPC64
bool "64-bit kernel"
default n
+ select IOVA
help
This option selects whether a 32-bit or a 64-bit kernel
will be built.
diff --git a/arch/powerpc/platforms/cell/iommu.c b/arch/powerpc/platforms/cell/iommu.c
index faabc3f..799e8e5 100644
--- a/arch/powerpc/platforms/cell/iommu.c
+++ b/arch/powerpc/platforms/cell/iommu.c
@@ -471,10 +471,9 @@ cell_iommu_setup_window(struct cbe_iommu *iommu, struct device_node *np,
* This code also assumes that we have a window that starts at 0,
* which is the case on all spider based blades.
*/
- __set_bit(0, window->table.it_map);
+ reserve_iova(&window->table.iovad, 0, 0);
tce_build_cell(&window->table, window->table.it_offset, 1,
(unsigned long)iommu->pad_page, DMA_TO_DEVICE);
- window->table.it_hint = window->table.it_blocksize;

return window;
}
diff --git a/arch/powerpc/sysdev/dart_iommu.c b/arch/powerpc/sysdev/dart_iommu.c
index e0e24b0..6c58ef5 100644
--- a/arch/powerpc/sysdev/dart_iommu.c
+++ b/arch/powerpc/sysdev/dart_iommu.c
@@ -37,6 +37,7 @@
#include <linux/dma-mapping.h>
#include <linux/vmalloc.h>
#include <linux/suspend.h>
+#include <linux/iova.h>
#include <asm/io.h>
#include <asm/prom.h>
#include <asm/iommu.h>
@@ -287,7 +288,8 @@ static void iommu_table_dart_setup(void)
/* Reserve the last page of the DART to avoid possible prefetch
* past the DART mapped area
*/
- set_bit(iommu_table_dart.it_size - 1, iommu_table_dart.it_map);
+ reserve_iova(&iommu_table_dart.iovad, iommu_table_dart.it_size - 1,
+ iommu_table_dart.it_size - 1);
}

static void pci_dma_dev_setup_dart(struct pci_dev *dev)
diff --git a/include/asm-powerpc/iommu.h b/include/asm-powerpc/iommu.h
index 4a82fdc..f497e7e 100644
--- a/include/asm-powerpc/iommu.h
+++ b/include/asm-powerpc/iommu.h
@@ -27,6 +27,7 @@
#include <linux/device.h>
#include <linux/dma-mapping.h>
#include <linux/bitops.h>
+#include <linux/iova.h>
#include <asm/machdep.h>
#include <asm/types.h>

@@ -61,11 +62,8 @@ struct iommu_table {
unsigned long it_index; /* which iommu table this is */
unsigned long it_type; /* type: PCI or Virtual Bus */
unsigned long it_blocksize; /* Entries in each block (cacheline) */
- unsigned long it_hint; /* Hint for next alloc */
- unsigned long it_largehint; /* Hint for large allocs */
- unsigned long it_halfpoint; /* Breaking point for small/large allocs */
spinlock_t it_lock; /* Protects it_map */
- unsigned long *it_map; /* A simple allocation bitmap for now */
+ struct iova_domain iovad;
};

struct scatterlist;
--
1.5.2.4

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