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-rw-r--r--arch/powerpc/include/asm/iommu.h18
-rw-r--r--arch/powerpc/kernel/iommu.c148
-rw-r--r--arch/powerpc/platforms/cell/iommu.c1
3 files changed, 128 insertions, 39 deletions
diff --git a/arch/powerpc/include/asm/iommu.h b/arch/powerpc/include/asm/iommu.h
index 957a83f43646..cbfe678e3dbe 100644
--- a/arch/powerpc/include/asm/iommu.h
+++ b/arch/powerpc/include/asm/iommu.h
@@ -53,6 +53,16 @@ static __inline__ __attribute_const__ int get_iommu_order(unsigned long size)
*/
#define IOMAP_MAX_ORDER 13
+#define IOMMU_POOL_HASHBITS 2
+#define IOMMU_NR_POOLS (1 << IOMMU_POOL_HASHBITS)
+
+struct iommu_pool {
+ unsigned long start;
+ unsigned long end;
+ unsigned long hint;
+ spinlock_t lock;
+} ____cacheline_aligned_in_smp;
+
struct iommu_table {
unsigned long it_busno; /* Bus number this table belongs to */
unsigned long it_size; /* Size of iommu table in entries */
@@ -61,10 +71,10 @@ 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 poolsize;
+ unsigned long nr_pools;
+ struct iommu_pool large_pool;
+ struct iommu_pool pools[IOMMU_NR_POOLS];
unsigned long *it_map; /* A simple allocation bitmap for now */
};
diff --git a/arch/powerpc/kernel/iommu.c b/arch/powerpc/kernel/iommu.c
index 70a212cec587..7bc94da1a837 100644
--- a/arch/powerpc/kernel/iommu.c
+++ b/arch/powerpc/kernel/iommu.c
@@ -33,6 +33,7 @@
#include <linux/bitmap.h>
#include <linux/iommu-helper.h>
#include <linux/crash_dump.h>
+#include <linux/hash.h>
#include <asm/io.h>
#include <asm/prom.h>
#include <asm/iommu.h>
@@ -58,6 +59,26 @@ static int __init setup_iommu(char *str)
__setup("iommu=", setup_iommu);
+static DEFINE_PER_CPU(unsigned int, iommu_pool_hash);
+
+/*
+ * We precalculate the hash to avoid doing it on every allocation.
+ *
+ * The hash is important to spread CPUs across all the pools. For example,
+ * on a POWER7 with 4 way SMT we want interrupts on the primary threads and
+ * with 4 pools all primary threads would map to the same pool.
+ */
+static int __init setup_iommu_pool_hash(void)
+{
+ unsigned int i;
+
+ for_each_possible_cpu(i)
+ per_cpu(iommu_pool_hash, i) = hash_32(i, IOMMU_POOL_HASHBITS);
+
+ return 0;
+}
+subsys_initcall(setup_iommu_pool_hash);
+
static unsigned long iommu_range_alloc(struct device *dev,
struct iommu_table *tbl,
unsigned long npages,
@@ -72,6 +93,8 @@ static unsigned long iommu_range_alloc(struct device *dev,
unsigned long align_mask;
unsigned long boundary_size;
unsigned long flags;
+ unsigned int pool_nr;
+ struct iommu_pool *pool;
align_mask = 0xffffffffffffffffl >> (64 - align_order);
@@ -84,38 +107,46 @@ static unsigned long iommu_range_alloc(struct device *dev,
return DMA_ERROR_CODE;
}
- spin_lock_irqsave(&(tbl->it_lock), flags);
+ /*
+ * We don't need to disable preemption here because any CPU can
+ * safely use any IOMMU pool.
+ */
+ pool_nr = __raw_get_cpu_var(iommu_pool_hash) & (tbl->nr_pools - 1);
- if (handle && *handle)
- start = *handle;
+ if (largealloc)
+ pool = &(tbl->large_pool);
else
- start = largealloc ? tbl->it_largehint : tbl->it_hint;
+ pool = &(tbl->pools[pool_nr]);
- /* Use only half of the table for small allocs (15 pages or less) */
- limit = largealloc ? tbl->it_size : tbl->it_halfpoint;
+ spin_lock_irqsave(&(pool->lock), flags);
+
+again:
+ if ((pass == 0) && handle && *handle)
+ start = *handle;
+ else
+ start = pool->hint;
- if (largealloc && start < tbl->it_halfpoint)
- start = tbl->it_halfpoint;
+ limit = pool->end;
/* 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:
+ start = pool->start;
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.
+ * but on second pass, start at 0 in pool 0.
*/
- if ((start & mask) >= limit || pass > 0)
- start = 0;
- else
+ if ((start & mask) >= limit || pass > 0) {
+ pool = &(tbl->pools[0]);
+ start = pool->start;
+ } else {
start &= mask;
+ }
}
if (dev)
@@ -129,17 +160,25 @@ static unsigned long iommu_range_alloc(struct device *dev,
tbl->it_offset, boundary_size >> IOMMU_PAGE_SHIFT,
align_mask);
if (n == -1) {
- 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;
+ if (likely(pass == 0)) {
+ /* First try the pool from the start */
+ pool->hint = pool->start;
pass++;
goto again;
+
+ } else if (pass <= tbl->nr_pools) {
+ /* Now try scanning all the other pools */
+ spin_unlock(&(pool->lock));
+ pool_nr = (pool_nr + 1) & (tbl->nr_pools - 1);
+ pool = &tbl->pools[pool_nr];
+ spin_lock(&(pool->lock));
+ pool->hint = pool->start;
+ pass++;
+ goto again;
+
} else {
- /* Third failure, give up */
- spin_unlock_irqrestore(&(tbl->it_lock), flags);
+ /* Give up */
+ spin_unlock_irqrestore(&(pool->lock), flags);
return DMA_ERROR_CODE;
}
}
@@ -149,10 +188,10 @@ static unsigned long iommu_range_alloc(struct device *dev,
/* 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;
+ pool->hint = end;
} else {
/* Overflow will be taken care of at the next allocation */
- tbl->it_hint = (end + tbl->it_blocksize - 1) &
+ pool->hint = (end + tbl->it_blocksize - 1) &
~(tbl->it_blocksize - 1);
}
@@ -160,7 +199,8 @@ static unsigned long iommu_range_alloc(struct device *dev,
if (handle)
*handle = end;
- spin_unlock_irqrestore(&(tbl->it_lock), flags);
+ spin_unlock_irqrestore(&(pool->lock), flags);
+
return n;
}
@@ -235,23 +275,45 @@ static bool iommu_free_check(struct iommu_table *tbl, dma_addr_t dma_addr,
return true;
}
+static struct iommu_pool *get_pool(struct iommu_table *tbl,
+ unsigned long entry)
+{
+ struct iommu_pool *p;
+ unsigned long largepool_start = tbl->large_pool.start;
+
+ /* The large pool is the last pool at the top of the table */
+ if (entry >= largepool_start) {
+ p = &tbl->large_pool;
+ } else {
+ unsigned int pool_nr = entry / tbl->poolsize;
+
+ BUG_ON(pool_nr > tbl->nr_pools);
+ p = &tbl->pools[pool_nr];
+ }
+
+ return p;
+}
+
static void __iommu_free(struct iommu_table *tbl, dma_addr_t dma_addr,
unsigned int npages)
{
unsigned long entry, free_entry;
unsigned long flags;
+ struct iommu_pool *pool;
entry = dma_addr >> IOMMU_PAGE_SHIFT;
free_entry = entry - tbl->it_offset;
+ pool = get_pool(tbl, free_entry);
+
if (!iommu_free_check(tbl, dma_addr, npages))
return;
ppc_md.tce_free(tbl, entry, npages);
- spin_lock_irqsave(&(tbl->it_lock), flags);
+ spin_lock_irqsave(&(pool->lock), flags);
bitmap_clear(tbl->it_map, free_entry, npages);
- spin_unlock_irqrestore(&(tbl->it_lock), flags);
+ spin_unlock_irqrestore(&(pool->lock), flags);
}
static void iommu_free(struct iommu_table *tbl, dma_addr_t dma_addr,
@@ -493,9 +555,8 @@ struct iommu_table *iommu_init_table(struct iommu_table *tbl, int nid)
unsigned long sz;
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;
+ unsigned int i;
+ struct iommu_pool *p;
/* number of bytes needed for the bitmap */
sz = (tbl->it_size + 7) >> 3;
@@ -514,9 +575,28 @@ struct iommu_table *iommu_init_table(struct iommu_table *tbl, int nid)
if (tbl->it_offset == 0)
set_bit(0, tbl->it_map);
- tbl->it_hint = 0;
- tbl->it_largehint = tbl->it_halfpoint;
- spin_lock_init(&tbl->it_lock);
+ /* We only split the IOMMU table if we have 1GB or more of space */
+ if ((tbl->it_size << IOMMU_PAGE_SHIFT) >= (1UL * 1024 * 1024 * 1024))
+ tbl->nr_pools = IOMMU_NR_POOLS;
+ else
+ tbl->nr_pools = 1;
+
+ /* We reserve the top 1/4 of the table for large allocations */
+ tbl->poolsize = (tbl->it_size * 3 / 4) / IOMMU_NR_POOLS;
+
+ for (i = 0; i < IOMMU_NR_POOLS; i++) {
+ p = &tbl->pools[i];
+ spin_lock_init(&(p->lock));
+ p->start = tbl->poolsize * i;
+ p->hint = p->start;
+ p->end = p->start + tbl->poolsize;
+ }
+
+ p = &tbl->large_pool;
+ spin_lock_init(&(p->lock));
+ p->start = tbl->poolsize * i;
+ p->hint = p->start;
+ p->end = tbl->it_size;
iommu_table_clear(tbl);
diff --git a/arch/powerpc/platforms/cell/iommu.c b/arch/powerpc/platforms/cell/iommu.c
index b9f509a34c01..c264969c9319 100644
--- a/arch/powerpc/platforms/cell/iommu.c
+++ b/arch/powerpc/platforms/cell/iommu.c
@@ -518,7 +518,6 @@ cell_iommu_setup_window(struct cbe_iommu *iommu, struct device_node *np,
__set_bit(0, window->table.it_map);
tce_build_cell(&window->table, window->table.it_offset, 1,
(unsigned long)iommu->pad_page, DMA_TO_DEVICE, NULL);
- window->table.it_hint = window->table.it_blocksize;
return window;
}
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-28 22:32:59 +0100