[PATCH v7 0/3] Generic IOMMU pooled allocator

[PATCH v7 0/3] Generic IOMMU pooled allocator

[Sowmini Varadhan]

Changes from patchv6: moved pool_hash initialization to
lib/iommu-common.c and cleaned up code duplication from 
sun4v/sun4u/ldc. 

Sowmini (2):
  Break up monolithic iommu table/lock into finer graularity pools and
    lock
  Make sparc64 use scalable lib/iommu-common.c functions

Sowmini Varadhan (1):
  Make LDC use common iommu poll management functions

 arch/sparc/include/asm/iommu_64.h |    7 +-
 arch/sparc/kernel/iommu.c         |  174 +++++++--------------------
 arch/sparc/kernel/iommu_common.h  |    8 --
 arch/sparc/kernel/ldc.c           |  152 ++++++++++--------------
 arch/sparc/kernel/pci_sun4v.c     |  179 +++++++++++++----------------
 include/linux/iommu-common.h      |   48 ++++++++
 lib/Makefile                      |    2 +-
 lib/iommu-common.c                |  235 +++++++++++++++++++++++++++++++++++++
 8 files changed, 475 insertions(+), 330 deletions(-)
 create mode 100644 include/linux/iommu-common.h
 create mode 100644 lib/iommu-common.c

[PATCH v7 RFC 1/3] sparc: Break up monolithic iommu table/lock into finer graularity pools and lock

[Sowmini Varadhan]

Investigation of multithreaded iperf experiments on an ethernet
interface show the iommu->lock as the hottest lock identified by
lockstat, with something of the order of  21M contentions out of
27M acquisitions, and an average wait time of 26 us for the lock.
This is not efficient. A more scalable design is to follow the ppc
model, where the iommu_table has multiple pools, each stretching
over a segment of the map, and with a separate lock for each pool.
This model allows for better parallelization of the iommu map search.

This patch adds the iommu range alloc/free function infrastructure.

Signed-off-by: Sowmini Varadhan <sowmini.varadhan@oracle.com>
---
v2 changes:
  - incorporate David Miller editorial comments: sparc specific
    fields moved from iommu-common into sparc's iommu_64.h
  - make the npools value an input parameter, for the case when
    the iommu map size is not very large
  - cookie_to_index mapping, and optimizations for span-boundary
    check, for use case such as LDC.
v3: eliminate iommu_sparc, rearrange the ->demap indirection to
    be invoked under the pool lock.

v4: David Miller review changes:
  - s/IOMMU_ERROR_CODE/DMA_ERROR_CODE
  - page_table_map_base and page_table_shift are unsigned long, not u32.

v5: Feedback from benh@kernel.crashing.org and aik@ozlabs.ru
  - removed ->cookie_to_index and ->demap indirection: caller should
    invoke these as needed before calling into the generic allocator

v6: Benh/DaveM discussion eliminationg iommu_tbl_ops, but retaining flush_all
    optimization.

v7: one-time initialization of pool_hash from iommu_tbl_pool_init()

 include/linux/iommu-common.h |   48 +++++++++
 lib/Makefile                 |    2 +-
 lib/iommu-common.c           |  235 ++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 284 insertions(+), 1 deletions(-)
 create mode 100644 include/linux/iommu-common.h
 create mode 100644 lib/iommu-common.c

diff --git a/include/linux/iommu-common.h b/include/linux/iommu-common.h
new file mode 100644
index 0000000..197111b
--- /dev/null
+++ b/include/linux/iommu-common.h
@@ -0,0 +1,48 @@
+#ifndef _LINUX_IOMMU_COMMON_H
+#define _LINUX_IOMMU_COMMON_H
+
+#include <linux/spinlock_types.h>
+#include <linux/device.h>
+#include <asm/page.h>
+
+#define IOMMU_POOL_HASHBITS     4
+#define IOMMU_NR_POOLS          (1 << IOMMU_POOL_HASHBITS)
+
+struct iommu_pool {
+	unsigned long	start;
+	unsigned long	end;
+	unsigned long	hint;
+	spinlock_t	lock;
+};
+
+struct iommu_table {
+	unsigned long		page_table_map_base;
+	unsigned long		page_table_shift;
+	unsigned long		nr_pools;
+	void			(*flush_all)(struct iommu_table *);
+	unsigned long		poolsize;
+	struct iommu_pool	arena_pool[IOMMU_NR_POOLS];
+	u32			flags;
+#define	IOMMU_HAS_LARGE_POOL	0x00000001
+#define	IOMMU_NO_SPAN_BOUND	0x00000002
+	struct iommu_pool	large_pool;
+	unsigned long		*map;
+};
+
+extern void iommu_tbl_pool_init(struct iommu_table *iommu,
+				unsigned long num_entries,
+				u32 page_table_shift,
+				void (*flush_all)(struct iommu_table *),
+				bool large_pool, u32 npools,
+				bool skip_span_boundary_check);
+
+extern unsigned long iommu_tbl_range_alloc(struct device *dev,
+					   struct iommu_table *iommu,
+					   unsigned long npages,
+					   unsigned long *handle);
+
+extern void iommu_tbl_range_free(struct iommu_table *iommu,
+				 u64 dma_addr, unsigned long npages,
+				 unsigned long entry);
+
+#endif
diff --git a/lib/Makefile b/lib/Makefile
index 3c3b30b..0ea2ac6 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -102,7 +102,7 @@ obj-$(CONFIG_AUDIT_GENERIC) += audit.o
 obj-$(CONFIG_AUDIT_COMPAT_GENERIC) += compat_audit.o
 
 obj-$(CONFIG_SWIOTLB) += swiotlb.o
-obj-$(CONFIG_IOMMU_HELPER) += iommu-helper.o
+obj-$(CONFIG_IOMMU_HELPER) += iommu-helper.o iommu-common.o
 obj-$(CONFIG_FAULT_INJECTION) += fault-inject.o
 obj-$(CONFIG_NOTIFIER_ERROR_INJECTION) += notifier-error-inject.o
 obj-$(CONFIG_CPU_NOTIFIER_ERROR_INJECT) += cpu-notifier-error-inject.o
diff --git a/lib/iommu-common.c b/lib/iommu-common.c
new file mode 100644
index 0000000..bb7e706
--- /dev/null
+++ b/lib/iommu-common.c
@@ -0,0 +1,235 @@
+/*
+ * IOMMU mmap management and range allocation functions.
+ * Based almost entirely upon the powerpc iommu allocator.
+ */
+
+#include <linux/export.h>
+#include <linux/bitmap.h>
+#include <linux/bug.h>
+#include <linux/iommu-helper.h>
+#include <linux/iommu-common.h>
+#include <linux/dma-mapping.h>
+#include <linux/hash.h>
+
+#define IOMMU_LARGE_ALLOC	15
+
+static	DEFINE_PER_CPU(unsigned int, iommu_pool_hash);
+
+static void setup_iommu_pool_hash(void)
+{
+	unsigned int i;
+	static bool do_once;
+
+	if (do_once)
+		return;
+	do_once = true;
+	for_each_possible_cpu(i)
+		per_cpu(iommu_pool_hash, i) = hash_32(i, IOMMU_POOL_HASHBITS);
+}
+
+/*
+ * Initialize iommu_pool entries for the iommu_table. `num_entries'
+ * is the number of table entries. If `large_pool' is set to true,
+ * the top 1/4 of the table will be set aside for pool allocations
+ * of more than IOMMU_LARGE_ALLOC pages.
+ */
+extern void iommu_tbl_pool_init(struct iommu_table *iommu,
+				unsigned long num_entries,
+				u32 page_table_shift,
+				void (*flush_all)(struct iommu_table *),
+				bool large_pool, u32 npools,
+				bool skip_span_boundary_check)
+{
+	unsigned int start, i;
+	struct iommu_pool *p = &(iommu->large_pool);
+
+	setup_iommu_pool_hash();
+	if (npools == 0)
+		iommu->nr_pools = IOMMU_NR_POOLS;
+	else
+		iommu->nr_pools = npools;
+	BUG_ON(npools > IOMMU_NR_POOLS);
+
+	iommu->page_table_shift = page_table_shift;
+	iommu->flush_all = flush_all;
+	start = 0;
+	if (skip_span_boundary_check)
+		iommu->flags |= IOMMU_NO_SPAN_BOUND;
+	if (large_pool)
+		iommu->flags |= IOMMU_HAS_LARGE_POOL;
+
+	if (!large_pool)
+		iommu->poolsize = num_entries/iommu->nr_pools;
+	else
+		iommu->poolsize = (num_entries * 3 / 4)/iommu->nr_pools;
+	for (i = 0; i < iommu->nr_pools; i++) {
+		spin_lock_init(&(iommu->arena_pool[i].lock));
+		iommu->arena_pool[i].start = start;
+		iommu->arena_pool[i].hint = start;
+		start += iommu->poolsize; /* start for next pool */
+		iommu->arena_pool[i].end = start - 1;
+	}
+	if (!large_pool)
+		return;
+	/* initialize large_pool */
+	spin_lock_init(&(p->lock));
+	p->start = start;
+	p->hint = p->start;
+	p->end = num_entries;
+}
+EXPORT_SYMBOL(iommu_tbl_pool_init);
+
+unsigned long iommu_tbl_range_alloc(struct device *dev,
+				struct iommu_table *iommu,
+				unsigned long npages,
+				unsigned long *handle)
+{
+	unsigned int pool_hash = __this_cpu_read(iommu_pool_hash);
+	unsigned long n, end, start, limit, boundary_size;
+	struct iommu_pool *arena;
+	int pass = 0;
+	unsigned int pool_nr;
+	unsigned int npools = iommu->nr_pools;
+	unsigned long flags;
+	bool large_pool = ((iommu->flags & IOMMU_HAS_LARGE_POOL) != 0);
+	bool largealloc = (large_pool && npages > IOMMU_LARGE_ALLOC);
+	unsigned long shift;
+
+	/* Sanity check */
+	if (unlikely(npages == 0)) {
+		printk_ratelimited("npages == 0\n");
+		return DMA_ERROR_CODE;
+	}
+
+	if (largealloc) {
+		arena = &(iommu->large_pool);
+		spin_lock_irqsave(&arena->lock, flags);
+		pool_nr = 0; /* to keep compiler happy */
+	} else {
+		/* pick out pool_nr */
+		pool_nr =  pool_hash & (npools - 1);
+		arena = &(iommu->arena_pool[pool_nr]);
+
+		/* find first available unlocked pool */
+		while (!spin_trylock_irqsave(&(arena->lock), flags)) {
+			pool_nr = (pool_nr + 1) & (iommu->nr_pools - 1);
+			arena = &(iommu->arena_pool[pool_nr]);
+		}
+	}
+
+ again:
+	if (pass == 0 && handle && *handle &&
+	    (*handle >= arena->start) && (*handle < arena->end))
+		start = *handle;
+	else
+		start = arena->hint;
+
+	limit = arena->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 beginning and flush.
+	 */
+	if (start >= limit) {
+		start = arena->start;
+		if (!large_pool && iommu->flush_all != NULL)
+			iommu->flush_all(iommu);
+	}
+
+	if (dev)
+		boundary_size = ALIGN(dma_get_seg_boundary(dev) + 1,
+				      1 << iommu->page_table_shift);
+	else
+		boundary_size = ALIGN(1UL << 32, 1 << iommu->page_table_shift);
+
+	shift = iommu->page_table_map_base >> iommu->page_table_shift;
+	boundary_size = boundary_size >> iommu->page_table_shift;
+	/*
+	 * if the skip_span_boundary_check had been set during init, we set
+	 * things up so that iommu_is_span_boundary() merely checks if the
+	 * (index + npages) < num_tsb_entries
+	 */
+	if ((iommu->flags & IOMMU_NO_SPAN_BOUND) != 0) {
+		shift = 0;
+		boundary_size = iommu->poolsize * iommu->nr_pools;
+	}
+	n = iommu_area_alloc(iommu->map, limit, start, npages, shift,
+			     boundary_size, 0);
+	if (n == -1) {
+		if (likely(pass == 0)) {
+			/* First failure, rescan from the beginning.  */
+			arena->hint = arena->start;
+			if (!large_pool && iommu->flush_all != NULL)
+				iommu->flush_all(iommu);
+			pass++;
+			goto again;
+		} else if (!largealloc && pass <= iommu->nr_pools) {
+			spin_unlock(&(arena->lock));
+			pool_nr = (pool_nr + 1) & (iommu->nr_pools - 1);
+			arena = &(iommu->arena_pool[pool_nr]);
+			while (!spin_trylock(&(arena->lock))) {
+				pool_nr = (pool_nr + 1) & (iommu->nr_pools - 1);
+				arena = &(iommu->arena_pool[pool_nr]);
+			}
+			arena->hint = arena->start;
+			pass++;
+			goto again;
+		} else {
+			/* give up */
+			spin_unlock_irqrestore(&(arena->lock), flags);
+			return DMA_ERROR_CODE;
+		}
+	}
+
+	end = n + npages;
+
+	arena->hint = end;
+
+	/* Update handle for SG allocations */
+	if (handle)
+		*handle = end;
+	spin_unlock_irqrestore(&(arena->lock), flags);
+
+	return n;
+}
+EXPORT_SYMBOL(iommu_tbl_range_alloc);
+
+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;
+	bool large_pool = ((tbl->flags & IOMMU_HAS_LARGE_POOL) != 0);
+
+	/* The large pool is the last pool at the top of the table */
+	if (large_pool && entry >= largepool_start) {
+		p = &tbl->large_pool;
+	} else {
+		unsigned int pool_nr = entry / tbl->poolsize;
+
+		BUG_ON(pool_nr >= tbl->nr_pools);
+		p = &tbl->arena_pool[pool_nr];
+	}
+	return p;
+}
+
+/* Caller supplies the index of the entry into the iommu map table
+ * itself when the mapping from dma_addr to the entry is not the
+ * default addr->entry mapping below.
+ */
+void iommu_tbl_range_free(struct iommu_table *iommu, u64 dma_addr,
+			  unsigned long npages, unsigned long entry)
+{
+	struct iommu_pool *pool;
+	unsigned long flags;
+	unsigned long shift = iommu->page_table_shift;
+
+	if (entry == DMA_ERROR_CODE) /* use default addr->entry mapping */
+		entry = (dma_addr - iommu->page_table_map_base) >> shift;
+	pool = get_pool(iommu, entry);
+
+	spin_lock_irqsave(&(pool->lock), flags);
+	bitmap_clear(iommu->map, entry, npages);
+	spin_unlock_irqrestore(&(pool->lock), flags);
+}
+EXPORT_SYMBOL(iommu_tbl_range_free);
-- 
1.7.1

[PATCH v7 RFC 2/3] sparc: Make sparc64 use scalable lib/iommu-common.c functions

[Sowmini Varadhan]

In iperf experiments running linux as the Tx side (TCP client) with
10 threads results in a severe performance drop when TSO is disabled,
indicating a weakness in the software that can be avoided by using
the scalable IOMMU arena DMA allocation.

Baseline numbers before this patch:
   with default settings (TSO enabled) :    9-9.5 Gbps
   Disable TSO using ethtool- drops badly:  2-3 Gbps.

After this patch, iperf client with 10 threads, can give a
throughput of at least 8.5 Gbps, even when TSO is disabled.

Signed-off-by: Sowmini Varadhan <sowmini.varadhan@oracle.com>
---
v2: moved sparc specific fileds into iommu_sparc
v3: converted all sparc users of iommu, so lot of cleanup and streamlining
v4: David Miller review change:
    - s/IOMMU_ERROR_CODE/DMA_ERROR_CODE
    - reverts pci_impl.h (now that all iommu usage has been converted)
v5: benh/aik feedback modifies the function signatures: pass in 
    modified args to iommmu_tbl_pool_init() and iommu_tbl_range_free()
v6: removed iommu_tbl_ops. Pass flush_all as function pointer to 
    iommu_tbl_pool_init
v7: move pool_hash initialization to iommu_tbl_pool_init()

 arch/sparc/include/asm/iommu_64.h |    7 +-
 arch/sparc/kernel/iommu.c         |  174 +++++++++---------------------------
 arch/sparc/kernel/iommu_common.h  |    8 --
 arch/sparc/kernel/pci_sun4v.c     |  179 ++++++++++++++++--------------------
 4 files changed, 127 insertions(+), 241 deletions(-)

diff --git a/arch/sparc/include/asm/iommu_64.h b/arch/sparc/include/asm/iommu_64.h
index 2b9321a..e3cd449 100644
--- a/arch/sparc/include/asm/iommu_64.h
+++ b/arch/sparc/include/asm/iommu_64.h
@@ -16,6 +16,7 @@
 #define IOPTE_WRITE   0x0000000000000002UL
 
 #define IOMMU_NUM_CTXS	4096
+#include <linux/iommu-common.h>
 
 struct iommu_arena {
 	unsigned long	*map;
@@ -24,11 +25,10 @@ struct iommu_arena {
 };
 
 struct iommu {
+	struct iommu_table	tbl;
 	spinlock_t		lock;
-	struct iommu_arena	arena;
-	void			(*flush_all)(struct iommu *);
+	u32			dma_addr_mask;
 	iopte_t			*page_table;
-	u32			page_table_map_base;
 	unsigned long		iommu_control;
 	unsigned long		iommu_tsbbase;
 	unsigned long		iommu_flush;
@@ -40,7 +40,6 @@ struct iommu {
 	unsigned long		dummy_page_pa;
 	unsigned long		ctx_lowest_free;
 	DECLARE_BITMAP(ctx_bitmap, IOMMU_NUM_CTXS);
-	u32			dma_addr_mask;
 };
 
 struct strbuf {
diff --git a/arch/sparc/kernel/iommu.c b/arch/sparc/kernel/iommu.c
index bfa4d0c..f7fdff2 100644
--- a/arch/sparc/kernel/iommu.c
+++ b/arch/sparc/kernel/iommu.c
@@ -13,6 +13,7 @@
 #include <linux/errno.h>
 #include <linux/iommu-helper.h>
 #include <linux/bitmap.h>
+#include <linux/iommu-common.h>
 
 #ifdef CONFIG_PCI
 #include <linux/pci.h>
@@ -45,8 +46,9 @@
 			       "i" (ASI_PHYS_BYPASS_EC_E))
 
 /* Must be invoked under the IOMMU lock. */
-static void iommu_flushall(struct iommu *iommu)
+static void iommu_flushall(struct iommu_table *iommu_table)
 {
+	struct iommu *iommu = container_of(iommu_table, struct iommu, tbl);
 	if (iommu->iommu_flushinv) {
 		iommu_write(iommu->iommu_flushinv, ~(u64)0);
 	} else {
@@ -87,94 +89,6 @@ static inline void iopte_make_dummy(struct iommu *iommu, iopte_t *iopte)
 	iopte_val(*iopte) = val;
 }
 
-/* Based almost entirely upon the ppc64 iommu allocator.  If you use the 'handle'
- * facility it must all be done in one pass while under the iommu lock.
- *
- * On sun4u platforms, we only flush the IOMMU once every time we've passed
- * over the entire page table doing allocations.  Therefore we only ever advance
- * the hint and cannot backtrack it.
- */
-unsigned long iommu_range_alloc(struct device *dev,
-				struct iommu *iommu,
-				unsigned long npages,
-				unsigned long *handle)
-{
-	unsigned long n, end, start, limit, boundary_size;
-	struct iommu_arena *arena = &iommu->arena;
-	int pass = 0;
-
-	/* 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 = arena->hint;
-
-	limit = arena->limit;
-
-	/* 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 beginning and flush.
-	 */
-	if (start >= limit) {
-		start = 0;
-		if (iommu->flush_all)
-			iommu->flush_all(iommu);
-	}
-
- again:
-
-	if (dev)
-		boundary_size = ALIGN(dma_get_seg_boundary(dev) + 1,
-				      1 << IO_PAGE_SHIFT);
-	else
-		boundary_size = ALIGN(1UL << 32, 1 << IO_PAGE_SHIFT);
-
-	n = iommu_area_alloc(arena->map, limit, start, npages,
-			     iommu->page_table_map_base >> IO_PAGE_SHIFT,
-			     boundary_size >> IO_PAGE_SHIFT, 0);
-	if (n == -1) {
-		if (likely(pass < 1)) {
-			/* First failure, rescan from the beginning.  */
-			start = 0;
-			if (iommu->flush_all)
-				iommu->flush_all(iommu);
-			pass++;
-			goto again;
-		} else {
-			/* Second failure, give up */
-			return DMA_ERROR_CODE;
-		}
-	}
-
-	end = n + npages;
-
-	arena->hint = end;
-
-	/* Update handle for SG allocations */
-	if (handle)
-		*handle = end;
-
-	return n;
-}
-
-void iommu_range_free(struct iommu *iommu, dma_addr_t dma_addr, unsigned long npages)
-{
-	struct iommu_arena *arena = &iommu->arena;
-	unsigned long entry;
-
-	entry = (dma_addr - iommu->page_table_map_base) >> IO_PAGE_SHIFT;
-
-	bitmap_clear(arena->map, entry, npages);
-}
-
 int iommu_table_init(struct iommu *iommu, int tsbsize,
 		     u32 dma_offset, u32 dma_addr_mask,
 		     int numa_node)
@@ -187,22 +101,20 @@ int iommu_table_init(struct iommu *iommu, int tsbsize,
 	/* Setup initial software IOMMU state. */
 	spin_lock_init(&iommu->lock);
 	iommu->ctx_lowest_free = 1;
-	iommu->page_table_map_base = dma_offset;
+	iommu->tbl.page_table_map_base = dma_offset;
 	iommu->dma_addr_mask = dma_addr_mask;
 
 	/* Allocate and initialize the free area map.  */
 	sz = num_tsb_entries / 8;
 	sz = (sz + 7UL) & ~7UL;
-	iommu->arena.map = kmalloc_node(sz, GFP_KERNEL, numa_node);
-	if (!iommu->arena.map) {
-		printk(KERN_ERR "IOMMU: Error, kmalloc(arena.map) failed.\n");
+	iommu->tbl.map = kmalloc_node(sz, GFP_KERNEL, numa_node);
+	if (!iommu->tbl.map)
 		return -ENOMEM;
-	}
-	memset(iommu->arena.map, 0, sz);
-	iommu->arena.limit = num_tsb_entries;
+	memset(iommu->tbl.map, 0, sz);
 
-	if (tlb_type != hypervisor)
-		iommu->flush_all = iommu_flushall;
+	iommu_tbl_pool_init(&iommu->tbl, num_tsb_entries, IO_PAGE_SHIFT,
+			    (tlb_type != hypervisor ? iommu_flushall : NULL),
+			    false, 1, false);
 
 	/* Allocate and initialize the dummy page which we
 	 * set inactive IO PTEs to point to.
@@ -235,18 +147,19 @@ int iommu_table_init(struct iommu *iommu, int tsbsize,
 	iommu->dummy_page = 0UL;
 
 out_free_map:
-	kfree(iommu->arena.map);
-	iommu->arena.map = NULL;
+	kfree(iommu->tbl.map);
+	iommu->tbl.map = NULL;
 
 	return -ENOMEM;
 }
 
-static inline iopte_t *alloc_npages(struct device *dev, struct iommu *iommu,
+static inline iopte_t *alloc_npages(struct device *dev,
+				    struct iommu *iommu,
 				    unsigned long npages)
 {
 	unsigned long entry;
 
-	entry = iommu_range_alloc(dev, iommu, npages, NULL);
+	entry = iommu_tbl_range_alloc(dev, &iommu->tbl, npages, NULL);
 	if (unlikely(entry == DMA_ERROR_CODE))
 		return NULL;
 
@@ -284,7 +197,7 @@ static void *dma_4u_alloc_coherent(struct device *dev, size_t size,
 				   dma_addr_t *dma_addrp, gfp_t gfp,
 				   struct dma_attrs *attrs)
 {
-	unsigned long flags, order, first_page;
+	unsigned long order, first_page;
 	struct iommu *iommu;
 	struct page *page;
 	int npages, nid;
@@ -306,16 +219,14 @@ static void *dma_4u_alloc_coherent(struct device *dev, size_t size,
 
 	iommu = dev->archdata.iommu;
 
-	spin_lock_irqsave(&iommu->lock, flags);
 	iopte = alloc_npages(dev, iommu, size >> IO_PAGE_SHIFT);
-	spin_unlock_irqrestore(&iommu->lock, flags);
 
 	if (unlikely(iopte == NULL)) {
 		free_pages(first_page, order);
 		return NULL;
 	}
 
-	*dma_addrp = (iommu->page_table_map_base +
+	*dma_addrp = (iommu->tbl.page_table_map_base +
 		      ((iopte - iommu->page_table) << IO_PAGE_SHIFT));
 	ret = (void *) first_page;
 	npages = size >> IO_PAGE_SHIFT;
@@ -336,16 +247,12 @@ static void dma_4u_free_coherent(struct device *dev, size_t size,
 				 struct dma_attrs *attrs)
 {
 	struct iommu *iommu;
-	unsigned long flags, order, npages;
+	unsigned long order, npages;
 
 	npages = IO_PAGE_ALIGN(size) >> IO_PAGE_SHIFT;
 	iommu = dev->archdata.iommu;
 
-	spin_lock_irqsave(&iommu->lock, flags);
-
-	iommu_range_free(iommu, dvma, npages);
-
-	spin_unlock_irqrestore(&iommu->lock, flags);
+	iommu_tbl_range_free(&iommu->tbl, dvma, npages, DMA_ERROR_CODE);
 
 	order = get_order(size);
 	if (order < 10)
@@ -375,8 +282,8 @@ static dma_addr_t dma_4u_map_page(struct device *dev, struct page *page,
 	npages = IO_PAGE_ALIGN(oaddr + sz) - (oaddr & IO_PAGE_MASK);
 	npages >>= IO_PAGE_SHIFT;
 
-	spin_lock_irqsave(&iommu->lock, flags);
 	base = alloc_npages(dev, iommu, npages);
+	spin_lock_irqsave(&iommu->lock, flags);
 	ctx = 0;
 	if (iommu->iommu_ctxflush)
 		ctx = iommu_alloc_ctx(iommu);
@@ -385,7 +292,7 @@ static dma_addr_t dma_4u_map_page(struct device *dev, struct page *page,
 	if (unlikely(!base))
 		goto bad;
 
-	bus_addr = (iommu->page_table_map_base +
+	bus_addr = (iommu->tbl.page_table_map_base +
 		    ((base - iommu->page_table) << IO_PAGE_SHIFT));
 	ret = bus_addr | (oaddr & ~IO_PAGE_MASK);
 	base_paddr = __pa(oaddr & IO_PAGE_MASK);
@@ -496,7 +403,7 @@ static void dma_4u_unmap_page(struct device *dev, dma_addr_t bus_addr,
 	npages = IO_PAGE_ALIGN(bus_addr + sz) - (bus_addr & IO_PAGE_MASK);
 	npages >>= IO_PAGE_SHIFT;
 	base = iommu->page_table +
-		((bus_addr - iommu->page_table_map_base) >> IO_PAGE_SHIFT);
+		((bus_addr - iommu->tbl.page_table_map_base) >> IO_PAGE_SHIFT);
 	bus_addr &= IO_PAGE_MASK;
 
 	spin_lock_irqsave(&iommu->lock, flags);
@@ -515,11 +422,10 @@ static void dma_4u_unmap_page(struct device *dev, dma_addr_t bus_addr,
 	for (i = 0; i < npages; i++)
 		iopte_make_dummy(iommu, base + i);
 
-	iommu_range_free(iommu, bus_addr, npages);
-
 	iommu_free_ctx(iommu, ctx);
-
 	spin_unlock_irqrestore(&iommu->lock, flags);
+
+	iommu_tbl_range_free(&iommu->tbl, bus_addr, npages, DMA_ERROR_CODE);
 }
 
 static int dma_4u_map_sg(struct device *dev, struct scatterlist *sglist,
@@ -567,7 +473,7 @@ static int dma_4u_map_sg(struct device *dev, struct scatterlist *sglist,
 	max_seg_size = dma_get_max_seg_size(dev);
 	seg_boundary_size = ALIGN(dma_get_seg_boundary(dev) + 1,
 				  IO_PAGE_SIZE) >> IO_PAGE_SHIFT;
-	base_shift = iommu->page_table_map_base >> IO_PAGE_SHIFT;
+	base_shift = iommu->tbl.page_table_map_base >> IO_PAGE_SHIFT;
 	for_each_sg(sglist, s, nelems, i) {
 		unsigned long paddr, npages, entry, out_entry = 0, slen;
 		iopte_t *base;
@@ -581,7 +487,8 @@ static int dma_4u_map_sg(struct device *dev, struct scatterlist *sglist,
 		/* Allocate iommu entries for that segment */
 		paddr = (unsigned long) SG_ENT_PHYS_ADDRESS(s);
 		npages = iommu_num_pages(paddr, slen, IO_PAGE_SIZE);
-		entry = iommu_range_alloc(dev, iommu, npages, &handle);
+		entry = iommu_tbl_range_alloc(dev, &iommu->tbl, npages,
+					      &handle);
 
 		/* Handle failure */
 		if (unlikely(entry == DMA_ERROR_CODE)) {
@@ -594,7 +501,7 @@ static int dma_4u_map_sg(struct device *dev, struct scatterlist *sglist,
 		base = iommu->page_table + entry;
 
 		/* Convert entry to a dma_addr_t */
-		dma_addr = iommu->page_table_map_base +
+		dma_addr = iommu->tbl.page_table_map_base +
 			(entry << IO_PAGE_SHIFT);
 		dma_addr |= (s->offset & ~IO_PAGE_MASK);
 
@@ -654,15 +561,17 @@ static int dma_4u_map_sg(struct device *dev, struct scatterlist *sglist,
 			vaddr = s->dma_address & IO_PAGE_MASK;
 			npages = iommu_num_pages(s->dma_address, s->dma_length,
 						 IO_PAGE_SIZE);
-			iommu_range_free(iommu, vaddr, npages);
 
-			entry = (vaddr - iommu->page_table_map_base)
+			entry = (vaddr - iommu->tbl.page_table_map_base)
 				>> IO_PAGE_SHIFT;
 			base = iommu->page_table + entry;
 
 			for (j = 0; j < npages; j++)
 				iopte_make_dummy(iommu, base + j);
 
+			iommu_tbl_range_free(&iommu->tbl, vaddr, npages,
+					     DMA_ERROR_CODE);
+
 			s->dma_address = DMA_ERROR_CODE;
 			s->dma_length = 0;
 		}
@@ -677,17 +586,19 @@ static int dma_4u_map_sg(struct device *dev, struct scatterlist *sglist,
 /* If contexts are being used, they are the same in all of the mappings
  * we make for a particular SG.
  */
-static unsigned long fetch_sg_ctx(struct iommu *iommu, struct scatterlist *sg)
+static unsigned long fetch_sg_ctx(struct iommu *iommu,
+				  struct scatterlist *sg)
 {
 	unsigned long ctx = 0;
 
 	if (iommu->iommu_ctxflush) {
 		iopte_t *base;
 		u32 bus_addr;
+		struct iommu_table *tbl = &iommu->tbl;
 
 		bus_addr = sg->dma_address & IO_PAGE_MASK;
 		base = iommu->page_table +
-			((bus_addr - iommu->page_table_map_base) >> IO_PAGE_SHIFT);
+		       ((bus_addr - tbl->page_table_map_base) >> IO_PAGE_SHIFT);
 
 		ctx = (iopte_val(*base) & IOPTE_CONTEXT) >> 47UL;
 	}
@@ -723,9 +634,8 @@ static void dma_4u_unmap_sg(struct device *dev, struct scatterlist *sglist,
 		if (!len)
 			break;
 		npages = iommu_num_pages(dma_handle, len, IO_PAGE_SIZE);
-		iommu_range_free(iommu, dma_handle, npages);
 
-		entry = ((dma_handle - iommu->page_table_map_base)
+		entry = ((dma_handle - iommu->tbl.page_table_map_base)
 			 >> IO_PAGE_SHIFT);
 		base = iommu->page_table + entry;
 
@@ -737,6 +647,8 @@ static void dma_4u_unmap_sg(struct device *dev, struct scatterlist *sglist,
 		for (i = 0; i < npages; i++)
 			iopte_make_dummy(iommu, base + i);
 
+		iommu_tbl_range_free(&iommu->tbl, dma_handle, npages,
+				     DMA_ERROR_CODE);
 		sg = sg_next(sg);
 	}
 
@@ -770,9 +682,10 @@ static void dma_4u_sync_single_for_cpu(struct device *dev,
 	if (iommu->iommu_ctxflush &&
 	    strbuf->strbuf_ctxflush) {
 		iopte_t *iopte;
+		struct iommu_table *tbl = &iommu->tbl;
 
 		iopte = iommu->page_table +
-			((bus_addr - iommu->page_table_map_base)>>IO_PAGE_SHIFT);
+			((bus_addr - tbl->page_table_map_base)>>IO_PAGE_SHIFT);
 		ctx = (iopte_val(*iopte) & IOPTE_CONTEXT) >> 47UL;
 	}
 
@@ -805,9 +718,10 @@ static void dma_4u_sync_sg_for_cpu(struct device *dev,
 	if (iommu->iommu_ctxflush &&
 	    strbuf->strbuf_ctxflush) {
 		iopte_t *iopte;
+		struct iommu_table *tbl = &iommu->tbl;
 
-		iopte = iommu->page_table +
-			((sglist[0].dma_address - iommu->page_table_map_base) >> IO_PAGE_SHIFT);
+		iopte = iommu->page_table + ((sglist[0].dma_address -
+			tbl->page_table_map_base) >> IO_PAGE_SHIFT);
 		ctx = (iopte_val(*iopte) & IOPTE_CONTEXT) >> 47UL;
 	}
 
diff --git a/arch/sparc/kernel/iommu_common.h b/arch/sparc/kernel/iommu_common.h
index 1ec0de4..f4be0d7 100644
--- a/arch/sparc/kernel/iommu_common.h
+++ b/arch/sparc/kernel/iommu_common.h
@@ -48,12 +48,4 @@ static inline int is_span_boundary(unsigned long entry,
 	return iommu_is_span_boundary(entry, nr, shift, boundary_size);
 }
 
-unsigned long iommu_range_alloc(struct device *dev,
-				struct iommu *iommu,
-				unsigned long npages,
-				unsigned long *handle);
-void iommu_range_free(struct iommu *iommu,
-		      dma_addr_t dma_addr,
-		      unsigned long npages);
-
 #endif /* _IOMMU_COMMON_H */
diff --git a/arch/sparc/kernel/pci_sun4v.c b/arch/sparc/kernel/pci_sun4v.c
index 49d33b1..be45e8b 100644
--- a/arch/sparc/kernel/pci_sun4v.c
+++ b/arch/sparc/kernel/pci_sun4v.c
@@ -15,6 +15,7 @@
 #include <linux/export.h>
 #include <linux/log2.h>
 #include <linux/of_device.h>
+#include <linux/iommu-common.h>
 
 #include <asm/iommu.h>
 #include <asm/irq.h>
@@ -155,14 +156,12 @@ static void *dma_4v_alloc_coherent(struct device *dev, size_t size,
 
 	iommu = dev->archdata.iommu;
 
-	spin_lock_irqsave(&iommu->lock, flags);
-	entry = iommu_range_alloc(dev, iommu, npages, NULL);
-	spin_unlock_irqrestore(&iommu->lock, flags);
+	entry = iommu_tbl_range_alloc(dev, &iommu->tbl, npages, NULL);
 
 	if (unlikely(entry == DMA_ERROR_CODE))
 		goto range_alloc_fail;
 
-	*dma_addrp = (iommu->page_table_map_base +
+	*dma_addrp = (iommu->tbl.page_table_map_base +
 		      (entry << IO_PAGE_SHIFT));
 	ret = (void *) first_page;
 	first_page = __pa(first_page);
@@ -188,45 +187,46 @@ static void *dma_4v_alloc_coherent(struct device *dev, size_t size,
 	return ret;
 
 iommu_map_fail:
-	/* Interrupts are disabled.  */
-	spin_lock(&iommu->lock);
-	iommu_range_free(iommu, *dma_addrp, npages);
-	spin_unlock_irqrestore(&iommu->lock, flags);
+	iommu_tbl_range_free(&iommu->tbl, *dma_addrp, npages, DMA_ERROR_CODE);
 
 range_alloc_fail:
 	free_pages(first_page, order);
 	return NULL;
 }
 
+static void dma_4v_iommu_demap(void *demap_arg, unsigned long entry,
+			       unsigned long npages)
+{
+	u32 devhandle = *(u32 *)demap_arg;
+	unsigned long num, flags;
+
+	local_irq_save(flags);
+	do {
+		num = pci_sun4v_iommu_demap(devhandle,
+					    HV_PCI_TSBID(0, entry),
+					    npages);
+
+		entry += num;
+		npages -= num;
+	} while (npages != 0);
+	local_irq_restore(flags);
+}
+
 static void dma_4v_free_coherent(struct device *dev, size_t size, void *cpu,
 				 dma_addr_t dvma, struct dma_attrs *attrs)
 {
 	struct pci_pbm_info *pbm;
 	struct iommu *iommu;
-	unsigned long flags, order, npages, entry;
+	unsigned long order, npages, entry;
 	u32 devhandle;
 
 	npages = IO_PAGE_ALIGN(size) >> IO_PAGE_SHIFT;
 	iommu = dev->archdata.iommu;
 	pbm = dev->archdata.host_controller;
 	devhandle = pbm->devhandle;
-	entry = ((dvma - iommu->page_table_map_base) >> IO_PAGE_SHIFT);
-
-	spin_lock_irqsave(&iommu->lock, flags);
-
-	iommu_range_free(iommu, dvma, npages);
-
-	do {
-		unsigned long num;
-
-		num = pci_sun4v_iommu_demap(devhandle, HV_PCI_TSBID(0, entry),
-					    npages);
-		entry += num;
-		npages -= num;
-	} while (npages != 0);
-
-	spin_unlock_irqrestore(&iommu->lock, flags);
-
+	entry = ((dvma - iommu->tbl.page_table_map_base) >> IO_PAGE_SHIFT);
+	dma_4v_iommu_demap(&devhandle, entry, npages);
+	iommu_tbl_range_free(&iommu->tbl, dvma, npages, DMA_ERROR_CODE);
 	order = get_order(size);
 	if (order < 10)
 		free_pages((unsigned long)cpu, order);
@@ -253,14 +253,12 @@ static dma_addr_t dma_4v_map_page(struct device *dev, struct page *page,
 	npages = IO_PAGE_ALIGN(oaddr + sz) - (oaddr & IO_PAGE_MASK);
 	npages >>= IO_PAGE_SHIFT;
 
-	spin_lock_irqsave(&iommu->lock, flags);
-	entry = iommu_range_alloc(dev, iommu, npages, NULL);
-	spin_unlock_irqrestore(&iommu->lock, flags);
+	entry = iommu_tbl_range_alloc(dev, &iommu->tbl, npages, NULL);
 
 	if (unlikely(entry == DMA_ERROR_CODE))
 		goto bad;
 
-	bus_addr = (iommu->page_table_map_base +
+	bus_addr = (iommu->tbl.page_table_map_base +
 		    (entry << IO_PAGE_SHIFT));
 	ret = bus_addr | (oaddr & ~IO_PAGE_MASK);
 	base_paddr = __pa(oaddr & IO_PAGE_MASK);
@@ -290,11 +288,7 @@ static dma_addr_t dma_4v_map_page(struct device *dev, struct page *page,
 	return DMA_ERROR_CODE;
 
 iommu_map_fail:
-	/* Interrupts are disabled.  */
-	spin_lock(&iommu->lock);
-	iommu_range_free(iommu, bus_addr, npages);
-	spin_unlock_irqrestore(&iommu->lock, flags);
-
+	iommu_tbl_range_free(&iommu->tbl, bus_addr, npages, DMA_ERROR_CODE);
 	return DMA_ERROR_CODE;
 }
 
@@ -304,7 +298,7 @@ static void dma_4v_unmap_page(struct device *dev, dma_addr_t bus_addr,
 {
 	struct pci_pbm_info *pbm;
 	struct iommu *iommu;
-	unsigned long flags, npages;
+	unsigned long npages;
 	long entry;
 	u32 devhandle;
 
@@ -321,22 +315,9 @@ static void dma_4v_unmap_page(struct device *dev, dma_addr_t bus_addr,
 	npages = IO_PAGE_ALIGN(bus_addr + sz) - (bus_addr & IO_PAGE_MASK);
 	npages >>= IO_PAGE_SHIFT;
 	bus_addr &= IO_PAGE_MASK;
-
-	spin_lock_irqsave(&iommu->lock, flags);
-
-	iommu_range_free(iommu, bus_addr, npages);
-
-	entry = (bus_addr - iommu->page_table_map_base) >> IO_PAGE_SHIFT;
-	do {
-		unsigned long num;
-
-		num = pci_sun4v_iommu_demap(devhandle, HV_PCI_TSBID(0, entry),
-					    npages);
-		entry += num;
-		npages -= num;
-	} while (npages != 0);
-
-	spin_unlock_irqrestore(&iommu->lock, flags);
+	entry = (bus_addr - iommu->tbl.page_table_map_base) >> IO_PAGE_SHIFT;
+	dma_4v_iommu_demap(&devhandle, entry, npages);
+	iommu_tbl_range_free(&iommu->tbl, bus_addr, npages, DMA_ERROR_CODE);
 }
 
 static int dma_4v_map_sg(struct device *dev, struct scatterlist *sglist,
@@ -371,14 +352,14 @@ static int dma_4v_map_sg(struct device *dev, struct scatterlist *sglist,
 	/* Init first segment length for backout at failure */
 	outs->dma_length = 0;
 
-	spin_lock_irqsave(&iommu->lock, flags);
+	local_irq_save(flags);
 
 	iommu_batch_start(dev, prot, ~0UL);
 
 	max_seg_size = dma_get_max_seg_size(dev);
 	seg_boundary_size = ALIGN(dma_get_seg_boundary(dev) + 1,
 				  IO_PAGE_SIZE) >> IO_PAGE_SHIFT;
-	base_shift = iommu->page_table_map_base >> IO_PAGE_SHIFT;
+	base_shift = iommu->tbl.page_table_map_base >> IO_PAGE_SHIFT;
 	for_each_sg(sglist, s, nelems, i) {
 		unsigned long paddr, npages, entry, out_entry = 0, slen;
 
@@ -391,7 +372,8 @@ static int dma_4v_map_sg(struct device *dev, struct scatterlist *sglist,
 		/* Allocate iommu entries for that segment */
 		paddr = (unsigned long) SG_ENT_PHYS_ADDRESS(s);
 		npages = iommu_num_pages(paddr, slen, IO_PAGE_SIZE);
-		entry = iommu_range_alloc(dev, iommu, npages, &handle);
+		entry = iommu_tbl_range_alloc(dev, &iommu->tbl, npages,
+					      &handle);
 
 		/* Handle failure */
 		if (unlikely(entry == DMA_ERROR_CODE)) {
@@ -404,7 +386,7 @@ static int dma_4v_map_sg(struct device *dev, struct scatterlist *sglist,
 		iommu_batch_new_entry(entry);
 
 		/* Convert entry to a dma_addr_t */
-		dma_addr = iommu->page_table_map_base +
+		dma_addr = iommu->tbl.page_table_map_base +
 			(entry << IO_PAGE_SHIFT);
 		dma_addr |= (s->offset & ~IO_PAGE_MASK);
 
@@ -451,7 +433,7 @@ static int dma_4v_map_sg(struct device *dev, struct scatterlist *sglist,
 	if (unlikely(err < 0L))
 		goto iommu_map_failed;
 
-	spin_unlock_irqrestore(&iommu->lock, flags);
+	local_irq_restore(flags);
 
 	if (outcount < incount) {
 		outs = sg_next(outs);
@@ -469,7 +451,8 @@ static int dma_4v_map_sg(struct device *dev, struct scatterlist *sglist,
 			vaddr = s->dma_address & IO_PAGE_MASK;
 			npages = iommu_num_pages(s->dma_address, s->dma_length,
 						 IO_PAGE_SIZE);
-			iommu_range_free(iommu, vaddr, npages);
+			iommu_tbl_range_free(&iommu->tbl, vaddr, npages,
+					     DMA_ERROR_CODE);
 			/* XXX demap? XXX */
 			s->dma_address = DMA_ERROR_CODE;
 			s->dma_length = 0;
@@ -477,7 +460,7 @@ static int dma_4v_map_sg(struct device *dev, struct scatterlist *sglist,
 		if (s == outs)
 			break;
 	}
-	spin_unlock_irqrestore(&iommu->lock, flags);
+	local_irq_restore(flags);
 
 	return 0;
 }
@@ -489,7 +472,7 @@ static void dma_4v_unmap_sg(struct device *dev, struct scatterlist *sglist,
 	struct pci_pbm_info *pbm;
 	struct scatterlist *sg;
 	struct iommu *iommu;
-	unsigned long flags;
+	unsigned long flags, entry;
 	u32 devhandle;
 
 	BUG_ON(direction == DMA_NONE);
@@ -498,33 +481,27 @@ static void dma_4v_unmap_sg(struct device *dev, struct scatterlist *sglist,
 	pbm = dev->archdata.host_controller;
 	devhandle = pbm->devhandle;
 	
-	spin_lock_irqsave(&iommu->lock, flags);
+	local_irq_save(flags);
 
 	sg = sglist;
 	while (nelems--) {
 		dma_addr_t dma_handle = sg->dma_address;
 		unsigned int len = sg->dma_length;
-		unsigned long npages, entry;
+		unsigned long npages;
+		struct iommu_table *tbl = &iommu->tbl;
+		unsigned long shift = IO_PAGE_SHIFT;
 
 		if (!len)
 			break;
 		npages = iommu_num_pages(dma_handle, len, IO_PAGE_SIZE);
-		iommu_range_free(iommu, dma_handle, npages);
-
-		entry = ((dma_handle - iommu->page_table_map_base) >> IO_PAGE_SHIFT);
-		while (npages) {
-			unsigned long num;
-
-			num = pci_sun4v_iommu_demap(devhandle, HV_PCI_TSBID(0, entry),
-						    npages);
-			entry += num;
-			npages -= num;
-		}
-
+		entry = ((dma_handle - tbl->page_table_map_base) >> shift);
+		dma_4v_iommu_demap(&devhandle, entry, npages);
+		iommu_tbl_range_free(&iommu->tbl, dma_handle, npages,
+				     DMA_ERROR_CODE);
 		sg = sg_next(sg);
 	}
 
-	spin_unlock_irqrestore(&iommu->lock, flags);
+	local_irq_restore(flags);
 }
 
 static struct dma_map_ops sun4v_dma_ops = {
@@ -550,30 +527,33 @@ static void pci_sun4v_scan_bus(struct pci_pbm_info *pbm, struct device *parent)
 }
 
 static unsigned long probe_existing_entries(struct pci_pbm_info *pbm,
-					    struct iommu *iommu)
+					    struct iommu_table *iommu)
 {
-	struct iommu_arena *arena = &iommu->arena;
-	unsigned long i, cnt = 0;
+	struct iommu_pool *pool;
+	unsigned long i, pool_nr, cnt = 0;
 	u32 devhandle;
 
 	devhandle = pbm->devhandle;
-	for (i = 0; i < arena->limit; i++) {
-		unsigned long ret, io_attrs, ra;
-
-		ret = pci_sun4v_iommu_getmap(devhandle,
-					     HV_PCI_TSBID(0, i),
-					     &io_attrs, &ra);
-		if (ret == HV_EOK) {
-			if (page_in_phys_avail(ra)) {
-				pci_sun4v_iommu_demap(devhandle,
-						      HV_PCI_TSBID(0, i), 1);
-			} else {
-				cnt++;
-				__set_bit(i, arena->map);
+	for (pool_nr = 0; pool_nr < iommu->nr_pools; pool_nr++) {
+		pool = &(iommu->arena_pool[pool_nr]);
+		for (i = pool->start; i <= pool->end; i++) {
+			unsigned long ret, io_attrs, ra;
+
+			ret = pci_sun4v_iommu_getmap(devhandle,
+						     HV_PCI_TSBID(0, i),
+						     &io_attrs, &ra);
+			if (ret == HV_EOK) {
+				if (page_in_phys_avail(ra)) {
+					pci_sun4v_iommu_demap(devhandle,
+							      HV_PCI_TSBID(0,
+							      i), 1);
+				} else {
+					cnt++;
+					__set_bit(i, iommu->map);
+				}
 			}
 		}
 	}
-
 	return cnt;
 }
 
@@ -601,22 +581,23 @@ static int pci_sun4v_iommu_init(struct pci_pbm_info *pbm)
 	dma_offset = vdma[0];
 
 	/* Setup initial software IOMMU state. */
-	spin_lock_init(&iommu->lock);
 	iommu->ctx_lowest_free = 1;
-	iommu->page_table_map_base = dma_offset;
+	iommu->tbl.page_table_map_base = dma_offset;
 	iommu->dma_addr_mask = dma_mask;
 
 	/* Allocate and initialize the free area map.  */
 	sz = (num_tsb_entries + 7) / 8;
 	sz = (sz + 7UL) & ~7UL;
-	iommu->arena.map = kzalloc(sz, GFP_KERNEL);
-	if (!iommu->arena.map) {
+	iommu->tbl.map = kzalloc(sz, GFP_KERNEL);
+	if (!iommu->tbl.map) {
 		printk(KERN_ERR PFX "Error, kmalloc(arena.map) failed.\n");
 		return -ENOMEM;
 	}
-	iommu->arena.limit = num_tsb_entries;
-
-	sz = probe_existing_entries(pbm, iommu);
+	iommu_tbl_pool_init(&iommu->tbl, num_tsb_entries, IO_PAGE_SHIFT,
+			    NULL, false /* no large_pool */,
+			    0 /* default npools */,
+			    false /* want span boundary checking */);
+	sz = probe_existing_entries(pbm, &iommu->tbl);
 	if (sz)
 		printk("%s: Imported %lu TSB entries from OBP\n",
 		       pbm->name, sz);
-- 
1.7.1

[PATCH v7 RFC 3/3] sparc: Make LDC use common iommu poll management functions

[Sowmini Varadhan]

Note that this conversion is only being done to consolidate the
code and ensure that the common code provides the sufficient
abstraction. It is not expected to result in any noticeable
performance improvement, as there is typically one ldc_iommu
per vnet_port, and each one has 8k entries, with a typical
request for 1-4 pages.  Thus LDC uses npools == 1.

Signed-off-by: Sowmini Varadhan <sowmini.varadhan@oracle.com>
---
v3: added this file to be a consumer of the common iommu library
v4: removed ->cookie_to_index and ->demap from iommu_tbl_ops and instead
    inline these calls into ldc before calling into iommu-common
v6: remove iommu_tbl_ops
v7: move pool_hash initialization to iommu_tbl_pool_init

 arch/sparc/kernel/ldc.c |  152 ++++++++++++++++++++---------------------------
 1 files changed, 64 insertions(+), 88 deletions(-)

diff --git a/arch/sparc/kernel/ldc.c b/arch/sparc/kernel/ldc.c
index 274a9f5..e858968 100644
--- a/arch/sparc/kernel/ldc.c
+++ b/arch/sparc/kernel/ldc.c
@@ -15,6 +15,7 @@
 #include <linux/list.h>
 #include <linux/init.h>
 #include <linux/bitmap.h>
+#include <linux/iommu-common.h>
 
 #include <asm/hypervisor.h>
 #include <asm/iommu.h>
@@ -27,6 +28,10 @@
 #define DRV_MODULE_VERSION	"1.1"
 #define DRV_MODULE_RELDATE	"July 22, 2008"
 
+#define COOKIE_PGSZ_CODE	0xf000000000000000ULL
+#define COOKIE_PGSZ_CODE_SHIFT	60ULL
+
+
 static char version[] =
 	DRV_MODULE_NAME ".c:v" DRV_MODULE_VERSION " (" DRV_MODULE_RELDATE ")\n";
 #define LDC_PACKET_SIZE		64
@@ -98,10 +103,10 @@ static const struct ldc_mode_ops stream_ops;
 int ldom_domaining_enabled;
 
 struct ldc_iommu {
-	/* Protects arena alloc/free.  */
+	/* Protects ldc_unmap.  */
 	spinlock_t			lock;
-	struct iommu_arena		arena;
 	struct ldc_mtable_entry		*page_table;
+	struct iommu_table		iommu_table;
 };
 
 struct ldc_channel {
@@ -998,31 +1003,59 @@ static void free_queue(unsigned long num_entries, struct ldc_packet *q)
 	free_pages((unsigned long)q, order);
 }
 
+static unsigned long ldc_cookie_to_index(u64 cookie, void *arg)
+{
+	u64 szcode = cookie >> COOKIE_PGSZ_CODE_SHIFT;
+	/* struct ldc_iommu *ldc_iommu = (struct ldc_iommu *)arg; */
+
+	cookie &= ~COOKIE_PGSZ_CODE;
+
+	return (cookie >> (13ULL + (szcode * 3ULL)));
+}
+
+static void ldc_demap(struct ldc_iommu *iommu, unsigned long id, u64 cookie,
+		      unsigned long entry, unsigned long npages)
+{
+	struct ldc_mtable_entry *base;
+	unsigned long i, shift;
+
+	shift = (cookie >> COOKIE_PGSZ_CODE_SHIFT) * 3;
+	base = iommu->page_table + entry;
+	for (i = 0; i < npages; i++) {
+		if (base->cookie)
+			sun4v_ldc_revoke(id, cookie + (i << shift),
+					 base->cookie);
+		base->mte = 0;
+	}
+}
+
 /* XXX Make this configurable... XXX */
 #define LDC_IOTABLE_SIZE	(8 * 1024)
 
-static int ldc_iommu_init(struct ldc_channel *lp)
+static int ldc_iommu_init(const char *name, struct ldc_channel *lp)
 {
 	unsigned long sz, num_tsb_entries, tsbsize, order;
-	struct ldc_iommu *iommu = &lp->iommu;
+	struct ldc_iommu *ldc_iommu = &lp->iommu;
+	struct iommu_table *iommu = &ldc_iommu->iommu_table;
 	struct ldc_mtable_entry *table;
 	unsigned long hv_err;
 	int err;
 
 	num_tsb_entries = LDC_IOTABLE_SIZE;
 	tsbsize = num_tsb_entries * sizeof(struct ldc_mtable_entry);
-
-	spin_lock_init(&iommu->lock);
+	spin_lock_init(&ldc_iommu->lock);
 
 	sz = num_tsb_entries / 8;
 	sz = (sz + 7UL) & ~7UL;
-	iommu->arena.map = kzalloc(sz, GFP_KERNEL);
-	if (!iommu->arena.map) {
+	iommu->map = kzalloc(sz, GFP_KERNEL);
+	if (!iommu->map) {
 		printk(KERN_ERR PFX "Alloc of arena map failed, sz=%lu\n", sz);
 		return -ENOMEM;
 	}
-
-	iommu->arena.limit = num_tsb_entries;
+	iommu_tbl_pool_init(iommu, num_tsb_entries, PAGE_SHIFT,
+			    NULL, false /* no large pool */,
+			    1 /* npools */,
+			    true /* skip span boundary check */);
 
 	order = get_order(tsbsize);
 
@@ -1037,7 +1070,7 @@ static int ldc_iommu_init(struct ldc_channel *lp)
 
 	memset(table, 0, PAGE_SIZE << order);
 
-	iommu->page_table = table;
+	ldc_iommu->page_table = table;
 
 	hv_err = sun4v_ldc_set_map_table(lp->id, __pa(table),
 					 num_tsb_entries);
@@ -1049,31 +1082,32 @@ static int ldc_iommu_init(struct ldc_channel *lp)
 
 out_free_table:
 	free_pages((unsigned long) table, order);
-	iommu->page_table = NULL;
+	ldc_iommu->page_table = NULL;
 
 out_free_map:
-	kfree(iommu->arena.map);
-	iommu->arena.map = NULL;
+	kfree(iommu->map);
+	iommu->map = NULL;
 
 	return err;
 }
 
 static void ldc_iommu_release(struct ldc_channel *lp)
 {
-	struct ldc_iommu *iommu = &lp->iommu;
+	struct ldc_iommu *ldc_iommu = &lp->iommu;
+	struct iommu_table *iommu = &ldc_iommu->iommu_table;
 	unsigned long num_tsb_entries, tsbsize, order;
 
 	(void) sun4v_ldc_set_map_table(lp->id, 0, 0);
 
-	num_tsb_entries = iommu->arena.limit;
+	num_tsb_entries = iommu->poolsize * iommu->nr_pools;
 	tsbsize = num_tsb_entries * sizeof(struct ldc_mtable_entry);
 	order = get_order(tsbsize);
 
-	free_pages((unsigned long) iommu->page_table, order);
-	iommu->page_table = NULL;
+	free_pages((unsigned long) ldc_iommu->page_table, order);
+	ldc_iommu->page_table = NULL;
 
-	kfree(iommu->arena.map);
-	iommu->arena.map = NULL;
+	kfree(iommu->map);
+	iommu->map = NULL;
 }
 
 struct ldc_channel *ldc_alloc(unsigned long id,
@@ -1140,7 +1174,7 @@ struct ldc_channel *ldc_alloc(unsigned long id,
 
 	lp->id = id;
 
-	err = ldc_iommu_init(lp);
+	err = ldc_iommu_init(name, lp);
 	if (err)
 		goto out_free_ldc;
 
@@ -1885,40 +1919,6 @@ int ldc_read(struct ldc_channel *lp, void *buf, unsigned int size)
 }
 EXPORT_SYMBOL(ldc_read);
 
-static long arena_alloc(struct ldc_iommu *iommu, unsigned long npages)
-{
-	struct iommu_arena *arena = &iommu->arena;
-	unsigned long n, start, end, limit;
-	int pass;
-
-	limit = arena->limit;
-	start = arena->hint;
-	pass = 0;
-
-again:
-	n = bitmap_find_next_zero_area(arena->map, limit, start, npages, 0);
-	end = n + npages;
-	if (unlikely(end >= limit)) {
-		if (likely(pass < 1)) {
-			limit = start;
-			start = 0;
-			pass++;
-			goto again;
-		} else {
-			/* Scanned the whole thing, give up. */
-			return -1;
-		}
-	}
-	bitmap_set(arena->map, n, npages);
-
-	arena->hint = end;
-
-	return n;
-}
-
-#define COOKIE_PGSZ_CODE	0xf000000000000000ULL
-#define COOKIE_PGSZ_CODE_SHIFT	60ULL
-
 static u64 pagesize_code(void)
 {
 	switch (PAGE_SIZE) {
@@ -1945,23 +1945,13 @@ static u64 make_cookie(u64 index, u64 pgsz_code, u64 page_offset)
 		page_offset);
 }
 
-static u64 cookie_to_index(u64 cookie, unsigned long *shift)
-{
-	u64 szcode = cookie >> COOKIE_PGSZ_CODE_SHIFT;
-
-	cookie &= ~COOKIE_PGSZ_CODE;
-
-	*shift = szcode * 3;
-
-	return (cookie >> (13ULL + (szcode * 3ULL)));
-}
 
 static struct ldc_mtable_entry *alloc_npages(struct ldc_iommu *iommu,
 					     unsigned long npages)
 {
 	long entry;
 
-	entry = arena_alloc(iommu, npages);
+	entry = iommu_tbl_range_alloc(NULL, &iommu->iommu_table, npages, NULL);
 	if (unlikely(entry < 0))
 		return NULL;
 
@@ -2090,7 +2080,7 @@ int ldc_map_sg(struct ldc_channel *lp,
 	       struct ldc_trans_cookie *cookies, int ncookies,
 	       unsigned int map_perm)
 {
-	unsigned long i, npages, flags;
+	unsigned long i, npages;
 	struct ldc_mtable_entry *base;
 	struct cookie_state state;
 	struct ldc_iommu *iommu;
@@ -2109,9 +2099,7 @@ int ldc_map_sg(struct ldc_channel *lp,
 
 	iommu = &lp->iommu;
 
-	spin_lock_irqsave(&iommu->lock, flags);
 	base = alloc_npages(iommu, npages);
-	spin_unlock_irqrestore(&iommu->lock, flags);
 
 	if (!base)
 		return -ENOMEM;
@@ -2136,7 +2124,7 @@ int ldc_map_single(struct ldc_channel *lp,
 		   struct ldc_trans_cookie *cookies, int ncookies,
 		   unsigned int map_perm)
 {
-	unsigned long npages, pa, flags;
+	unsigned long npages, pa;
 	struct ldc_mtable_entry *base;
 	struct cookie_state state;
 	struct ldc_iommu *iommu;
@@ -2152,9 +2140,7 @@ int ldc_map_single(struct ldc_channel *lp,
 
 	iommu = &lp->iommu;
 
-	spin_lock_irqsave(&iommu->lock, flags);
 	base = alloc_npages(iommu, npages);
-	spin_unlock_irqrestore(&iommu->lock, flags);
 
 	if (!base)
 		return -ENOMEM;
@@ -2172,35 +2158,25 @@ int ldc_map_single(struct ldc_channel *lp,
 }
 EXPORT_SYMBOL(ldc_map_single);
 
+
 static void free_npages(unsigned long id, struct ldc_iommu *iommu,
 			u64 cookie, u64 size)
 {
-	struct iommu_arena *arena = &iommu->arena;
-	unsigned long i, shift, index, npages;
-	struct ldc_mtable_entry *base;
+	unsigned long npages, entry;
 
 	npages = PAGE_ALIGN(((cookie & ~PAGE_MASK) + size)) >> PAGE_SHIFT;
-	index = cookie_to_index(cookie, &shift);
-	base = iommu->page_table + index;
 
-	BUG_ON(index > arena->limit ||
-	       (index + npages) > arena->limit);
-
-	for (i = 0; i < npages; i++) {
-		if (base->cookie)
-			sun4v_ldc_revoke(id, cookie + (i << shift),
-					 base->cookie);
-		base->mte = 0;
-		__clear_bit(index + i, arena->map);
-	}
+	entry = ldc_cookie_to_index(cookie, iommu);
+	ldc_demap(iommu, id, cookie, entry, npages);
+	iommu_tbl_range_free(&iommu->iommu_table, cookie, npages, entry);
 }
 
 void ldc_unmap(struct ldc_channel *lp, struct ldc_trans_cookie *cookies,
 	       int ncookies)
 {
 	struct ldc_iommu *iommu = &lp->iommu;
-	unsigned long flags;
 	int i;
+	unsigned long flags;
 
 	spin_lock_irqsave(&iommu->lock, flags);
 	for (i = 0; i < ncookies; i++) {
-- 
1.7.1

Re: [PATCH v7 0/3] Generic IOMMU pooled allocator

[David Miller]

From: Sowmini Varadhan <sowmini.varadhan@oracle.com>
Date: Wed, 25 Mar 2015 13:34:45 -0400

> Changes from patchv6: moved pool_hash initialization to
> lib/iommu-common.c and cleaned up code duplication from 
> sun4v/sun4u/ldc. 

Looks good to me.

PowerPC folks, what do you think?

Re: [PATCH v7 0/3] Generic IOMMU pooled allocator

[Benjamin Herrenschmidt]

On Wed, 2015-03-25 at 14:12 -0400, David Miller wrote:
> From: Sowmini Varadhan <sowmini.varadhan@oracle.com>
> Date: Wed, 25 Mar 2015 13:34:45 -0400
> 
> > Changes from patchv6: moved pool_hash initialization to
> > lib/iommu-common.c and cleaned up code duplication from 
> > sun4v/sun4u/ldc. 
> 
> Looks good to me.
> 
> PowerPC folks, what do you think?

I'll give it another look today.

Cheers,
Ben.

Re: [PATCH v7 0/3] Generic IOMMU pooled allocator

[Sowmini Varadhan]

On (03/26/15 08:05), Benjamin Herrenschmidt wrote:
> > PowerPC folks, what do you think?
> 
> I'll give it another look today.
> 
> Cheers,
> Ben.

Hi Ben, 

did you have a chance to look at this?

--Sowmini

Re: [PATCH v7 RFC 1/3] sparc: Break up monolithic iommu table/lock into finer graularity pools and lock

[Benjamin Herrenschmidt]

On Wed, 2015-03-25 at 13:34 -0400, Sowmini Varadhan wrote:
> Investigation of multithreaded iperf experiments on an ethernet
> interface show the iommu->lock as the hottest lock identified by
> lockstat, with something of the order of  21M contentions out of
> 27M acquisitions, and an average wait time of 26 us for the lock.
> This is not efficient. A more scalable design is to follow the ppc
> model, where the iommu_table has multiple pools, each stretching
> over a segment of the map, and with a separate lock for each pool.
> This model allows for better parallelization of the iommu map search.
> 
 .../...
> 
> diff --git a/include/linux/iommu-common.h b/include/linux/iommu-common.h
> new file mode 100644
> index 0000000..197111b
> --- /dev/null
> +++ b/include/linux/iommu-common.h
> @@ -0,0 +1,48 @@
> +#ifndef _LINUX_IOMMU_COMMON_H
> +#define _LINUX_IOMMU_COMMON_H
> +
> +#include <linux/spinlock_types.h>
> +#include <linux/device.h>
> +#include <asm/page.h>
> +
> +#define IOMMU_POOL_HASHBITS     4
> +#define IOMMU_NR_POOLS          (1 << IOMMU_POOL_HASHBITS)

I don't like those macros. You changed the value from what we had on
powerpc. It could be that the new values are as good for us but I'd
like to do a bit differently. Can you make the bits a variable ? Or at
least an arch-provided macro which we can change later if needed ?

> +struct iommu_pool {
> +	unsigned long	start;
> +	unsigned long	end;
> +	unsigned long	hint;
> +	spinlock_t	lock;
> +};
> +
> +struct iommu_table {

Let's make it clear that this is for allocation of DMA space only, it
would thus make my life easier when adapting powerpc to use a different
names, something like "struct iommu_area" works for me, or "iommu
alloc_region" .. whatever you fancy the most.

> +	unsigned long		page_table_map_base;
> +	unsigned long		page_table_shift;

Minor nit but I'm not fan of the naming here, maybe just use
entry_shift ? I don't like too long identifiers :) Same for
base, could just be "base" or "table_base".

> +	unsigned long		nr_pools;
> +	void			(*flush_all)(struct iommu_table *);

Call this "lazy_flush", document that it is optional and when it is
called.

> +	unsigned long		poolsize;
> +	struct iommu_pool	arena_pool[IOMMU_NR_POOLS];

Why adding the 'arena' prefix ? What was wrong with "pools" in the
powerpc imlementation ?

> +	u32			flags;
> +#define	IOMMU_HAS_LARGE_POOL	0x00000001
> +#define	IOMMU_NO_SPAN_BOUND	0x00000002
> +	struct iommu_pool	large_pool;
> +	unsigned long		*map;
> +};
> +
> +extern void iommu_tbl_pool_init(struct iommu_table *iommu,
> +				unsigned long num_entries,
> +				u32 page_table_shift,
> +				void (*flush_all)(struct iommu_table *),
> +				bool large_pool, u32 npools,
> +				bool skip_span_boundary_check);
> +
> +extern unsigned long iommu_tbl_range_alloc(struct device *dev,
> +					   struct iommu_table *iommu,
> +					   unsigned long npages,
> +					   unsigned long *handle);
> +
> +extern void iommu_tbl_range_free(struct iommu_table *iommu,
> +				 u64 dma_addr, unsigned long npages,
> +				 unsigned long entry);
> +
> +#endif
> diff --git a/lib/Makefile b/lib/Makefile
> index 3c3b30b..0ea2ac6 100644
> --- a/lib/Makefile
> +++ b/lib/Makefile
> @@ -102,7 +102,7 @@ obj-$(CONFIG_AUDIT_GENERIC) += audit.o
>  obj-$(CONFIG_AUDIT_COMPAT_GENERIC) += compat_audit.o
>  
>  obj-$(CONFIG_SWIOTLB) += swiotlb.o
> -obj-$(CONFIG_IOMMU_HELPER) += iommu-helper.o
> +obj-$(CONFIG_IOMMU_HELPER) += iommu-helper.o iommu-common.o
>  obj-$(CONFIG_FAULT_INJECTION) += fault-inject.o
>  obj-$(CONFIG_NOTIFIER_ERROR_INJECTION) += notifier-error-inject.o
>  obj-$(CONFIG_CPU_NOTIFIER_ERROR_INJECT) += cpu-notifier-error-inject.o
> diff --git a/lib/iommu-common.c b/lib/iommu-common.c
> new file mode 100644
> index 0000000..bb7e706
> --- /dev/null
> +++ b/lib/iommu-common.c
> @@ -0,0 +1,235 @@
> +/*
> + * IOMMU mmap management and range allocation functions.
> + * Based almost entirely upon the powerpc iommu allocator.
> + */
> +
> +#include <linux/export.h>
> +#include <linux/bitmap.h>
> +#include <linux/bug.h>
> +#include <linux/iommu-helper.h>
> +#include <linux/iommu-common.h>
> +#include <linux/dma-mapping.h>
> +#include <linux/hash.h>
> +
> +#define IOMMU_LARGE_ALLOC	15

Make that a variable, here too, the arch might want to tweak it.

I think 15 is actually not a good value for powerpc with 4k iommu pages
and 64k PAGE_SIZE, we should make the above some kind of factor of
PAGE_SHIFT - iommu_page_shift.

> +static	DEFINE_PER_CPU(unsigned int, iommu_pool_hash);
> +
> +static void setup_iommu_pool_hash(void)
> +{
> +	unsigned int i;
> +	static bool do_once;
> +
> +	if (do_once)
> +		return;
> +	do_once = true;
> +	for_each_possible_cpu(i)
> +		per_cpu(iommu_pool_hash, i) = hash_32(i, IOMMU_POOL_HASHBITS);
> +}
> +
> +/*
> + * Initialize iommu_pool entries for the iommu_table. `num_entries'
> + * is the number of table entries. If `large_pool' is set to true,
> + * the top 1/4 of the table will be set aside for pool allocations
> + * of more than IOMMU_LARGE_ALLOC pages.
> + */
> +extern void iommu_tbl_pool_init(struct iommu_table *iommu,
> +				unsigned long num_entries,
> +				u32 page_table_shift,
> +				void (*flush_all)(struct iommu_table *),
> +				bool large_pool, u32 npools,
> +				bool skip_span_boundary_check)
> +{
> +	unsigned int start, i;
> +	struct iommu_pool *p = &(iommu->large_pool);
> +
> +	setup_iommu_pool_hash();
> +	if (npools == 0)
> +		iommu->nr_pools = IOMMU_NR_POOLS;
> +	else
> +		iommu->nr_pools = npools;
> +	BUG_ON(npools > IOMMU_NR_POOLS);
> +
> +	iommu->page_table_shift = page_table_shift;
> +	iommu->flush_all = flush_all;
> +	start = 0;
> +	if (skip_span_boundary_check)
> +		iommu->flags |= IOMMU_NO_SPAN_BOUND;
> +	if (large_pool)
> +		iommu->flags |= IOMMU_HAS_LARGE_POOL;
> +
> +	if (!large_pool)
> +		iommu->poolsize = num_entries/iommu->nr_pools;
> +	else
> +		iommu->poolsize = (num_entries * 3 / 4)/iommu->nr_pools;
> +	for (i = 0; i < iommu->nr_pools; i++) {
> +		spin_lock_init(&(iommu->arena_pool[i].lock));
> +		iommu->arena_pool[i].start = start;
> +		iommu->arena_pool[i].hint = start;
> +		start += iommu->poolsize; /* start for next pool */
> +		iommu->arena_pool[i].end = start - 1;
> +	}
> +	if (!large_pool)
> +		return;
> +	/* initialize large_pool */
> +	spin_lock_init(&(p->lock));
> +	p->start = start;
> +	p->hint = p->start;
> +	p->end = num_entries;
> +}
> +EXPORT_SYMBOL(iommu_tbl_pool_init);
> +
> +unsigned long iommu_tbl_range_alloc(struct device *dev,
> +				struct iommu_table *iommu,
> +				unsigned long npages,
> +				unsigned long *handle)
> +{
> +	unsigned int pool_hash = __this_cpu_read(iommu_pool_hash);
> +	unsigned long n, end, start, limit, boundary_size;
> +	struct iommu_pool *arena;
> +	int pass = 0;
> +	unsigned int pool_nr;
> +	unsigned int npools = iommu->nr_pools;
> +	unsigned long flags;
> +	bool large_pool = ((iommu->flags & IOMMU_HAS_LARGE_POOL) != 0);
> +	bool largealloc = (large_pool && npages > IOMMU_LARGE_ALLOC);
> +	unsigned long shift;
> +
> +	/* Sanity check */
> +	if (unlikely(npages == 0)) {
> +		printk_ratelimited("npages == 0\n");

You removed the WARN_ON here which had the nice property of giving you a
backtrace which points to the offender. The above message alone is
useless.

> +		return DMA_ERROR_CODE;
> +	}
> +
> +	if (largealloc) {
> +		arena = &(iommu->large_pool);

Nit but here too, why change "pool" to "arena" ?

> +		spin_lock_irqsave(&arena->lock, flags);
> +		pool_nr = 0; /* to keep compiler happy */
> +	} else {
> +		/* pick out pool_nr */
> +		pool_nr =  pool_hash & (npools - 1);
> +		arena = &(iommu->arena_pool[pool_nr]);
> +
> +		/* find first available unlocked pool */
> +		while (!spin_trylock_irqsave(&(arena->lock), flags)) {
> +			pool_nr = (pool_nr + 1) & (iommu->nr_pools - 1);
> +			arena = &(iommu->arena_pool[pool_nr]);
> +		}
> +	}

I am not certain about the "first unlocked pool"... We take the lock for
a fairly short amount of time, I have the gut feeling that the cache
line bouncing introduced by looking at a different pool may well cost
more than waiting a bit longer. Did do some measurements of that
optimisation ?

> + again:
> +	if (pass == 0 && handle && *handle &&
> +	    (*handle >= arena->start) && (*handle < arena->end))
> +		start = *handle;
> +	else
> +		start = arena->hint;
> +
> +	limit = arena->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 beginning and flush.
> +	 */
> +	if (start >= limit) {
> +		start = arena->start;
> +		if (!large_pool && iommu->flush_all != NULL)
> +			iommu->flush_all(iommu);
> +	}

I am not too fan of the 2 copies of that logic. On the other hand you
may have no choice since we do need to do the flush when we wrap even
if we end up failing or pool hopping.

> +
> +	if (dev)
> +		boundary_size = ALIGN(dma_get_seg_boundary(dev) + 1,
> +				      1 << iommu->page_table_shift);
> +	else
> +		boundary_size = ALIGN(1UL << 32, 1 << iommu->page_table_shift);
> +
> +	shift = iommu->page_table_map_base >> iommu->page_table_shift;
> +	boundary_size = boundary_size >> iommu->page_table_shift;
> +	/*
> +	 * if the skip_span_boundary_check had been set during init, we set
> +	 * things up so that iommu_is_span_boundary() merely checks if the
> +	 * (index + npages) < num_tsb_entries
> +	 */
> +	if ((iommu->flags & IOMMU_NO_SPAN_BOUND) != 0) {
> +		shift = 0;
> +		boundary_size = iommu->poolsize * iommu->nr_pools;
> +	}
> +	n = iommu_area_alloc(iommu->map, limit, start, npages, shift,
> +			     boundary_size, 0);
> +	if (n == -1) {
> +		if (likely(pass == 0)) {
> +			/* First failure, rescan from the beginning.  */
> +			arena->hint = arena->start;
> +			if (!large_pool && iommu->flush_all != NULL)
> +				iommu->flush_all(iommu);
> +			pass++;
> +			goto again;
> +		} else if (!largealloc && pass <= iommu->nr_pools) {
> +			spin_unlock(&(arena->lock));
> +			pool_nr = (pool_nr + 1) & (iommu->nr_pools - 1);
> +			arena = &(iommu->arena_pool[pool_nr]);
> +			while (!spin_trylock(&(arena->lock))) {
> +				pool_nr = (pool_nr + 1) & (iommu->nr_pools - 1);
> +				arena = &(iommu->arena_pool[pool_nr]);
> +			}
> +			arena->hint = arena->start;

Here you just "wrapped" that new pool, so you need to do a flush. I'm
thinking you should probably use a local "need_flush" bool, which
applies to the current pool. You would do a test & call flush before
releasing a pool lock (so right above this or on function exit). To make
things simpler, the below becomes:

> +			pass++;
> +			goto again;
> +		} else {
> +			/* give up */
> +			spin_unlock_irqrestore(&(arena->lock), flags);
> +			return DMA_ERROR_CODE;
> +		}
> +	}

		else {
			n = DMA_ERROR_CODE;
			goto bail;
		}

So you have only one exit point.

> +
> +	end = n + npages;
> +
> +	arena->hint = end;
> +
> +	/* Update handle for SG allocations */
> +	if (handle)
> +		*handle = end;
> +	spin_unlock_irqrestore(&(arena->lock), flags);
> +
> +	return n;
> +}
> +EXPORT_SYMBOL(iommu_tbl_range_alloc);
> +
> +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;
> +	bool large_pool = ((tbl->flags & IOMMU_HAS_LARGE_POOL) != 0);
> +
> +	/* The large pool is the last pool at the top of the table */
> +	if (large_pool && entry >= largepool_start) {
> +		p = &tbl->large_pool;
> +	} else {
> +		unsigned int pool_nr = entry / tbl->poolsize;
> +
> +		BUG_ON(pool_nr >= tbl->nr_pools);
> +		p = &tbl->arena_pool[pool_nr];
> +	}
> +	return p;
> +}
> +
> +/* Caller supplies the index of the entry into the iommu map table
> + * itself when the mapping from dma_addr to the entry is not the
> + * default addr->entry mapping below.
> + */
> +void iommu_tbl_range_free(struct iommu_table *iommu, u64 dma_addr,
> +			  unsigned long npages, unsigned long entry)
> +{
> +	struct iommu_pool *pool;
> +	unsigned long flags;
> +	unsigned long shift = iommu->page_table_shift;
> +
> +	if (entry == DMA_ERROR_CODE) /* use default addr->entry mapping */
> +		entry = (dma_addr - iommu->page_table_map_base) >> shift;
> +	pool = get_pool(iommu, entry);
> +
> +	spin_lock_irqsave(&(pool->lock), flags);
> +	bitmap_clear(iommu->map, entry, npages);
> +	spin_unlock_irqrestore(&(pool->lock), flags);
> +}
> +EXPORT_SYMBOL(iommu_tbl_range_free);

Re: [PATCH v7 RFC 1/3] sparc: Break up monolithic iommu table/lock into finer graularity pools and lock

[Sowmini Varadhan]

On (03/30/15 14:24), Benjamin Herrenschmidt wrote:
> > +
> > +#define IOMMU_POOL_HASHBITS     4
> > +#define IOMMU_NR_POOLS          (1 << IOMMU_POOL_HASHBITS)
> 
> I don't like those macros. You changed the value from what we had on
> powerpc. It could be that the new values are as good for us but I'd
> like to do a bit differently. Can you make the bits a variable ? Or at
> least an arch-provided macro which we can change later if needed ?

Actuallly, this are just the upper bound (16) on the number of pools.

The actual number is selected by the value passed to the 
iommu_tbl_range_init(), and is not hard-coded (as was the case with
the power-pc code).

Thus powerpc can continue to use 4 pools without any loss of 
generality.

   :
> Let's make it clear that this is for allocation of DMA space only, it
> would thus make my life easier when adapting powerpc to use a different
> names, something like "struct iommu_area" works for me, or "iommu
> alloc_region" .. whatever you fancy the most.
  :
> Why adding the 'arena' prefix ? What was wrong with "pools" in the
> powerpc imlementation ?

for the same reason you want to re-baptize iommu_table above- at
the time, I was doing it to minimize conflicts with existing usage.
But I can rename everything if you like. 

> > +#define IOMMU_LARGE_ALLOC	15
> 
> Make that a variable, here too, the arch might want to tweak it.
> 
> I think 15 is actually not a good value for powerpc with 4k iommu pages
> and 64k PAGE_SIZE, we should make the above some kind of factor of
> PAGE_SHIFT - iommu_page_shift.

Ok.

> > +	/* Sanity check */
> > +	if (unlikely(npages == 0)) {
> > +		printk_ratelimited("npages == 0\n");
> 
> You removed the WARN_ON here which had the nice property of giving you a
> backtrace which points to the offender. The above message alone is
> useless.

yes, the original code was generating checkpatch warnings and errors.
That's why I removed it. 

> I am not certain about the "first unlocked pool"... We take the lock for
> a fairly short amount of time, I have the gut feeling that the cache
> line bouncing introduced by looking at a different pool may well cost
> more than waiting a bit longer. Did do some measurements of that
> optimisation ?

if you are really only taking it for a short amount of time, then
the trylock should just succeed, so there is no cache line bouncing.

But yes, I did instrument it with iperf, and there was lock contention
on the spinlock, which was eliminted by the trylock. 

I'll fix the rest of the variable naming etc nits and send out
a new version later today.

--Sowmini

Re: [PATCH v7 RFC 1/3] sparc: Break up monolithic iommu table/lock into finer graularity pools and lock

[Benjamin Herrenschmidt]

On Mon, 2015-03-30 at 06:38 -0400, Sowmini Varadhan wrote:
> On (03/30/15 14:24), Benjamin Herrenschmidt wrote:
> > > +
> > > +#define IOMMU_POOL_HASHBITS     4
> > > +#define IOMMU_NR_POOLS          (1 << IOMMU_POOL_HASHBITS)
> > 
> > I don't like those macros. You changed the value from what we had on
> > powerpc. It could be that the new values are as good for us but I'd
> > like to do a bit differently. Can you make the bits a variable ? Or at
> > least an arch-provided macro which we can change later if needed ?
> 
> Actuallly, this are just the upper bound (16) on the number of pools.
> 
> The actual number is selected by the value passed to the 
> iommu_tbl_range_init(), and is not hard-coded (as was the case with
> the power-pc code).
> 
> Thus powerpc can continue to use 4 pools without any loss of 
> generality.

Right, but it affects the way we hash... not a huge deal though.

>    :
> > Let's make it clear that this is for allocation of DMA space only, it
> > would thus make my life easier when adapting powerpc to use a different
> > names, something like "struct iommu_area" works for me, or "iommu
> > alloc_region" .. whatever you fancy the most.
>   :
> > Why adding the 'arena' prefix ? What was wrong with "pools" in the
> > powerpc imlementation ?
> 
> for the same reason you want to re-baptize iommu_table above- at
> the time, I was doing it to minimize conflicts with existing usage.
> But I can rename everything if you like. 

But in that case it doesn't make much sense and makes the names longer.
Those are just "pools", it's sufficient.

> > > +#define IOMMU_LARGE_ALLOC	15
> > 
> > Make that a variable, here too, the arch might want to tweak it.
> > 
> > I think 15 is actually not a good value for powerpc with 4k iommu pages
> > and 64k PAGE_SIZE, we should make the above some kind of factor of
> > PAGE_SHIFT - iommu_page_shift.
> 
> Ok.
> 
> > > +	/* Sanity check */
> > > +	if (unlikely(npages == 0)) {
> > > +		printk_ratelimited("npages == 0\n");
> > 
> > You removed the WARN_ON here which had the nice property of giving you a
> > backtrace which points to the offender. The above message alone is
> > useless.
> 
> yes, the original code was generating checkpatch warnings and errors.
> That's why I removed it. 

Put it back please, and ignore checkpatch, it's become an annoyance more
than anything else.

Note that nowadays, you can probably use WARN_ON_ONCE(npages == 0); in
place of the whole construct.

> > I am not certain about the "first unlocked pool"... We take the lock for
> > a fairly short amount of time, I have the gut feeling that the cache
> > line bouncing introduced by looking at a different pool may well cost
> > more than waiting a bit longer. Did do some measurements of that
> > optimisation ?
> 
> if you are really only taking it for a short amount of time, then
> the trylock should just succeed, so there is no cache line bouncing.

No that's not my point. The lock is only taken for a short time but
might still collide, the bouncing in that case will probably (at least
that's my feeling) hurt more than help.

However, I have another concern with your construct. Essentially you
spin looking for an unlocked pool without a cpu_relax. Now it's unlikely
but you *can* end up eating cycles, which on a high SMT like POWER8
might mean slowing down the actual owner of the pool lock. 

> But yes, I did instrument it with iperf, and there was lock contention
> on the spinlock, which was eliminted by the trylock. 

What is iperf ? What does that mean "there was lock contention" ? IE,
was the overall performance improved or not ? Removing contention by
trading it for cache line bouncing will not necessarily help. I'm not
saying this is a bad optimisation but it makes the code messy and I
think deserves some solid numbers demonstrating its worth.

> I'll fix the rest of the variable naming etc nits and send out
> a new version later today.

There was also an actual bug in the case where you hop'ed to a new pool
and forgot the flush.

Cheers,
Ben.

Re: [PATCH v7 RFC 1/3] sparc: Break up monolithic iommu table/lock into finer graularity pools and lock

[Sowmini Varadhan]

On (03/30/15 21:55), Benjamin Herrenschmidt wrote:
> 
> No that's not my point. The lock is only taken for a short time but
> might still collide, the bouncing in that case will probably (at least
> that's my feeling) hurt more than help.
> 
> However, I have another concern with your construct. Essentially you
> spin looking for an unlocked pool without a cpu_relax. Now it's unlikely
> but you *can* end up eating cycles, which on a high SMT like POWER8
> might mean slowing down the actual owner of the pool lock. 

So I tried looking at the code, and perhaps there is some arch-specific
subtlety here that I am missing, but where does spin_lock itself
do the cpu_relax? afaict, LOCK_CONTENDED() itself does not have this.


> What is iperf ? What does that mean "there was lock contention" ? IE,
> was the overall performance improved or not ? Removing contention by
> trading it for cache line bouncing will not necessarily help. I'm not
> saying this is a bad optimisation but it makes the code messy and I
> think deserves some solid numbers demonstrating its worth.

iperf is a network perf benchmark. I'll try to regenerate some 
numbers today and get some instrumentation of cache-line bounces
vs trylock misses.
   
> There was also an actual bug in the case where you hop'ed to a new pool
> and forgot the flush.

yes, thanks for catching that, I'll fix that too, of course.

--Sowmini

Re: [PATCH v7 RFC 1/3] sparc: Break up monolithic iommu table/lock into finer graularity pools and lock

[Sowmini Varadhan]

On (03/30/15 09:01), Sowmini Varadhan wrote:
> 
> So I tried looking at the code, and perhaps there is some arch-specific
> subtlety here that I am missing, but where does spin_lock itself
> do the cpu_relax? afaict, LOCK_CONTENDED() itself does not have this.

To answer my question:
I'd missed the CONFIG_LOCK_STAT (which David Ahern pointed out to me).
the above is only true for the LOCK_STAT case.

In any case, I ran some experiments today: I was running 
iperf [http://en.wikipedia.org/wiki/Iperf] over ixgbe, which
is where I'd noticed the original perf issues for sparc. I was
running iperf2 (which is more aggressively threaded than iperf3) with
8, 10, 16, 20 threads, and with TSO turned off. In each case, I was
making sure that I was able to reach 9.X Gbps (this is a 10Gbps link)

I dont see any significant difference in the perf profile between the
spin_trylock and the spin_lock version (other than, of course, the change
to the lock-contention for the trylock version). I looked at the
perf profiled cache-misses (works out to about 1400M for 10 threads,
with or without the trylock).

I'm still waiting for some of the IB folks to try out the spin_lock
version (they had also seen some significant perf improvements from
breaking down the monolithic lock into multiple pools, so their workload
is also sensitive to this)

But as such, it looks like it doesnt matter much, whether you use
the trylock to find the first available pool, or block on the spin_lock.
I'll let folks on this list vote on this one (assuming the IB tests also 
come out without a significant variation between the 2 locking choices).

--Sowmini

Re: [PATCH v7 RFC 1/3] sparc: Break up monolithic iommu table/lock into finer graularity pools and lock

[Benjamin Herrenschmidt]

On Mon, 2015-03-30 at 17:15 -0400, Sowmini Varadhan wrote:
> On (03/30/15 09:01), Sowmini Varadhan wrote:
> > 
> > So I tried looking at the code, and perhaps there is some arch-specific
> > subtlety here that I am missing, but where does spin_lock itself
> > do the cpu_relax? afaict, LOCK_CONTENDED() itself does not have this.
> 
> To answer my question:
> I'd missed the CONFIG_LOCK_STAT (which David Ahern pointed out to me).
> the above is only true for the LOCK_STAT case.

powerpc:

static inline void arch_spin_lock(arch_spinlock_t *lock)
{
	CLEAR_IO_SYNC;
	while (1) {
		if (likely(__arch_spin_trylock(lock) == 0))
			break;
		do {
			HMT_low();
			if (SHARED_PROCESSOR)
				__spin_yield(lock);
		} while (unlikely(lock->slock != 0));
		HMT_medium();
	}
}

The HMT_* statements are what reduces the thread prio. Additionally,
the yield thingy is something that allows us to relinguish out time
slice to the partition owning the lock if it's not currently scheduled
by the hypervisor.

> In any case, I ran some experiments today: I was running 
> iperf [http://en.wikipedia.org/wiki/Iperf] over ixgbe, which
> is where I'd noticed the original perf issues for sparc. I was
> running iperf2 (which is more aggressively threaded than iperf3) with
> 8, 10, 16, 20 threads, and with TSO turned off. In each case, I was
> making sure that I was able to reach 9.X Gbps (this is a 10Gbps link)
> 
> I dont see any significant difference in the perf profile between the
> spin_trylock and the spin_lock version (other than, of course, the change
> to the lock-contention for the trylock version). I looked at the
> perf profiled cache-misses (works out to about 1400M for 10 threads,
> with or without the trylock).
> 
> I'm still waiting for some of the IB folks to try out the spin_lock
> version (they had also seen some significant perf improvements from
> breaking down the monolithic lock into multiple pools, so their workload
> is also sensitive to this)
> 
> But as such, it looks like it doesnt matter much, whether you use
> the trylock to find the first available pool, or block on the spin_lock.
> I'll let folks on this list vote on this one (assuming the IB tests also 
> come out without a significant variation between the 2 locking choices).

Provided that the IB test doesn't come up with a significant difference,
I definitely vote for the simpler version of doing a normal spin_lock.

Cheers,
Ben.

Re: [PATCH v7 RFC 1/3] sparc: Break up monolithic iommu table/lock into finer graularity pools and lock

[Sowmini Varadhan]

On (03/31/15 08:28), Benjamin Herrenschmidt wrote:
> 
> Provided that the IB test doesn't come up with a significant difference,
> I definitely vote for the simpler version of doing a normal spin_lock.

sounds good. let me wait for the confirmation from IB,
and I'll send out patchv8 soon after. 

FWIW, I'm ok with all the other comments- thanks for the feedback.

--Sowmini