alpha: make IOMMU respect the segment boundary limits

This patch makes the IOMMU code not allocate a memory area spanning LLD's
segment boundary.

is_span_boundary() judges whether a memory area spans LLD's segment boundary.
If iommu_arena_find_pages() finds such a area, it tries to find the next
available memory area.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 34 insertions, 6 deletions

diff --git a/arch/alpha/kernel/pci_iommu.c b/arch/alpha/kernel/pci_iommu.c
index e54f829528cb..54540c369c90 100644
--- a/arch/alpha/kernel/pci_iommu.c
+++ b/arch/alpha/kernel/pci_iommu.c
@@ -126,13 +126,34 @@ iommu_arena_new(struct pci_controller *hose, dma_addr_t base,
         return iommu_arena_new_node(0, hose, base, window_size, align);
 }
 
+static inline int is_span_boundary(unsigned int index, unsigned int nr,
+                                   unsigned long shift,
+                                   unsigned long boundary_size)
+{
+        shift = (shift + index) & (boundary_size - 1);
+        return shift + nr > boundary_size;
+}
+
 /* Must be called with the arena lock held */
 static long
-iommu_arena_find_pages(struct pci_iommu_arena *arena, long n, long mask)
+iommu_arena_find_pages(struct device *dev, struct pci_iommu_arena *arena,
+                       long n, long mask)
 {
         unsigned long *ptes;
         long i, p, nent;
         int pass = 0;
+        unsigned long base;
+        unsigned long boundary_size;
+
+        BUG_ON(arena->dma_base & ~PAGE_MASK);
+        base = arena->dma_base >> PAGE_SHIFT;
+        if (dev)
+                boundary_size = ALIGN(dma_get_max_seg_size(dev) + 1, PAGE_SIZE)
+                        >> PAGE_SHIFT;
+        else
+                boundary_size = ALIGN(1UL << 32, PAGE_SIZE) >> PAGE_SHIFT;
+
+        BUG_ON(!is_power_of_2(boundary_size));
 
         /* Search forward for the first mask-aligned sequence of N free ptes */
         ptes = arena->ptes;
@@ -142,6 +163,11 @@ iommu_arena_find_pages(struct pci_iommu_arena *arena, long n, long mask)
 
 again:
         while (i < n && p+i < nent) {
+                if (!i && is_span_boundary(p, n, base, boundary_size)) {
+                        p = ALIGN(p + 1, mask + 1);
+                        goto again;
+                }
+
                 if (ptes[p+i])
                         p = ALIGN(p + i + 1, mask + 1), i = 0;
                 else
@@ -170,7 +196,8 @@ again:
 }
 
 static long
-iommu_arena_alloc(struct pci_iommu_arena *arena, long n, unsigned int align)
+iommu_arena_alloc(struct device *dev, struct pci_iommu_arena *arena, long n,
+                  unsigned int align)
 {
         unsigned long flags;
         unsigned long *ptes;
@@ -181,7 +208,7 @@ iommu_arena_alloc(struct pci_iommu_arena *arena, long n, unsigned int align)
         /* Search for N empty ptes */
         ptes = arena->ptes;
         mask = max(align, arena->align_entry) - 1;
-        p = iommu_arena_find_pages(arena, n, mask);
+        p = iommu_arena_find_pages(dev, arena, n, mask);
         if (p < 0) {
                 spin_unlock_irqrestore(&arena->lock, flags);
                 return -1;
@@ -231,6 +258,7 @@ pci_map_single_1(struct pci_dev *pdev, void *cpu_addr, size_t size,
         unsigned long paddr;
         dma_addr_t ret;
         unsigned int align = 0;
+        struct device *dev = pdev ? &pdev->dev : NULL;
 
         paddr = __pa(cpu_addr);
 
@@ -278,7 +306,7 @@ pci_map_single_1(struct pci_dev *pdev, void *cpu_addr, size_t size,
         /* Force allocation to 64KB boundary for ISA bridges. */
         if (pdev && pdev == isa_bridge)
                 align = 8;
-        dma_ofs = iommu_arena_alloc(arena, npages, align);
+        dma_ofs = iommu_arena_alloc(dev, arena, npages, align);
         if (dma_ofs < 0) {
                 printk(KERN_WARNING "pci_map_single failed: "
                        "could not allocate dma page tables\n");
@@ -565,7 +593,7 @@ sg_fill(struct device *dev, struct scatterlist *leader, struct scatterlist *end,
 
         paddr &= ~PAGE_MASK;
         npages = calc_npages(paddr + size);
-        dma_ofs = iommu_arena_alloc(arena, npages, 0);
+        dma_ofs = iommu_arena_alloc(dev, arena, npages, 0);
         if (dma_ofs < 0) {
                 /* If we attempted a direct map above but failed, die.  */
                 if (leader->dma_address == 0)
@@ -832,7 +860,7 @@ iommu_reserve(struct pci_iommu_arena *arena, long pg_count, long align_mask)
 
         /* Search for N empty ptes.  */
         ptes = arena->ptes;
-        p = iommu_arena_find_pages(arena, pg_count, align_mask);
+        p = iommu_arena_find_pages(NULL, arena, pg_count, align_mask);
         if (p < 0) {
                 spin_unlock_irqrestore(&arena->lock, flags);
                 return -1;