On 8/23/2022 10:07 PM, Rob Clark wrote:
From: Rob Clark <robdclark@xxxxxxxxxxxx>
Using map_pages/unmap_pages cuts down on the # of pgtable walks needed
in the process of finding where to insert/remove an entry. The end
result is ~5-10x faster than mapping a single page at a time.
v2: Rename iommu_pgsize(), drop obsolete comments, fix error handling
in msm_iommu_pagetable_map()
Signed-off-by: Rob Clark <robdclark@xxxxxxxxxxxx>
---
drivers/gpu/drm/msm/msm_iommu.c | 101 +++++++++++++++++++++++++++-----
1 file changed, 86 insertions(+), 15 deletions(-)
diff --git a/drivers/gpu/drm/msm/msm_iommu.c b/drivers/gpu/drm/msm/msm_iommu.c
index a54ed354578b..5577cea7c009 100644
--- a/drivers/gpu/drm/msm/msm_iommu.c
+++ b/drivers/gpu/drm/msm/msm_iommu.c
@@ -21,6 +21,7 @@ struct msm_iommu_pagetable {
struct msm_mmu base;
struct msm_mmu *parent;
struct io_pgtable_ops *pgtbl_ops;
+ unsigned long pgsize_bitmap; /* Bitmap of page sizes in use */
phys_addr_t ttbr;
u32 asid;
};
@@ -29,23 +30,84 @@ static struct msm_iommu_pagetable *to_pagetable(struct msm_mmu *mmu)
return container_of(mmu, struct msm_iommu_pagetable, base);
}
+/* based on iommu_pgsize() in iommu.c: */
+static size_t calc_pgsize(struct msm_iommu_pagetable *pagetable,
+ unsigned long iova, phys_addr_t paddr,
+ size_t size, size_t *count)
+{
+ unsigned int pgsize_idx, pgsize_idx_next;
+ unsigned long pgsizes;
+ size_t offset, pgsize, pgsize_next;
+ unsigned long addr_merge = paddr | iova;
+
+ /* Page sizes supported by the hardware and small enough for @size */
+ pgsizes = pagetable->pgsize_bitmap & GENMASK(__fls(size), 0);
+
+ /* Constrain the page sizes further based on the maximum alignment */
+ if (likely(addr_merge))
+ pgsizes &= GENMASK(__ffs(addr_merge), 0);
+
+ /* Make sure we have at least one suitable page size */
+ BUG_ON(!pgsizes);
+
+ /* Pick the biggest page size remaining */
+ pgsize_idx = __fls(pgsizes);
+ pgsize = BIT(pgsize_idx);
+ if (!count)
+ return pgsize;
+
+ /* Find the next biggest support page size, if it exists */
+ pgsizes = pagetable->pgsize_bitmap & ~GENMASK(pgsize_idx, 0);
+ if (!pgsizes)
+ goto out_set_count;
+
+ pgsize_idx_next = __ffs(pgsizes);
+ pgsize_next = BIT(pgsize_idx_next);
+
+ /*
+ * There's no point trying a bigger page size unless the virtual
+ * and physical addresses are similarly offset within the larger page.
+ */
+ if ((iova ^ paddr) & (pgsize_next - 1))
+ goto out_set_count;
+
+ /* Calculate the offset to the next page size alignment boundary */
+ offset = pgsize_next - (addr_merge & (pgsize_next - 1));
+
+ /*
+ * If size is big enough to accommodate the larger page, reduce
+ * the number of smaller pages.
+ */
+ if (offset + pgsize_next <= size)
+ size = offset;
+
+out_set_count:
+ *count = size >> pgsize_idx;
+ return pgsize;
+}
+
Can we keep this in iommu driver? Seems useful to other drivers too.
Perhaps implement an sg friendly version of iopgtble ops, like
unmap_sg() maybe!
-Akhil.
static int msm_iommu_pagetable_unmap(struct msm_mmu *mmu, u64 iova,
size_t size)
{
struct msm_iommu_pagetable *pagetable = to_pagetable(mmu);
struct io_pgtable_ops *ops = pagetable->pgtbl_ops;
- size_t unmapped = 0;
- /* Unmap the block one page at a time */
while (size) {
- unmapped += ops->unmap(ops, iova, 4096, NULL);
- iova += 4096;
- size -= 4096;
+ size_t unmapped, pgsize, count;
+
+ pgsize = calc_pgsize(pagetable, iova, iova, size, &count);
+
+ unmapped = ops->unmap_pages(ops, iova, pgsize, count, NULL);
+ if (!unmapped)
+ break;
+
+ iova += unmapped;
+ size -= unmapped;
}
iommu_flush_iotlb_all(to_msm_iommu(pagetable->parent)->domain);
- return (unmapped == size) ? 0 : -EINVAL;
+ return (size == 0) ? 0 : -EINVAL;
}
static int msm_iommu_pagetable_map(struct msm_mmu *mmu, u64 iova,
@@ -54,7 +116,6 @@ static int msm_iommu_pagetable_map(struct msm_mmu *mmu, u64 iova,
struct msm_iommu_pagetable *pagetable = to_pagetable(mmu);
struct io_pgtable_ops *ops = pagetable->pgtbl_ops;
struct scatterlist *sg;
- size_t mapped = 0;
u64 addr = iova;
unsigned int i;
@@ -62,17 +123,26 @@ static int msm_iommu_pagetable_map(struct msm_mmu *mmu, u64 iova,
size_t size = sg->length;
phys_addr_t phys = sg_phys(sg);
- /* Map the block one page at a time */
while (size) {
- if (ops->map(ops, addr, phys, 4096, prot, GFP_KERNEL)) {
- msm_iommu_pagetable_unmap(mmu, iova, mapped);
+ size_t pgsize, count, mapped = 0;
+ int ret;
+
+ pgsize = calc_pgsize(pagetable, addr, phys, size, &count);
+
+ ret = ops->map_pages(ops, addr, phys, pgsize, count,
+ prot, GFP_KERNEL, &mapped);
+
+ /* map_pages could fail after mapping some of the pages,
+ * so update the counters before error handling.
+ */
+ phys += mapped;
+ addr += mapped;
+ size -= mapped;
+
+ if (ret) {
+ msm_iommu_pagetable_unmap(mmu, iova, addr - iova);
return -EINVAL;
}
-
- phys += 4096;
- addr += 4096;
- size -= 4096;
- mapped += 4096;
}
}
@@ -207,6 +277,7 @@ struct msm_mmu *msm_iommu_pagetable_create(struct msm_mmu *parent)
/* Needed later for TLB flush */
pagetable->parent = parent;
+ pagetable->pgsize_bitmap = ttbr0_cfg.pgsize_bitmap;
pagetable->ttbr = ttbr0_cfg.arm_lpae_s1_cfg.ttbr;
/*
