[Xen-devel] [RFC v01 2/3] arm: omap: translate iommu mapping to 4K pages

[Andrii Tseglytskyi <andrii.tseglytskyi@xxxxxxxxxxxxxxx>]

Patch introduces the following algorithm:
- enumerates all first level translation entries
- for each section creates 256 pages, each page is 4096 bytes
- for each supersection creates 4096 pages, each page is 4096 bytes
- flush cache to synchronize Cortex M15 and IOMMU

This algorithm make possible to use 4K mapping only.

Change-Id: Ie2cf45f23e0c170e9ba9d58f8dbb917348fdbd33
Signed-off-by: Andrii Tseglytskyi <andrii.tseglytskyi@xxxxxxxxxxxxxxx>
---
 xen/arch/arm/omap_iommu.c |   50 +++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 46 insertions(+), 4 deletions(-)

diff --git a/xen/arch/arm/omap_iommu.c b/xen/arch/arm/omap_iommu.c
index 4dab30f..7ec03a2 100644
--- a/xen/arch/arm/omap_iommu.c
+++ b/xen/arch/arm/omap_iommu.c
@@ -72,6 +72,9 @@
 #define PTRS_PER_IOPTE         (1UL << (IOPGD_SHIFT - IOPTE_SMALL_SHIFT))
 #define IOPTE_TABLE_SIZE       (PTRS_PER_IOPTE * sizeof(u32))
 
+/* 16 sections in supersection */
+#define IOSECTION_PER_IOSUPER  (1UL << (IOSUPER_SHIFT - IOPGD_SHIFT))
+
 /*
  * some descriptor attributes.
  */
@@ -117,6 +120,9 @@ static struct mmu_info *mmu_list[] = {
        &omap_dsp_mmu,
 };
 
+static bool translate_supersections_to_pages = true;
+static bool translate_sections_to_pages = true;
+
 #define mmu_for_each(pfunc, data)                                              
\
 ({                                                                             
                                \
        u32 __i;                                                                
                        \
@@ -213,6 +219,29 @@ static u32 mmu_translate_pgentry(struct domain *dom, u32 
iopgd, u32 da, u32 mask
        return vaddr;
 }
 
+static u32 mmu_iopte_alloc(struct mmu_info *mmu, struct domain *dom, u32 
iopgd, u32 sect_num)
+{
+       u32 *iopte = NULL;
+       u32 i;
+
+       iopte = xzalloc_bytes(PAGE_SIZE);
+       if (!iopte) {
+               printk("%s Fail to alloc 2nd level table\n", mmu->name);
+               return 0;
+       }
+
+       for (i = 0; i < PTRS_PER_IOPTE; i++) {
+               u32 da, vaddr, iopgd_tmp;
+               da = (sect_num << IOSECTION_SHIFT) + (i << IOPTE_SMALL_SHIFT);
+               iopgd_tmp = (iopgd & IOSECTION_MASK) + (i << IOPTE_SMALL_SHIFT);
+               vaddr = mmu_translate_pgentry(dom, iopgd_tmp, da, 
IOPTE_SMALL_MASK);
+               iopte[i] = vaddr | IOPTE_SMALL;
+       }
+
+       flush_xen_dcache_va_range(iopte, PAGE_SIZE);
+       return __pa(iopte) | IOPGD_TABLE;
+}
+
 /*
  * on boot table is empty
  */
@@ -245,13 +274,26 @@ static int mmu_translate_pagetable(struct domain *dom, 
struct mmu_info *mmu)
 
                /* "supersection" 16 Mb */
                if (iopgd_is_super(iopgd)) {
-                       da = i << IOSECTION_SHIFT;
-                       mmu->pagetable[i] = mmu_translate_pgentry(dom, iopgd, 
da, IOSUPER_MASK);
+                       if(likely(translate_supersections_to_pages)) {
+                               u32 j, iopgd_tmp;
+                               for (j = 0 ; j < IOSECTION_PER_IOSUPER; j++) {
+                                       iopgd_tmp = iopgd + (j * 
IOSECTION_SIZE);
+                                       mmu->pagetable[i + j] = 
mmu_iopte_alloc(mmu, dom, iopgd_tmp, i);
+                               }
+                               i += (j - 1);
+                       } else {
+                               da = i << IOSECTION_SHIFT;
+                               mmu->pagetable[i] = mmu_translate_pgentry(dom, 
iopgd, da, IOSUPER_MASK);
+                       }
 
                /* "section" 1Mb */
                } else if (iopgd_is_section(iopgd)) {
-                       da = i << IOSECTION_SHIFT;
-                       mmu->pagetable[i] = mmu_translate_pgentry(dom, iopgd, 
da, IOSECTION_MASK);
+                       if (likely(translate_sections_to_pages)) {
+                               mmu->pagetable[i] = mmu_iopte_alloc(mmu, dom, 
iopgd, i);
+                       } else {
+                               da = i << IOSECTION_SHIFT;
+                               mmu->pagetable[i] = mmu_translate_pgentry(dom, 
iopgd, da, IOSECTION_MASK);
+                       }
 
                /* "table" */
                } else if (iopgd_is_table(iopgd)) {
-- 
1.7.9.5


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