gpu: nvgpu: gmmu programming rewrite

Update the high level mapping logic. Instead of iterating over the
GPU VA iterate over the scatter-gather table chunks. As a result
each GMMU page table update call is simplified dramatically.

This also modifies the chip level code to no longer require an SGL
as an argument. Each call to the chip level code will be guaranteed
to be contiguous so it only has to worry about making a mapping from
virt -> phys.

This removes the dependency on Linux that the chip code currently
has. With this patch the core GMMU code still uses the Linux SGL but
the logic is highly transferable to a different, nvgpu specific,
scatter gather list format in the near future.

The last major update is to push most of the page table attribute
arguments to a struct. That struct is passed on through the various
mapping levels. This makes the funtions calls more simple and
easier to follow.

JIRA NVGPU-30

Change-Id: Ibb6b11755f99818fe642622ca0bd4cbed054f602
Signed-off-by: Alex Waterman <alexw@nvidia.com>
Reviewed-on: https://git-master/r/1484104
Reviewed-by: Terje Bergstrom <tbergstrom@nvidia.com>
GVS: Gerrit_Virtual_Submit

1 files changed, 591 insertions, 385 deletions

diff --git a/drivers/gpu/nvgpu/common/mm/gmmu.c b/drivers/gpu/nvgpu/common/mm/gmmu.c
index 06291600..ec1bc095 100644
--- a/drivers/gpu/nvgpu/common/mm/gmmu.c
+++ b/drivers/gpu/nvgpu/common/mm/gmmu.c
@@ -25,115 +25,26 @@
 #include "gk20a/gk20a.h"
 #include "gk20a/mm_gk20a.h"
 
-#define gmmu_dbg(g, fmt, args...)                       \
-        nvgpu_log(g, gpu_dbg_map, fmt, ##args)
-#define gmmu_dbg_v(g, fmt, args...)                     \
-        nvgpu_log(g, gpu_dbg_map_v, fmt, ##args)
-
-static int map_gmmu_pages(struct gk20a *g, struct gk20a_mm_entry *entry)
-{
-        return nvgpu_mem_begin(g, &entry->mem);
-}
-
-static void unmap_gmmu_pages(struct gk20a *g, struct gk20a_mm_entry *entry)
-{
-        nvgpu_mem_end(g, &entry->mem);
-}
-
-static int nvgpu_alloc_gmmu_pages(struct vm_gk20a *vm, u32 order,
-                                  struct gk20a_mm_entry *entry)
-{
-        struct gk20a *g = gk20a_from_vm(vm);
-        u32 num_pages = 1 << order;
-        u32 len = num_pages * PAGE_SIZE;
-        int err;
-
-        err = nvgpu_dma_alloc(g, len, &entry->mem);
-
-        if (err) {
-                nvgpu_err(g, "memory allocation failed");
-                return -ENOMEM;
-        }
-
-        return 0;
-}
-
-void nvgpu_free_gmmu_pages(struct vm_gk20a *vm,
-                           struct gk20a_mm_entry *entry)
-{
-        struct gk20a *g = gk20a_from_vm(vm);
-
-        if (!entry->mem.size)
-                return;
-
-        if (entry->woffset) /* fake shadow mem */
-                return;
-
-        nvgpu_dma_free(g, &entry->mem);
-}
-
-/*
- * Allocate a phys contig region big enough for a full
- * sized gmmu page table for the given gmmu_page_size.
- * the whole range is zeroed so it's "invalid"/will fault.
- *
- * If a previous entry is supplied, its memory will be used for
- * suballocation for this next entry too, if there is space.
- */
-int nvgpu_zalloc_gmmu_page_table(struct vm_gk20a *vm,
-                                 enum gmmu_pgsz_gk20a pgsz_idx,
-                                 const struct gk20a_mmu_level *l,
-                                 struct gk20a_mm_entry *entry,
-                                 struct gk20a_mm_entry *prev_entry)
-{
-        int err = -ENOMEM;
-        int order;
-        struct gk20a *g = gk20a_from_vm(vm);
-        u32 bytes;
-
-        /* allocate enough pages for the table */
-        order = l->hi_bit[pgsz_idx] - l->lo_bit[pgsz_idx] + 1;
-        order += ilog2(l->entry_size);
-        bytes = 1 << order;
-        order -= PAGE_SHIFT;
-        if (order < 0 && prev_entry) {
-                /* try to suballocate from previous chunk */
-                u32 capacity = prev_entry->mem.size / bytes;
-                u32 prev = prev_entry->woffset * sizeof(u32) / bytes;
-                u32 free = capacity - prev - 1;
-
-                nvgpu_log(g, gpu_dbg_pte, "cap %d prev %d free %d bytes %d",
-                                capacity, prev, free, bytes);
-
-                if (free) {
-                        memcpy(&entry->mem, &prev_entry->mem,
-                                        sizeof(entry->mem));
-                        entry->woffset = prev_entry->woffset
-                                + bytes / sizeof(u32);
-                        err = 0;
-                }
-        }
-
-        if (err) {
-                /* no suballoc space */
-                order = max(0, order);
-                err = nvgpu_alloc_gmmu_pages(vm, order, entry);
-                entry->woffset = 0;
-        }
-
-        nvgpu_log(g, gpu_dbg_pte, "entry = 0x%p, addr=%08llx, size %d, woff %x",
-                  entry,
-                  (entry->mem.priv.sgt &&
-                   entry->mem.aperture == APERTURE_SYSMEM) ?
-                  g->ops.mm.get_iova_addr(g, entry->mem.priv.sgt->sgl, 0) : 0,
-                  order, entry->woffset);
-        if (err)
-                return err;
-        entry->pgsz = pgsz_idx;
-        entry->mem.skip_wmb = true;
-
-        return err;
-}
+#define __gmmu_dbg(g, attrs, fmt, args...)                              \
+        do {                                                            \
+                if (attrs->debug)                                       \
+                        nvgpu_info(g, fmt, ##args);                     \
+                else                                                    \
+                        nvgpu_log(g, gpu_dbg_map, fmt, ##args);         \
+        } while (0)
+
+#define __gmmu_dbg_v(g, attrs, fmt, args...)                            \
+        do {                                                            \
+                if (attrs->debug)                                       \
+                        nvgpu_info(g, fmt, ##args);                     \
+                else                                                    \
+                        nvgpu_log(g, gpu_dbg_map_v, fmt, ##args);       \
+        } while (0)
+
+static int pd_allocate(struct vm_gk20a *vm,
+                       struct nvgpu_gmmu_pd *pd,
+                       const struct gk20a_mmu_level *l,
+                       struct nvgpu_gmmu_attrs *attrs);
 
 /*
  * Core GMMU map function for the kernel to use. If @addr is 0 then the GPU
@@ -225,103 +136,484 @@ void nvgpu_gmmu_unmap(struct vm_gk20a *vm, struct nvgpu_mem *mem, u64 gpu_va)
         nvgpu_mutex_release(&vm->update_gmmu_lock);
 }
 
-static int update_gmmu_level_locked(struct vm_gk20a *vm,
-                                    struct gk20a_mm_entry *pte,
-                                    enum gmmu_pgsz_gk20a pgsz_idx,
-                                    struct scatterlist **sgl,
-                                    u64 *offset,
-                                    u64 *iova,
-                                    u64 gpu_va, u64 gpu_end,
-                                    u8 kind_v, u64 *ctag,
-                                    bool cacheable, bool unmapped_pte,
-                                    int rw_flag,
-                                    bool sparse,
-                                    int lvl,
-                                    bool priv,
-                                    enum nvgpu_aperture aperture)
+int nvgpu_gmmu_init_page_table(struct vm_gk20a *vm)
+{
+        /*
+         * Need this just for page size. Everything else can be ignored. Also
+         * note that we can just use pgsz 0 (i.e small pages) since the number
+         * of bits present in the top level PDE are the same for small/large
+         * page VMs.
+         */
+        struct nvgpu_gmmu_attrs attrs = {
+                .pgsz = 0,
+        };
+
+        return pd_allocate(vm, &vm->pdb, &vm->mmu_levels[0], &attrs);
+}
+
+
+/*
+ * Ensure that there's a CPU mapping for the page directory memory. This won't
+ * always be the case for 32 bit systems since we may need to save kernel
+ * virtual memory.
+ */
+static int map_gmmu_pages(struct gk20a *g, struct nvgpu_gmmu_pd *entry)
+{
+        return nvgpu_mem_begin(g, &entry->mem);
+}
+
+/*
+ * Handle any necessary CPU unmap semantics for a page directories DMA memory.
+ * For 64 bit platforms this is a noop.
+ */
+static void unmap_gmmu_pages(struct gk20a *g, struct nvgpu_gmmu_pd *entry)
+{
+        nvgpu_mem_end(g, &entry->mem);
+}
+
+static int nvgpu_alloc_gmmu_pages(struct vm_gk20a *vm, u32 bytes,
+                                  struct nvgpu_gmmu_pd *pd)
 {
         struct gk20a *g = gk20a_from_vm(vm);
-        const struct gk20a_mmu_level *l = &vm->mmu_levels[lvl];
-        const struct gk20a_mmu_level *next_l = &vm->mmu_levels[lvl+1];
-        int err = 0;
-        u32 pde_i;
-        u64 pde_size = 1ULL << (u64)l->lo_bit[pgsz_idx];
-        struct gk20a_mm_entry *next_pte = NULL, *prev_pte = NULL;
+        unsigned long flags = NVGPU_DMA_FORCE_CONTIGUOUS;
+        int err;
+
+        /*
+         * On arm32 vmalloc space is a precious commodity so we do not map pages
+         * by default.
+         */
+        if (!IS_ENABLED(CONFIG_ARM64))
+                flags |= NVGPU_DMA_NO_KERNEL_MAPPING;
+
+        err = nvgpu_dma_alloc_flags(g, flags, bytes, &pd->mem);
+        if (err)
+                return -ENOMEM;
+
+        return 0;
+}
+
+void nvgpu_free_gmmu_pages(struct vm_gk20a *vm,
+                           struct nvgpu_gmmu_pd *pd)
+{
+        struct gk20a *g = gk20a_from_vm(vm);
+
+        nvgpu_dma_free(g, &pd->mem);
+}
+
+/*
+ * Return the _physical_ address of a page directory.
+ */
+u64 nvgpu_pde_phys_addr(struct gk20a *g, struct nvgpu_gmmu_pd *pd)
+{
+        if (g->mm.has_physical_mode)
+                return sg_phys(pd->mem.priv.sgt->sgl);
+        else
+                return nvgpu_mem_get_base_addr(g, &pd->mem, 0);
+}
+
+/*
+ * Return the aligned length based on the page size in attrs.
+ */
+static u64 nvgpu_align_map_length(struct vm_gk20a *vm, u64 length,
+                                  struct nvgpu_gmmu_attrs *attrs)
+{
+        u64 page_size = vm->gmmu_page_sizes[attrs->pgsz];
+
+        return ALIGN(length, page_size);
+}
+
+static u32 pd_entries(const struct gk20a_mmu_level *l,
+                      struct nvgpu_gmmu_attrs *attrs)
+{
+        /*
+         * Number of entries in a PD is easy to compute from the number of bits
+         * used to index the page directory. That is simply 2 raised to the
+         * number of bits.
+         */
+        return 1UL << (l->hi_bit[attrs->pgsz] - l->lo_bit[attrs->pgsz] + 1UL);
+}
+
+/*
+ * Computes the size of a PD table.
+ */
+static u32 pd_size(const struct gk20a_mmu_level *l,
+                   struct nvgpu_gmmu_attrs *attrs)
+{
+        return pd_entries(l, attrs) * l->entry_size;
+}
+
+/*
+ * Allocate a physically contiguous region big enough for a gmmu page table
+ * of the specified level and page size. The whole range is zeroed so that any
+ * accesses will fault until proper values are programmed.
+ */
+static int pd_allocate(struct vm_gk20a *vm,
+                       struct nvgpu_gmmu_pd *pd,
+                       const struct gk20a_mmu_level *l,
+                       struct nvgpu_gmmu_attrs *attrs)
+{
+        int err;
 
-        gk20a_dbg_fn("");
+        if (pd->mem.size)
+                return 0;
 
-        pde_i = (gpu_va & ((1ULL << ((u64)l->hi_bit[pgsz_idx]+1)) - 1ULL))
-                >> (u64)l->lo_bit[pgsz_idx];
+        err = nvgpu_alloc_gmmu_pages(vm, pd_size(l, attrs), pd);
+        if (err) {
+                nvgpu_info(vm->mm->g, "error allocating page directory!");
+                return err;
+        }
 
-        gk20a_dbg(gpu_dbg_pte, "size_idx=%d, l: %d, [%llx,%llx], iova=%llx",
-                  pgsz_idx, lvl, gpu_va, gpu_end-1, *iova);
+        /*
+         * One mb() is done after all mapping operations. Don't need individual
+         * barriers for each PD write.
+         */
+        pd->mem.skip_wmb = true;
 
-        while (gpu_va < gpu_end) {
-                u64 next = min((gpu_va + pde_size) & ~(pde_size-1), gpu_end);
+        return 0;
+}
 
-                /* Allocate next level */
+/*
+ * Compute what page directory index at the passed level the passed virtual
+ * address corresponds to. @attrs is necessary for determining the page size
+ * which is used to pick the right bit offsets for the GMMU level.
+ */
+static u32 pd_index(const struct gk20a_mmu_level *l, u64 virt,
+                    struct nvgpu_gmmu_attrs *attrs)
+{
+        u64 pd_mask = (1ULL << ((u64)l->hi_bit[attrs->pgsz] + 1)) - 1ULL;
+        u32 pd_shift = (u64)l->lo_bit[attrs->pgsz];
+
+        /*
+         * For convenience we don't bother computing the lower bound of the
+         * mask; it's easier to just shift it off.
+         */
+        return (virt & pd_mask) >> pd_shift;
+}
+
+static int pd_allocate_children(struct vm_gk20a *vm,
+                                const struct gk20a_mmu_level *l,
+                                struct nvgpu_gmmu_pd *pd,
+                                struct nvgpu_gmmu_attrs *attrs)
+{
+        struct gk20a *g = gk20a_from_vm(vm);
+
+        if (pd->entries)
+                return 0;
+
+        pd->num_entries = pd_entries(l, attrs);
+        pd->entries = nvgpu_vzalloc(g, sizeof(struct nvgpu_gmmu_pd) *
+                                    pd->num_entries);
+        if (!pd->entries)
+                return -ENOMEM;
+
+        return 0;
+}
+
+/*
+ * This function programs the GMMU based on two ranges: a physical range and a
+ * GPU virtual range. The virtual is mapped to the physical. Physical in this
+ * case can mean either a real physical sysmem address or a IO virtual address
+ * (for instance when a system has an IOMMU running).
+ *
+ * The rest of the parameters are for describing the actual mapping itself.
+ *
+ * This function recursively calls itself for handling PDEs. At the final level
+ * a PTE handler is called. The phys and virt ranges are adjusted for each
+ * recursion so that each invocation of this function need only worry about the
+ * range it is passed.
+ *
+ * phys_addr will always point to a contiguous range - the discontiguous nature
+ * of DMA buffers is taken care of at the layer above this.
+ */
+static int __set_pd_level(struct vm_gk20a *vm,
+                          struct nvgpu_gmmu_pd *pd,
+                          int lvl,
+                          u64 phys_addr,
+                          u64 virt_addr, u64 length,
+                          struct nvgpu_gmmu_attrs *attrs)
+{
+        int err = 0;
+        u64 pde_range;
+        struct gk20a *g = gk20a_from_vm(vm);
+        struct nvgpu_gmmu_pd *next_pd = NULL;
+        const struct gk20a_mmu_level *l      = &vm->mmu_levels[lvl];
+        const struct gk20a_mmu_level *next_l = &vm->mmu_levels[lvl + 1];
+
+        /*
+         * 5 levels for Pascal+. For pre-pascal we only have 2. This puts
+         * offsets into the page table debugging code which makes it easier to
+         * see what level prints are from.
+         */
+        static const char *__lvl_debug[] = {
+                "",          /* L=0 */
+                "  ",        /* L=1 */
+                "    ",      /* L=2 */
+                "      ",    /* L=3 */
+                "        ",  /* L=4 */
+        };
+
+        pde_range = 1ULL << (u64)l->lo_bit[attrs->pgsz];
+
+        __gmmu_dbg_v(g, attrs,
+                     "L=%d   %sGPU virt %#-12llx +%#-9llx -> phys %#-12llx",
+                     lvl,
+                     __lvl_debug[lvl],
+                     virt_addr,
+                     length,
+                     phys_addr);
+
+        /*
+         * Iterate across the mapping in chunks the size of this level's PDE.
+         * For each of those chunks program our level's PDE and then, if there's
+         * a next level, program the next level's PDEs/PTEs.
+         */
+        while (length) {
+                u32 pd_idx = pd_index(l, virt_addr, attrs);
+                u64 chunk_size;
+                u64 target_addr;
+
+                /*
+                 * Truncate the pde_range when the virtual address does not
+                 * start at a PDE boundary.
+                 */
+                chunk_size = min(length,
+                                 pde_range - (virt_addr & (pde_range - 1)));
+
+                /*
+                 * If the next level has an update_entry function then we know
+                 * that _this_ level points to PDEs (not PTEs). Thus we need to
+                 * have a bunch of children PDs.
+                 */
                 if (next_l->update_entry) {
-                        if (!pte->entries) {
-                                int num_entries =
-                                        1 <<
-                                         (l->hi_bit[pgsz_idx]
-                                          - l->lo_bit[pgsz_idx] + 1);
-                                pte->entries =
-                                        nvgpu_vzalloc(g,
-                                                sizeof(struct gk20a_mm_entry) *
-                                                num_entries);
-                                if (!pte->entries)
-                                        return -ENOMEM;
-                                pte->pgsz = pgsz_idx;
-                                pte->num_entries = num_entries;
-                        }
-                        prev_pte = next_pte;
-                        next_pte = pte->entries + pde_i;
-
-                        if (!next_pte->mem.size) {
-                                err = nvgpu_zalloc_gmmu_page_table(vm,
-                                        pgsz_idx, next_l, next_pte, prev_pte);
-                                if (err)
-                                        return err;
-                        }
+                        if (pd_allocate_children(vm, l, pd, attrs))
+                                return -ENOMEM;
+
+                        /*
+                         * Get the next PD so that we know what to put in this
+                         * current PD. If the next level is actually PTEs then
+                         * we don't need this - we will just use the real
+                         * physical target.
+                         */
+                        next_pd = &pd->entries[pd_idx];
+
+                        /*
+                         * Allocate the backing memory for next_pd.
+                         */
+                        if (pd_allocate(vm, next_pd, next_l, attrs))
+                                return -ENOMEM;
                 }
 
-                err = l->update_entry(vm, pte, pde_i, pgsz_idx,
-                                sgl, offset, iova,
-                                kind_v, ctag, cacheable, unmapped_pte,
-                                rw_flag, sparse, priv, aperture);
-                if (err)
-                        return err;
+                /*
+                 * This is the address we want to program into the actual PDE/
+                 * PTE. When the next level is PDEs we need the target address
+                 * to be the table of PDEs. When the next level is PTEs the
+                 * target addr is the real physical address we are aiming for.
+                 */
+                target_addr = next_pd ? nvgpu_pde_phys_addr(g, next_pd) :
+                                        phys_addr;
+
+                l->update_entry(vm, l,
+                                pd, pd_idx,
+                                virt_addr,
+                                target_addr,
+                                attrs);
 
                 if (next_l->update_entry) {
-                        /* get cpu access to the ptes */
-                        err = map_gmmu_pages(g, next_pte);
+                        err = map_gmmu_pages(g, next_pd);
                         if (err) {
                                 nvgpu_err(g,
-                                           "couldn't map ptes for update as=%d",
-                                           vm_aspace_id(vm));
+                                          "couldn't map ptes for update as=%d",
+                                          vm_aspace_id(vm));
                                 return err;
                         }
-                        err = update_gmmu_level_locked(vm, next_pte,
-                                pgsz_idx,
-                                sgl,
-                                offset,
-                                iova,
-                                gpu_va,
-                                next,
-                                kind_v, ctag, cacheable, unmapped_pte,
-                                rw_flag, sparse, lvl+1, priv, aperture);
-                        unmap_gmmu_pages(g, next_pte);
+
+                        err = __set_pd_level(vm, next_pd,
+                                             lvl + 1,
+                                             phys_addr,
+                                             virt_addr,
+                                             chunk_size,
+                                             attrs);
+                        unmap_gmmu_pages(g, next_pd);
 
                         if (err)
                                 return err;
                 }
 
-                pde_i++;
-                gpu_va = next;
+                virt_addr += chunk_size;
+
+                /*
+                 * Only add to phys_addr if it's non-zero. A zero value implies
+                 * we are unmapping as as a result we don't want to place
+                 * non-zero phys addresses in the PTEs. A non-zero phys-addr
+                 * would also confuse the lower level PTE programming code.
+                 */
+                if (phys_addr)
+                        phys_addr += chunk_size;
+                length -= chunk_size;
+        }
+
+        __gmmu_dbg_v(g, attrs, "L=%d   %s%s", lvl, __lvl_debug[lvl], "ret!");
+
+        return 0;
+}
+
+/*
+ * VIDMEM version of the update_ptes logic.
+ */
+static int __nvgpu_gmmu_update_page_table_vidmem(struct vm_gk20a *vm,
+                                                 struct sg_table *sgt,
+                                                 u64 space_to_skip,
+                                                 u64 virt_addr,
+                                                 u64 length,
+                                                 struct nvgpu_gmmu_attrs *attrs)
+{
+        struct nvgpu_page_alloc *alloc = NULL;
+        struct page_alloc_chunk *chunk = NULL;
+        u64 phys_addr, chunk_length;
+        int err = 0;
+
+        if (!sgt) {
+                /*
+                 * This is considered an unmap. Just pass in 0 as the physical
+                 * address for the entire GPU range.
+                 */
+                err = __set_pd_level(vm, &vm->pdb,
+                                     0,
+                                     0,
+                                     virt_addr, length,
+                                     attrs);
+                return err;
+        }
+
+        alloc = get_vidmem_page_alloc(sgt->sgl);
+
+        /*
+         * Otherwise iterate across all the chunks in this allocation and
+         * map them.
+         */
+        nvgpu_list_for_each_entry(chunk, &alloc->alloc_chunks,
+                                  page_alloc_chunk, list_entry) {
+                if (space_to_skip &&
+                    space_to_skip >= chunk->length) {
+                        space_to_skip -= chunk->length;
+                        continue;
+                }
+
+                phys_addr = chunk->base + space_to_skip;
+                chunk_length = min(length, (chunk->length - space_to_skip));
+
+                err = __set_pd_level(vm, &vm->pdb,
+                                     0,
+                                     phys_addr,
+                                     virt_addr, length,
+                                     attrs);
+                if (err)
+                        break;
+
+                /* Space has been skipped so zero this for future chunks. */
+                space_to_skip = 0;
+
+                /*
+                 * Update the map pointer and the remaining length.
+                 */
+                virt_addr += chunk_length;
+                length    -= chunk_length;
+
+                if (length == 0)
+                        break;
         }
 
-        gk20a_dbg_fn("done");
+        return err;
+}
+
+static int __nvgpu_gmmu_update_page_table_sysmem(struct vm_gk20a *vm,
+                                                 struct sg_table *sgt,
+                                                 u64 space_to_skip,
+                                                 u64 virt_addr,
+                                                 u64 length,
+                                                 struct nvgpu_gmmu_attrs *attrs)
+{
+        int err;
+        struct scatterlist *sgl;
+        struct gk20a *g = gk20a_from_vm(vm);
+
+        if (!sgt) {
+                /*
+                 * This is considered an unmap. Just pass in 0 as the physical
+                 * address for the entire GPU range.
+                 */
+                err = __set_pd_level(vm, &vm->pdb,
+                                     0,
+                                     0,
+                                     virt_addr, length,
+                                     attrs);
+                return err;
+        }
+
+        /*
+         * At this point we have a Linux scatter-gather list pointing to some
+         * number of discontiguous chunks of memory. Iterate over that list and
+         * generate a GMMU map call for each chunk. There are two possibilities:
+         * either the IOMMU is enabled or not. When the IOMMU is enabled the
+         * mapping is simple since the "physical" address is actually a virtual
+         * IO address and will be contiguous. The no-IOMMU case is more
+         * complicated. We will have to iterate over the SGT and do a separate
+         * map for each chunk of the SGT.
+         */
+        sgl = sgt->sgl;
+
+        if (!g->mm.bypass_smmu) {
+                u64 io_addr = g->ops.mm.get_iova_addr(g, sgl, 0);
+
+                io_addr += space_to_skip;
+
+                err = __set_pd_level(vm, &vm->pdb,
+                                     0,
+                                     io_addr,
+                                     virt_addr,
+                                     length,
+                                     attrs);
+
+                return err;
+        }
+
+        /*
+         * Finally: last possible case: do the no-IOMMU mapping. In this case we
+         * really are mapping physical pages directly.
+         */
+        while (sgl) {
+                u64 phys_addr;
+                u64 chunk_length;
+
+                /*
+                 * Cut out sgl ents for space_to_skip.
+                 */
+                if (space_to_skip && space_to_skip >= sgl->length) {
+                        space_to_skip -= sgl->length;
+                        sgl = sg_next(sgl);
+                        continue;
+                }
+
+                phys_addr = sg_phys(sgl) + space_to_skip;
+                chunk_length = min(length, sgl->length - space_to_skip);
+
+                err = __set_pd_level(vm, &vm->pdb,
+                                     0,
+                                     phys_addr,
+                                     virt_addr,
+                                     chunk_length,
+                                     attrs);
+                if (err)
+                        return err;
+
+                space_to_skip = 0;
+                virt_addr += chunk_length;
+                length    -= chunk_length;
+                sgl        = sg_next(sgl);
+
+                if (length == 0)
+                        break;
+        }
 
         return 0;
 }
@@ -332,8 +624,8 @@ static int update_gmmu_level_locked(struct vm_gk20a *vm,
  * physical* address.
  *
  * The update of each level of the page tables is farmed out to chip specific
- * implementations. But the logic around that is generic to all chips. Every chip
- * has some number of PDE levels and then a PTE level.
+ * implementations. But the logic around that is generic to all chips. Every
+ * chip has some number of PDE levels and then a PTE level.
  *
  * Each chunk of the incoming SGT is sent to the chip specific implementation
  * of page table update.
@@ -341,148 +633,81 @@ static int update_gmmu_level_locked(struct vm_gk20a *vm,
  * [*] Note: the "physical" address may actually be an IO virtual address in the
  *     case of SMMU usage.
  */
-static int update_gmmu_ptes_locked(struct vm_gk20a *vm,
-                                   enum gmmu_pgsz_gk20a pgsz_idx,
-                                   struct sg_table *sgt,
-                                   u64 buffer_offset,
-                                   u64 gpu_va, u64 gpu_end,
-                                   u8 kind_v, u32 ctag_offset,
-                                   bool cacheable, bool unmapped_pte,
-                                   int rw_flag,
-                                   bool sparse,
-                                   bool priv,
-                                   enum nvgpu_aperture aperture)
+static int __nvgpu_gmmu_update_page_table(struct vm_gk20a *vm,
+                                          struct sg_table *sgt,
+                                          u64 space_to_skip,
+                                          u64 virt_addr,
+                                          u64 length,
+                                          struct nvgpu_gmmu_attrs *attrs)
 {
         struct gk20a *g = gk20a_from_vm(vm);
-        int ctag_granularity = g->ops.fb.compression_page_size(g);
-        u64 ctag = (u64)ctag_offset * (u64)ctag_granularity;
-        u64 iova = 0;
-        u64 space_to_skip = buffer_offset;
-        u64 map_size = gpu_end - gpu_va;
-        u32 page_size  = vm->gmmu_page_sizes[pgsz_idx];
+        u32 page_size;
         int err;
-        struct scatterlist *sgl = NULL;
-        struct nvgpu_page_alloc *alloc = NULL;
-        struct page_alloc_chunk *chunk = NULL;
-        u64 length;
 
         /* note: here we need to map kernel to small, since the
          * low-level mmu code assumes 0 is small and 1 is big pages */
-        if (pgsz_idx == gmmu_page_size_kernel)
-                pgsz_idx = gmmu_page_size_small;
+        if (attrs->pgsz == gmmu_page_size_kernel)
+                attrs->pgsz = gmmu_page_size_small;
+
+        page_size = vm->gmmu_page_sizes[attrs->pgsz];
 
         if (space_to_skip & (page_size - 1))
                 return -EINVAL;
 
+        /*
+         * Update length to be aligned to the passed page size.
+         */
+        length = nvgpu_align_map_length(vm, length, attrs);
+
         err = map_gmmu_pages(g, &vm->pdb);
         if (err) {
-                nvgpu_err(g,
-                           "couldn't map ptes for update as=%d",
-                           vm_aspace_id(vm));
+                nvgpu_err(g, "couldn't map ptes for update as=%d",
+                          vm_aspace_id(vm));
                 return err;
         }
 
-        if (aperture == APERTURE_VIDMEM) {
-                gmmu_dbg_v(g, "vidmem map size_idx=%d, gpu_va=[%llx,%llx]",
-                           pgsz_idx, gpu_va, gpu_end-1);
-
-                if (sgt) {
-                        alloc = get_vidmem_page_alloc(sgt->sgl);
-
-                        nvgpu_list_for_each_entry(chunk, &alloc->alloc_chunks,
-                                                 page_alloc_chunk, list_entry) {
-                                if (space_to_skip &&
-                                    space_to_skip > chunk->length) {
-                                        space_to_skip -= chunk->length;
-                                } else {
-                                        iova = chunk->base + space_to_skip;
-                                        length = chunk->length - space_to_skip;
-                                        length = min(length, map_size);
-                                        space_to_skip = 0;
-
-                                        err = update_gmmu_level_locked(vm,
-                                                &vm->pdb, pgsz_idx,
-                                                &sgl,
-                                                &space_to_skip,
-                                                &iova,
-                                                gpu_va, gpu_va + length,
-                                                kind_v, &ctag,
-                                                cacheable, unmapped_pte,
-                                                rw_flag, sparse, 0, priv,
-                                                aperture);
-                                        if (err)
-                                                break;
-
-                                        /* need to set explicit zero here */
-                                        space_to_skip = 0;
-                                        gpu_va += length;
-                                        map_size -= length;
-
-                                        if (!map_size)
-                                                break;
-                                }
-                        }
-                } else {
-                        err = update_gmmu_level_locked(vm, &vm->pdb, pgsz_idx,
-                                        &sgl,
-                                        &space_to_skip,
-                                        &iova,
-                                        gpu_va, gpu_end,
-                                        kind_v, &ctag,
-                                        cacheable, unmapped_pte, rw_flag,
-                                        sparse, 0, priv,
-                                        aperture);
-                }
-        } else {
-                gmmu_dbg_v(g,
-                           "pgsz=%-6d, gpu_va: %#-12llx +%#-6llx  phys: %#-12llx "
-                           "buffer offset: %-4lld, nents: %d",
-                           page_size,
-                           gpu_va, gpu_end - gpu_va,
-                           sgt ? g->ops.mm.get_iova_addr(g, sgt->sgl, 0) : 0ULL,
-                           buffer_offset,
-                           sgt ? sgt->nents : 0);
-
-                if (sgt) {
-                        iova = g->ops.mm.get_iova_addr(vm->mm->g, sgt->sgl, 0);
-                        if (!vm->mm->bypass_smmu && iova) {
-                                iova += space_to_skip;
-                        } else {
-                                sgl = sgt->sgl;
-
-                                gk20a_dbg(gpu_dbg_pte, "chunk address %llx, size %d",
-                                                (u64)sg_phys(sgl),
-                                                sgl->length);
-
-                                while (space_to_skip && sgl &&
-                                      space_to_skip + page_size > sgl->length) {
-                                        space_to_skip -= sgl->length;
-                                        sgl = sg_next(sgl);
-                                        gk20a_dbg(gpu_dbg_pte, "chunk address %llx, size %d",
-                                                        (u64)sg_phys(sgl),
-                                                        sgl->length);
-                                }
-
-                                iova = sg_phys(sgl) + space_to_skip;
-                        }
-                }
-
-                err = update_gmmu_level_locked(vm, &vm->pdb, pgsz_idx,
-                                &sgl,
-                                &space_to_skip,
-                                &iova,
-                                gpu_va, gpu_end,
-                                kind_v, &ctag,
-                                cacheable, unmapped_pte, rw_flag,
-                                sparse, 0, priv,
-                                aperture);
-        }
+        __gmmu_dbg(g, attrs,
+                   "vm=%s "
+                   "%-5s GPU virt %#-12llx +%#-9llx    phys %#-12llx "
+                   "phys offset: %#-4llx;  pgsz: %3dkb perm=%-2s | "
+                   "kind=%#02x APT=%-6s %c%c%c",
+                   vm->name,
+                   sgt ? "MAP" : "UNMAP",
+                   virt_addr,
+                   length,
+                   sgt ? g->ops.mm.get_iova_addr(g, sgt->sgl, 0) : 0ULL,
+                   space_to_skip,
+                   page_size >> 10,
+                   nvgpu_gmmu_perm_str(attrs->rw_flag),
+                   attrs->kind_v,
+                   nvgpu_aperture_str(attrs->aperture),
+                   attrs->cacheable ? 'C' : 'V', /* C = cached, V = volatile. */
+                   attrs->sparse    ? 'S' : '-',
+                   attrs->priv      ? 'P' : '-');
+
+        /*
+         * Handle VIDMEM progamming. Currently uses a different scatter list
+         * format.
+         */
+        if (attrs->aperture == APERTURE_VIDMEM)
+                err = __nvgpu_gmmu_update_page_table_vidmem(vm,
+                                                            sgt,
+                                                            space_to_skip,
+                                                            virt_addr,
+                                                            length,
+                                                            attrs);
+        else
+                err = __nvgpu_gmmu_update_page_table_sysmem(vm,
+                                                            sgt,
+                                                            space_to_skip,
+                                                            virt_addr,
+                                                            length,
+                                                            attrs);
 
         unmap_gmmu_pages(g, &vm->pdb);
-
         mb();
 
-        gk20a_dbg_fn("done");
+        __gmmu_dbg(g, attrs, "%-5s Done!", sgt ? "MAP" : "UNMAP");
 
         return err;
 }
@@ -500,32 +725,44 @@ static int update_gmmu_ptes_locked(struct vm_gk20a *vm,
  * have the update_gmmu_lock aquired.
  */
 u64 gk20a_locked_gmmu_map(struct vm_gk20a *vm,
-                        u64 map_offset,
-                        struct sg_table *sgt,
-                        u64 buffer_offset,
-                        u64 size,
-                        int pgsz_idx,
-                        u8 kind_v,
-                        u32 ctag_offset,
-                        u32 flags,
-                        int rw_flag,
-                        bool clear_ctags,
-                        bool sparse,
-                        bool priv,
-                        struct vm_gk20a_mapping_batch *batch,
-                        enum nvgpu_aperture aperture)
+                          u64 vaddr,
+                          struct sg_table *sgt,
+                          u64 buffer_offset,
+                          u64 size,
+                          int pgsz_idx,
+                          u8 kind_v,
+                          u32 ctag_offset,
+                          u32 flags,
+                          int rw_flag,
+                          bool clear_ctags,
+                          bool sparse,
+                          bool priv,
+                          struct vm_gk20a_mapping_batch *batch,
+                          enum nvgpu_aperture aperture)
 {
+        struct gk20a *g = gk20a_from_vm(vm);
         int err = 0;
         bool allocated = false;
-        struct gk20a *g = gk20a_from_vm(vm);
         int ctag_granularity = g->ops.fb.compression_page_size(g);
-        u32 ctag_lines = DIV_ROUND_UP_ULL(size, ctag_granularity);
-
-        /* Allocate (or validate when map_offset != 0) the virtual address. */
-        if (!map_offset) {
-                map_offset = __nvgpu_vm_alloc_va(vm, size,
-                                          pgsz_idx);
-                if (!map_offset) {
+        struct nvgpu_gmmu_attrs attrs = {
+                .pgsz      = pgsz_idx,
+                .kind_v    = kind_v,
+                .ctag      = (u64)ctag_offset * (u64)ctag_granularity,
+                .cacheable = flags & NVGPU_MAP_BUFFER_FLAGS_CACHEABLE_TRUE,
+                .rw_flag   = rw_flag,
+                .sparse    = sparse,
+                .priv      = priv,
+                .valid     = !(flags & NVGPU_AS_MAP_BUFFER_FLAGS_UNMAPPED_PTE),
+                .aperture  = aperture
+        };
+
+        /*
+         * Only allocate a new GPU VA range if we haven't already been passed a
+         * GPU VA range. This facilitates fixed mappings.
+         */
+        if (!vaddr) {
+                vaddr = __nvgpu_vm_alloc_va(vm, size, pgsz_idx);
+                if (!vaddr) {
                         nvgpu_err(g, "failed to allocate va space");
                         err = -ENOMEM;
                         goto fail_alloc;
@@ -533,34 +770,8 @@ u64 gk20a_locked_gmmu_map(struct vm_gk20a *vm,
                 allocated = true;
         }
 
-        gmmu_dbg(g,
-                 "gv: 0x%04x_%08x + 0x%-7llx "
-                 "[dma: 0x%02x_%08x, pa: 0x%02x_%08x] "
-                 "pgsz=%-3dKb as=%-2d ctags=%d start=%d "
-                 "kind=0x%x flags=0x%x apt=%s",
-                 u64_hi32(map_offset), u64_lo32(map_offset), size,
-                 sgt ? u64_hi32((u64)sg_dma_address(sgt->sgl)) : 0,
-                 sgt ? u64_lo32((u64)sg_dma_address(sgt->sgl)) : 0,
-                 sgt ? u64_hi32((u64)sg_phys(sgt->sgl)) : 0,
-                 sgt ? u64_lo32((u64)sg_phys(sgt->sgl)) : 0,
-                 vm->gmmu_page_sizes[pgsz_idx] >> 10, vm_aspace_id(vm),
-                 ctag_lines, ctag_offset,
-                 kind_v, flags, nvgpu_aperture_str(aperture));
-
-        err = update_gmmu_ptes_locked(vm, pgsz_idx,
-                                      sgt,
-                                      buffer_offset,
-                                      map_offset, map_offset + size,
-                                      kind_v,
-                                      ctag_offset,
-                                      flags &
-                                      NVGPU_MAP_BUFFER_FLAGS_CACHEABLE_TRUE,
-                                      flags &
-                                      NVGPU_AS_MAP_BUFFER_FLAGS_UNMAPPED_PTE,
-                                      rw_flag,
-                                      sparse,
-                                      priv,
-                                      aperture);
+        err = __nvgpu_gmmu_update_page_table(vm, sgt, buffer_offset,
+                                             vaddr, size, &attrs);
         if (err) {
                 nvgpu_err(g, "failed to update ptes on map");
                 goto fail_validate;
@@ -571,26 +782,37 @@ u64 gk20a_locked_gmmu_map(struct vm_gk20a *vm,
         else
                 batch->need_tlb_invalidate = true;
 
-        return map_offset;
+        return vaddr;
 fail_validate:
         if (allocated)
-                __nvgpu_vm_free_va(vm, map_offset, pgsz_idx);
+                __nvgpu_vm_free_va(vm, vaddr, pgsz_idx);
 fail_alloc:
         nvgpu_err(g, "%s: failed with err=%d", __func__, err);
         return 0;
 }
 
 void gk20a_locked_gmmu_unmap(struct vm_gk20a *vm,
-                        u64 vaddr,
-                        u64 size,
-                        int pgsz_idx,
-                        bool va_allocated,
-                        int rw_flag,
-                        bool sparse,
-                        struct vm_gk20a_mapping_batch *batch)
+                             u64 vaddr,
+                             u64 size,
+                             int pgsz_idx,
+                             bool va_allocated,
+                             int rw_flag,
+                             bool sparse,
+                             struct vm_gk20a_mapping_batch *batch)
 {
         int err = 0;
         struct gk20a *g = gk20a_from_vm(vm);
+        struct nvgpu_gmmu_attrs attrs = {
+                .pgsz      = pgsz_idx,
+                .kind_v    = 0,
+                .ctag      = 0,
+                .cacheable = 0,
+                .rw_flag   = rw_flag,
+                .sparse    = sparse,
+                .priv      = 0,
+                .valid     = 0,
+                .aperture  = APERTURE_INVALID,
+        };
 
         if (va_allocated) {
                 err = __nvgpu_vm_free_va(vm, vaddr, pgsz_idx);
@@ -601,27 +823,11 @@ void gk20a_locked_gmmu_unmap(struct vm_gk20a *vm,
         }
 
         /* unmap here needs to know the page size we assigned at mapping */
-        err = update_gmmu_ptes_locked(vm,
-                                pgsz_idx,
-                                NULL, /* n/a for unmap */
-                                0,
-                                vaddr,
-                                vaddr + size,
-                                0, 0, false /* n/a for unmap */,
-                                false, rw_flag,
-                                sparse, 0,
-                                APERTURE_INVALID); /* don't care for unmap */
+        err = __nvgpu_gmmu_update_page_table(vm, NULL, 0,
+                                             vaddr, size, &attrs);
         if (err)
                 nvgpu_err(g, "failed to update gmmu ptes on unmap");
 
-        /* flush l2 so any dirty lines are written out *now*.
-         *  also as we could potentially be switching this buffer
-         * from nonvolatile (l2 cacheable) to volatile (l2 non-cacheable) at
-         * some point in the future we need to invalidate l2.  e.g. switching
-         * from a render buffer unmap (here) to later using the same memory
-         * for gmmu ptes.  note the positioning of this relative to any smmu
-         * unmapping (below). */
-
         if (!batch) {
                 gk20a_mm_l2_flush(g, true);
                 g->ops.fb.tlb_invalidate(g, &vm->pdb.mem);