drm/panthor: Split panthor_vm_prepare_map_op_ctx() to prepare for reclaim

We're gonna need just the page table reservation logic when we restore
evicted BO mappings, so let's prepare for that by extracting the
op_ctx init and page table pre-allocation into separate helpers.

v2:
- Collect R-bs

v3:
- No changes

v4:
- No changes

v5:
- No changes

v6:
- No changes

v7:
- No changes

Reviewed-by: Liviu Dudau <liviu.dudau@arm.com>
Reviewed-by: Steven Price <steven.price@arm.com>
Link: https://patch.msgid.link/20260401134854.2275433-9-boris.brezillon@collabora.com
Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>

diff --git a/drivers/gpu/drm/panthor/panthor_mmu.c b/drivers/gpu/drm/panthor/panthor_mmu.c
index 1f42ff505883fd72f3c0f763ce3115a197314947..b78f694ca92b4603536557cc63be58c789a9affa 100644 (file)
--- a/drivers/gpu/drm/panthor/panthor_mmu.c
+++ b/drivers/gpu/drm/panthor/panthor_mmu.c
@@ -1175,6 +1175,44 @@ panthor_vm_op_ctx_prealloc_vmas(struct panthor_vm_op_ctx *op_ctx)
        return 0;
 }
 
+static void panthor_vm_init_op_ctx(struct panthor_vm_op_ctx *op_ctx,
+                                  u64 size, u64 va, u32 flags)
+{
+       memset(op_ctx, 0, sizeof(*op_ctx));
+       op_ctx->flags = flags;
+       op_ctx->va.range = size;
+       op_ctx->va.addr = va;
+}
+
+static int panthor_vm_op_ctx_prealloc_pts(struct panthor_vm_op_ctx *op_ctx)
+{
+       u64 size = op_ctx->va.range;
+       u64 va = op_ctx->va.addr;
+       int ret;
+
+       /* L1, L2 and L3 page tables.
+        * We could optimize L3 allocation by iterating over the sgt and merging
+        * 2M contiguous blocks, but it's simpler to over-provision and return
+        * the pages if they're not used.
+        */
+       u64 pt_count = ((ALIGN(va + size, 1ull << 39) - ALIGN_DOWN(va, 1ull << 39)) >> 39) +
+                      ((ALIGN(va + size, 1ull << 30) - ALIGN_DOWN(va, 1ull << 30)) >> 30) +
+                      ((ALIGN(va + size, 1ull << 21) - ALIGN_DOWN(va, 1ull << 21)) >> 21);
+
+       op_ctx->rsvd_page_tables.pages = kzalloc_objs(*op_ctx->rsvd_page_tables.pages,
+                                                     pt_count);
+       if (!op_ctx->rsvd_page_tables.pages)
+               return -ENOMEM;
+
+       ret = kmem_cache_alloc_bulk(pt_cache, GFP_KERNEL, pt_count,
+                                   op_ctx->rsvd_page_tables.pages);
+       op_ctx->rsvd_page_tables.count = ret;
+       if (ret != pt_count)
+               return -ENOMEM;
+
+       return 0;
+}
+
 #define PANTHOR_VM_BIND_OP_MAP_FLAGS \
        (DRM_PANTHOR_VM_BIND_OP_MAP_READONLY | \
         DRM_PANTHOR_VM_BIND_OP_MAP_NOEXEC | \
@@ -1190,7 +1228,6 @@ static int panthor_vm_prepare_map_op_ctx(struct panthor_vm_op_ctx *op_ctx,
 {
        struct drm_gpuvm_bo *preallocated_vm_bo;
        struct sg_table *sgt = NULL;
-       u64 pt_count;
        int ret;
 
        if (!bo)
@@ -1209,10 +1246,7 @@ static int panthor_vm_prepare_map_op_ctx(struct panthor_vm_op_ctx *op_ctx,
            bo->exclusive_vm_root_gem != panthor_vm_root_gem(vm))
                return -EINVAL;
 
-       memset(op_ctx, 0, sizeof(*op_ctx));
-       op_ctx->flags = flags;
-       op_ctx->va.range = size;
-       op_ctx->va.addr = va;
+       panthor_vm_init_op_ctx(op_ctx, size, va, flags);
 
        ret = panthor_vm_op_ctx_prealloc_vmas(op_ctx);
        if (ret)
@@ -1244,29 +1278,9 @@ static int panthor_vm_prepare_map_op_ctx(struct panthor_vm_op_ctx *op_ctx,
        op_ctx->map.vm_bo = drm_gpuvm_bo_obtain_prealloc(preallocated_vm_bo);
        op_ctx->map.bo_offset = offset;
 
-       /* L1, L2 and L3 page tables.
-        * We could optimize L3 allocation by iterating over the sgt and merging
-        * 2M contiguous blocks, but it's simpler to over-provision and return
-        * the pages if they're not used.
-        */
-       pt_count = ((ALIGN(va + size, 1ull << 39) - ALIGN_DOWN(va, 1ull << 39)) >> 39) +
-                  ((ALIGN(va + size, 1ull << 30) - ALIGN_DOWN(va, 1ull << 30)) >> 30) +
-                  ((ALIGN(va + size, 1ull << 21) - ALIGN_DOWN(va, 1ull << 21)) >> 21);
-
-       op_ctx->rsvd_page_tables.pages = kzalloc_objs(*op_ctx->rsvd_page_tables.pages,
-                                                     pt_count);
-       if (!op_ctx->rsvd_page_tables.pages) {
-               ret = -ENOMEM;
-               goto err_cleanup;
-       }
-
-       ret = kmem_cache_alloc_bulk(pt_cache, GFP_KERNEL, pt_count,
-                                   op_ctx->rsvd_page_tables.pages);
-       op_ctx->rsvd_page_tables.count = ret;
-       if (ret != pt_count) {
-               ret = -ENOMEM;
+       ret = panthor_vm_op_ctx_prealloc_pts(op_ctx);
+       if (ret)
                goto err_cleanup;
-       }
 
        /* Insert BO into the extobj list last, when we know nothing can fail. */
        if (bo->base.resv != panthor_vm_resv(vm)) {