[PATCH v2 7/7] drm/panthor: Add support for repeated mappings
From: Caterina Shablia
Date: Thu Jul 03 2025 - 11:38:29 EST
From: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxx>
This allows us to optimize mapping of a relatively small
portion of a BO over and over in a large VA range, which
is useful to support Vulkan sparse bindings in an efficient
way.
Signed-off-by: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxx>
Co-developed-by: Caterina Shablia <caterina.shablia@xxxxxxxxxxxxx>
Signed-off-by: Caterina Shablia <caterina.shablia@xxxxxxxxxxxxx>
---
drivers/gpu/drm/panthor/panthor_drv.c | 3 +-
drivers/gpu/drm/panthor/panthor_mmu.c | 78 ++++++++++++++++++++++++---
include/uapi/drm/panthor_drm.h | 23 ++++++++
3 files changed, 95 insertions(+), 9 deletions(-)
diff --git a/drivers/gpu/drm/panthor/panthor_drv.c b/drivers/gpu/drm/panthor/panthor_drv.c
index 1116f2d2826e..585c07b07c42 100644
--- a/drivers/gpu/drm/panthor/panthor_drv.c
+++ b/drivers/gpu/drm/panthor/panthor_drv.c
@@ -1608,6 +1608,7 @@ static void panthor_debugfs_init(struct drm_minor *minor)
* - 1.3 - adds DRM_PANTHOR_GROUP_STATE_INNOCENT flag
* - 1.4 - adds DRM_IOCTL_PANTHOR_BO_SET_LABEL ioctl
* - 1.5 - adds DRM_PANTHOR_SET_USER_MMIO_OFFSET ioctl
+ * - 1.6 - adds DRM_PANTHOR_VM_BIND_OP_MAP_REPEAT flag
*/
static const struct drm_driver panthor_drm_driver = {
.driver_features = DRIVER_RENDER | DRIVER_GEM | DRIVER_SYNCOBJ |
@@ -1621,7 +1622,7 @@ static const struct drm_driver panthor_drm_driver = {
.name = "panthor",
.desc = "Panthor DRM driver",
.major = 1,
- .minor = 5,
+ .minor = 6,
.gem_create_object = panthor_gem_create_object,
.gem_prime_import_sg_table = drm_gem_shmem_prime_import_sg_table,
diff --git a/drivers/gpu/drm/panthor/panthor_mmu.c b/drivers/gpu/drm/panthor/panthor_mmu.c
index a7852485e638..adea26985c31 100644
--- a/drivers/gpu/drm/panthor/panthor_mmu.c
+++ b/drivers/gpu/drm/panthor/panthor_mmu.c
@@ -202,6 +202,9 @@ struct panthor_vm_op_ctx {
/** @map.bo_offset: Offset in the buffer object. */
u64 bo_offset;
+ /** @bo_repeat_range: Repeated BO range. */
+ u32 bo_repeat_range;
+
/**
* @map.sgt: sg-table pointing to pages backing the GEM object.
*
@@ -1007,6 +1010,26 @@ panthor_vm_map_pages(struct panthor_vm *vm, u64 iova, int prot,
return 0;
}
+static int
+panthor_vm_repeated_map_pages(struct panthor_vm *vm, u64 iova, int prot,
+ struct sg_table *sgt, u64 offset, u64 size,
+ u64 count)
+{
+ /* FIXME: we really need to optimize this at the io_pgtable level. */
+ for (u64 i = 0; i < count; i++) {
+ int ret;
+
+ ret = panthor_vm_map_pages(vm, iova + (size * i), prot,
+ sgt, offset, size);
+ if (ret) {
+ panthor_vm_unmap_pages(vm, iova, size * (i - 1));
+ return ret;
+ }
+ }
+
+ return 0;
+}
+
static int flags_to_prot(u32 flags)
{
int prot = 0;
@@ -1203,12 +1226,14 @@ panthor_vm_op_ctx_prealloc_vmas(struct panthor_vm_op_ctx *op_ctx)
(DRM_PANTHOR_VM_BIND_OP_MAP_READONLY | \
DRM_PANTHOR_VM_BIND_OP_MAP_NOEXEC | \
DRM_PANTHOR_VM_BIND_OP_MAP_UNCACHED | \
+ DRM_PANTHOR_VM_BIND_OP_MAP_REPEAT | \
DRM_PANTHOR_VM_BIND_OP_TYPE_MASK)
static int panthor_vm_prepare_map_op_ctx(struct panthor_vm_op_ctx *op_ctx,
struct panthor_vm *vm,
struct panthor_gem_object *bo,
u64 offset,
+ u32 repeat_range,
u64 size, u64 va,
u32 flags)
{
@@ -1224,9 +1249,22 @@ static int panthor_vm_prepare_map_op_ctx(struct panthor_vm_op_ctx *op_ctx,
(flags & DRM_PANTHOR_VM_BIND_OP_TYPE_MASK) != DRM_PANTHOR_VM_BIND_OP_TYPE_MAP)
return -EINVAL;
- /* Make sure the VA and size are aligned and in-bounds. */
- if (size > bo->base.base.size || offset > bo->base.base.size - size)
- return -EINVAL;
+ if (!(flags & DRM_PANTHOR_VM_BIND_OP_MAP_REPEAT)) {
+ /* Make sure the VA and size are aligned and in-bounds. */
+ if (size > bo->base.base.size || offset > bo->base.base.size - size)
+ return -EINVAL;
+ } else {
+ /* Make sure the repeat_range is in-bounds. */
+ if (repeat_range > bo->base.base.size || offset > bo->base.base.size - repeat_range)
+ return -EINVAL;
+
+ /* Make sure size is a multiple of repeat_range */
+
+ u64 repeat_count = size;
+
+ if (do_div(repeat_count, repeat_range))
+ return -EINVAL;
+ }
/* If the BO has an exclusive VM attached, it can't be mapped to other VMs. */
if (bo->exclusive_vm_root_gem &&
@@ -1295,6 +1333,7 @@ static int panthor_vm_prepare_map_op_ctx(struct panthor_vm_op_ctx *op_ctx,
drm_gem_shmem_unpin(&bo->base);
op_ctx->map.bo_offset = offset;
+ op_ctx->map.bo_repeat_range = repeat_range;
/* L1, L2 and L3 page tables.
* We could optimize L3 allocation by iterating over the sgt and merging
@@ -2112,9 +2151,22 @@ static int panthor_gpuva_sm_step_map(struct drm_gpuva_op *op, void *priv)
panthor_vma_init(vma, op_ctx->flags & PANTHOR_VM_MAP_FLAGS);
- ret = panthor_vm_map_pages(vm, op->map.va.addr, flags_to_prot(vma->flags),
- op_ctx->map.sgt, op->map.gem.offset,
- op->map.va.range);
+ if (op_ctx->flags & DRM_PANTHOR_VM_BIND_OP_MAP_REPEAT) {
+ u64 repeat_count = op->map.va.range;
+
+ do_div(repeat_count, op->map.gem.range);
+ ret = panthor_vm_repeated_map_pages(vm, op->map.va.addr,
+ flags_to_prot(vma->flags),
+ op_ctx->map.sgt,
+ op->map.gem.offset,
+ op->map.gem.range,
+ repeat_count);
+ } else {
+ ret = panthor_vm_map_pages(vm, op->map.va.addr,
+ flags_to_prot(vma->flags),
+ op_ctx->map.sgt, op->map.gem.offset,
+ op->map.va.range);
+ }
if (ret)
return ret;
@@ -2237,7 +2289,7 @@ panthor_vm_exec_op(struct panthor_vm *vm, struct panthor_vm_op_ctx *op,
switch (op_type) {
case DRM_PANTHOR_VM_BIND_OP_TYPE_MAP: {
- const struct drm_gpuvm_map_req map_req = {
+ struct drm_gpuvm_map_req map_req = {
.va.addr = op->va.addr,
.va.range = op->va.range,
.gem.obj = op->map.vm_bo->obj,
@@ -2249,6 +2301,11 @@ panthor_vm_exec_op(struct panthor_vm *vm, struct panthor_vm_op_ctx *op,
break;
}
+ if (op->flags & DRM_PANTHOR_VM_BIND_OP_MAP_REPEAT) {
+ map_req.flags |= DRM_GPUVA_REPEAT;
+ map_req.gem.range = op->map.bo_repeat_range;
+ }
+
ret = drm_gpuvm_sm_map(&vm->base, vm, &map_req);
break;
}
@@ -2497,6 +2554,7 @@ panthor_vm_bind_prepare_op_ctx(struct drm_file *file,
ret = panthor_vm_prepare_map_op_ctx(op_ctx, vm,
gem ? to_panthor_bo(gem) : NULL,
op->bo_offset,
+ op->bo_repeat_range,
op->size,
op->va,
op->flags);
@@ -2698,7 +2756,11 @@ int panthor_vm_map_bo_range(struct panthor_vm *vm, struct panthor_gem_object *bo
struct panthor_vm_op_ctx op_ctx;
int ret;
- ret = panthor_vm_prepare_map_op_ctx(&op_ctx, vm, bo, offset, size, va, flags);
+ /* TODO: would be nice to replace with assert instead */
+ if (flags & DRM_PANTHOR_VM_BIND_OP_MAP_REPEAT)
+ return -EINVAL;
+
+ ret = panthor_vm_prepare_map_op_ctx(&op_ctx, vm, bo, offset, 0, size, va, flags);
if (ret)
return ret;
diff --git a/include/uapi/drm/panthor_drm.h b/include/uapi/drm/panthor_drm.h
index e1f43deb7eca..ad278bc234b0 100644
--- a/include/uapi/drm/panthor_drm.h
+++ b/include/uapi/drm/panthor_drm.h
@@ -496,6 +496,17 @@ enum drm_panthor_vm_bind_op_flags {
*/
DRM_PANTHOR_VM_BIND_OP_MAP_UNCACHED = 1 << 2,
+ /**
+ * @DRM_PANTHOR_VM_BIND_OP_MAP_REPEAT: Repeat a BO range
+ *
+ * Only valid with DRM_PANTHOR_VM_BIND_OP_TYPE_MAP.
+ *
+ * When this is set, a BO range is repeated over the VA range.
+ * drm_panthor_vm_bind_op::bo_repeat_range defines the size of the
+ * BO range to repeat.
+ */
+ DRM_PANTHOR_VM_BIND_OP_MAP_REPEAT = 1 << 3,
+
/**
* @DRM_PANTHOR_VM_BIND_OP_TYPE_MASK: Mask used to determine the type of operation.
*/
@@ -560,6 +571,18 @@ struct drm_panthor_vm_bind_op {
*/
struct drm_panthor_obj_array syncs;
+ /**
+ * @bo_repeat_range: The size of the range to be repeated.
+ *
+ * Must be zero if DRM_PANTHOR_VM_BIND_OP_MAP_REPEAT is not set in
+ * flags.
+ *
+ * Size must be a multiple of bo_repeat_range.
+ */
+ __u32 bo_repeat_range;
+
+ /** @pad: Padding field. MBZ. */
+ __u32 pad;
};
/**
--
2.47.2