drm/amdkfd: Add kfd gtt sub-allocator functions

This patch adds new kfd gtt sub-allocator functions that service the amdkfd
driver when it wants to use gtt memory.

The sub-allocator uses a bitmap to handle the memory area that was transferred
to it during init. It divides the memory area into chunks, according to chunk
size parameter.

The allocation function will allocate contiguous chunks from that memory area,
according to the requested size. If the requested size is smaller than the
chunk size, a single chunk will be allocated.

v2: Do some more verifications on parameters that are passed into
kfd_gtt_sa_init()

Signed-off-by: Oded Gabbay <oded.gabbay@amd.com>
Reviewed-by: Alexey Skidanov <Alexey.skidanov@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdkfd/kfd_device.c

@@ -67,6 +67,10 @@ static const struct kfd_deviceid supported_devices[] = {
 	{ 0x131D, &kaveri_device_info },	/* Kaveri */
 };
 
+static int kfd_gtt_sa_init(struct kfd_dev *kfd, unsigned int buf_size,
+				unsigned int chunk_size);
+static void kfd_gtt_sa_fini(struct kfd_dev *kfd);
+
 static const struct kfd_device_info *lookup_device_info(unsigned short did)
 {
 	size_t i;
@@ -307,3 +311,185 @@ void kgd2kfd_interrupt(struct kfd_dev *kfd, const void *ih_ring_entry)
 		spin_unlock(&kfd->interrupt_lock);
 	}
 }
+
+static int kfd_gtt_sa_init(struct kfd_dev *kfd, unsigned int buf_size,
+				unsigned int chunk_size)
+{
+	unsigned int num_of_bits;
+
+	BUG_ON(!kfd);
+	BUG_ON(!kfd->gtt_mem);
+	BUG_ON(buf_size < chunk_size);
+	BUG_ON(buf_size == 0);
+	BUG_ON(chunk_size == 0);
+
+	kfd->gtt_sa_chunk_size = chunk_size;
+	kfd->gtt_sa_num_of_chunks = buf_size / chunk_size;
+
+	num_of_bits = kfd->gtt_sa_num_of_chunks / BITS_PER_BYTE;
+	BUG_ON(num_of_bits == 0);
+
+	kfd->gtt_sa_bitmap = kzalloc(num_of_bits, GFP_KERNEL);
+
+	if (!kfd->gtt_sa_bitmap)
+		return -ENOMEM;
+
+	pr_debug("kfd: gtt_sa_num_of_chunks = %d, gtt_sa_bitmap = %p\n",
+			kfd->gtt_sa_num_of_chunks, kfd->gtt_sa_bitmap);
+
+	mutex_init(&kfd->gtt_sa_lock);
+
+	return 0;
+
+}
+
+static void kfd_gtt_sa_fini(struct kfd_dev *kfd)
+{
+	mutex_destroy(&kfd->gtt_sa_lock);
+	kfree(kfd->gtt_sa_bitmap);
+}
+
+static inline uint64_t kfd_gtt_sa_calc_gpu_addr(uint64_t start_addr,
+						unsigned int bit_num,
+						unsigned int chunk_size)
+{
+	return start_addr + bit_num * chunk_size;
+}
+
+static inline uint32_t *kfd_gtt_sa_calc_cpu_addr(void *start_addr,
+						unsigned int bit_num,
+						unsigned int chunk_size)
+{
+	return (uint32_t *) ((uint64_t) start_addr + bit_num * chunk_size);
+}
+
+int kfd_gtt_sa_allocate(struct kfd_dev *kfd, unsigned int size,
+			struct kfd_mem_obj **mem_obj)
+{
+	unsigned int found, start_search, cur_size;
+
+	BUG_ON(!kfd);
+
+	if (size == 0)
+		return -EINVAL;
+
+	if (size > kfd->gtt_sa_num_of_chunks * kfd->gtt_sa_chunk_size)
+		return -ENOMEM;
+
+	*mem_obj = kmalloc(sizeof(struct kfd_mem_obj), GFP_KERNEL);
+	if ((*mem_obj) == NULL)
+		return -ENOMEM;
+
+	pr_debug("kfd: allocated mem_obj = %p for size = %d\n", *mem_obj, size);
+
+	start_search = 0;
+
+	mutex_lock(&kfd->gtt_sa_lock);
+
+kfd_gtt_restart_search:
+	/* Find the first chunk that is free */
+	found = find_next_zero_bit(kfd->gtt_sa_bitmap,
+					kfd->gtt_sa_num_of_chunks,
+					start_search);
+
+	pr_debug("kfd: found = %d\n", found);
+
+	/* If there wasn't any free chunk, bail out */
+	if (found == kfd->gtt_sa_num_of_chunks)
+		goto kfd_gtt_no_free_chunk;
+
+	/* Update fields of mem_obj */
+	(*mem_obj)->range_start = found;
+	(*mem_obj)->range_end = found;
+	(*mem_obj)->gpu_addr = kfd_gtt_sa_calc_gpu_addr(
+					kfd->gtt_start_gpu_addr,
+					found,
+					kfd->gtt_sa_chunk_size);
+	(*mem_obj)->cpu_ptr = kfd_gtt_sa_calc_cpu_addr(
+					kfd->gtt_start_cpu_ptr,
+					found,
+					kfd->gtt_sa_chunk_size);
+
+	pr_debug("kfd: gpu_addr = %p, cpu_addr = %p\n",
+			(uint64_t *) (*mem_obj)->gpu_addr, (*mem_obj)->cpu_ptr);
+
+	/* If we need only one chunk, mark it as allocated and get out */
+	if (size <= kfd->gtt_sa_chunk_size) {
+		pr_debug("kfd: single bit\n");
+		set_bit(found, kfd->gtt_sa_bitmap);
+		goto kfd_gtt_out;
+	}
+
+	/* Otherwise, try to see if we have enough contiguous chunks */
+	cur_size = size - kfd->gtt_sa_chunk_size;
+	do {
+		(*mem_obj)->range_end =
+			find_next_zero_bit(kfd->gtt_sa_bitmap,
+					kfd->gtt_sa_num_of_chunks, ++found);
+		/*
+		 * If next free chunk is not contiguous than we need to
+		 * restart our search from the last free chunk we found (which
+		 * wasn't contiguous to the previous ones
+		 */
+		if ((*mem_obj)->range_end != found) {
+			start_search = found;
+			goto kfd_gtt_restart_search;
+		}
+
+		/*
+		 * If we reached end of buffer, bail out with error
+		 */
+		if (found == kfd->gtt_sa_num_of_chunks)
+			goto kfd_gtt_no_free_chunk;
+
+		/* Check if we don't need another chunk */
+		if (cur_size <= kfd->gtt_sa_chunk_size)
+			cur_size = 0;
+		else
+			cur_size -= kfd->gtt_sa_chunk_size;
+
+	} while (cur_size > 0);
+
+	pr_debug("kfd: range_start = %d, range_end = %d\n",
+		(*mem_obj)->range_start, (*mem_obj)->range_end);
+
+	/* Mark the chunks as allocated */
+	for (found = (*mem_obj)->range_start;
+		found <= (*mem_obj)->range_end;
+		found++)
+		set_bit(found, kfd->gtt_sa_bitmap);
+
+kfd_gtt_out:
+	mutex_unlock(&kfd->gtt_sa_lock);
+	return 0;
+
+kfd_gtt_no_free_chunk:
+	pr_debug("kfd: allocation failed with mem_obj = %p\n", mem_obj);
+	mutex_unlock(&kfd->gtt_sa_lock);
+	kfree(mem_obj);
+	return -ENOMEM;
+}
+
+int kfd_gtt_sa_free(struct kfd_dev *kfd, struct kfd_mem_obj *mem_obj)
+{
+	unsigned int bit;
+
+	BUG_ON(!kfd);
+	BUG_ON(!mem_obj);
+
+	pr_debug("kfd: free mem_obj = %p, range_start = %d, range_end = %d\n",
+			mem_obj, mem_obj->range_start, mem_obj->range_end);
+
+	mutex_lock(&kfd->gtt_sa_lock);
+
+	/* Mark the chunks as free */
+	for (bit = mem_obj->range_start;
+		bit <= mem_obj->range_end;
+		bit++)
+		clear_bit(bit, kfd->gtt_sa_bitmap);
+
+	mutex_unlock(&kfd->gtt_sa_lock);
+
+	kfree(mem_obj);
+	return 0;
+}

drivers/gpu/drm/amd/amdkfd/kfd_priv.h

@@ -518,6 +518,13 @@ unsigned int kfd_queue_id_to_doorbell(struct kfd_dev *kfd,
 					struct kfd_process *process,
 					unsigned int queue_id);
 
+/* GTT Sub-Allocator */
+
+int kfd_gtt_sa_allocate(struct kfd_dev *kfd, unsigned int size,
+			struct kfd_mem_obj **mem_obj);
+
+int kfd_gtt_sa_free(struct kfd_dev *kfd, struct kfd_mem_obj *mem_obj);
+
 extern struct device *kfd_device;
 
 /* Topology */