drm/amdkfd: Update KFD TTM mem limit

Use the helper function in TTM to get TTM memory
limit and set KFD's internal mem limit. This ensures
that KFD's TTM mem limit and actual TTM mem limit are
exactly same.
Signed-off-by: Mukul Joshi <mukul.joshi@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c

@@ -53,7 +53,6 @@ int amdgpu_amdkfd_init(void)
 	amdgpu_amdkfd_total_mem_size *= si.mem_unit;
 
 	ret = kgd2kfd_init();
-	amdgpu_amdkfd_gpuvm_init_mem_limits();
 	kfd_initialized = !ret;
 
 	return ret;
@@ -143,6 +142,8 @@ void amdgpu_amdkfd_device_init(struct amdgpu_device *adev)
 	int i;
 	int last_valid_bit;
 
+	amdgpu_amdkfd_gpuvm_init_mem_limits();
+
 	if (adev->kfd.dev) {
 		struct kgd2kfd_shared_resources gpu_resources = {
 			.compute_vmid_bitmap =

drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c

@@ -36,6 +36,7 @@
 #include <uapi/linux/kfd_ioctl.h>
 #include "amdgpu_xgmi.h"
 #include "kfd_smi_events.h"
+#include <drm/ttm/ttm_tt.h>
 
 /* Userptr restore delay, just long enough to allow consecutive VM
  * changes to accumulate
@@ -110,13 +111,16 @@ void amdgpu_amdkfd_gpuvm_init_mem_limits(void)
 	struct sysinfo si;
 	uint64_t mem;
 
+	if (kfd_mem_limit.max_system_mem_limit)
+		return;
+
 	si_meminfo(&si);
 	mem = si.freeram - si.freehigh;
 	mem *= si.mem_unit;
 
 	spin_lock_init(&kfd_mem_limit.mem_limit_lock);
 	kfd_mem_limit.max_system_mem_limit = mem - (mem >> 4);
-	kfd_mem_limit.max_ttm_mem_limit = (mem >> 1) - (mem >> 3);
+	kfd_mem_limit.max_ttm_mem_limit = ttm_tt_pages_limit() << PAGE_SHIFT;
 	pr_debug("Kernel memory limit %lluM, TTM limit %lluM\n",
 		(kfd_mem_limit.max_system_mem_limit >> 20),
 		(kfd_mem_limit.max_ttm_mem_limit >> 20));