[PATCH 2/2] drm/amdkfd: Allow memory oversubscription on small APUs

[Lang Yu <Lang.Yu@xxxxxxx>]

The default ttm_tt_pages_limit is 1/2 of system memory.
It is prone to out of memory with such a configuration.

Signed-off-by: Lang Yu <Lang.Yu@xxxxxxx>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c       |  2 +-
 drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h       |  4 ++--
 drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c | 12 +++++++++---
 3 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c
index 3295838e9a1d..c01c6f3ab562 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c
@@ -167,7 +167,7 @@ void amdgpu_amdkfd_device_init(struct amdgpu_device *adev)
 	int i;
 	int last_valid_bit;
 
-	amdgpu_amdkfd_gpuvm_init_mem_limits();
+	amdgpu_amdkfd_gpuvm_init_mem_limits(adev);
 
 	if (adev->kfd.dev) {
 		struct kgd2kfd_shared_resources gpu_resources = {
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h
index 1de021ebdd46..13284dbd8c58 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h
@@ -363,7 +363,7 @@ u64 amdgpu_amdkfd_xcp_memory_size(struct amdgpu_device *adev, int xcp_id);
 
 
 #if IS_ENABLED(CONFIG_HSA_AMD)
-void amdgpu_amdkfd_gpuvm_init_mem_limits(void);
+void amdgpu_amdkfd_gpuvm_init_mem_limits(struct amdgpu_device *adev);
 void amdgpu_amdkfd_gpuvm_destroy_cb(struct amdgpu_device *adev,
 				struct amdgpu_vm *vm);
 
@@ -376,7 +376,7 @@ void amdgpu_amdkfd_release_notify(struct amdgpu_bo *bo);
 void amdgpu_amdkfd_reserve_system_mem(uint64_t size);
 #else
 static inline
-void amdgpu_amdkfd_gpuvm_init_mem_limits(void)
+void amdgpu_amdkfd_gpuvm_init_mem_limits(struct amdgpu_device *adev)
 {
 }
 
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
index 7eb5afcc4895..a3e623a320b3 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
@@ -60,6 +60,7 @@ static struct {
 	int64_t system_mem_used;
 	int64_t ttm_mem_used;
 	spinlock_t mem_limit_lock;
+	bool alow_oversubscribe;
 } kfd_mem_limit;
 
 static const char * const domain_bit_to_string[] = {
@@ -110,7 +111,7 @@ static bool reuse_dmamap(struct amdgpu_device *adev, struct amdgpu_device *bo_ad
  *  System (TTM + userptr) memory - 15/16th System RAM
  *  TTM memory - 3/8th System RAM
  */
-void amdgpu_amdkfd_gpuvm_init_mem_limits(void)
+void amdgpu_amdkfd_gpuvm_init_mem_limits(struct amdgpu_device *adev)
 {
 	struct sysinfo si;
 	uint64_t mem;
@@ -130,6 +131,7 @@ void amdgpu_amdkfd_gpuvm_init_mem_limits(void)
 		kfd_mem_limit.max_system_mem_limit -= AMDGPU_RESERVE_MEM_LIMIT;
 
 	kfd_mem_limit.max_ttm_mem_limit = ttm_tt_pages_limit() << PAGE_SHIFT;
+	kfd_mem_limit.alow_oversubscribe = !!(adev->flags & AMD_IS_APU);
 	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));
@@ -221,8 +223,12 @@ int amdgpu_amdkfd_reserve_mem_limit(struct amdgpu_device *adev,
 	     kfd_mem_limit.max_ttm_mem_limit) ||
 	    (adev && xcp_id >= 0 && adev->kfd.vram_used[xcp_id] + vram_needed >
 	     vram_size - reserved_for_pt - atomic64_read(&adev->vram_pin_size))) {
-		ret = -ENOMEM;
-		goto release;
+		if (kfd_mem_limit.alow_oversubscribe) {
+			pr_warn_ratelimited("Memory is getting oversubscried.\n");
+		} else {
+			ret = -ENOMEM;
+			goto release;
+		}
 	}
 
 	/* Update memory accounting by decreasing available system
-- 
2.25.1