[PATCH v3 2/3] drm/amdkfd: Set svm range max pages

[Philip Yang]

This will be used to split giant svm range into smaller ranges, to
support VRAM overcommitment by giant range and improve GPU retry fault
recover on giant range.

Signed-off-by: Philip Yang <Philip.Yang at amd.com>
---
 drivers/gpu/drm/amd/amdkfd/kfd_migrate.c |  2 ++
 drivers/gpu/drm/amd/amdkfd/kfd_svm.c     | 21 +++++++++++++++++++++
 drivers/gpu/drm/amd/amdkfd/kfd_svm.h     |  3 +++
 3 files changed, 26 insertions(+)

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c b/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c
index 9667015a6cbc..b1f87aa6138b 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c
@@ -1019,6 +1019,8 @@ int svm_migrate_init(struct amdgpu_device *adev)
 
 	amdgpu_amdkfd_reserve_system_mem(SVM_HMM_PAGE_STRUCT_SIZE(size));
 
+	svm_range_set_max_pages(adev);
+
 	pr_info("HMM registered %ldMB device memory\n", size >> 20);
 
 	return 0;
diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_svm.c b/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
index b592aee6d9d6..9d855890658e 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
@@ -46,6 +46,12 @@
  */
 #define AMDGPU_SVM_RANGE_RETRY_FAULT_PENDING	(2UL * NSEC_PER_MSEC)
 
+/* Giant svm range split into smaller ranges based on this, it is decided using
+ * minimum of all dGPU/APU 1/32 VRAM size, between 2MB to 1GB and alignment to
+ * power of 2MB.
+ */
+uint64_t max_svm_range_pages;
+
 struct criu_svm_metadata {
 	struct list_head list;
 	struct kfd_criu_svm_range_priv_data data;
@@ -1870,6 +1876,21 @@ static struct svm_range *svm_range_clone(struct svm_range *old)
 	return new;
 }
 
+void svm_range_set_max_pages(struct amdgpu_device *adev)
+{
+	uint64_t max_pages;
+	uint64_t pages, _pages;
+
+	/* 1/32 VRAM size in pages */
+	pages = adev->gmc.real_vram_size >> 17;
+	pages = clamp(pages, 1ULL << 9, 1ULL << 18);
+	pages = rounddown_pow_of_two(pages);
+	do {
+		max_pages = READ_ONCE(max_svm_range_pages);
+		_pages = min_not_zero(max_pages, pages);
+	} while (cmpxchg(&max_svm_range_pages, max_pages, _pages) != max_pages);
+}
+
 /**
  * svm_range_add - add svm range and handle overlap
  * @p: the range add to this process svms
diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_svm.h b/drivers/gpu/drm/amd/amdkfd/kfd_svm.h
index eab7f6d3b13c..9156b041ef17 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_svm.h
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_svm.h
@@ -204,6 +204,9 @@ void svm_range_list_lock_and_flush_work(struct svm_range_list *svms, struct mm_s
 #define KFD_IS_SVM_API_SUPPORTED(dev) ((dev)->pgmap.type != 0)
 
 void svm_range_bo_unref_async(struct svm_range_bo *svm_bo);
+
+void svm_range_set_max_pages(struct amdgpu_device *adev);
+
 #else
 
 struct kfd_process;
-- 
2.35.1