[RFC PATCH v2 4/8] drm/amdkfd: add SPM support for SVM

[Alex Sierra]

When CPU is connected throug XGMI, it has coherent
access to VRAM resource. In this case that resource
is taken from a table in the device gmc aperture base.
This resource is used along with the device type, which could
be DEVICE_PRIVATE or DEVICE_GENERIC to create the device
page map region.

Signed-off-by: Alex Sierra <alex.sierra at amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling at amd.com>
---
 drivers/gpu/drm/amd/amdkfd/kfd_migrate.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c b/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c
index c8ca3252cbc2..f5939449a99f 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c
@@ -895,6 +895,7 @@ int svm_migrate_init(struct amdgpu_device *adev)
 	struct resource *res;
 	unsigned long size;
 	void *r;
+	bool xgmi_connected_to_cpu = adev->gmc.xgmi.connected_to_cpu;
 
 	/* Page migration works on Vega10 or newer */
 	if (kfddev->device_info->asic_family < CHIP_VEGA10)
@@ -907,17 +908,22 @@ int svm_migrate_init(struct amdgpu_device *adev)
 	 * should remove reserved size
 	 */
 	size = ALIGN(adev->gmc.real_vram_size, 2ULL << 20);
-	res = devm_request_free_mem_region(adev->dev, &iomem_resource, size);
+	if (xgmi_connected_to_cpu)
+		res = lookup_resource(&iomem_resource, adev->gmc.aper_base);
+	else
+		res = devm_request_free_mem_region(adev->dev, &iomem_resource, size);
+
 	if (IS_ERR(res))
 		return -ENOMEM;
 
-	pgmap->type = MEMORY_DEVICE_PRIVATE;
 	pgmap->nr_range = 1;
 	pgmap->range.start = res->start;
 	pgmap->range.end = res->end;
+	pgmap->type = xgmi_connected_to_cpu ?
+				MEMORY_DEVICE_GENERIC : MEMORY_DEVICE_PRIVATE;
 	pgmap->ops = &svm_migrate_pgmap_ops;
 	pgmap->owner = SVM_ADEV_PGMAP_OWNER(adev);
-	pgmap->flags = MIGRATE_VMA_SELECT_DEVICE_PRIVATE;
+	pgmap->flags = 0;
 	r = devm_memremap_pages(adev->dev, pgmap);
 	if (IS_ERR(r)) {
 		pr_err("failed to register HMM device memory\n");
-- 
2.17.1