drm/amdkfd: Add module option for testing large-BAR functionality

Simulate large-BAR system by exporting only visible memory. This
limits the amount of available VRAM to the size of the BAR, but
enables CPU access to VRAM.

Signed-off-by: Felix Kuehling <Felix.Kuehling@amd.com>
Acked-by: Oded Gabbay <oded.gabbay@gmail.com>
Signed-off-by: Oded Gabbay <oded.gabbay@gmail.com>

4 files changed, 19 insertions, 0 deletions

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c b/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
index ec0b2c0284ec..cd679cf1fd30 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
@@ -1151,6 +1151,11 @@ bool kfd_dev_is_large_bar(struct kfd_dev *dev)
 {
         struct kfd_local_mem_info mem_info;
 
+        if (debug_largebar) {
+                pr_debug("Simulate large-bar allocation on non large-bar machine\n");
+                return true;
+        }
+
         if (dev->device_info->needs_iommu_device)
                 return false;
 
diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_crat.c b/drivers/gpu/drm/amd/amdkfd/kfd_crat.c
index d85112224f1d..4f126ef6139b 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_crat.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_crat.c
@@ -1117,6 +1117,9 @@ static int kfd_create_vcrat_image_gpu(void *pcrat_image,
         sub_type_hdr = (typeof(sub_type_hdr))((char *)sub_type_hdr +
                         sub_type_hdr->length);
 
+        if (debug_largebar)
+                local_mem_info.local_mem_size_private = 0;
+
         if (local_mem_info.local_mem_size_private == 0)
                 ret = kfd_fill_gpu_memory_affinity(&avail_size,
                                 kdev, HSA_MEM_HEAP_TYPE_FB_PUBLIC,
diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_module.c b/drivers/gpu/drm/amd/amdkfd/kfd_module.c
index 65574c6a10b3..b0acb0603883 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_module.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_module.c
@@ -71,6 +71,11 @@ module_param(send_sigterm, int, 0444);
 MODULE_PARM_DESC(send_sigterm,
         "Send sigterm to HSA process on unhandled exception (0 = disable, 1 = enable)");
 
+int debug_largebar;
+module_param(debug_largebar, int, 0444);
+MODULE_PARM_DESC(debug_largebar,
+        "Debug large-bar flag used to simulate large-bar capability on non-large bar machine (0 = disable, 1 = enable)");
+
 int ignore_crat;
 module_param(ignore_crat, int, 0444);
 MODULE_PARM_DESC(ignore_crat,
diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_priv.h b/drivers/gpu/drm/amd/amdkfd/kfd_priv.h
index aa9386356587..db27f9f13696 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_priv.h
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_priv.h
@@ -105,6 +105,12 @@ extern int cwsr_enable;
 extern int send_sigterm;
 
 /*
+ * This kernel module is used to simulate large bar machine on non-large bar
+ * enabled machines.
+ */
+extern int debug_largebar;
+
+/*
  * Ignore CRAT table during KFD initialization, can be used to work around
  * broken CRAT tables on some AMD systems
  */