[PATCH] drm/amdgpu: Add use_xgmi_p2p module parameter

[Alex Sierra]

This parameter controls xGMI p2p communication, which is enabled by
default. However, it can be disabled by setting it to 0. In case xGMI
p2p is disabled in a dGPU, PCIe p2p interface will be used instead.
This parameter is ignored in GPUs that do not support xGMI
p2p configuration.

Signed-off-by: Alex Sierra <alex.sierra at amd.com>
Acked-by: Luben Tuikov <luben.tuikov at amd.com>
Acked-by: Harish Kasiviswanathan <Harish.Kasiviswanathan at amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu.h     | 1 +
 drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c | 8 ++++++++
 drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c  | 4 ++--
 3 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
index f97848a0ed14..7e95d8bd2338 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
@@ -217,6 +217,7 @@ extern int amdgpu_mes;
 extern int amdgpu_noretry;
 extern int amdgpu_force_asic_type;
 extern int amdgpu_smartshift_bias;
+extern int amdgpu_use_xgmi_p2p;
 #ifdef CONFIG_HSA_AMD
 extern int sched_policy;
 extern bool debug_evictions;
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
index 2f8eafb6cf22..6156265f3178 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
@@ -181,6 +181,7 @@ int amdgpu_tmz = -1; /* auto */
 int amdgpu_reset_method = -1; /* auto */
 int amdgpu_num_kcq = -1;
 int amdgpu_smartshift_bias;
+int amdgpu_use_xgmi_p2p = -1;
 
 static void amdgpu_drv_delayed_reset_work_handler(struct work_struct *work);
 
@@ -677,6 +678,13 @@ MODULE_PARM_DESC(force_asic_type,
 	"A non negative value used to specify the asic type for all supported GPUs");
 module_param_named(force_asic_type, amdgpu_force_asic_type, int, 0444);
 
+/**
+ * DOC: use_xgmi_p2p (int)
+ * Enables/disables XGMI P2P interface (0 = disable, 1 = enable). The Default is -1 (enabled).
+ */
+MODULE_PARM_DESC(use_xgmi_p2p,
+	"Disable XGMI P2P interface (0 = disable; 1 = enable; -1 default, enabled)");
+module_param_named(use_xgmi_p2p, amdgpu_use_xgmi_p2p, int, 0444);
 
 
 #ifdef CONFIG_HSA_AMD
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
index 207cd01435b5..bbe1bac61f15 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
@@ -2330,8 +2330,8 @@ struct amdgpu_bo_va *amdgpu_vm_bo_add(struct amdgpu_device *adev,
 #else
 	dma_resv_assert_held(amdkcl_ttm_resvp(&vm->root.bo->tbo));
 #endif
-
-	if (amdgpu_dmabuf_is_xgmi_accessible(adev, bo)) {
+	if (amdgpu_use_xgmi_p2p &&
+	    amdgpu_dmabuf_is_xgmi_accessible(adev, bo)) {
 		bo_va->is_xgmi = true;
 		/* Power up XGMI if it can be potentially used */
 		amdgpu_xgmi_set_pstate(adev, AMDGPU_XGMI_PSTATE_MAX_VEGA20);
-- 
2.32.0