[PATCH 6/6] drm/amdgpu: enable foreign DMA-buf objects v2

[Felix Kuehling]

From: Christian König <christian.koenig at amd.com>

We should be able to handle BOs from other instances as well.

v2:
* Add a module option that is off-by-default
* Use new DRM helper function to check the exporting driver

Signed-off-by: Christian König <christian.koenig at amd.com>
Signed-off-by: Felix Kuehling <Felix.Kuehling at amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu.h       |  4 +++
 drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c   |  6 +++-
 drivers/gpu/drm/amd/amdgpu/amdgpu_prime.c | 60 +++++++++++++++++++++++++++++++
 3 files changed, 69 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
index 9fa3cee..46d9aeb 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
@@ -129,6 +129,8 @@
 extern int amdgpu_cik_support;
 #endif
 
+extern int amdgpu_p2p_sharing;
+
 #define AMDGPU_DEFAULT_GTT_SIZE_MB		3072ULL /* 3GB by default */
 #define AMDGPU_WAIT_IDLE_TIMEOUT_IN_MS	        3000
 #define AMDGPU_MAX_USEC_TIMEOUT			100000	/* 100 ms */
@@ -471,6 +473,8 @@ struct drm_gem_object *
 struct dma_buf *amdgpu_gem_prime_export(struct drm_device *dev,
 					struct drm_gem_object *gobj,
 					int flags);
+struct drm_gem_object *amdgpu_gem_prime_import(struct drm_device *dev,
+					       struct dma_buf *dma_buf);
 int amdgpu_gem_prime_pin(struct drm_gem_object *obj);
 void amdgpu_gem_prime_unpin(struct drm_gem_object *obj);
 struct reservation_object *amdgpu_gem_prime_res_obj(struct drm_gem_object *);
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
index 2cdf844..ab00864 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
@@ -120,6 +120,7 @@
 int amdgpu_param_buf_per_se = 0;
 int amdgpu_job_hang_limit = 0;
 int amdgpu_lbpw = -1;
+int amdgpu_p2p_sharing = 0;
 
 MODULE_PARM_DESC(vramlimit, "Restrict VRAM for testing, in megabytes");
 module_param_named(vramlimit, amdgpu_vram_limit, int, 0600);
@@ -289,6 +290,9 @@
 module_param_named(cik_support, amdgpu_cik_support, int, 0444);
 #endif
 
+MODULE_PARM_DESC(p2p_sharing, "Enable P2P buffer sharing (1 = enabled, 0 = disabled (default))");
+module_param_named(p2p_sharing, amdgpu_p2p_sharing, int, 0444);
+
 
 static const struct pci_device_id pciidlist[] = {
 #ifdef  CONFIG_DRM_AMDGPU_SI
@@ -835,7 +839,7 @@ long amdgpu_drm_ioctl(struct file *filp,
 	.prime_handle_to_fd = drm_gem_prime_handle_to_fd,
 	.prime_fd_to_handle = drm_gem_prime_fd_to_handle,
 	.gem_prime_export = amdgpu_gem_prime_export,
-	.gem_prime_import = drm_gem_prime_import,
+	.gem_prime_import = amdgpu_gem_prime_import,
 	.gem_prime_pin = amdgpu_gem_prime_pin,
 	.gem_prime_unpin = amdgpu_gem_prime_unpin,
 	.gem_prime_res_obj = amdgpu_gem_prime_res_obj,
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_prime.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_prime.c
index b9425ed..21a34ba 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_prime.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_prime.c
@@ -159,3 +159,63 @@ struct dma_buf *amdgpu_gem_prime_export(struct drm_device *dev,
 
 	return drm_gem_prime_export(dev, gobj, flags);
 }
+
+static struct drm_gem_object *
+amdgpu_gem_prime_foreign_bo(struct amdgpu_device *adev, struct amdgpu_bo *bo)
+{
+	struct amdgpu_gem_object *gobj;
+	int r;
+
+	ww_mutex_lock(&bo->tbo.resv->lock, NULL);
+
+	list_for_each_entry(gobj, &bo->gem_objects, list) {
+		if (gobj->base.dev != adev->ddev)
+			continue;
+
+		ww_mutex_unlock(&bo->tbo.resv->lock);
+		drm_gem_object_reference(&gobj->base);
+		return &gobj->base;
+	}
+
+
+	gobj = kzalloc(sizeof(struct amdgpu_gem_object), GFP_KERNEL);
+	if (unlikely(!gobj)) {
+		ww_mutex_unlock(&bo->tbo.resv->lock);
+		return ERR_PTR(-ENOMEM);
+	}
+
+	r = drm_gem_object_init(adev->ddev, &gobj->base, amdgpu_bo_size(bo));
+	if (unlikely(r)) {
+		kfree(gobj);
+		ww_mutex_unlock(&bo->tbo.resv->lock);
+		return ERR_PTR(r);
+	}
+
+	list_add(&gobj->list, &bo->gem_objects);
+	gobj->bo = amdgpu_bo_ref(bo);
+	bo->flags |= AMDGPU_GEM_CREATE_CPU_ACCESS_REQUIRED;
+
+	ww_mutex_unlock(&bo->tbo.resv->lock);
+
+	return &gobj->base;
+}
+
+struct drm_gem_object *amdgpu_gem_prime_import(struct drm_device *dev,
+					       struct dma_buf *dma_buf)
+{
+	struct amdgpu_device *adev = dev->dev_private;
+
+	if (amdgpu_p2p_sharing) {
+		struct drm_gem_object *obj =
+			drm_gem_prime_dmabuf_to_object(dma_buf, dev->driver);
+
+		if (obj && obj->dev != dev) {
+			/* It's a amdgpu_bo from a different driver instance */
+			struct amdgpu_bo *bo = gem_to_amdgpu_bo(obj);
+
+			return amdgpu_gem_prime_foreign_bo(adev, bo);
+		}
+	}
+
+	return drm_gem_prime_import(dev, dma_buf);
+}
-- 
1.9.1