[PATCH v2 1/3] drm/amdgpu: Don't pin VRAM without DMABUF_MOVE_NOTIFY

[Felix Kuehling]

Pinning of VRAM is for peer devices that don't support dynamic attachment
and move notifiers. But it requires that all such peer devices are able to
access VRAM via PCIe P2P. Any device without P2P access requires migration
to GTT, which fails if the memory is already pinned for another peer
device.

Sharing between GPUs should not require pinning in VRAM. However, if
DMABUF_MOVE_NOTIFY is disabled in the kernel build, even DMABufs shared
between GPUs must be pinned, which can lead to failures and functional
regressions on systems where some peer GPUs are not P2P accessible.

Disable VRAM pinning if move notifiers are disabled in the kernel build
to fix regressions when sharing BOs between GPUs.

v2: ensure domains is not 0, add GTT if necessary

Signed-off-by: Felix Kuehling <felix.kuehling at amd.com>
Tested-by: Hao (Claire) Zhou <hao.zhou at amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c
index 667080cc9ae1..3c2c32a252d4 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c
@@ -81,17 +81,26 @@ static int amdgpu_dma_buf_pin(struct dma_buf_attachment *attach)
 
 	dma_resv_assert_held(dmabuf->resv);
 
-	/*
-	 * Try pinning into VRAM to allow P2P with RDMA NICs without ODP
+	/* Try pinning into VRAM to allow P2P with RDMA NICs without ODP
 	 * support if all attachments can do P2P. If any attachment can't do
 	 * P2P just pin into GTT instead.
+	 *
+	 * To avoid with conflicting pinnings between GPUs and RDMA when move
+	 * notifiers are disabled, only allow pinning in VRAM when move
+	 * notiers are enabled.
 	 */
-	list_for_each_entry(attach, &dmabuf->attachments, node)
-		if (!attach->peer2peer)
-			domains &= ~AMDGPU_GEM_DOMAIN_VRAM;
+	if (!IS_ENABLED(CONFIG_DMABUF_MOVE_NOTIFY)) {
+		domains &= ~AMDGPU_GEM_DOMAIN_VRAM;
+	} else {
+		list_for_each_entry(attach, &dmabuf->attachments, node)
+			if (!attach->peer2peer)
+				domains &= ~AMDGPU_GEM_DOMAIN_VRAM;
+	}
 
 	if (domains & AMDGPU_GEM_DOMAIN_VRAM)
 		bo->flags |= AMDGPU_GEM_CREATE_CPU_ACCESS_REQUIRED;
+	else if (!domains)
+		domains = AMDGPU_GEM_DOMAIN_GTT;
 
 	return amdgpu_bo_pin(bo, domains);
 }
-- 
2.34.1