drm/amdgpu: ensure no PCIe peer access for CPU XGMI iolinks

[Why] Devices with CPU XGMI iolink do not support PCIe peer access.

Signed-off-by: Alex Sierra <alex.sierra@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
(cherry picked from commit b6116052456e26480af9aff29e9d016aeed539d0)

Change-Id: I76c0090638f12adbe05b0b3d29d57fd05cdb626e

drivers/gpu/drm/amd/amdgpu/amdgpu_device.c

@@ -5588,7 +5588,8 @@ bool amdgpu_device_is_peer_accessible(struct amdgpu_device *adev,
 		adev->gmc.aper_base + adev->gmc.aper_size - 1;
 
 #ifdef CONFIG_PCI_P2PDMA
-	p2p_access = !(pci_p2pdma_distance_many(adev->pdev,
+	bool p2p_access = !adev->gmc.xgmi.connected_to_cpu &&
+			  !(pci_p2pdma_distance_many(adev->pdev,
 					&peer_adev->dev, 1, true) < 0);
 #endif
 	return pcie_p2p && p2p_access && (adev->gmc.visible_vram_size &&