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

[Felix Kuehling]

On 2022-08-26 11:47, Alex Sierra wrote:
> [Why] Devices with CPU XGMI iolink do not support PCIe peer access.
>
> Signed-off-by: Alex Sierra <alex.sierra at amd.com>
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> index ce7d117efdb5..1ff66718639d 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> @@ -5538,7 +5538,8 @@ bool amdgpu_device_is_peer_accessible(struct amdgpu_device *adev,
>   	return pcie_p2p && p2p_access && (adev->gmc.visible_vram_size &&
>   		adev->gmc.real_vram_size == adev->gmc.visible_vram_size &&
>   		!(adev->gmc.aper_base & address_mask ||
> -		  aper_limit & address_mask));
> +		  aper_limit & address_mask) &&
> +		!adev->gmc.xgmi.connected_to_cpu);

Maybe it would be more readable if you added this to the initialization 
of p2p_access. In that case you can also save yourself the call to 
pci_p2pdma_distance_many and all the aperture checks. Like this:

	bool p2p_access = !adev->gmc.xgmi.connected_to_cpu &&
		!(pci_p2pdma_distance_many(adev->pdev, &peer_adev->dev, 1, true) < 0);

Regards,
   Felix


>   #else
>   	return false;
>   #endif