On 2024-08-16 3:29, Rahul Jain wrote:
> when trying to enable p2p the amdgpu_device_is_peer_accessible()
> checks the condition where address_mask overlaps the aper_base
> and hence returns 0, due to which the p2p disables for this platform
>
> IOMMU should remap the BAR addresses so the device can access
> them. Hence check if peer_adev is remapping DMA
>
> v5: (Felix, Alex)
> - fixing comment as per Alex feedback
> - refactor code as per Felix
>
> v4: (Alex)
> - fix the comment and description
>
> v3:
> - remove iommu_remap variable
>
> v2: (Alex)
> - Fix as per review comments
> - add new function amdgpu_device_check_iommu_remap to check if iommu
> remap
>
> Signed-off-by: Rahul Jain <Rahul.Jain@xxxxxxx>
> ---
> drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 44 +++++++++++++++++-----
> 1 file changed, 34 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> index a6b8d0ba4758..e03b3357ae09 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> @@ -3952,6 +3952,25 @@ static void amdgpu_device_check_iommu_direct_map(struct amdgpu_device *adev)
> adev->ram_is_direct_mapped = true;
> }
>
> +/**
> + * amdgpu_device_check_iommu_remap - Check if DMA remapping is enabled.
> + *
> + * @adev: amdgpu_device pointer
> + *
> + * return if IOMMU remapping bar address
> + */
> +static bool amdgpu_device_check_iommu_remap(struct amdgpu_device *adev)
> +{
> + struct iommu_domain *domain;
> +
> + domain = iommu_get_domain_for_dev(adev->dev);
> + if (domain && (domain->type == IOMMU_DOMAIN_DMA ||
> + domain->type == IOMMU_DOMAIN_DMA_FQ))
> + return true;
> +
> + return false;
> +}
> +
> static const struct attribute *amdgpu_dev_attributes[] = {
> &dev_attr_pcie_replay_count.attr,
> NULL
> @@ -6127,21 +6146,26 @@ bool amdgpu_device_is_peer_accessible(struct amdgpu_device *adev,
> struct amdgpu_device *peer_adev)
> {
> #ifdef CONFIG_HSA_AMD_P2P
> - uint64_t address_mask = peer_adev->dev->dma_mask ?
> - ~*peer_adev->dev->dma_mask : ~((1ULL << 32) - 1);
> - resource_size_t aper_limit =
> - adev->gmc.aper_base + adev->gmc.aper_size - 1;
> bool p2p_access =
> !adev->gmc.xgmi.connected_to_cpu &&
> !(pci_p2pdma_distance(adev->pdev, peer_adev->dev, false) < 0);
>
> - 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));
> -#else
> - return false;
> + bool is_large_bar = adev->gmc.visible_vram_size &&
> + adev->gmc.real_vram_size == adev->gmc.visible_vram_size;
> + bool p2p_addressable = amdgpu_device_check_iommu_remap(peer_adev);
> +
> + if (!p2p_addressable) {
> + uint64_t address_mask = peer_adev->dev->dma_mask ?
> + ~*peer_adev->dev->dma_mask : ~((1ULL << 32) - 1);
> + resource_size_t aper_limit =
> + adev->gmc.aper_base + adev->gmc.aper_size - 1;
> +
> + p2p_addressable = !(adev->gmc.aper_base & address_mask ||
> + aper_limit & address_mask);
> + }
> + return is_large_bar && p2p_access && p2p_addressable;
> #endif
> + return false;
You changed the #else into a #endif. Logically that's OK, but it may cause a compiler warning about unreachable code because the program can never reach the "return false;" statement when CONFIG_HSA_AMD_P2P is enabled. It's probably safer to leave the #else to make sure this compiles without warnings on current and future compilers.
With that fixed, this patch is
Reviewed-by: Felix Kuehling <felix.kuehling@xxxxxxx>
> }
>
> int amdgpu_device_baco_enter(struct drm_device *dev)
