Re: [PATCH v8 01/11] iommu: Add DMA ownership management interfaces

[Robin Murphy]

On 2022-03-08 05:44, Lu Baolu wrote:
> Multiple devices may be placed in the same IOMMU group because they
> cannot be isolated from each other. These devices must either be
> entirely under kernel control or userspace control, never a mixture.
>
> This adds dma ownership management in iommu core and exposes several
> interfaces for the device drivers and the device userspace assignment
> framework (i.e. VFIO), so that any conflict between user and kernel
> controlled dma could be detected at the beginning.
>
> The device driver oriented interfaces are,
>
> 	int iommu_device_use_default_domain(struct device *dev);
> 	void iommu_device_unuse_default_domain(struct device *dev);
>
> By calling iommu_device_use_default_domain(), the device driver tells
> the iommu layer that the device dma is handled through the kernel DMA
> APIs. The iommu layer will manage the IOVA and use the default domain
> for DMA address translation.
>
> The device user-space assignment framework oriented interfaces are,
>
> 	int iommu_group_claim_dma_owner(struct iommu_group *group,
> 					void *owner);
> 	void iommu_group_release_dma_owner(struct iommu_group *group);
> 	bool iommu_group_dma_owner_claimed(struct iommu_group *group);
>
> The device userspace assignment must be disallowed if the DMA owner
> claiming interface returns failure.

Reviewed-by: Robin Murphy <robin.murphy@xxxxxxx>

> Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
> Signed-off-by: Kevin Tian <kevin.tian@xxxxxxxxx>
> Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>