On 2023/3/8 8:35, Jason Gunthorpe wrote:
From: Nicolin Chen<nicolinc@xxxxxxxxxx> qemu has a need to replace the translations associated with a domain when the guest does large-scale operations like switching between an IDENTITY domain and, say, dma-iommu.c. Currently, it does this by replacing all the mappings in a single domain, but this is very inefficient and means that domains have to be per-device rather than per-translation. Provide a high-level API to allow replacements of one domain with another. This is similar to a detach/attach cycle except it doesn't force the group to go to the blocking domain in-between. By removing this forced blocking domain the iommu driver has the opportunity to implement a non-disruptive replacement of the domain to the greatest extent its hardware allows. This allows the qemu emulation of the vIOMMU to be more complete, as real hardware often has a non-distruptive replacement capability. It could be possible to address this by simply removing the protection from the iommu_attach_group(), but it is not so clear if that is safe for the few users. Thus, add a new API to serve this new purpose. All drivers are already required to support changing between active UNMANAGED domains when using their attach_dev ops. This API is expected to be used only by IOMMUFD, so add to the iommu-priv header and mark it as IOMMUFD_INTERNAL. Suggested-by: Jason Gunthorpe<jgg@xxxxxxxxxx> Reviewed-by: Kevin Tian<kevin.tian@xxxxxxxxx> Signed-off-by: Nicolin Chen<nicolinc@xxxxxxxxxx> Signed-off-by: Jason Gunthorpe<jgg@xxxxxxxxxx>
Reviewed-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx> Best regards, baolu
