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iommufd: Add IOMMU_IOAS_CHANGE_PROCESS

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Add an ioctl that updates all DMA mappings to reflect the current process,
Change the mm and transfer locked memory accounting from old to current mm.
This will be used for live update, allowing an old process to hand the
iommufd device descriptor to a new process.  The new process calls the
ioctl.

IOMMU_IOAS_CHANGE_PROCESS only supports DMA mappings created with
IOMMU_IOAS_MAP_FILE, because the kernel metadata for such mappings does
not depend on the userland VA of the pages (which is different in the new
process).
IOMMU_IOAS_CHANGE_PROCESS fails if other types of mappings are present.

This is a revised version of code originally provided by Jason.

Link: https://patch.msgid.link/r/1731527497-16091-4-git-send-email-steven.sistare@oracle.com
Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
This commit is contained in:
Steve Sistare
2024-11-13 11:51:36 -08:00
committed by Jason Gunthorpe
parent 051ae5aa73
commit 829ed62649
5 changed files with 174 additions and 0 deletions
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include/uapi/linux/iommufd.h
+23
View File
@@ -54,6 +54,7 @@ enum {
IOMMUFD_CMD_IOAS_MAP_FILE = 0x8f,
IOMMUFD_CMD_VIOMMU_ALLOC = 0x90,
IOMMUFD_CMD_VDEVICE_ALLOC = 0x91,
IOMMUFD_CMD_IOAS_CHANGE_PROCESS = 0x92,
};
/**
@@ -972,4 +973,26 @@ struct iommu_vdevice_alloc {
__aligned_u64 virt_id;
};
#define IOMMU_VDEVICE_ALLOC _IO(IOMMUFD_TYPE, IOMMUFD_CMD_VDEVICE_ALLOC)
/**
* struct iommu_ioas_change_process - ioctl(VFIO_IOAS_CHANGE_PROCESS)
* @size: sizeof(struct iommu_ioas_change_process)
* @__reserved: Must be 0
*
* This transfers pinned memory counts for every memory map in every IOAS
* in the context to the current process. This only supports maps created
* with IOMMU_IOAS_MAP_FILE, and returns EINVAL if other maps are present.
* If the ioctl returns a failure status, then nothing is changed.
*
* This API is useful for transferring operation of a device from one process
* to another, such as during userland live update.
*/
struct iommu_ioas_change_process {
__u32 size;
__u32 __reserved;
};
#define IOMMU_IOAS_CHANGE_PROCESS \
_IO(IOMMUFD_TYPE, IOMMUFD_CMD_IOAS_CHANGE_PROCESS)
#endif