* Kirti Wankhede (kwankh...@nvidia.com) wrote:
> - Defined MIGRATION region type and sub-type.
> - Defined VFIO device states during migration process.
> - Defined vfio_device_migration_info structure which will be placed at 0th
> offset of migration region to get/set VFIO device related information.
> Defined actions and members of structure usage for each action:
> * To convey VFIO device state to be transitioned to.
> * To get pending bytes yet to be migrated for VFIO device
> * To ask driver to write data to migration region and return number of
> bytes
> written in the region
> * In migration resume path, user space app writes to migration region and
> communicates it to vendor driver.
> * Get bitmap of dirty pages from vendor driver from given start address
>
> Signed-off-by: Kirti Wankhede <kwankh...@nvidia.com>
> Reviewed-by: Neo Jia <c...@nvidia.com>
<snip>
> + * Action Get buffer:
> + * On this action, vendor driver should write data to migration region
> and
> + * return number of bytes written in the region.
> + * data.offset [output] : offset in the region from where data is
> written.
> + * data.size [output] : number of bytes written in migration buffer by
> + * vendor driver.
<snip>
> + */
> +
> +struct vfio_device_migration_info {
> + __u32 device_state; /* VFIO device state */
> + struct {
> + __u64 precopy_only;
> + __u64 compatible;
> + __u64 postcopy_only;
> + __u64 threshold_size;
> + } pending;
> + struct {
> + __u64 offset; /* offset */
> + __u64 size; /* size */
> + } data;
I'm curious how the offsets/size work; how does the
kernel driver know the maximum size of state it's allowed to write?
Why would it pick a none-0 offset into the output region?
Without having dug further these feel like i/o rather than just output;
i.e. the calling process says 'put it at that offset and you've got size
bytes' and the kernel replies with 'I did put it at offset and I wrote
only this size bytes'
Dave
> + struct {
> + __u64 start_addr;
> + __u64 total;
> + __u64 copied;
> + } dirty_pfns;
> +} __attribute__((packed));
> +
> /* -------- API for Type1 VFIO IOMMU -------- */
>
> /**
> --
> 2.7.0
>
--
Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK
