On 20.05.25 12:28, Chenyi Qiang wrote:
A new state_change() helper is introduced for RamBlockAttribute to efficiently notify all registered RamDiscardListeners, including VFIO listeners, about memory conversion events in guest_memfd. The VFIO listener can dynamically DMA map/unmap shared pages based on conversion types: - For conversions from shared to private, the VFIO system ensures the discarding of shared mapping from the IOMMU. - For conversions from private to shared, it triggers the population of the shared mapping into the IOMMU. Currently, memory conversion failures cause QEMU to quit instead of resuming the guest or retrying the operation. It would be a future work to add more error handling or rollback mechanisms once conversion failures are allowed. For example, in-place conversion of guest_memfd could retry the unmap operation during the conversion from shared to private. However, for now, keep the complex error handling out of the picture as it is not required: - If a conversion request is made for a page already in the desired state, the helper simply returns success. - For requests involving a range partially in the desired state, there is no such scenario in practice at present. Simply return error. - If a conversion request is declined by other systems, such as a failure from VFIO during notify_to_populated(), the failure is returned directly. As for notify_to_discard(), VFIO cannot fail unmap/unpin, so no error is returned. Note that the bitmap status is updated before callbacks, allowing listeners to handle memory based on the latest status. Signed-off-by: Chenyi Qiang <chenyi.qiang@xxxxxxxxx> ---
I think this should be squashed into the previous patch: I fail to see why the split makes sense.
-- Cheers, David / dhildenb
