Use VFIO_DEVICE_FEATURE_MIG_DATA_SIZE uAPI to query the device data size and report it in vfio_save_pending() instead of the hardcoded value that is currently used.
Signed-off-by: Avihai Horon <avih...@nvidia.com> --- hw/vfio/migration.c | 27 ++++++++++++++++++++------- linux-headers/linux/vfio.h | 13 +++++++++++++ 2 files changed, 33 insertions(+), 7 deletions(-) diff --git a/hw/vfio/migration.c b/hw/vfio/migration.c index e8068b9147..8ade901383 100644 --- a/hw/vfio/migration.c +++ b/hw/vfio/migration.c @@ -225,14 +225,27 @@ static void vfio_save_pending(void *opaque, uint64_t threshold_size, uint64_t *res_precopy, uint64_t *res_postcopy) { VFIODevice *vbasedev = opaque; + uint64_t buf[DIV_ROUND_UP(sizeof(struct vfio_device_feature) + + sizeof(struct vfio_device_feature_mig_data_size), + sizeof(uint64_t))] = {}; + struct vfio_device_feature *feature = (void *)buf; + struct vfio_device_feature_mig_data_size *mig_data_size = + (void *)feature->data; + + feature->argsz = sizeof(buf); + feature->flags = + VFIO_DEVICE_FEATURE_GET | VFIO_DEVICE_FEATURE_MIG_DATA_SIZE; - /* - * VFIO migration protocol v2 currently doesn't have an API to get pending - * device state size. Until such API is introduced, report some big - * arbitrary pending size so the device will be taken into account for - * downtime limit calculations. - */ - *res_postcopy += VFIO_MIG_PENDING_SIZE; + if (ioctl(vbasedev->fd, VFIO_DEVICE_FEATURE, feature)) { + if (errno != ENOTTY) { + return; + } + + /* Kernel doesn't support VFIO_DEVICE_FEATURE_MIG_DATA_SIZE */ + *res_postcopy += VFIO_MIG_PENDING_SIZE; + } else { + *res_postcopy += mig_data_size->stop_copy_length; + } trace_vfio_save_pending(vbasedev->name, *res_precopy, *res_postcopy); } diff --git a/linux-headers/linux/vfio.h b/linux-headers/linux/vfio.h index ede44b5572..5c4ddf424f 100644 --- a/linux-headers/linux/vfio.h +++ b/linux-headers/linux/vfio.h @@ -986,6 +986,19 @@ enum vfio_device_mig_state { VFIO_DEVICE_STATE_RUNNING_P2P = 5, }; +/* + * Upon VFIO_DEVICE_FEATURE_GET read back the estimated data length that will + * be required to complete stop copy. + * + * Note: Can be called on each device state. + */ + +struct vfio_device_feature_mig_data_size { + __aligned_u64 stop_copy_length; +}; + +#define VFIO_DEVICE_FEATURE_MIG_DATA_SIZE 9 + /* -------- API for Type1 VFIO IOMMU -------- */ /** -- 2.21.3