On Tue, Jul 09, 2019 at 05:49:16PM +0800, Kirti Wankhede wrote:
> Added .save_live_pending, .save_live_iterate and .save_live_complete_precopy
> functions. These functions handles pre-copy and stop-and-copy phase.
>
> In _SAVING|_RUNNING device state or pre-copy phase:
> - read pending_bytes
> - read data_offset - indicates kernel driver to write data to staging
> buffer which is mmapped.
> - read data_size - amount of data in bytes written by vendor driver in
> migration
> region.
> - if data section is trapped, pread() from data_offset of data_size.
> - if data section is mmaped, read mmaped buffer of data_size.
> - Write data packet to file stream as below:
> {VFIO_MIG_FLAG_DEV_DATA_STATE, data_size, actual data,
> VFIO_MIG_FLAG_END_OF_STATE }
>
> In _SAVING device state or stop-and-copy phase
> a. read config space of device and save to migration file stream. This
> doesn't need to be from vendor driver. Any other special config state
> from driver can be saved as data in following iteration.
> b. read pending_bytes
> c. read data_offset - indicates kernel driver to write data to staging
> buffer which is mmapped.
> d. read data_size - amount of data in bytes written by vendor driver in
> migration region.
> e. if data section is trapped, pread() from data_offset of data_size.
> f. if data section is mmaped, read mmaped buffer of data_size.
> g. Write data packet as below:
> {VFIO_MIG_FLAG_DEV_DATA_STATE, data_size, actual data}
> h. iterate through steps b to g while (pending_bytes > 0)
> i. Write {VFIO_MIG_FLAG_END_OF_STATE}
>
> When data region is mapped, its user's responsibility to read data from
> data_offset of data_size before moving to next steps.
>
each iteration, vendor driver has to set data_offset for device data once
and for dirty page once. it's really cumbersome.
could dirty page and device data use different data_offset? e.g.
data_offset, dirty_page_offset? or just keep them constant after being
read first time?
> .save_live_iterate runs outside the iothread lock in the migration case, which
> could race with asynchronous call to get dirty page list causing data
> corruption
> in mapped migration region. Mutex added here to serial migration buffer read
> operation.
>
> Signed-off-by: Kirti Wankhede <kwankh...@nvidia.com>
> Reviewed-by: Neo Jia <c...@nvidia.com>
> ---
> hw/vfio/migration.c | 246
> +++++++++++++++++++++++++++++++++++++++++++++++++++
> hw/vfio/trace-events | 6 ++
> 2 files changed, 252 insertions(+)
>
> diff --git a/hw/vfio/migration.c b/hw/vfio/migration.c
> index 0597a45fda2d..4e9b4cce230b 100644
> --- a/hw/vfio/migration.c
> +++ b/hw/vfio/migration.c
> @@ -117,6 +117,138 @@ static int vfio_migration_set_state(VFIODevice
> *vbasedev, uint32_t state)
> return 0;
> }
>
> +static void *find_data_region(VFIORegion *region,
> + uint64_t data_offset,
> + uint64_t data_size)
> +{
> + void *ptr = NULL;
> + int i;
> +
> + for (i = 0; i < region->nr_mmaps; i++) {
> + if ((data_offset >= region->mmaps[i].offset) &&
> + (data_offset < region->mmaps[i].offset + region->mmaps[i].size)
> &&
> + (data_size <= region->mmaps[i].size)) {
> + ptr = region->mmaps[i].mmap + (data_offset -
> + region->mmaps[i].offset);
> + break;
> + }
> + }
> + return ptr;
> +}
> +
> +static int vfio_save_buffer(QEMUFile *f, VFIODevice *vbasedev)
> +{
> + VFIOMigration *migration = vbasedev->migration;
> + VFIORegion *region = &migration->region.buffer;
> + uint64_t data_offset = 0, data_size = 0;
> + int ret;
> +
> + ret = pread(vbasedev->fd, &data_offset, sizeof(data_offset),
> + region->fd_offset + offsetof(struct
> vfio_device_migration_info,
> + data_offset));
> + if (ret != sizeof(data_offset)) {
> + error_report("%s: Failed to get migration buffer data offset %d",
> + vbasedev->name, ret);
> + return -EINVAL;
> + }
> +
> + ret = pread(vbasedev->fd, &data_size, sizeof(data_size),
> + region->fd_offset + offsetof(struct
> vfio_device_migration_info,
> + data_size));
> + if (ret != sizeof(data_size)) {
> + error_report("%s: Failed to get migration buffer data size %d",
> + vbasedev->name, ret);
> + return -EINVAL;
> + }
> +
> + if (data_size > 0) {
> + void *buf = NULL;
> + bool buffer_mmaped;
> +
> + if (region->mmaps) {
> + buf = find_data_region(region, data_offset, data_size);
> + }
> +
> + buffer_mmaped = (buf != NULL) ? true : false;
> +
> + if (!buffer_mmaped) {
> + buf = g_try_malloc0(data_size);
> + if (!buf) {
> + error_report("%s: Error allocating buffer ", __func__);
> + return -ENOMEM;
> + }
> +
> + ret = pread(vbasedev->fd, buf, data_size,
> + region->fd_offset + data_offset);
> + if (ret != data_size) {
> + error_report("%s: Failed to get migration data %d",
> + vbasedev->name, ret);
> + g_free(buf);
> + return -EINVAL;
> + }
> + }
> +
> + qemu_put_be64(f, data_size);
> + qemu_put_buffer(f, buf, data_size);
> +
> + if (!buffer_mmaped) {
> + g_free(buf);
> + }
> + migration->pending_bytes -= data_size;
> + } else {
> + qemu_put_be64(f, data_size);
> + }
> +
> + trace_vfio_save_buffer(vbasedev->name, data_offset, data_size,
> + migration->pending_bytes);
> +
> + ret = qemu_file_get_error(f);
> + if (ret) {
> + return ret;
> + }
> +
> + return data_size;
> +}
> +
> +static int vfio_update_pending(VFIODevice *vbasedev)
> +{
> + VFIOMigration *migration = vbasedev->migration;
> + VFIORegion *region = &migration->region.buffer;
> + uint64_t pending_bytes = 0;
> + int ret;
> +
> + ret = pread(vbasedev->fd, &pending_bytes, sizeof(pending_bytes),
> + region->fd_offset + offsetof(struct
> vfio_device_migration_info,
> + pending_bytes));
> + if ((ret < 0) || (ret != sizeof(pending_bytes))) {
> + error_report("%s: Failed to get pending bytes %d",
> + vbasedev->name, ret);
> + migration->pending_bytes = 0;
> + return (ret < 0) ? ret : -EINVAL;
> + }
> +
> + migration->pending_bytes = pending_bytes;
> + trace_vfio_update_pending(vbasedev->name, pending_bytes);
> + return 0;
> +}
> +
> +static int vfio_save_device_config_state(QEMUFile *f, void *opaque)
> +{
> + VFIODevice *vbasedev = opaque;
> +
> + qemu_put_be64(f, VFIO_MIG_FLAG_DEV_CONFIG_STATE);
> +
> + if (vbasedev->ops && vbasedev->ops->vfio_save_config) {
> + vbasedev->ops->vfio_save_config(vbasedev, f);
> + }
> +
> + qemu_put_be64(f, VFIO_MIG_FLAG_END_OF_STATE);
> +
> + trace_vfio_save_device_config_state(vbasedev->name);
> +
> + return qemu_file_get_error(f);
> +}
> +
> /* ---------------------------------------------------------------------- */
>
> static int vfio_save_setup(QEMUFile *f, void *opaque)
> @@ -178,9 +310,123 @@ static void vfio_save_cleanup(void *opaque)
> trace_vfio_save_cleanup(vbasedev->name);
> }
>
> +static void vfio_save_pending(QEMUFile *f, void *opaque,
> + uint64_t threshold_size,
> + uint64_t *res_precopy_only,
> + uint64_t *res_compatible,
> + uint64_t *res_postcopy_only)
> +{
> + VFIODevice *vbasedev = opaque;
> + VFIOMigration *migration = vbasedev->migration;
> + int ret;
> +
> + ret = vfio_update_pending(vbasedev);
> + if (ret) {
> + return;
> + }
> +
> + *res_precopy_only += migration->pending_bytes;
> +
> + trace_vfio_save_pending(vbasedev->name, *res_precopy_only,
> + *res_postcopy_only, *res_compatible);
> +}
> +
> +static int vfio_save_iterate(QEMUFile *f, void *opaque)
> +{
> + VFIODevice *vbasedev = opaque;
> + VFIOMigration *migration = vbasedev->migration;
> + int ret, data_size;
> +
> + qemu_put_be64(f, VFIO_MIG_FLAG_DEV_DATA_STATE);
> +
> + qemu_mutex_lock(&migration->lock);
> + data_size = vfio_save_buffer(f, vbasedev);
> + qemu_mutex_unlock(&migration->lock);
> +
> + if (data_size < 0) {
> + error_report("%s: vfio_save_buffer failed %s", vbasedev->name,
> + strerror(errno));
> + return data_size;
> + }
> +
> + qemu_put_be64(f, VFIO_MIG_FLAG_END_OF_STATE);
> +
> + ret = qemu_file_get_error(f);
> + if (ret) {
> + return ret;
> + }
> +
> + trace_vfio_save_iterate(vbasedev->name, data_size);
> + if (data_size == 0) {
> + /* indicates data finished, goto complete phase */
> + return 1;
> + }
> +
> + return 0;
> +}
> +
> +static int vfio_save_complete_precopy(QEMUFile *f, void *opaque)
> +{
> + VFIODevice *vbasedev = opaque;
> + VFIOMigration *migration = vbasedev->migration;
> + int ret;
> +
> + ret = vfio_migration_set_state(vbasedev, VFIO_DEVICE_STATE_SAVING);
I think this state is already set in vm state change handler, where
~VFIO_DEVICE_STATE_RUNNING is applied to (VFIO_DEVICE_STATE_RUNNING |
VFIO_DEVICE_STATE_SAVING).
Why VFIO_DEVICE_STATE_SAVING is redundantly set here?
> + if (ret) {
> + error_report("%s: Failed to set state STOP and SAVING",
> + vbasedev->name);
> + return ret;
> + }
> +
> + ret = vfio_save_device_config_state(f, opaque);
> + if (ret) {
> + return ret;
> + }
> +
> + ret = vfio_update_pending(vbasedev);
> + if (ret) {
> + return ret;
> + }
> +
> + while (migration->pending_bytes > 0) {
> + qemu_put_be64(f, VFIO_MIG_FLAG_DEV_DATA_STATE);
> + ret = vfio_save_buffer(f, vbasedev);
> + if (ret < 0) {
> + error_report("%s: Failed to save buffer", vbasedev->name);
> + return ret;
> + } else if (ret == 0) {
> + break;
> + }
> +
> + ret = vfio_update_pending(vbasedev);
> + if (ret) {
> + return ret;
> + }
> + }
> +
> + qemu_put_be64(f, VFIO_MIG_FLAG_END_OF_STATE);
> +
> + ret = qemu_file_get_error(f);
> + if (ret) {
> + return ret;
> + }
> +
> + ret = vfio_migration_set_state(vbasedev, ~VFIO_DEVICE_STATE_MASK);
This state is a little weird.
Thanks
Yan
> + if (ret) {
> + error_report("%s: Failed to set state STOPPED", vbasedev->name);
> + return ret;
> + }
> +
> + trace_vfio_save_complete_precopy(vbasedev->name);
> + return ret;
> +}
> +
> static SaveVMHandlers savevm_vfio_handlers = {
> .save_setup = vfio_save_setup,
> .save_cleanup = vfio_save_cleanup,
> + .save_live_pending = vfio_save_pending,
> + .save_live_iterate = vfio_save_iterate,
> + .save_live_complete_precopy = vfio_save_complete_precopy,
> };
>
> /* ---------------------------------------------------------------------- */
> diff --git a/hw/vfio/trace-events b/hw/vfio/trace-events
> index 4bb43f18f315..bdf40ba368c7 100644
> --- a/hw/vfio/trace-events
> +++ b/hw/vfio/trace-events
> @@ -151,3 +151,9 @@ vfio_vmstate_change(char *name, int running, const char
> *reason, uint32_t dev_st
> vfio_migration_state_notifier(char *name, int state) " (%s) state %d"
> vfio_save_setup(char *name) " (%s)"
> vfio_save_cleanup(char *name) " (%s)"
> +vfio_save_buffer(char *name, uint64_t data_offset, uint64_t data_size,
> uint64_t pending) " (%s) Offset 0x%"PRIx64" size 0x%"PRIx64" pending
> 0x%"PRIx64
> +vfio_update_pending(char *name, uint64_t pending) " (%s) pending 0x%"PRIx64
> +vfio_save_device_config_state(char *name) " (%s)"
> +vfio_save_pending(char *name, uint64_t precopy, uint64_t postcopy, uint64_t
> compatible) " (%s) precopy 0x%"PRIx64" postcopy 0x%"PRIx64" compatible
> 0x%"PRIx64
> +vfio_save_iterate(char *name, int data_size) " (%s) data_size %d"
> +vfio_save_complete_precopy(char *name) " (%s)"
> --
> 2.7.0
>
