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Re: [PATCH QEMU v23 09/18] vfio: Add save state functions to SaveVMHandl
From: |
Dr. David Alan Gilbert |
Subject: |
Re: [PATCH QEMU v23 09/18] vfio: Add save state functions to SaveVMHandlers |
Date: |
Thu, 21 May 2020 16:37:40 +0100 |
User-agent: |
Mutt/1.13.4 (2020-02-15) |
* Kirti Wankhede (address@hidden) 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. If pending_bytes > 0, go through below steps.
> - read data_offset - indicates kernel driver to write data to staging
> buffer.
> - read data_size - amount of data in bytes written by vendor driver in
> migration region.
> - read data_size bytes of data from data_offset in the migration region.
> - 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. If pending_bytes > 0, go through below steps.
> c. read data_offset - indicates kernel driver to write data to staging
> buffer.
> d. read data_size - amount of data in bytes written by vendor driver in
> migration region.
> e. read data_size bytes of data from data_offset in the migration region.
> f. Write data packet as below:
> {VFIO_MIG_FLAG_DEV_DATA_STATE, data_size, actual data}
> g. iterate through steps b to f while (pending_bytes > 0)
> h. 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.
>
> Signed-off-by: Kirti Wankhede <address@hidden>
> Reviewed-by: Neo Jia <address@hidden>
> ---
> hw/vfio/migration.c | 254
> +++++++++++++++++++++++++++++++++++++++++-
> hw/vfio/trace-events | 6 +
> include/hw/vfio/vfio-common.h | 1 +
> 3 files changed, 260 insertions(+), 1 deletion(-)
>
> diff --git a/hw/vfio/migration.c b/hw/vfio/migration.c
> index 773c8d16b1c1..d90bd2296afd 100644
> --- a/hw/vfio/migration.c
> +++ b/hw/vfio/migration.c
> @@ -139,6 +139,137 @@ static int vfio_migration_set_state(VFIODevice
> *vbasedev, uint32_t mask,
> 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) &&
that checks the bit we want to map starts at or after this region
> + (data_offset < region->mmaps[i].offset + region->mmaps[i].size)
> &&
and the bit we want to map starts before the end of this region
> + (data_size <= region->mmaps[i].size)) {
Shouldn't that check take into account the offset? If
data_offset-mmaps[i].offset is almost mmaps[i].size then we would be
accessing data_size after the end of the region?
> + ptr = region->mmaps[i].mmap + (data_offset -
> + region->mmaps[i].offset);
> + break;
> + }
> + }
> + return ptr;
> +}
> +
> +static int vfio_save_buffer(QEMUFile *f, VFIODevice *vbasedev)
^^^ do you need to make this int64_t or ssize_t - internally
to this function it's uint64_t but you're also returning errors.
(and then fix up the trace_ and callers below)
> +{
> + VFIOMigration *migration = vbasedev->migration;
> + VFIORegion *region = &migration->region;
> + 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);
> +
> + if (!buffer_mmaped) {
> + buf = g_try_malloc(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);
> + }
> + } 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;
> + 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))) {
You read values from the vfio buffer in a few places and don't check the
sizeof() in ret; this either needs wrapping in a
function/macro/something or doing consistently.
> + 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)
> @@ -157,7 +288,7 @@ static int vfio_save_setup(QEMUFile *f, void *opaque)
> qemu_mutex_unlock_iothread();
> if (ret) {
> error_report("%s: Failed to mmap VFIO migration region %d: %s",
> - vbasedev->name, migration->region.index,
> + vbasedev->name, migration->region.nr,
> strerror(-ret));
> return ret;
> }
> @@ -190,9 +321,130 @@ 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);
> +
> + if (migration->pending_bytes == 0) {
> + ret = vfio_update_pending(vbasedev);
> + if (ret) {
> + return ret;
> + }
> +
> + if (migration->pending_bytes == 0) {
> + /* indicates data finished, goto complete phase */
Is that right that you've sent a DEV_DATA_STATE but not an END_OF_STATE?
> + return 1;
> + }
> + }
> +
> + data_size = vfio_save_buffer(f, vbasedev);
> +
> + 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);
> +
> + 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_RUNNING,
> + VFIO_DEVICE_STATE_SAVING);
> + 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_SAVING, 0);
> + 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 86c18def016e..9a1c5e17d97f 100644
> --- a/hw/vfio/trace-events
> +++ b/hw/vfio/trace-events
> @@ -151,3 +151,9 @@ vfio_vmstate_change(const char *name, int running, const
> char *reason, uint32_t
> vfio_migration_state_notifier(const char *name, const char *state) " (%s)
> state %s"
> vfio_save_setup(const char *name) " (%s)"
> vfio_save_cleanup(const char *name) " (%s)"
> +vfio_save_buffer(const 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(const char *name, uint64_t pending) " (%s) pending
> 0x%"PRIx64
> +vfio_save_device_config_state(const char *name) " (%s)"
> +vfio_save_pending(const char *name, uint64_t precopy, uint64_t postcopy,
> uint64_t compatible) " (%s) precopy 0x%"PRIx64" postcopy 0x%"PRIx64"
> compatible 0x%"PRIx64
> +vfio_save_iterate(const char *name, int data_size) " (%s) data_size %d"
> +vfio_save_complete_precopy(const char *name) " (%s)"
> diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
> index 28f55f66d019..c78033e4149d 100644
> --- a/include/hw/vfio/vfio-common.h
> +++ b/include/hw/vfio/vfio-common.h
> @@ -60,6 +60,7 @@ typedef struct VFIORegion {
>
> typedef struct VFIOMigration {
> VFIORegion region;
> + uint64_t pending_bytes;
> } VFIOMigration;
>
> typedef struct VFIOAddressSpace {
> --
> 2.7.0
>
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK
- Re: [PATCH QEMU v23 05/18] vfio: Add migration region initialization and finalize function, (continued)
- [PATCH QEMU v23 09/18] vfio: Add save state functions to SaveVMHandlers, Kirti Wankhede, 2020/05/20
- [PATCH QEMU v23 10/18] vfio: Add load state functions to SaveVMHandlers, Kirti Wankhede, 2020/05/20
- [PATCH QEMU v23 11/18] iommu: add callback to get address limit IOMMU supports, Kirti Wankhede, 2020/05/20
- [PATCH QEMU v23 12/18] memory: Set DIRTY_MEMORY_MIGRATION when IOMMU is enabled, Kirti Wankhede, 2020/05/20
- [PATCH QEMU v23 13/18] vfio: Get migration capability flags for container, Kirti Wankhede, 2020/05/20
- [PATCH QEMU v23 14/18] vfio: Add function to start and stop dirty pages tracking, Kirti Wankhede, 2020/05/20