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Re: [PATCH v16 QEMU 09/16] vfio: Add save state functions to SaveVMHandl
From: |
Alex Williamson |
Subject: |
Re: [PATCH v16 QEMU 09/16] vfio: Add save state functions to SaveVMHandlers |
Date: |
Wed, 25 Mar 2020 16:03:11 -0600 |
On Wed, 25 Mar 2020 02:39:07 +0530
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 | 245
> +++++++++++++++++++++++++++++++++++++++++-
> hw/vfio/trace-events | 6 ++
> include/hw/vfio/vfio-common.h | 1 +
> 3 files changed, 251 insertions(+), 1 deletion(-)
>
> diff --git a/hw/vfio/migration.c b/hw/vfio/migration.c
> index 033f76526e49..ecbeed5182c2 100644
> --- a/hw/vfio/migration.c
> +++ b/hw/vfio/migration.c
> @@ -138,6 +138,137 @@ 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) &&
> + (data_offset < region->mmaps[i].offset + region->mmaps[i].size)
> &&
> + (data_size <= region->mmaps[i].size)) {
(data_offset - region->mmaps[i].offset) can be non-zero, so this test
is invalid. Additionally the uapi does not require that a give data
chunk fits exclusively within an mmap'd area, it may overlap one or
more mmap'd sections of the region, possibly with non-mmap'd areas
included.
> + 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;
> + 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;
The ternary is unnecessary, "? true : false" is redundant.
> +
> + if (!buffer_mmaped) {
> + buf = g_try_malloc0(data_size);
Why do we need zero'd memory?
> + 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);
This can segfault when mmap'd given the above assumptions about size
and layout.
> +
> + if (!buffer_mmaped) {
> + g_free(buf);
> + }
> + } else {
> + qemu_put_be64(f, data_size);
We insert a zero? Couldn't we add the section header and end here and
skip it entirely?
> + }
> +
> + 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))) {
> + 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)
> @@ -154,7 +285,7 @@ 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;
> }
> @@ -194,9 +325,121 @@ 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;
> + int ret, data_size;
> +
> + qemu_put_be64(f, VFIO_MIG_FLAG_DEV_DATA_STATE);
> +
> + 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);
> + if (data_size == 0) {
> + /* indicates data finished, goto complete phase */
> + return 1;
But it's pending_bytes not data_size that indicates we're done. How do
we get away with ignoring pending_bytes for the save_live_iterate phase?
> + }
> +
> + 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 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)"
> 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 {
- Re: [PATCH v16 QEMU 04/16] vfio: Add save and load functions for VFIO PCI devices, (continued)
Re: [PATCH v16 QEMU 04/16] vfio: Add save and load functions for VFIO PCI devices, Dr. David Alan Gilbert, 2020/03/26
[PATCH v16 QEMU 05/16] vfio: Add migration region initialization and finalize function, Kirti Wankhede, 2020/03/24
[PATCH v16 QEMU 06/16] vfio: Add VM state change handler to know state of VM, Kirti Wankhede, 2020/03/24
[PATCH v16 QEMU 07/16] vfio: Add migration state change notifier, Kirti Wankhede, 2020/03/24
[PATCH v16 QEMU 08/16] vfio: Register SaveVMHandlers for VFIO device, Kirti Wankhede, 2020/03/24
[PATCH v16 QEMU 09/16] vfio: Add save state functions to SaveVMHandlers, Kirti Wankhede, 2020/03/24
- Re: [PATCH v16 QEMU 09/16] vfio: Add save state functions to SaveVMHandlers,
Alex Williamson <=
[PATCH v16 QEMU 10/16] vfio: Add load state functions to SaveVMHandlers, Kirti Wankhede, 2020/03/24
[PATCH v16 QEMU 11/16] iommu: add callback to get address limit IOMMU supports, Kirti Wankhede, 2020/03/24
[PATCH v16 QEMU 12/16] memory: Set DIRTY_MEMORY_MIGRATION when IOMMU is enabled, Kirti Wankhede, 2020/03/24
[PATCH v16 QEMU 13/16] vfio: Add function to start and stop dirty pages tracking, Kirti Wankhede, 2020/03/24
[PATCH v16 QEMU 14/16] vfio: Add vfio_listener_log_sync to mark dirty pages, Kirti Wankhede, 2020/03/24
[PATCH v16 QEMU 15/16] vfio: Add ioctl to get dirty pages bitmap during dma unmap., Kirti Wankhede, 2020/03/24