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vfio/mlx5: Improve the target side flow to reduce downtime

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Improve the target side flow to reduce downtime as of below.

- Support reading an optional record which includes the expected
  stop_copy size.
- Once the source sends this record data, which expects to be sent as
  part of the pre_copy flow, prepare the data buffers that may be large
  enough to hold the final stop_copy data.

The above reduces the migration downtime as the relevant stuff that is
needed to load the image data is prepared ahead as part of pre_copy.

Signed-off-by: Yishai Hadas <yishaih@nvidia.com>
Link: https://lore.kernel.org/r/20230124144955.139901-4-yishaih@nvidia.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
This commit is contained in:
Yishai Hadas 2023-01-24 16:49:55 +02:00 committed by Alex Williamson
parent b04e2e86e9
commit f4f0c25e5d
2 changed files with 105 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
drivers/vfio/pci/mlx5/cmd.h
View File

@ -27,6 +27,8 @@ enum mlx5_vf_migf_state {
enum mlx5_vf_load_state {
MLX5_VF_LOAD_STATE_READ_IMAGE_NO_HEADER,
MLX5_VF_LOAD_STATE_READ_HEADER,
MLX5_VF_LOAD_STATE_PREP_HEADER_DATA,
MLX5_VF_LOAD_STATE_READ_HEADER_DATA,
MLX5_VF_LOAD_STATE_PREP_IMAGE,
MLX5_VF_LOAD_STATE_READ_IMAGE,
MLX5_VF_LOAD_STATE_LOAD_IMAGE,
@ -59,7 +61,6 @@ struct mlx5_vhca_data_buffer {
loff_t start_pos;
u64 length;
u64 allocated_length;
u64 header_image_size;
u32 mkey;
enum dma_data_direction dma_dir;
u8 dmaed:1;
@ -89,6 +90,9 @@ struct mlx5_vf_migration_file {
enum mlx5_vf_load_state load_state;
u32 pdn;
loff_t max_pos;
u64 record_size;
u32 record_tag;
u64 stop_copy_prep_size;
u64 pre_copy_initial_bytes;
struct mlx5_vhca_data_buffer *buf;
struct mlx5_vhca_data_buffer *buf_header;

111
drivers/vfio/pci/mlx5/main.c
View File

@ -703,6 +703,56 @@ mlx5vf_resume_read_image(struct mlx5_vf_migration_file *migf,
return 0;
}
static int
mlx5vf_resume_read_header_data(struct mlx5_vf_migration_file *migf,
struct mlx5_vhca_data_buffer *vhca_buf,
const char __user **buf, size_t *len,
loff_t *pos, ssize_t *done)
{
size_t copy_len, to_copy;
size_t required_data;
u8 *to_buff;
int ret;
required_data = migf->record_size - vhca_buf->length;
to_copy = min_t(size_t, *len, required_data);
copy_len = to_copy;
while (to_copy) {
ret = mlx5vf_append_page_to_mig_buf(vhca_buf, buf, &to_copy, pos,
done);
if (ret)
return ret;
}
*len -= copy_len;
if (vhca_buf->length == migf->record_size) {
switch (migf->record_tag) {
case MLX5_MIGF_HEADER_TAG_STOP_COPY_SIZE:
{
struct page *page;
page = mlx5vf_get_migration_page(vhca_buf, 0);
if (!page)
return -EINVAL;
to_buff = kmap_local_page(page);
migf->stop_copy_prep_size = min_t(u64,
le64_to_cpup((__le64 *)to_buff), MAX_LOAD_SIZE);
kunmap_local(to_buff);
break;
}
default:
/* Optional tag */
break;
}
migf->load_state = MLX5_VF_LOAD_STATE_READ_HEADER;
migf->max_pos += migf->record_size;
vhca_buf->length = 0;
}
return 0;
}
static int
mlx5vf_resume_read_header(struct mlx5_vf_migration_file *migf,
struct mlx5_vhca_data_buffer *vhca_buf,
@ -733,23 +783,38 @@ mlx5vf_resume_read_header(struct mlx5_vf_migration_file *migf,
*len -= copy_len;
vhca_buf->length += copy_len;
if (vhca_buf->length == sizeof(struct mlx5_vf_migration_header)) {
u64 flags;
u64 record_size;
u32 flags;
vhca_buf->header_image_size = le64_to_cpup((__le64 *)to_buff);
if (vhca_buf->header_image_size > MAX_LOAD_SIZE) {
record_size = le64_to_cpup((__le64 *)to_buff);
if (record_size > MAX_LOAD_SIZE) {
ret = -ENOMEM;
goto end;
}
flags = le64_to_cpup((__le64 *)(to_buff +
migf->record_size = record_size;
flags = le32_to_cpup((__le32 *)(to_buff +
offsetof(struct mlx5_vf_migration_header, flags)));
if (flags) {
ret = -EOPNOTSUPP;
goto end;
migf->record_tag = le32_to_cpup((__le32 *)(to_buff +
offsetof(struct mlx5_vf_migration_header, tag)));
switch (migf->record_tag) {
case MLX5_MIGF_HEADER_TAG_FW_DATA:
migf->load_state = MLX5_VF_LOAD_STATE_PREP_IMAGE;
break;
case MLX5_MIGF_HEADER_TAG_STOP_COPY_SIZE:
migf->load_state = MLX5_VF_LOAD_STATE_PREP_HEADER_DATA;
break;
default:
if (!(flags & MLX5_MIGF_HEADER_FLAGS_TAG_OPTIONAL)) {
ret = -EOPNOTSUPP;
goto end;
}
/* We may read and skip this optional record data */
migf->load_state = MLX5_VF_LOAD_STATE_PREP_HEADER_DATA;
}
migf->load_state = MLX5_VF_LOAD_STATE_PREP_IMAGE;
migf->max_pos += vhca_buf->length;
vhca_buf->length = 0;
*has_work = true;
}
end:
@ -793,9 +858,34 @@ static ssize_t mlx5vf_resume_write(struct file *filp, const char __user *buf,
if (ret)
goto out_unlock;
break;
case MLX5_VF_LOAD_STATE_PREP_HEADER_DATA:
if (vhca_buf_header->allocated_length < migf->record_size) {
mlx5vf_free_data_buffer(vhca_buf_header);
migf->buf_header = mlx5vf_alloc_data_buffer(migf,
migf->record_size, DMA_NONE);
if (IS_ERR(migf->buf_header)) {
ret = PTR_ERR(migf->buf_header);
migf->buf_header = NULL;
goto out_unlock;
}
vhca_buf_header = migf->buf_header;
}
vhca_buf_header->start_pos = migf->max_pos;
migf->load_state = MLX5_VF_LOAD_STATE_READ_HEADER_DATA;
break;
case MLX5_VF_LOAD_STATE_READ_HEADER_DATA:
ret = mlx5vf_resume_read_header_data(migf, vhca_buf_header,
&buf, &len, pos, &done);
if (ret)
goto out_unlock;
break;
case MLX5_VF_LOAD_STATE_PREP_IMAGE:
{
u64 size = vhca_buf_header->header_image_size;
u64 size = max(migf->record_size,
migf->stop_copy_prep_size);
if (vhca_buf->allocated_length < size) {
mlx5vf_free_data_buffer(vhca_buf);
@ -824,7 +914,7 @@ static ssize_t mlx5vf_resume_write(struct file *filp, const char __user *buf,
break;
case MLX5_VF_LOAD_STATE_READ_IMAGE:
ret = mlx5vf_resume_read_image(migf, vhca_buf,
vhca_buf_header->header_image_size,
migf->record_size,
&buf, &len, pos, &done, &has_work);
if (ret)
goto out_unlock;
@ -837,7 +927,6 @@ static ssize_t mlx5vf_resume_write(struct file *filp, const char __user *buf,
/* prep header buf for next image */
vhca_buf_header->length = 0;
vhca_buf_header->header_image_size = 0;
/* prep data buf for next image */
vhca_buf->length = 0;