Re: [PATCH 09/26] drm/xe/pf: Expose VF migration data size over debugfs

[Matthew Brost <matthew.brost@intel.com>]

On Sat, Oct 11, 2025 at 09:38:30PM +0200, Michał Winiarski wrote:
> The size is normally used to make a decision on when to stop the device
> (mainly when it's in a pre_copy state).
> 
> Signed-off-by: Michał Winiarski <michal.winiarski@intel.com>
> ---
>  drivers/gpu/drm/xe/xe_gt_sriov_pf_migration.c | 18 ++++++++++
>  drivers/gpu/drm/xe/xe_gt_sriov_pf_migration.h |  2 ++
>  drivers/gpu/drm/xe/xe_sriov_pf_debugfs.c      | 34 +++++++++++++++++++
>  drivers/gpu/drm/xe/xe_sriov_pf_migration.c    | 30 ++++++++++++++++
>  drivers/gpu/drm/xe/xe_sriov_pf_migration.h    |  1 +
>  5 files changed, 85 insertions(+)
> 
> diff --git a/drivers/gpu/drm/xe/xe_gt_sriov_pf_migration.c b/drivers/gpu/drm/xe/xe_gt_sriov_pf_migration.c
> index 582aaf062cbd4..50f09994e2854 100644
> --- a/drivers/gpu/drm/xe/xe_gt_sriov_pf_migration.c
> +++ b/drivers/gpu/drm/xe/xe_gt_sriov_pf_migration.c
> @@ -395,6 +395,24 @@ ssize_t xe_gt_sriov_pf_migration_write_guc_state(struct xe_gt *gt, unsigned int
>  }
>  #endif /* CONFIG_DEBUG_FS */
>  
> +/**
> + * xe_gt_sriov_pf_migration_size() - Total size of migration data from all components within a GT
> + * @gt: the &struct xe_gt
> + * @vfid: the VF identifier
> + *
> + * This function is for PF only.
> + *
> + * Return: total migration data size in bytes or a negative error code on failure.
> + */
> +ssize_t xe_gt_sriov_pf_migration_size(struct xe_gt *gt, unsigned int vfid)
> +{
> +	ssize_t total = 0;
> +
> +	xe_gt_assert(gt, IS_SRIOV_PF(gt_to_xe(gt)));
> +
> +	return total;
> +}
> +
>  /**
>   * xe_gt_sriov_pf_migration_ring_empty() - Check if a migration ring is empty
>   * @gt: the &struct xe_gt
> diff --git a/drivers/gpu/drm/xe/xe_gt_sriov_pf_migration.h b/drivers/gpu/drm/xe/xe_gt_sriov_pf_migration.h
> index 1e4dc46413823..e5298d35d7d7e 100644
> --- a/drivers/gpu/drm/xe/xe_gt_sriov_pf_migration.h
> +++ b/drivers/gpu/drm/xe/xe_gt_sriov_pf_migration.h
> @@ -15,6 +15,8 @@ int xe_gt_sriov_pf_migration_init(struct xe_gt *gt);
>  int xe_gt_sriov_pf_migration_save_guc_state(struct xe_gt *gt, unsigned int vfid);
>  int xe_gt_sriov_pf_migration_restore_guc_state(struct xe_gt *gt, unsigned int vfid);
>  
> +ssize_t xe_gt_sriov_pf_migration_size(struct xe_gt *gt, unsigned int vfid);
> +
>  bool xe_gt_sriov_pf_migration_ring_empty(struct xe_gt *gt, unsigned int vfid);
>  int xe_gt_sriov_pf_migration_ring_produce(struct xe_gt *gt, unsigned int vfid,
>  					  struct xe_sriov_pf_migration_data *data);
> diff --git a/drivers/gpu/drm/xe/xe_sriov_pf_debugfs.c b/drivers/gpu/drm/xe/xe_sriov_pf_debugfs.c
> index ce780719760a6..b06e893fe54cf 100644
> --- a/drivers/gpu/drm/xe/xe_sriov_pf_debugfs.c
> +++ b/drivers/gpu/drm/xe/xe_sriov_pf_debugfs.c
> @@ -13,6 +13,7 @@
>  #include "xe_sriov_pf_control.h"
>  #include "xe_sriov_pf_debugfs.h"
>  #include "xe_sriov_pf_helpers.h"
> +#include "xe_sriov_pf_migration.h"
>  #include "xe_sriov_pf_migration_data.h"
>  #include "xe_sriov_pf_service.h"
>  #include "xe_sriov_printk.h"
> @@ -203,6 +204,38 @@ static const struct file_operations data_vf_fops = {
>  	.llseek		= default_llseek,
>  };
>  
> +static ssize_t size_read(struct file *file, char __user *ubuf, size_t count, loff_t *ppos)
> +{
> +	struct dentry *dent = file_dentry(file);
> +	struct dentry *vfdentry = dent->d_parent;
> +	struct dentry *migration_dentry = vfdentry->d_parent;
> +	unsigned int vfid = (uintptr_t)vfdentry->d_inode->i_private;
> +	struct xe_device *xe = migration_dentry->d_inode->i_private;
> +	char buf[21];
> +	ssize_t ret;
> +	int len;
> +
> +	xe_assert(xe, vfid);
> +	xe_sriov_pf_assert_vfid(xe, vfid);
> +
> +	xe_pm_runtime_get(xe);

You don't need a PM ref here as this is purely software (i.e, the
hardware is not touched).

Matt

> +	ret = xe_sriov_pf_migration_size(xe, vfid);
> +	xe_pm_runtime_put(xe);
> +	if (ret < 0)
> +		return ret;
> +
> +	len = scnprintf(buf, sizeof(buf), "%zd\n", ret);
> +
> +	return simple_read_from_buffer(ubuf, count, ppos, buf, len);
> +}
> +
> +static const struct file_operations size_vf_fops = {
> +	.owner		= THIS_MODULE,
> +	.open		= simple_open,
> +	.read		= size_read,
> +	.llseek		= default_llseek,
> +};
> +
>  static void pf_populate_vf(struct xe_device *xe, struct dentry *vfdent)
>  {
>  	debugfs_create_file("pause", 0200, vfdent, xe, &pause_vf_fops);
> @@ -212,6 +245,7 @@ static void pf_populate_vf(struct xe_device *xe, struct dentry *vfdent)
>  	debugfs_create_file("save", 0600, vfdent, xe, &save_vf_fops);
>  	debugfs_create_file("restore", 0600, vfdent, xe, &restore_vf_fops);
>  	debugfs_create_file("migration_data", 0600, vfdent, xe, &data_vf_fops);
> +	debugfs_create_file("migration_size", 0400, vfdent, xe, &size_vf_fops);
>  }
>  
>  static void pf_populate_with_tiles(struct xe_device *xe, struct dentry *dent, unsigned int vfid)
> diff --git a/drivers/gpu/drm/xe/xe_sriov_pf_migration.c b/drivers/gpu/drm/xe/xe_sriov_pf_migration.c
> index a0cfac456ba0b..6b247581dec65 100644
> --- a/drivers/gpu/drm/xe/xe_sriov_pf_migration.c
> +++ b/drivers/gpu/drm/xe/xe_sriov_pf_migration.c
> @@ -249,3 +249,33 @@ int xe_sriov_pf_migration_produce(struct xe_device *xe, unsigned int vfid,
>  
>  	return xe_gt_sriov_pf_migration_ring_produce(gt, vfid, data);
>  }
> +
> +/**
> + * xe_sriov_pf_migration_size() - Total size of migration data from all components within a device
> + * @xe: the &struct xe_device
> + * @vfid: the VF identifier
> + *
> + * This function is for PF only.
> + *
> + * Return: total migration data size in bytes or a negative error code on failure.
> + */
> +ssize_t xe_sriov_pf_migration_size(struct xe_device *xe, unsigned int vfid)
> +{
> +	size_t size = 0;
> +	struct xe_gt *gt;
> +	ssize_t ret;
> +	u8 gt_id;
> +
> +	xe_assert(xe, IS_SRIOV_PF(xe));
> +
> +	for_each_gt(gt, xe, gt_id) {
> +		ret = xe_gt_sriov_pf_migration_size(gt, vfid);
> +		if (ret < 0) {
> +			size = ret;
> +			break;
> +		}
> +		size += ret;
> +	}
> +
> +	return size;
> +}
> diff --git a/drivers/gpu/drm/xe/xe_sriov_pf_migration.h b/drivers/gpu/drm/xe/xe_sriov_pf_migration.h
> index f2020ba19c2da..887ea3e9632bd 100644
> --- a/drivers/gpu/drm/xe/xe_sriov_pf_migration.h
> +++ b/drivers/gpu/drm/xe/xe_sriov_pf_migration.h
> @@ -14,6 +14,7 @@ struct xe_device;
>  #ifdef CONFIG_PCI_IOV
>  int xe_sriov_pf_migration_init(struct xe_device *xe);
>  bool xe_sriov_pf_migration_supported(struct xe_device *xe);
> +ssize_t xe_sriov_pf_migration_size(struct xe_device *xe, unsigned int vfid);
>  struct xe_sriov_pf_migration_data *
>  xe_sriov_pf_migration_consume(struct xe_device *xe, unsigned int vfid);
>  int xe_sriov_pf_migration_produce(struct xe_device *xe, unsigned int vfid,
> -- 
> 2.50.1
>