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

Michał Winiarski
2025-10-21T00:37:17Z

On Sun, Oct 12, 2025 at 12:15:22PM -0700, Matthew Brost wrote:
> 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).

Not in the case of GuC migration data size. While in this patch GuC is
not yet present as a migration data resource, we should assume that
xe_sriov_pf_migration_size needs a PM ref.

Thanks,
-Michał

>
> 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
> >