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Message-ID: <dwcgtmtzzx3bjp5ibl2gzrp52gshna6iydi556p5lxd5ofk7sp@f67aavazuzu4>
Date: Tue, 4 Nov 2025 13:39:04 +0100
From: Michał Winiarski <michal.winiarski@...el.com>
To: Matthew Brost <matthew.brost@...el.com>
CC: Alex Williamson <alex@...zbot.org>, Lucas De Marchi
<lucas.demarchi@...el.com>, Thomas Hellström
<thomas.hellstrom@...ux.intel.com>, Rodrigo Vivi <rodrigo.vivi@...el.com>,
Jason Gunthorpe <jgg@...pe.ca>, Yishai Hadas <yishaih@...dia.com>, Kevin Tian
<kevin.tian@...el.com>, Shameer Kolothum <skolothumtho@...dia.com>,
<intel-xe@...ts.freedesktop.org>, <linux-kernel@...r.kernel.org>,
<kvm@...r.kernel.org>, Michal Wajdeczko <michal.wajdeczko@...el.com>,
<dri-devel@...ts.freedesktop.org>, Jani Nikula <jani.nikula@...ux.intel.com>,
Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>, Tvrtko Ursulin
<tursulin@...ulin.net>, David Airlie <airlied@...il.com>, Simona Vetter
<simona@...ll.ch>, Lukasz Laguna <lukasz.laguna@...el.com>, Christoph Hellwig
<hch@...radead.org>
Subject: Re: [PATCH v3 22/28] drm/xe/pf: Handle VRAM migration data as part
of PF control
On Mon, Nov 03, 2025 at 02:37:29PM -0800, Matthew Brost wrote:
> On Thu, Oct 30, 2025 at 09:31:29PM +0100, Michał Winiarski wrote:
> > Connect the helpers to allow save and restore of VRAM migration data in
> > stop_copy / resume device state.
> >
> > Co-developed-by: Lukasz Laguna <lukasz.laguna@...el.com>
> > Signed-off-by: Lukasz Laguna <lukasz.laguna@...el.com>
> > Signed-off-by: Michał Winiarski <michal.winiarski@...el.com>
> > ---
> > drivers/gpu/drm/xe/xe_gt_sriov_pf_control.c | 15 ++
> > drivers/gpu/drm/xe/xe_gt_sriov_pf_migration.c | 213 ++++++++++++++++++
> > drivers/gpu/drm/xe/xe_gt_sriov_pf_migration.h | 5 +
> > .../drm/xe/xe_gt_sriov_pf_migration_types.h | 2 +
> > drivers/gpu/drm/xe/xe_sriov_pf_control.c | 3 +
> > 5 files changed, 238 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/xe/xe_gt_sriov_pf_control.c b/drivers/gpu/drm/xe/xe_gt_sriov_pf_control.c
> > index 7cd7cae950bc7..de0f63610e780 100644
> > --- a/drivers/gpu/drm/xe/xe_gt_sriov_pf_control.c
> > +++ b/drivers/gpu/drm/xe/xe_gt_sriov_pf_control.c
> > @@ -880,6 +880,18 @@ static int pf_handle_vf_save_data(struct xe_gt *gt, unsigned int vfid)
> > return -EAGAIN;
> > }
> >
> > + if (xe_gt_sriov_pf_migration_save_test(gt, vfid, XE_SRIOV_MIGRATION_DATA_TYPE_VRAM)) {
> > + ret = xe_gt_sriov_pf_migration_vram_save(gt, vfid);
> > + if (ret == -EAGAIN)
> > + return -EAGAIN;
> > + else if (ret)
> > + return ret;
> > +
> > + xe_gt_sriov_pf_migration_save_clear(gt, vfid, XE_SRIOV_MIGRATION_DATA_TYPE_VRAM);
> > +
> > + return -EAGAIN;
> > + }
> > +
> > return 0;
> > }
> >
> > @@ -1095,6 +1107,9 @@ static int pf_handle_vf_restore_data(struct xe_gt *gt, unsigned int vfid)
> > case XE_SRIOV_MIGRATION_DATA_TYPE_GUC:
> > ret = xe_gt_sriov_pf_migration_guc_restore(gt, vfid, data);
> > break;
> > + case XE_SRIOV_MIGRATION_DATA_TYPE_VRAM:
> > + ret = xe_gt_sriov_pf_migration_vram_restore(gt, vfid, data);
> > + break;
> > default:
> > xe_gt_sriov_notice(gt, "Skipping VF%u unknown data type: %d\n", vfid, data->type);
> > break;
> > 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 5e90aeafeeb41..7ccd43545fdac 100644
> > --- a/drivers/gpu/drm/xe/xe_gt_sriov_pf_migration.c
> > +++ b/drivers/gpu/drm/xe/xe_gt_sriov_pf_migration.c
> > @@ -19,6 +19,7 @@
> > #include "xe_gt_sriov_printk.h"
> > #include "xe_guc_buf.h"
> > #include "xe_guc_ct.h"
> > +#include "xe_migrate.h"
> > #include "xe_mmio.h"
> > #include "xe_sriov.h"
> > #include "xe_sriov_migration_data.h"
> > @@ -505,6 +506,207 @@ int xe_gt_sriov_pf_migration_mmio_restore(struct xe_gt *gt, unsigned int vfid,
> > return pf_restore_vf_mmio_mig_data(gt, vfid, data);
> > }
> >
> > +static ssize_t pf_migration_vram_size(struct xe_gt *gt, unsigned int vfid)
> > +{
> > + if (!xe_gt_is_main_type(gt))
> > + return 0;
> > +
> > + return xe_gt_sriov_pf_config_get_lmem(gt, vfid);
> > +}
> > +
> > +static struct dma_fence *__pf_save_restore_vram(struct xe_gt *gt, unsigned int vfid,
> > + struct xe_bo *vram, u64 vram_offset,
> > + struct xe_bo *sysmem, u64 sysmem_offset,
> > + size_t size, bool save)
> > +{
> > + struct dma_fence *ret = NULL;
> > + struct drm_exec exec;
> > + int err;
> > +
> > + drm_exec_init(&exec, DRM_EXEC_INTERRUPTIBLE_WAIT, 0);
>
> It is a bit incongruent that the dma-resv lock is interruptible here.
>
> > + drm_exec_until_all_locked(&exec) {
> > + err = drm_exec_lock_obj(&exec, &vram->ttm.base);
> > + drm_exec_retry_on_contention(&exec);
> > + if (err) {
> > + ret = ERR_PTR(err);
> > + goto err;
> > + }
> > +
> > + err = drm_exec_lock_obj(&exec, &sysmem->ttm.base);
> > + drm_exec_retry_on_contention(&exec);
> > + if (err) {
> > + ret = ERR_PTR(err);
> > + goto err;
> > + }
> > + }
> > +
> > + ret = xe_migrate_vram_copy_chunk(vram, vram_offset, sysmem, sysmem_offset, size,
> > + save ? XE_MIGRATE_COPY_TO_SRAM : XE_MIGRATE_COPY_TO_VRAM);
> > +
> > +err:
> > + drm_exec_fini(&exec);
> > +
> > + return ret;
> > +}
> > +
> > +#define PF_VRAM_SAVE_RESTORE_TIMEOUT (5 * HZ)
> > +static int pf_save_vram_chunk(struct xe_gt *gt, unsigned int vfid,
> > + struct xe_bo *src_vram, u64 src_vram_offset,
> > + size_t size)
> > +{
> > + struct xe_sriov_migration_data *data;
> > + struct dma_fence *fence;
> > + int ret;
> > +
> > + data = xe_sriov_migration_data_alloc(gt_to_xe(gt));
> > + if (!data)
> > + return -ENOMEM;
> > +
> > + ret = xe_sriov_migration_data_init(data, gt->tile->id, gt->info.id,
> > + XE_SRIOV_MIGRATION_DATA_TYPE_VRAM,
> > + src_vram_offset, size);
> > + if (ret)
> > + goto fail;
> > +
> > + fence = __pf_save_restore_vram(gt, vfid,
> > + src_vram, src_vram_offset,
> > + data->bo, 0, size, true);
> > +
> > + ret = dma_fence_wait_timeout(fence, false, PF_VRAM_SAVE_RESTORE_TIMEOUT);
>
> Then here the dma-fence wait is non-interruptible.
>
> > + dma_fence_put(fence);
> > + if (!ret) {
> > + ret = -ETIME;
> > + goto fail;
> > + }
> > +
> > + xe_gt_sriov_dbg_verbose(gt, "VF%u VRAM data save (%zu bytes)\n", vfid, size);
> > + pf_dump_mig_data(gt, vfid, data);
> > +
> > + ret = xe_gt_sriov_pf_migration_save_produce(gt, vfid, data);
> > + if (ret)
> > + goto fail;
> > +
> > + return 0;
> > +
> > +fail:
> > + xe_sriov_migration_data_free(data);
> > + return ret;
> > +}
> > +
> > +#define VF_VRAM_STATE_CHUNK_MAX_SIZE SZ_512M
> > +static int pf_save_vf_vram_mig_data(struct xe_gt *gt, unsigned int vfid)
> > +{
> > + struct xe_gt_sriov_migration_data *migration = pf_pick_gt_migration(gt, vfid);
> > + loff_t *offset = &migration->save.vram_offset;
> > + struct xe_bo *vram;
> > + size_t vram_size, chunk_size;
> > + int ret;
> > +
> > + vram = xe_gt_sriov_pf_config_get_lmem_obj(gt, vfid);
> > + if (!vram)
> > + return -ENXIO;
> > +
> > + vram_size = xe_bo_size(vram);
> > +
> > + xe_gt_assert(gt, *offset < vram_size);
> > +
> > + chunk_size = min(vram_size - *offset, VF_VRAM_STATE_CHUNK_MAX_SIZE);
> > +
> > + ret = pf_save_vram_chunk(gt, vfid, vram, *offset, chunk_size);
> > + if (ret)
> > + goto fail;
> > +
> > + *offset += chunk_size;
> > +
> > + xe_bo_put(vram);
> > +
> > + if (*offset < vram_size)
> > + return -EAGAIN;
> > +
> > + return 0;
> > +
> > +fail:
> > + xe_bo_put(vram);
> > + xe_gt_sriov_err(gt, "Failed to save VF%u VRAM data (%pe)\n", vfid, ERR_PTR(ret));
> > + return ret;
> > +}
> > +
> > +static int pf_restore_vf_vram_mig_data(struct xe_gt *gt, unsigned int vfid,
> > + struct xe_sriov_migration_data *data)
> > +{
> > + u64 end = data->hdr.offset + data->hdr.size;
> > + struct dma_fence *fence;
> > + struct xe_bo *vram;
> > + size_t size;
> > + int ret = 0;
> > +
> > + vram = xe_gt_sriov_pf_config_get_lmem_obj(gt, vfid);
> > + if (!vram)
> > + return -ENXIO;
> > +
> > + size = xe_bo_size(vram);
> > +
> > + if (end > size || end < data->hdr.size) {
> > + ret = -EINVAL;
> > + goto err;
> > + }
> > +
> > + xe_gt_sriov_dbg_verbose(gt, "VF%u VRAM data restore (%llu bytes)\n", vfid, data->size);
> > + pf_dump_mig_data(gt, vfid, data);
> > +
> > + fence = __pf_save_restore_vram(gt, vfid, vram, data->hdr.offset,
> > + data->bo, 0, data->hdr.size, false);
> > + ret = dma_fence_wait_timeout(fence, false, PF_VRAM_SAVE_RESTORE_TIMEOUT);
>
> And also here the dma-fence wait is non-interruptible.
>
> Aside from the incongruence, the usage of drm-exec, dma-fences looks correct.
All of this code is executed from the PF control state worker, so using
non-interruptible sleep is fine.
I'll drop the DRM_EXEC_INTERRUPTIBLE_WAIT flag from drm_exec_init().
Thanks,
-Michał
>
> Matt
>
> > + dma_fence_put(fence);
> > + if (!ret) {
> > + ret = -ETIME;
> > + goto err;
> > + }
> > +
> > + return 0;
> > +err:
> > + xe_bo_put(vram);
> > + xe_gt_sriov_err(gt, "Failed to restore VF%u VRAM data (%pe)\n", vfid, ERR_PTR(ret));
> > + return ret;
> > +}
> > +
> > +/**
> > + * xe_gt_sriov_pf_migration_vram_save() - Save VF VRAM migration data.
> > + * @gt: the &xe_gt
> > + * @vfid: the VF identifier (can't be 0)
> > + *
> > + * This function is for PF only.
> > + *
> > + * Return: 0 on success or a negative error code on failure.
> > + */
> > +int xe_gt_sriov_pf_migration_vram_save(struct xe_gt *gt, unsigned int vfid)
> > +{
> > + xe_gt_assert(gt, IS_SRIOV_PF(gt_to_xe(gt)));
> > + xe_gt_assert(gt, vfid != PFID);
> > + xe_gt_assert(gt, vfid <= xe_sriov_pf_get_totalvfs(gt_to_xe(gt)));
> > +
> > + return pf_save_vf_vram_mig_data(gt, vfid);
> > +}
> > +
> > +/**
> > + * xe_gt_sriov_pf_migration_vram_restore() - Restore VF VRAM migration data.
> > + * @gt: the &xe_gt
> > + * @vfid: the VF identifier (can't be 0)
> > + *
> > + * This function is for PF only.
> > + *
> > + * Return: 0 on success or a negative error code on failure.
> > + */
> > +int xe_gt_sriov_pf_migration_vram_restore(struct xe_gt *gt, unsigned int vfid,
> > + struct xe_sriov_migration_data *data)
> > +{
> > + xe_gt_assert(gt, IS_SRIOV_PF(gt_to_xe(gt)));
> > + xe_gt_assert(gt, vfid != PFID);
> > + xe_gt_assert(gt, vfid <= xe_sriov_pf_get_totalvfs(gt_to_xe(gt)));
> > +
> > + return pf_restore_vf_vram_mig_data(gt, vfid, data);
> > +}
> > +
> > /**
> > * xe_gt_sriov_pf_migration_size() - Total size of migration data from all components within a GT.
> > * @gt: the &xe_gt
> > @@ -544,6 +746,13 @@ ssize_t xe_gt_sriov_pf_migration_size(struct xe_gt *gt, unsigned int vfid)
> > size += sizeof(struct xe_sriov_pf_migration_hdr);
> > total += size;
> >
> > + size = pf_migration_vram_size(gt, vfid);
> > + if (size < 0)
> > + return size;
> > + if (size > 0)
> > + size += sizeof(struct xe_sriov_pf_migration_hdr);
> > + total += size;
> > +
> > return total;
> > }
> >
> > @@ -602,6 +811,7 @@ void xe_gt_sriov_pf_migration_save_init(struct xe_gt *gt, unsigned int vfid)
> > struct xe_gt_sriov_migration_data *migration = pf_pick_gt_migration(gt, vfid);
> >
> > migration->save.data_remaining = 0;
> > + migration->save.vram_offset = 0;
> >
> > xe_gt_assert(gt, pf_migration_guc_size(gt, vfid) > 0);
> > set_bit(XE_SRIOV_MIGRATION_DATA_TYPE_GUC, &migration->save.data_remaining);
> > @@ -611,6 +821,9 @@ void xe_gt_sriov_pf_migration_save_init(struct xe_gt *gt, unsigned int vfid)
> >
> > xe_gt_assert(gt, pf_migration_mmio_size(gt, vfid) > 0);
> > set_bit(XE_SRIOV_MIGRATION_DATA_TYPE_MMIO, &migration->save.data_remaining);
> > +
> > + if (pf_migration_vram_size(gt, vfid) > 0)
> > + set_bit(XE_SRIOV_MIGRATION_DATA_TYPE_VRAM, &migration->save.data_remaining);
> > }
> >
> > /**
> > 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 b0eec94fea3a6..85b43b2cceb73 100644
> > --- a/drivers/gpu/drm/xe/xe_gt_sriov_pf_migration.h
> > +++ b/drivers/gpu/drm/xe/xe_gt_sriov_pf_migration.h
> > @@ -25,6 +25,11 @@ int xe_gt_sriov_pf_migration_ggtt_restore(struct xe_gt *gt, unsigned int vfid,
> > int xe_gt_sriov_pf_migration_mmio_save(struct xe_gt *gt, unsigned int vfid);
> > int xe_gt_sriov_pf_migration_mmio_restore(struct xe_gt *gt, unsigned int vfid,
> > struct xe_sriov_migration_data *data);
> > +int xe_gt_sriov_pf_migration_vram_save(struct xe_gt *gt, unsigned int vfid);
> > +int xe_gt_sriov_pf_migration_vram_restore(struct xe_gt *gt, unsigned int vfid,
> > + struct xe_sriov_migration_data *data);
> > +
> > +void xe_gt_sriov_pf_migration_save_init(struct xe_gt *gt, unsigned int vfid);
> >
> > ssize_t xe_gt_sriov_pf_migration_size(struct xe_gt *gt, unsigned int vfid);
> >
> > diff --git a/drivers/gpu/drm/xe/xe_gt_sriov_pf_migration_types.h b/drivers/gpu/drm/xe/xe_gt_sriov_pf_migration_types.h
> > index 9f24878690d9c..f50c64241e9c0 100644
> > --- a/drivers/gpu/drm/xe/xe_gt_sriov_pf_migration_types.h
> > +++ b/drivers/gpu/drm/xe/xe_gt_sriov_pf_migration_types.h
> > @@ -20,6 +20,8 @@ struct xe_gt_sriov_migration_data {
> > struct {
> > /** @save.data_remaining: bitmap of migration types that need to be saved */
> > unsigned long data_remaining;
> > + /** @save.vram_offset: last saved offset within VRAM, used for chunked VRAM save */
> > + loff_t vram_offset;
> > } save;
> > };
> >
> > diff --git a/drivers/gpu/drm/xe/xe_sriov_pf_control.c b/drivers/gpu/drm/xe/xe_sriov_pf_control.c
> > index c2768848daba1..aac8ecb861545 100644
> > --- a/drivers/gpu/drm/xe/xe_sriov_pf_control.c
> > +++ b/drivers/gpu/drm/xe/xe_sriov_pf_control.c
> > @@ -5,6 +5,7 @@
> >
> > #include "xe_device.h"
> > #include "xe_gt_sriov_pf_control.h"
> > +#include "xe_gt_sriov_pf_migration.h"
> > #include "xe_sriov_migration_data.h"
> > #include "xe_sriov_pf_control.h"
> > #include "xe_sriov_printk.h"
> > @@ -171,6 +172,8 @@ int xe_sriov_pf_control_trigger_save_vf(struct xe_device *xe, unsigned int vfid)
> > return ret;
> >
> > for_each_gt(gt, xe, id) {
> > + xe_gt_sriov_pf_migration_save_init(gt, vfid);
> > +
> > ret = xe_gt_sriov_pf_control_trigger_save_vf(gt, vfid);
> > if (ret)
> > return ret;
> > --
> > 2.50.1
> >
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