Re: [PATCH v2 21/34] drm/xe/vf: Stop and flush CTs in VF post migration recovery

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

On Wed, Sep 24, 2025 at 01:21:19PM +0200, Michal Wajdeczko wrote:
> 
> 
> On 9/24/2025 3:15 AM, Matthew Brost wrote:
> > Flushing CTs (i.e., progressing all pending G2H messages) gives VF
> > post-migration recovery an accurate view of which H2G messages the GuC
> > has processed, enabling the GuC submission state machine to correctly
> > rebuild all state.
> > 
> > Also, stop all CT traffic, as the CT is not live during VF
> > post-migration recovery.
> 
> this is what I was looking for, some comments below, but LGTM
> > 
> > Signed-off-by: Matthew Brost <matthew.brost@intel.com>
> > ---
> >  drivers/gpu/drm/xe/xe_gt_sriov_vf.c |  2 ++
> >  drivers/gpu/drm/xe/xe_guc_ct.c      | 11 +++++++++++
> >  drivers/gpu/drm/xe/xe_guc_ct.h      |  1 +
> >  3 files changed, 14 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/xe/xe_gt_sriov_vf.c b/drivers/gpu/drm/xe/xe_gt_sriov_vf.c
> > index e79ab4a2a273..071c2c5e0d0a 100644
> > --- a/drivers/gpu/drm/xe/xe_gt_sriov_vf.c
> > +++ b/drivers/gpu/drm/xe/xe_gt_sriov_vf.c
> > @@ -23,6 +23,7 @@
> >  #include "xe_gt_sriov_vf.h"
> >  #include "xe_gt_sriov_vf_types.h"
> >  #include "xe_guc.h"
> > +#include "xe_guc_ct.h"
> >  #include "xe_guc_hxg_helpers.h"
> >  #include "xe_guc_relay.h"
> >  #include "xe_guc_submit.h"
> > @@ -1185,6 +1186,7 @@ static void vf_post_migration_shutdown(struct xe_gt *gt)
> >  	gt->sriov.vf.migration.recovery_queued = false;
> >  	spin_unlock_irq(&gt->sriov.vf.migration.lock);
> >  
> > +	xe_guc_ct_flush(&gt->uc.guc.ct);
> >  	xe_guc_submit_pause(&gt->uc.guc);
> >  }
> >  
> > diff --git a/drivers/gpu/drm/xe/xe_guc_ct.c b/drivers/gpu/drm/xe/xe_guc_ct.c
> > index aa9fb08f7856..d4a132b81b86 100644
> > --- a/drivers/gpu/drm/xe/xe_guc_ct.c
> > +++ b/drivers/gpu/drm/xe/xe_guc_ct.c
> > @@ -574,6 +574,17 @@ void xe_guc_ct_disable(struct xe_guc_ct *ct)
> >  	stop_g2h_handler(ct);
> >  }
> >  
> > +/**
> > + * xe_guc_ct_flush - Flush all processing of G2H / H2G
> 
> Flush and stop ?
> 

Sure.

> > + * @ct: the &xe_guc_ct
> > + */
> > +void xe_guc_ct_flush(struct xe_guc_ct *ct)
> > +{
> 
> do we care about ct being not initialized yet?
> 

I don't see how a VF can be moved if the driver isn't loaded. Maybe can
an assert here to ensure this assumption is correct?


> > +	receive_g2h(ct);
> > +	wake_up_all(&ct->g2h_fence_wq);
> 
> this is part of the guc_ct_change_state() called by below stop
> isn't that sufficient ?
> 

Agree not needed, let me drop this.

Matt

> > +	xe_guc_ct_stop(ct);
> > +}
> > +
> >  /**
> >   * xe_guc_ct_stop - Set GuC to stopped state
> >   * @ct: the &xe_guc_ct
> > diff --git a/drivers/gpu/drm/xe/xe_guc_ct.h b/drivers/gpu/drm/xe/xe_guc_ct.h
> > index d6c81325a76c..1e32a59817cc 100644
> > --- a/drivers/gpu/drm/xe/xe_guc_ct.h
> > +++ b/drivers/gpu/drm/xe/xe_guc_ct.h
> > @@ -17,6 +17,7 @@ int xe_guc_ct_init_post_hwconfig(struct xe_guc_ct *ct);
> >  int xe_guc_ct_enable(struct xe_guc_ct *ct);
> >  void xe_guc_ct_disable(struct xe_guc_ct *ct);
> >  void xe_guc_ct_stop(struct xe_guc_ct *ct);
> > +void xe_guc_ct_flush(struct xe_guc_ct *ct);
> >  void xe_guc_ct_fast_path(struct xe_guc_ct *ct);
> >  
> >  struct xe_guc_ct_snapshot *xe_guc_ct_snapshot_capture(struct xe_guc_ct *ct);
>