Re: [PATCH v2 17/34] drm/xe/vf: Don't allow GT reset to be queued during VF post migration recovery

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

On Sat, Sep 27, 2025 at 04:59:26AM +0200, Lis, Tomasz wrote:
> 
> On 9/24/2025 3:15 AM, Matthew Brost wrote:
> > With well behaved software, this should never happen.
> 
> Not a very reassuring description.
> 
> But the patch doesn't really lead to ignoring that situation as that
> sentence suggests; there is a bailout from reset if VF recovery is in
> progress.
> 
> This will work fine (for migration, it's actually better as we don't need
> any reset of the new HW), and adds way less code. I'd just improve the
> description.
> 

Let me make the description a bit more verbose.

Matt

> -Tomasz
> 
> > Signed-off-by: Matthew Brost <matthew.brost@intel.com>
> > ---
> >   drivers/gpu/drm/xe/xe_gt.c          |  9 -------
> >   drivers/gpu/drm/xe/xe_gt_sriov_vf.c |  7 -----
> >   drivers/gpu/drm/xe/xe_guc_submit.c  | 41 +++--------------------------
> >   drivers/gpu/drm/xe/xe_guc_submit.h  |  3 ---
> >   4 files changed, 4 insertions(+), 56 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/xe/xe_gt.c b/drivers/gpu/drm/xe/xe_gt.c
> > index 3e0ad7e5b5df..1a4796cd885b 100644
> > --- a/drivers/gpu/drm/xe/xe_gt.c
> > +++ b/drivers/gpu/drm/xe/xe_gt.c
> > @@ -803,11 +803,6 @@ static int do_gt_restart(struct xe_gt *gt)
> >   	return 0;
> >   }
> > -static int gt_wait_reset_unblock(struct xe_gt *gt)
> > -{
> > -	return xe_guc_wait_reset_unblock(&gt->uc.guc);
> > -}
> > -
> >   static int gt_reset(struct xe_gt *gt)
> >   {
> >   	unsigned int fw_ref;
> > @@ -822,10 +817,6 @@ static int gt_reset(struct xe_gt *gt)
> >   	xe_gt_info(gt, "reset started\n");
> > -	err = gt_wait_reset_unblock(gt);
> > -	if (!err)
> > -		xe_gt_warn(gt, "reset block failed to get lifted");
> > -
> >   	xe_pm_runtime_get(gt_to_xe(gt));
> >   	if (xe_fault_inject_gt_reset()) {
> > diff --git a/drivers/gpu/drm/xe/xe_gt_sriov_vf.c b/drivers/gpu/drm/xe/xe_gt_sriov_vf.c
> > index 4eaffad6ebcf..b8e02bba7360 100644
> > --- a/drivers/gpu/drm/xe/xe_gt_sriov_vf.c
> > +++ b/drivers/gpu/drm/xe/xe_gt_sriov_vf.c
> > @@ -1175,17 +1175,11 @@ void xe_gt_sriov_vf_print_version(struct xe_gt *gt, struct drm_printer *p)
> >   static void vf_post_migration_shutdown(struct xe_gt *gt)
> >   {
> > -	int ret = 0;
> > -
> >   	spin_lock_irq(&gt->sriov.vf.migration.lock);
> >   	gt->sriov.vf.migration.recovery_queued = false;
> >   	spin_unlock_irq(&gt->sriov.vf.migration.lock);
> >   	xe_guc_submit_pause(&gt->uc.guc);
> > -	ret |= xe_guc_submit_reset_block(&gt->uc.guc);
> > -
> > -	if (ret)
> > -		xe_gt_sriov_info(gt, "migration recovery encountered ongoing reset\n");
> >   }
> >   static size_t post_migration_scratch_size(struct xe_device *xe)
> > @@ -1219,7 +1213,6 @@ static void vf_post_migration_kickstart(struct xe_gt *gt)
> >   	 */
> >   	xe_irq_resume(gt_to_xe(gt));
> > -	xe_guc_submit_reset_unblock(&gt->uc.guc);
> >   	xe_guc_submit_unpause(&gt->uc.guc);
> >   }
> > diff --git a/drivers/gpu/drm/xe/xe_guc_submit.c b/drivers/gpu/drm/xe/xe_guc_submit.c
> > index cd5e506527fe..b82976f031e5 100644
> > --- a/drivers/gpu/drm/xe/xe_guc_submit.c
> > +++ b/drivers/gpu/drm/xe/xe_guc_submit.c
> > @@ -27,6 +27,7 @@
> >   #include "xe_gt.h"
> >   #include "xe_gt_clock.h"
> >   #include "xe_gt_printk.h"
> > +#include "xe_gt_sriov_vf.h"
> >   #include "xe_guc.h"
> >   #include "xe_guc_capture.h"
> >   #include "xe_guc_ct.h"
> > @@ -2182,47 +2183,13 @@ static void guc_exec_queue_stop(struct xe_guc *guc, struct xe_exec_queue *q)
> >   	}
> >   }
> > -/**
> > - * xe_guc_submit_reset_block - Disallow reset calls on given GuC.
> > - * @guc: the &xe_guc struct instance
> > - */
> > -int xe_guc_submit_reset_block(struct xe_guc *guc)
> > -{
> > -	return atomic_fetch_or(1, &guc->submission_state.reset_blocked);
> > -}
> > -
> > -/**
> > - * xe_guc_submit_reset_unblock - Allow back reset calls on given GuC.
> > - * @guc: the &xe_guc struct instance
> > - */
> > -void xe_guc_submit_reset_unblock(struct xe_guc *guc)
> > -{
> > -	atomic_set_release(&guc->submission_state.reset_blocked, 0);
> > -	wake_up_all(&guc->ct.wq);
> > -}
> > -
> > -static int guc_submit_reset_is_blocked(struct xe_guc *guc)
> > -{
> > -	return atomic_read_acquire(&guc->submission_state.reset_blocked);
> > -}
> > -
> > -/* Maximum time of blocking reset */
> > -#define RESET_BLOCK_PERIOD_MAX (HZ * 5)
> > -
> > -/**
> > - * xe_guc_wait_reset_unblock - Wait until reset blocking flag is lifted, or timeout.
> > - * @guc: the &xe_guc struct instance
> > - */
> > -int xe_guc_wait_reset_unblock(struct xe_guc *guc)
> > -{
> > -	return wait_event_timeout(guc->ct.wq,
> > -				  !guc_submit_reset_is_blocked(guc), RESET_BLOCK_PERIOD_MAX);
> > -}
> > -
> >   int xe_guc_submit_reset_prepare(struct xe_guc *guc)
> >   {
> >   	int ret;
> > +	if (WARN_ON_ONCE(xe_gt_sriov_vf_recovery_inprogress(guc_to_gt(guc))))
> > +		return 0;
> > +
> >   	if (!guc->submission_state.initialized)
> >   		return 0;
> > diff --git a/drivers/gpu/drm/xe/xe_guc_submit.h b/drivers/gpu/drm/xe/xe_guc_submit.h
> > index 5b4a0a6fd818..f535fe3895e5 100644
> > --- a/drivers/gpu/drm/xe/xe_guc_submit.h
> > +++ b/drivers/gpu/drm/xe/xe_guc_submit.h
> > @@ -22,9 +22,6 @@ void xe_guc_submit_stop(struct xe_guc *guc);
> >   int xe_guc_submit_start(struct xe_guc *guc);
> >   void xe_guc_submit_pause(struct xe_guc *guc);
> >   void xe_guc_submit_unpause(struct xe_guc *guc);
> > -int xe_guc_submit_reset_block(struct xe_guc *guc);
> > -void xe_guc_submit_reset_unblock(struct xe_guc *guc);
> > -int xe_guc_wait_reset_unblock(struct xe_guc *guc);
> >   void xe_guc_submit_wedge(struct xe_guc *guc);
> >   int xe_guc_read_stopped(struct xe_guc *guc);