Hi Mauro and Chris,

On Mon, Jul 04, 2022 at 09:09:28AM +0100, Mauro Carvalho Chehab wrote:
> From: Chris Wilson <chris.p.wil...@intel.com>
> 
> Don't allow two engines to be reset in parallel, as they would both
> try to select a reset bit (and send requests to common registers)
> and wait on that register, at the same time. Serialize control of
> the reset requests/acks using the uncore->lock, which will also ensure
> that no other GT state changes at the same time as the actual reset.
> 
> Cc: sta...@vger.kernel.org # Up to 4.4
> Reported-by: Mika Kuoppala <mika.kuopp...@linux.intel.com>
> Signed-off-by: Chris Wilson <ch...@chris-wilson.co.uk>
> Cc: Mika Kuoppala <mika.kuopp...@linux.intel.com>
> Reviewed-by: Andi Shyti <andi.sh...@intel.com>
> Acked-by: Thomas Hellström <thomas.hellst...@linux.intel.com>
> Signed-off-by: Mauro Carvalho Chehab <mche...@kernel.org>

sorry for the delay but I wanted to understand what has been
agreed between you and Tvrtko about the Cc'ing the stable list.

Anyway, I confirm my review here.

Andi

> ---
> 
> To avoid mailbombing on a large number of people, only mailing lists were C/C 
> on the cover.
> See [PATCH v3 0/2] at: 
> https://lore.kernel.org/all/cover.1656921701.git.mche...@kernel.org/
> 
>  drivers/gpu/drm/i915/gt/intel_reset.c | 37 ++++++++++++++++++++-------
>  1 file changed, 28 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/gt/intel_reset.c 
> b/drivers/gpu/drm/i915/gt/intel_reset.c
> index a5338c3fde7a..c68d36fb5bbd 100644
> --- a/drivers/gpu/drm/i915/gt/intel_reset.c
> +++ b/drivers/gpu/drm/i915/gt/intel_reset.c
> @@ -300,9 +300,9 @@ static int gen6_hw_domain_reset(struct intel_gt *gt, u32 
> hw_domain_mask)
>       return err;
>  }
>  
> -static int gen6_reset_engines(struct intel_gt *gt,
> -                           intel_engine_mask_t engine_mask,
> -                           unsigned int retry)
> +static int __gen6_reset_engines(struct intel_gt *gt,
> +                             intel_engine_mask_t engine_mask,
> +                             unsigned int retry)
>  {
>       struct intel_engine_cs *engine;
>       u32 hw_mask;
> @@ -321,6 +321,20 @@ static int gen6_reset_engines(struct intel_gt *gt,
>       return gen6_hw_domain_reset(gt, hw_mask);
>  }
>  
> +static int gen6_reset_engines(struct intel_gt *gt,
> +                           intel_engine_mask_t engine_mask,
> +                           unsigned int retry)
> +{
> +     unsigned long flags;
> +     int ret;
> +
> +     spin_lock_irqsave(&gt->uncore->lock, flags);
> +     ret = __gen6_reset_engines(gt, engine_mask, retry);
> +     spin_unlock_irqrestore(&gt->uncore->lock, flags);
> +
> +     return ret;
> +}
> +
>  static struct intel_engine_cs *find_sfc_paired_vecs_engine(struct 
> intel_engine_cs *engine)
>  {
>       int vecs_id;
> @@ -487,9 +501,9 @@ static void gen11_unlock_sfc(struct intel_engine_cs 
> *engine)
>       rmw_clear_fw(uncore, sfc_lock.lock_reg, sfc_lock.lock_bit);
>  }
>  
> -static int gen11_reset_engines(struct intel_gt *gt,
> -                            intel_engine_mask_t engine_mask,
> -                            unsigned int retry)
> +static int __gen11_reset_engines(struct intel_gt *gt,
> +                              intel_engine_mask_t engine_mask,
> +                              unsigned int retry)
>  {
>       struct intel_engine_cs *engine;
>       intel_engine_mask_t tmp;
> @@ -583,8 +597,11 @@ static int gen8_reset_engines(struct intel_gt *gt,
>       struct intel_engine_cs *engine;
>       const bool reset_non_ready = retry >= 1;
>       intel_engine_mask_t tmp;
> +     unsigned long flags;
>       int ret;
>  
> +     spin_lock_irqsave(&gt->uncore->lock, flags);
> +
>       for_each_engine_masked(engine, gt, engine_mask, tmp) {
>               ret = gen8_engine_reset_prepare(engine);
>               if (ret && !reset_non_ready)
> @@ -612,17 +629,19 @@ static int gen8_reset_engines(struct intel_gt *gt,
>        * This is best effort, so ignore any error from the initial reset.
>        */
>       if (IS_DG2(gt->i915) && engine_mask == ALL_ENGINES)
> -             gen11_reset_engines(gt, gt->info.engine_mask, 0);
> +             __gen11_reset_engines(gt, gt->info.engine_mask, 0);
>  
>       if (GRAPHICS_VER(gt->i915) >= 11)
> -             ret = gen11_reset_engines(gt, engine_mask, retry);
> +             ret = __gen11_reset_engines(gt, engine_mask, retry);
>       else
> -             ret = gen6_reset_engines(gt, engine_mask, retry);
> +             ret = __gen6_reset_engines(gt, engine_mask, retry);
>  
>  skip_reset:
>       for_each_engine_masked(engine, gt, engine_mask, tmp)
>               gen8_engine_reset_cancel(engine);
>  
> +     spin_unlock_irqrestore(&gt->uncore->lock, flags);
> +
>       return ret;
>  }
>  
> -- 
> 2.36.1

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