linux-kernel - Re: [PATCH 3/6] drm/i915/gt: Skip TLB invalidations once wedged

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Message-ID: <fb554850-e8f2-f136-fe80-4664719f8312@linux.intel.com>
Date:   Thu, 16 Jun 2022 08:25:42 +0100
From:   Tvrtko Ursulin <tvrtko.ursulin@...ux.intel.com>
To:     Mauro Carvalho Chehab <mchehab@...nel.org>
Cc:     Chris Wilson <chris.p.wilson@...el.com>,
        Fei Yang <fei.yang@...el.com>,
        Michał Winiarski <michal.winiarski@...el.com>,
        Thomas Hellstrom <thomas.hellstrom@...el.com>,
        Andi Shyti <andi.shyti@...ux.intel.com>,
        Daniel Vetter <daniel@...ll.ch>,
        Daniele Ceraolo Spurio <daniele.ceraolospurio@...el.com>,
        Dave Airlie <airlied@...hat.com>,
        David Airlie <airlied@...ux.ie>,
        Jani Nikula <jani.nikula@...ux.intel.com>,
        John Harrison <John.C.Harrison@...el.com>,
        Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
        Lucas De Marchi <lucas.demarchi@...el.com>,
        Matt Roper <matthew.d.roper@...el.com>,
        Matthew Auld <matthew.auld@...el.com>,
        Rodrigo Vivi <rodrigo.vivi@...el.com>,
        dri-devel@...ts.freedesktop.org, intel-gfx@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org, mauro.chehab@...ux.intel.com,
        stable@...r.kernel.org,
        Thomas Hellström 
        <thomas.hellstrom@...ux.intel.com>
Subject: Re: [PATCH 3/6] drm/i915/gt: Skip TLB invalidations once wedged


On 15/06/2022 16:27, Mauro Carvalho Chehab wrote:
> From: Chris Wilson <chris.p.wilson@...el.com>
> 
> Skip all further TLB invalidations once the device is wedged and
> had been reset, as, on such cases, it can no longer process instructions
> on the GPU and the user no longer has access to the TLB's in each engine.
> 
> Fixes: 7938d61591d3 ("drm/i915: Flush TLBs before releasing backing store")

Are there any real problems fixed or it's just a logical thing to do? 
Not much harm tagging it as fixes in terms of process since it is tiny 
but, again, wanting a clear picture.

Regards,

Tvrtko

> Signed-off-by: Chris Wilson <chris.p.wilson@...el.com>
> Cc: Fei Yang <fei.yang@...el.com>
> Cc: Andi Shyti <andi.shyti@...ux.intel.com>
> Cc: stable@...r.kernel.org
> Acked-by: Thomas Hellström <thomas.hellstrom@...ux.intel.com>
> Signed-off-by: Mauro Carvalho Chehab <mchehab@...nel.org>
> ---
> 
> See [PATCH 0/6] at: https://lore.kernel.org/all/cover.1655306128.git.mchehab@kernel.org/
> 
>   drivers/gpu/drm/i915/gt/intel_gt.c | 3 +++
>   1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/gt/intel_gt.c b/drivers/gpu/drm/i915/gt/intel_gt.c
> index 61b7ec5118f9..fb4fd5273ca4 100644
> --- a/drivers/gpu/drm/i915/gt/intel_gt.c
> +++ b/drivers/gpu/drm/i915/gt/intel_gt.c
> @@ -1226,6 +1226,9 @@ void intel_gt_invalidate_tlbs(struct intel_gt *gt)
>   	if (I915_SELFTEST_ONLY(gt->awake == -ENODEV))
>   		return;
>   
> +	if (intel_gt_is_wedged(gt))
> +		return;
> +
>   	if (GRAPHICS_VER(i915) == 12) {
>   		regs = gen12_regs;
>   		num = ARRAY_SIZE(gen12_regs);