All of lore.kernel.org
 help / color / mirror / Atom feed
From: John Harrison <john.c.harrison@intel.com>
To: Greg KH <greg@kroah.com>
Cc: stable@vger.kernel.org, "Chris Wilson" <chris@chris-wilson.co.uk>,
	"Joonas Lahtinen" <joonas.lahtinen@linux.intel.com>,
	"Jani Nikula" <jani.nikula@linux.intel.com>,
	"Rodrigo Vivi" <rodrigo.vivi@intel.com>,
	"Tvrtko Ursulin" <tvrtko.ursulin@linux.intel.com>,
	intel-gfx@lists.freedesktop.org,
	"Jouni Högander" <jouni.hogander@intel.com>,
	"Daniele Ceraolo Spurio" <daniele.ceraolospurio@intel.com>,
	"Jani Nikula" <jani.nikula@intel.com>
Subject: Re: [PATCH 5.4.y] drm/i915: Don't use BAR mappings for ring buffers with LLC
Date: Wed, 15 Mar 2023 10:07:53 -0700	[thread overview]
Message-ID: <a5cf5572-4160-3efb-4f80-aaf53aa06efe@intel.com> (raw)
In-Reply-To: <ZBF48kVhFmXIsR+K@kroah.com>

On 3/15/2023 00:51, Greg KH wrote:
> On Mon, Mar 13, 2023 at 07:22:11PM -0700, John.C.Harrison@Intel.com wrote:
>> From: John Harrison <John.C.Harrison@Intel.com>
>>
>> Direction from hardware is that ring buffers should never be mapped
>> via the BAR on systems with LLC. There are too many caching pitfalls
>> due to the way BAR accesses are routed. So it is safest to just not
>> use it.
>>
>> Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
>> Fixes: 9d80841ea4c9 ("drm/i915: Allow ringbuffers to be bound anywhere")
>> Cc: Chris Wilson <chris@chris-wilson.co.uk>
>> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
>> Cc: Jani Nikula <jani.nikula@linux.intel.com>
>> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
>> Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
>> Cc: intel-gfx@lists.freedesktop.org
>> Cc: <stable@vger.kernel.org> # v4.9+
>> Tested-by: Jouni Högander <jouni.hogander@intel.com>
>> Reviewed-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
>> Link: https://patchwork.freedesktop.org/patch/msgid/20230216011101.1909009-3-John.C.Harrison@Intel.com
>> (cherry picked from commit 65c08339db1ada87afd6cfe7db8e60bb4851d919)
>> Signed-off-by: Jani Nikula <jani.nikula@intel.com>
>> (cherry picked from commit 85636167e3206c3fbd52254fc432991cc4e90194)
>> Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
>> ---
>>   drivers/gpu/drm/i915/gt/intel_ringbuffer.c | 4 ++--
>>   1 file changed, 2 insertions(+), 2 deletions(-)
> Also queued up for 5.10.y, you forgot that one :)
I'm still working through the backlog of them.

Note that these patches must all be applied as a pair. The 'don't use 
stolen' can be applied in isolation but won't totally fix the problem. 
However, applying 'don't use BAR mappings' without applying the stolen 
patch first will results in problems such as the failure to boot that 
was recently reported and resulted in a revert in one of the trees.

John.

>
> thanks,
>
> greg k-h


WARNING: multiple messages have this Message-ID (diff)
From: John Harrison <john.c.harrison@intel.com>
To: Greg KH <greg@kroah.com>
Cc: Jani Nikula <jani.nikula@intel.com>,
	intel-gfx@lists.freedesktop.org,
	Chris Wilson <chris@chris-wilson.co.uk>,
	stable@vger.kernel.org, Rodrigo Vivi <rodrigo.vivi@intel.com>
Subject: Re: [Intel-gfx] [PATCH 5.4.y] drm/i915: Don't use BAR mappings for ring buffers with LLC
Date: Wed, 15 Mar 2023 10:07:53 -0700	[thread overview]
Message-ID: <a5cf5572-4160-3efb-4f80-aaf53aa06efe@intel.com> (raw)
In-Reply-To: <ZBF48kVhFmXIsR+K@kroah.com>

On 3/15/2023 00:51, Greg KH wrote:
> On Mon, Mar 13, 2023 at 07:22:11PM -0700, John.C.Harrison@Intel.com wrote:
>> From: John Harrison <John.C.Harrison@Intel.com>
>>
>> Direction from hardware is that ring buffers should never be mapped
>> via the BAR on systems with LLC. There are too many caching pitfalls
>> due to the way BAR accesses are routed. So it is safest to just not
>> use it.
>>
>> Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
>> Fixes: 9d80841ea4c9 ("drm/i915: Allow ringbuffers to be bound anywhere")
>> Cc: Chris Wilson <chris@chris-wilson.co.uk>
>> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
>> Cc: Jani Nikula <jani.nikula@linux.intel.com>
>> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
>> Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
>> Cc: intel-gfx@lists.freedesktop.org
>> Cc: <stable@vger.kernel.org> # v4.9+
>> Tested-by: Jouni Högander <jouni.hogander@intel.com>
>> Reviewed-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
>> Link: https://patchwork.freedesktop.org/patch/msgid/20230216011101.1909009-3-John.C.Harrison@Intel.com
>> (cherry picked from commit 65c08339db1ada87afd6cfe7db8e60bb4851d919)
>> Signed-off-by: Jani Nikula <jani.nikula@intel.com>
>> (cherry picked from commit 85636167e3206c3fbd52254fc432991cc4e90194)
>> Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
>> ---
>>   drivers/gpu/drm/i915/gt/intel_ringbuffer.c | 4 ++--
>>   1 file changed, 2 insertions(+), 2 deletions(-)
> Also queued up for 5.10.y, you forgot that one :)
I'm still working through the backlog of them.

Note that these patches must all be applied as a pair. The 'don't use 
stolen' can be applied in isolation but won't totally fix the problem. 
However, applying 'don't use BAR mappings' without applying the stolen 
patch first will results in problems such as the failure to boot that 
was recently reported and resulted in a revert in one of the trees.

John.

>
> thanks,
>
> greg k-h


  reply	other threads:[~2023-03-15 17:10 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-03-07 16:10 FAILED: patch "[PATCH] drm/i915: Don't use BAR mappings for ring buffers with LLC" failed to apply to 5.4-stable tree gregkh
2023-03-14  2:22 ` [PATCH 5.4.y] drm/i915: Don't use BAR mappings for ring buffers with LLC John.C.Harrison
2023-03-14  2:22   ` [Intel-gfx] " John.C.Harrison
2023-03-15  7:51   ` Greg KH
2023-03-15  7:51     ` Greg KH
2023-03-15 17:07     ` John Harrison [this message]
2023-03-15 17:07       ` [Intel-gfx] " John Harrison
2023-03-15 17:57       ` Greg KH
2023-03-15 17:57         ` [Intel-gfx] " Greg KH
2023-03-16 20:58         ` John Harrison
2023-03-16 20:58           ` [Intel-gfx] " John Harrison
2023-03-17 12:58           ` Greg KH
2023-03-17 12:58             ` [Intel-gfx] " Greg KH
2023-03-17 16:27             ` Jason Andryuk
2023-03-17 16:27               ` Jason Andryuk
2023-03-18  4:07             ` John Harrison
2023-03-18  4:07               ` [Intel-gfx] " John Harrison
2023-03-20 13:28               ` Greg KH
2023-03-20 13:28                 ` Greg KH
2023-03-14  2:32 ` [Intel-gfx] ✗ Fi.CI.BUILD: failure for drm/i915: Don't use BAR mappings for ring buffers with LLC (rev3) Patchwork

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=a5cf5572-4160-3efb-4f80-aaf53aa06efe@intel.com \
    --to=john.c.harrison@intel.com \
    --cc=chris@chris-wilson.co.uk \
    --cc=daniele.ceraolospurio@intel.com \
    --cc=greg@kroah.com \
    --cc=intel-gfx@lists.freedesktop.org \
    --cc=jani.nikula@intel.com \
    --cc=jani.nikula@linux.intel.com \
    --cc=joonas.lahtinen@linux.intel.com \
    --cc=jouni.hogander@intel.com \
    --cc=rodrigo.vivi@intel.com \
    --cc=stable@vger.kernel.org \
    --cc=tvrtko.ursulin@linux.intel.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.