linux-kernel - Re: [PATCH] drm/ttm: Print the memory decryption status just once

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CABQX2QNbbM-frtkVwYWZytUAqP0t0gyyd_tZc_s0bDxu+MaFUg@mail.gmail.com>
Date: Thu, 18 Apr 2024 07:38:00 -0400
From: Zack Rusin <zack.rusin@...adcom.com>
To: Christian König <christian.koenig@....com>, 
	dri-devel@...ts.freedesktop.org
Cc: Broadcom internal kernel review list <bcm-kernel-feedback-list@...adcom.com>, 
	Ian Forbes <ian.forbes@...adcom.com>, Martin Krastev <martin.krastev@...adcom.com>, 
	Maaz Mombasawala <maaz.mombasawala@...adcom.com>, 
	Thomas Hellström <thomas.hellstrom@...ux.intel.com>, 
	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH] drm/ttm: Print the memory decryption status just once

Ping on this one. If we don't want the "_once" then I can quickly
prepare a patch that just removes the logging altogether, because
while useful it's polluting up the kernel logs too much right now so
getting a fix in for 6.9 for this would be great.

z

On Mon, Apr 8, 2024 at 1:46 PM Zack Rusin <zack.rusin@...adcom.com> wrote:
>
> Sorry, apologies to everyone. By accident I replied off the list.
> Redoing it now on the list. More below.
>
> On Mon, Apr 8, 2024 at 12:10 PM Christian König
> <christian.koenig@....com> wrote:
> >
> > Am 08.04.24 um 18:04 schrieb Zack Rusin:
> > > On Mon, Apr 8, 2024 at 11:59 AM Christian König
> > > <christian.koenig@....com> wrote:
> > >> Am 08.04.24 um 17:56 schrieb Zack Rusin:
> > >>> Stop printing the TT memory decryption status info each time tt is created
> > >>> and instead print it just once.
> > >>>
> > >>> Reduces the spam in the system logs when running guests with SEV enabled.
> > >> Do we then really need this in the first place?
> > > Thomas asked for it just to have an indication when those paths are
> > > being used because they could potentially break things pretty bad. I
> > > think it is useful knowing that those paths are hit (but only once).
> > > It makes it pretty easy for me to tell whether bug reports with people
> > > who report black screen can be answered with "the kernel needs to be
> > > upgraded" ;)
> >
> > Sounds reasonable, but my expectation was rather that we would print
> > something on the device level.
> >
> > If that's not feasible for whatever reason than printing it once works
> > as well of course.
>
> TBH, I think it's pretty convenient to have the drm_info in the TT
> just to make sure that when drivers request use_dma_alloc on SEV
> systems TT turns decryption on correctly, i.e. it's a nice sanity
> check when reading the logs. But if you'd prefer it in the driver I
> can move this logic there as well.
>
> z