linux-kernel - Re: [GICv3 ITS]S2IDLE framework does not invoke syscore

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: <86tt6zkux7.wl-maz@kernel.org>
Date: Tue, 08 Apr 2025 07:51:32 +0100
From: Marc Zyngier <maz@...nel.org>
To: Donghyeok Choe <d7271.choe@...sung.com>
Cc: Sudeep Holla <sudeep.holla@....com>,
	Youngmin Nam <youngmin.nam@...sung.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Saravana Kannan <saravanak@...gle.com>,
	Ulf Hansson
	<ulf.hansson@...aro.org>,
	Vincent Guittot <vincent.guittot@...aro.org>,
	linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	kernel-team@...roid.com,
	hajun.sung@...sung.com,
	joonki.min@...sung.com,
	ne.yoo@...sung.com
Subject: Re: [GICv3 ITS]S2IDLE framework does not invoke syscore_ops in GICv3 ITS driver

On Mon, 07 Apr 2025 23:51:46 +0100,
Donghyeok Choe <d7271.choe@...sung.com> wrote:
> 
> [1  <text/plain; us-ascii (7bit)>]
> On Mon, Apr 07, 2025 at 10:17:43AM +0100, Sudeep Holla wrote:

> > Do you use any suspend/resume logic in drivers/irqchip/irq-gic-pm.c ?
> No, there are parts of the GIC that require secure access, so the
> GIC save/restore is performed by the firmware.
> Since the GIC-ITS is entirely controlled as a non-secure IP,
> I think it is more efficient to perform save/restore in the kernel.

More efficient? Give me *one* aspect of this save/restore sequence
that is done in a more efficiently way in the kernel. Dumping MMIO
accesses into memory has the exact same cost at EL1, El2 or EL3, and
splitting things along an arbitrary line to paper over bad firmware is
not a valid argument.

	M.

-- 
Without deviation from the norm, progress is not possible.