linux-kernel - Re: [PATCH v8 3/6] firmware: psci: Read and use vendor reset types

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: <CAE-0n50-h_h=oWt7BZ5ncX8JYfXmEpN7-HrZeC8wHrHZnGsJMA@mail.gmail.com>
Date: Fri, 8 Nov 2024 10:57:17 -0800
From: Stephen Boyd <swboyd@...omium.org>
To: Andy Yan <andy.yan@...k-chips.com>, Arnd Bergmann <arnd@...db.de>, 
	Bartosz Golaszewski <bartosz.golaszewski@...aro.org>, Bjorn Andersson <andersson@...nel.org>, 
	Catalin Marinas <catalin.marinas@....com>, Conor Dooley <conor+dt@...nel.org>, 
	Elliot Berman <quic_eberman@...cinc.com>, Konrad Dybcio <konradybcio@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Lorenzo Pieralisi <lpieralisi@...nel.org>, 
	Mark Rutland <mark.rutland@....com>, Olof Johansson <olof@...om.net>, Rob Herring <robh@...nel.org>, 
	Sebastian Reichel <sre@...nel.org>, Vinod Koul <vkoul@...nel.org>, Will Deacon <will@...nel.org>, 
	cros-qcom-dts-watchers@...omium.org
Cc: Satya Durga Srinivasu Prabhala <quic_satyap@...cinc.com>, Melody Olvera <quic_molvera@...cinc.com>, 
	Shivendra Pratap <quic_spratap@...cinc.com>, devicetree@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, 
	Florian Fainelli <florian.fainelli@...adcom.com>, linux-pm@...r.kernel.org, 
	linux-arm-msm@...r.kernel.org
Subject: Re: [PATCH v8 3/6] firmware: psci: Read and use vendor reset types

Quoting Elliot Berman (2024-11-07 15:38:27)
> SoC vendors have different types of resets and are controlled through
> various registers. For instance, Qualcomm chipsets can reboot to a
> "download mode" that allows a RAM dump to be collected. Another example
> is they also support writing a cookie that can be read by bootloader
> during next boot. PSCI offers a mechanism, SYSTEM_RESET2, for these
> vendor reset types to be implemented without requiring drivers for every
> register/cookie.
>
> Add support in PSCI to statically map reboot mode commands from
> userspace to a vendor reset and cookie value using the device tree.
>
> A separate initcall is needed to parse the devicetree, instead of using
> psci_dt_init because mm isn't sufficiently set up to allocate memory.
>
> Reboot mode framework is close but doesn't quite fit with the
> design and requirements for PSCI SYSTEM_RESET2. Some of these issues can
> be solved but doesn't seem reasonable in sum:
>  1. reboot mode registers against the reboot_notifier_list, which is too
>     early to call SYSTEM_RESET2. PSCI would need to remember the reset
>     type from the reboot-mode framework callback and use it
>     psci_sys_reset.
>  2. reboot mode assumes only one cookie/parameter is described in the
>     device tree. SYSTEM_RESET2 uses 2: one for the type and one for
>     cookie.
>  3. psci cpuidle driver already registers a driver against the
>     arm,psci-1.0 compatible. Refactoring would be needed to have both a
>     cpuidle and reboot-mode driver.
>
> Tested-by: Florian Fainelli <florian.fainelli@...adcom.com>
> Signed-off-by: Elliot Berman <quic_eberman@...cinc.com>
> ---

Reviewed-by: Stephen Boyd <swboyd@...omium.org>