From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 50832C54E58 for ; Tue, 12 Mar 2024 15:58:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=4p8hdd7nkC0rOmeop1ItjBs1bRslute8Awo3HsaucPs=; b=Y+MahH+3rjpPFB KDWm+rVOnQRbcmb8jrKGqPUd9Xo5JhIIVEeadAEAgMtnXqHw/ou2CpRwv25z+VWBULZL1fyz6o12u X9sLB5rDLWbw+MI/aQT7QP3Sbmom6igAWTmfB5kgn38USCxoAhtu5uXgAjmfzvAwK3+EIQx6NcbAo wm4M2LAsaIcv+ztyXSaCBB7RpPkOciByqWPfDNSByXaHuQ7Ppv4FzDdnNtniGSVAq8OKw/TMENNfr wYsgY/va3ezyiHCpYj7NAJU7d9yMlh1Wlkp1AqUPUNyGe8lGEwOSsMb2NWIDh4oNFJWpffHQHYNZ8 RF6xgfV7CzjYeELgRKjg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1rk4Vn-00000006Ts3-0Hav; Tue, 12 Mar 2024 15:57:55 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1rk4Vj-00000006TpX-31CO for linux-arm-kernel@lists.infradead.org; Tue, 12 Mar 2024 15:57:53 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id DE2391007; Tue, 12 Mar 2024 08:58:22 -0700 (PDT) Received: from bogus (e103737-lin.cambridge.arm.com [10.1.197.49]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 558A63F73F; Tue, 12 Mar 2024 08:57:42 -0700 (PDT) Date: Tue, 12 Mar 2024 15:57:39 +0000 From: Sudeep Holla To: David Woodhouse Cc: linux-arm-kernel@lists.infradead.org, kvm@vger.kernel.org, Paolo Bonzini , Jonathan Corbet , Marc Zyngier , Sudeep Holla , Oliver Upton , James Morse , Suzuki K Poulose , Zenghui Yu , Catalin Marinas , Will Deacon , Mark Rutland , Lorenzo Pieralisi , "Rafael J. Wysocki" , Len Brown , Pavel Machek , David Woodhouse , Mostafa Saleh , Jean-Philippe Brucker , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, kvmarm@lists.linux.dev, linux-pm@vger.kernel.org Subject: Re: [RFC PATCH 2/2] arm64: Use SYSTEM_OFF2 PSCI call to power off for hibernate Message-ID: References: <20240312135958.727765-1-dwmw2@infradead.org> <20240312135958.727765-3-dwmw2@infradead.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20240312135958.727765-3-dwmw2@infradead.org> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240312_085751_904434_A9CC98CA X-CRM114-Status: GOOD ( 36.99 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, Mar 12, 2024 at 01:51:29PM +0000, David Woodhouse wrote: > From: David Woodhouse > > The PSCI v1.3 specification (alpha) adds support for a SYSTEM_OFF2 > function which is analogous to ACPI S4 state. This will allow hosting > environments to determine that a guest is hibernated rather than just > powered off, and handle that state appropriately on subsequent launches. > > Since commit 60c0d45a7f7a ("efi/arm64: use UEFI for system reset and > poweroff") the EFI shutdown method is deliberately preferred over PSCI > or other methods. So register a SYS_OFF_MODE_POWER_OFF handler which > *only* handles the hibernation, leaving the original PSCI SYSTEM_OFF as > a last resort via the legacy pm_power_off function pointer. > > The hibernation code already exports a system_entering_hibernation() > function which is be used by the higher-priority handler to check for > hibernation. That existing function just returns the value of a static > boolean variable from hibernate.c, which was previously only set in the > hibernation_platform_enter() code path. Set the same flag in the simpler > code path around the call to kernel_power_off() too. > > An alternative way to hook SYSTEM_OFF2 into the hibernation code would > be to register a platform_hibernation_ops structure with an ->enter() > method which makes the new SYSTEM_OFF2 call. But that would have the > unwanted side-effect of making hibernation take a completely different > code path in hibernation_platform_enter(), invoking a lot of special dpm > callbacks. > > Another option might be to add a new SYS_OFF_MODE_HIBERNATE mode, with > fallback to SYS_OFF_MODE_POWER_OFF. Or to use the sys_off_data to > indicate whether the power off is for hibernation. > > But this version works and is relatively simple. > > Signed-off-by: David Woodhouse > --- > drivers/firmware/psci/psci.c | 35 +++++++++++++++++++++++++++++++++++ > kernel/power/hibernate.c | 5 ++++- > 2 files changed, 39 insertions(+), 1 deletion(-) > > diff --git a/drivers/firmware/psci/psci.c b/drivers/firmware/psci/psci.c > index d9629ff87861..69d2f6969438 100644 > --- a/drivers/firmware/psci/psci.c > +++ b/drivers/firmware/psci/psci.c > @@ -78,6 +78,7 @@ struct psci_0_1_function_ids get_psci_0_1_function_ids(void) > > static u32 psci_cpu_suspend_feature; > static bool psci_system_reset2_supported; > +static bool psci_system_off2_supported; > > static inline bool psci_has_ext_power_state(void) > { > @@ -333,6 +334,28 @@ static void psci_sys_poweroff(void) > invoke_psci_fn(PSCI_0_2_FN_SYSTEM_OFF, 0, 0, 0); > } > > +#ifdef CONFIG_HIBERNATION > +static int psci_sys_hibernate(struct sys_off_data *data) > +{ > + if (system_entering_hibernation()) > + invoke_psci_fn(PSCI_FN_NATIVE(1_3, SYSTEM_OFF2), > + PSCI_1_3_HIBERNATE_TYPE_OFF, 0, 0); > + return NOTIFY_DONE; > +} > + > +static int __init psci_hibernate_init(void) > +{ > + if (psci_system_off2_supported) { > + /* Higher priority than EFI shutdown, but only for hibernate */ > + register_sys_off_handler(SYS_OFF_MODE_POWER_OFF, > + SYS_OFF_PRIO_FIRMWARE + 2, > + psci_sys_hibernate, NULL); > + } > + return 0; > +} > +subsys_initcall(psci_hibernate_init); Looked briefly at register_sys_off_handler and it should be OK to call it from psci_init_system_off2() below. Any particular reason for having separate initcall to do this ? We can even eliminate the need for psci_init_system_off2 if it can be called from there. What am I missing ? -- Regards, Sudeep _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel