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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 46089EEAA52 for ; Thu, 14 Sep 2023 16:02:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241689AbjINQCl (ORCPT ); Thu, 14 Sep 2023 12:02:41 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50104 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241718AbjINQCO (ORCPT ); Thu, 14 Sep 2023 12:02:14 -0400 Received: from frasgout.his.huawei.com (frasgout.his.huawei.com [185.176.79.56]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B2E061FF2; Thu, 14 Sep 2023 09:02:00 -0700 (PDT) Received: from lhrpeml500005.china.huawei.com (unknown [172.18.147.200]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4Rmhlw1C71z67Jb4; Thu, 14 Sep 2023 23:57:16 +0800 (CST) Received: from localhost (10.202.227.76) by lhrpeml500005.china.huawei.com (7.191.163.240) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.31; Thu, 14 Sep 2023 17:01:56 +0100 Date: Thu, 14 Sep 2023 17:01:55 +0100 From: Jonathan Cameron To: James Morse CC: , , , , , , , , , Salil Mehta , Russell King , Jean-Philippe Brucker , , Subject: Re: [RFC PATCH v2 31/35] arm64: psci: Ignore DENIED CPUs Message-ID: <20230914170155.000065cf@Huawei.com> In-Reply-To: <20230913163823.7880-32-james.morse@arm.com> References: <20230913163823.7880-1-james.morse@arm.com> <20230913163823.7880-32-james.morse@arm.com> Organization: Huawei Technologies Research and Development (UK) Ltd. X-Mailer: Claws Mail 4.1.0 (GTK 3.24.33; x86_64-w64-mingw32) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.202.227.76] X-ClientProxiedBy: lhrpeml100005.china.huawei.com (7.191.160.25) To lhrpeml500005.china.huawei.com (7.191.163.240) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-acpi@vger.kernel.org On Wed, 13 Sep 2023 16:38:19 +0000 James Morse wrote: > From: Jean-Philippe Brucker > > When a CPU is marked as disabled, but online capable in the MADT, PSCI > applies some firmware policy to control when it can be brought online. > PSCI returns DENIED to a CPU_ON request if this is not currently > permitted. The OS can learn the current policy from the _STA enabled bit. > > Handle the PSCI DENIED return code gracefully instead of printing an > error. Specification reference would be good particularly as it's only been added as a possibility fairly recently. > > Signed-off-by: Jean-Philippe Brucker > [ morse: Rewrote commit message ] > Signed-off-by: James Morse > --- > arch/arm64/kernel/psci.c | 2 +- > arch/arm64/kernel/smp.c | 3 ++- > drivers/firmware/psci/psci.c | 2 ++ > 3 files changed, 5 insertions(+), 2 deletions(-) > > diff --git a/arch/arm64/kernel/psci.c b/arch/arm64/kernel/psci.c > index 29a8e444db83..4fcc0cdd757b 100644 > --- a/arch/arm64/kernel/psci.c > +++ b/arch/arm64/kernel/psci.c > @@ -40,7 +40,7 @@ static int cpu_psci_cpu_boot(unsigned int cpu) > { > phys_addr_t pa_secondary_entry = __pa_symbol(secondary_entry); > int err = psci_ops.cpu_on(cpu_logical_map(cpu), pa_secondary_entry); > - if (err) > + if (err && err != -EPROBE_DEFER) Hmm. EPROBE_DEFER has very specific meaning around driver requesting a retry when some other bit of the system has finished booting. I'm not sure it's a good idea for this use case. Maybe just keep to EPERM as psci_to_linux_errno() will return anyway. Seems valid to me, or is the requirement to use EPROBE_DEFER coming from further up the stack? > pr_err("failed to boot CPU%d (%d)\n", cpu, err); > > return err; > diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c > index 8c8f55721786..e958db987665 100644 > --- a/arch/arm64/kernel/smp.c > +++ b/arch/arm64/kernel/smp.c > @@ -124,7 +124,8 @@ int __cpu_up(unsigned int cpu, struct task_struct *idle) > /* Now bring the CPU into our world */ > ret = boot_secondary(cpu, idle); > if (ret) { > - pr_err("CPU%u: failed to boot: %d\n", cpu, ret); > + if (ret != -EPROBE_DEFER) > + pr_err("CPU%u: failed to boot: %d\n", cpu, ret); > return ret; > } > > diff --git a/drivers/firmware/psci/psci.c b/drivers/firmware/psci/psci.c > index d9629ff87861..f7ab3fed3528 100644 > --- a/drivers/firmware/psci/psci.c > +++ b/drivers/firmware/psci/psci.c > @@ -218,6 +218,8 @@ static int __psci_cpu_on(u32 fn, unsigned long cpuid, unsigned long entry_point) > int err; > > err = invoke_psci_fn(fn, cpuid, entry_point, 0); > + if (err == PSCI_RET_DENIED) > + return -EPROBE_DEFER; > return psci_to_linux_errno(err); > } >