From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751971AbeAZMbW (ORCPT ); Fri, 26 Jan 2018 07:31:22 -0500 Received: from foss.arm.com ([217.140.101.70]:46468 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751868AbeAZMbV (ORCPT ); Fri, 26 Jan 2018 07:31:21 -0500 Subject: Re: [PATCH 08/16] arm64: capabilities: Group handling of features and errata To: Dave Martin Cc: linux-arm-kernel@lists.infradead.org, mark.rutland@arm.com, ckadabi@codeaurora.org, ard.biesheuvel@linaro.org, marc.zyngier@arm.com, catalin.marinas@arm.com, will.deacon@arm.com, linux-kernel@vger.kernel.org, jnair@caviumnetworks.com References: <20180123122809.16269-1-suzuki.poulose@arm.com> <20180123122809.16269-9-suzuki.poulose@arm.com> <20180126114708.GP5862@e103592.cambridge.arm.com> From: Suzuki K Poulose Message-ID: Date: Fri, 26 Jan 2018 12:31:18 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.5.2 MIME-Version: 1.0 In-Reply-To: <20180126114708.GP5862@e103592.cambridge.arm.com> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 26/01/18 11:47, Dave Martin wrote: > On Tue, Jan 23, 2018 at 12:28:01PM +0000, Suzuki K Poulose wrote: >> So far we have had separate routes for triggering errata and feature > > "triggering errata" ? ;) > :-). Should have been "triggering errata and feature capability *checks*. > Maybe "[...] for determining whether to activate errata workarounds and > whether to enable feature capabilities." > >> capabilities. Also, we never allowed "features" based on local CPU >> and "errata" based on System wide safe registers. This patch >> groups the handling of errata and features and also allows them >> to have all the possible scopes. >> >> So, we now run through the arm64_features and arm64_errata: > > when? with this patch. > What about late cpus? > We don't detect any new capabilities on them. They continue to get verified against the enabled capabilities. >> 1) with SCOPE_LOCAL_CPU filter on each boot time enabeld CPUs, >> via update_cpu_local_capabilities(). > > "each [...] enabeld CPUs" -> "each [...] enabled CPU" > > Also, changing "boot time" -> "boot-time" helps avoid this being misread > as "on each boot", which could be taken to mean "each time a CPU comes > online". I'm guessing that's not the intended meaning here. OK >> /* >> - * The CPU Errata work arounds are detected and applied at boot time >> - * and the related information is freed soon after. If the new CPU requires >> - * an errata not detected at boot, fail this CPU. >> + * Check for all capablities within the scope of local CPU. >> + * This is run on all boot time activated CPUs. >> */ >> -static void verify_local_cpu_errata_workarounds(void) >> +static void update_cpu_local_capabilities(void) > > [Gaah, stupid git diff making function insertion look like function > modification. Sometimes --patience does a better job, but there seems > no foolproof solution... If you do a respin, it might be worth trying > it.] Will try, thanks for the suggestion. I didn't know about that :-) >> -static void __init setup_feature_capabilities(void) >> +static void __init setup_system_capabilities(void) >> { >> - update_cpu_capabilities(arm64_features, >> - ARM64_CPUCAP_TYPE_ALL, "detected feature:"); >> - enable_cpu_capabilities(arm64_features, ARM64_CPUCAP_TYPE_ALL); >> + /* >> + * We have finalised the system wide safe feature registers, >> + * finalise the capabilities that depend on it. >> + */ >> + update_system_capabilities(); >> + /* Enable all the available capabilities */ >> + enable_cpu_capabilities(ARM64_CPUCAP_TYPE_ALL); > > So setup_system_capabilities() enables _non_ system-wide capabilities/ > errata workarounds too? > Maybe this function should just have a different name, like > "setup_boot_capabilities" or similar? The problem with setup_boot_capabilities() is that it could conflict with "coming soon" setup_boot_cpu_capabilities(). May be, setup_boot_time_system_capabilities(). > > } >> >> DEFINE_STATIC_KEY_FALSE(arm64_const_caps_ready); >> @@ -1422,9 +1435,7 @@ void __init setup_cpu_features(void) >> u32 cwg; >> int cls; >> >> - /* Set the CPU feature capabilies */ >> - setup_feature_capabilities(); >> - enable_errata_workarounds(); >> + setup_system_capabilities(); >> mark_const_caps_ready(); >> setup_elf_hwcaps(arm64_elf_hwcaps); > > I wonder whether we could unify the elf hwcaps handling too. I was thinking about it today. The only catch is how do we know if we have "the capability", as it is spread across multiple bitmasks. (HWCAP, COMPAT_HWCAP, COMPAT_HWCAP2). Suzuki