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 134E4E71094 for ; Thu, 21 Sep 2023 16:37:32 +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=WBR6ONyTePdGSxs90qnIAGbkqaP3qjxYn6Qq7tVh+l0=; b=IGDyxU2NXuiRIV bVzHRbaa4Lc4XspRBUuurhteq9hIgp/d7M2v7MMz4PH2xRnfpIPGSs2Y+VxNJifmxaGm/L7r6Wwfb O2feyqppi8o2ZIc1RNz+5FleyVlzVUMu/pQ50tP31+VLZIrC6tXc86Y9bT5+bXp3SwV7ZM9Fa0myS NPizSMKatm1EhT4hmQ/axlj7hDETeihMW7WNP9UWpdj124O2Xy15qdTCS96IhyUi3K40gZJ1RZQmv NmgA9fzKJ8YvyfFLNCSrFwa41Df0zc6E5OB2Yn/sOu66JE1+gDOPm0v4zU1hq2XOGzMTaAolNvaEX TLcNE7isdtGymgZe/SYw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1qjMfq-006X79-04; Thu, 21 Sep 2023 16:37:06 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1qjMfl-006X6T-2t for linux-arm-kernel@lists.infradead.org; Thu, 21 Sep 2023 16:37:03 +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 6BEAE1A00; Thu, 21 Sep 2023 09:37:35 -0700 (PDT) Received: from FVFF77S0Q05N (unknown [10.57.36.171]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id D5AF73F59C; Thu, 21 Sep 2023 09:36:55 -0700 (PDT) Date: Thu, 21 Sep 2023 17:36:53 +0100 From: Mark Rutland To: Suzuki K Poulose Cc: linux-arm-kernel@lists.infradead.org, ardb@kernel.org, bertrand.marquis@arm.com, boris.ostrovsky@oracle.com, broonie@kernel.org, catalin.marinas@arm.com, daniel.lezcano@linaro.org, james.morse@arm.com, jgross@suse.com, maz@kernel.org, oliver.upton@linux.dev, pcc@google.com, sstabellini@kernel.org, tglx@linutronix.de, vladimir.murzin@arm.com, will@kernel.org Subject: Re: [PATCH 05/37] arm64: Add cpus_have_final_boot_cap() Message-ID: References: <20230919092850.1940729-1-mark.rutland@arm.com> <20230919092850.1940729-6-mark.rutland@arm.com> <55c9f428-b715-a2ae-5b89-d125a0104ea3@arm.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <55c9f428-b715-a2ae-5b89-d125a0104ea3@arm.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230921_093702_030646_A5168524 X-CRM114-Status: GOOD ( 32.03 ) 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 Thu, Sep 21, 2023 at 10:13:31AM +0100, Suzuki K Poulose wrote: > Hi Mark > > On 19/09/2023 10:28, Mark Rutland wrote: > > The cpus_have_final_boot_cap() function can be used to test a cpucap > > nit: cpus_have_final_cap() Thanks; fixed now. > > while also verifying that we do not consume the cpucap until system > > capabilities have been finalized. It would be helpful if we could do > > likewise for boot cpucaps. > > > > This patch adds a new cpus_have_final_boot_cap() helper which can be > > used to test a cpucap while also verifying that boot capabilities have > > been finalized. Users will be added in subsequent patches. > > > > Signed-off-by: Mark Rutland > > Cc: Catalin Marinas > > Cc: Mark Brown > > Cc: Suzuki K Poulose > > Cc: Will Deacon > > --- > > arch/arm64/include/asm/cpufeature.h | 27 +++++++++++++++++++++++++-- > > 1 file changed, 25 insertions(+), 2 deletions(-) > > > > diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h > > index 7d5317bc2429f..e832b86c6b57f 100644 > > --- a/arch/arm64/include/asm/cpufeature.h > > +++ b/arch/arm64/include/asm/cpufeature.h > > @@ -438,6 +438,11 @@ unsigned long cpu_get_elf_hwcap2(void); > > #define cpu_set_named_feature(name) cpu_set_feature(cpu_feature(name)) > > #define cpu_have_named_feature(name) cpu_have_feature(cpu_feature(name)) > > +static __always_inline bool boot_capabilities_finalized(void) > > +{ > > + return alternative_has_cap_likely(ARM64_ALWAYS_BOOT); > > +} > > + > > static __always_inline bool system_capabilities_finalized(void) > > { > > return alternative_has_cap_likely(ARM64_ALWAYS_SYSTEM); > > @@ -473,8 +478,26 @@ static __always_inline bool __cpus_have_const_cap(int num) > > /* > > * Test for a capability without a runtime check. > > * > > - * Before capabilities are finalized, this will BUG(). > > - * After capabilities are finalized, this is patched to avoid a runtime check. > > + * Before boot capabilities are finalized, this will BUG(). > > + * After boot capabilities are finalized, this is patched to avoid a runtime > > + * check. > > + * > > + * @num must be a compile-time constant. > > + */ > > +static __always_inline bool cpus_have_final_boot_cap(int num) > > +{ > > + if (boot_capabilities_finalized()) > > Does this need to make sure the cap is really a "BOOT" cap ? It is a bit of > an overkill, but prevents users from incorrectly assuming the cap is > finalised ? Do you have an idea in mind for how to do that? I had also wanted that, but we don't have the information available when compiling the callsites today since that's determined by the arm64_cpu_capabilities::type flags. We could us an alternative callback for boot_capabilities_finalized() that goes and checks the arm64_cpu_capabilities::type flags, but that doesn't seem very nice. Otherwise, given this only has a few users, I could have those directly use: BUG_ON(!boot_capabilities_finalized()); ... and remove cpus_have_final_boot_cap() for now? Thanks, Mark. > > > Suzuki > > > + return __cpus_have_const_cap(num); > > + else > > + BUG(); > > +} > > + > > +/* > > + * Test for a capability without a runtime check. > > + * > > + * Before system capabilities are finalized, this will BUG(). > > + * After system capabilities are finalized, this is patched to avoid a runtime > > + * check. > > * > > * @num must be a compile-time constant. > > */ > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel