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 8A1FAE82CDE for ; Thu, 5 Oct 2023 09:24:40 +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=vhU6HWdLWkhyXwBossqPr/5U6nQaeb6Q3ujtfdVx7nQ=; b=1iXfmxWeACC3Im C4nzR0tVgPLDt6dfVjfOZuqKSB+lfN1jXTpj/jiu+aR70Kftqot1s8+dw+wZpY59iUBwRUFNR5/Tz 9G2BtQgp90V1wkXBUuqZvU+vMf3RQxZKWor8+OZc028zxV3KHafXIhqUvPvteXukNdBqbxsbch13D 05gv1w1kHSwtnILsWoOOKRDTqwztzVb+3ksAyIPAezvvCubTM55EJWBKFSqelKUkJM9Ya6yrJlGnM bB5UfMS0Qb/KgCQNqcYMCTXb2rNHW9RD4WJNOafwZHzTml9qBILVLygYCAGphxaNmUkW+NvGFNBFr M1yF3oQf9GytZMTdr1wQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1qoKaZ-001koH-1U; Thu, 05 Oct 2023 09:24:11 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1qoKaV-001knd-0b for linux-arm-kernel@lists.infradead.org; Thu, 05 Oct 2023 09:24:09 +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 9C0141516; Thu, 5 Oct 2023 02:24:40 -0700 (PDT) Received: from FVFF77S0Q05N (unknown [10.57.94.58]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 8F68E3F5A1; Thu, 5 Oct 2023 02:23:59 -0700 (PDT) Date: Thu, 5 Oct 2023 10:23:54 +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: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20231005_022407_293857_40C808AD X-CRM114-Status: GOOD ( 29.18 ) 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 Fri, Sep 22, 2023 at 11:26:21AM +0100, Suzuki K Poulose wrote: > On 21/09/2023 17:36, Mark Rutland wrote: > > On Thu, Sep 21, 2023 at 10:13:31AM +0100, Suzuki K Poulose wrote: > > > On 19/09/2023 10:28, Mark Rutland wrote: > > > > /* > > > > * 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. > > > Thats what I had initially in mind, and is why I called it an > overkill. > > But may be another option is to have a different alternative construct > for all capabilities, which defaults to BUG() and then patched to > "false" or "true" based on the real status ? This may be more > complicated. > > > 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? > > I don't think that is necessary. We could keep your patch > as is, if we can't verify the boot capability easily. I had a go at reworking this to automatically do the right thing, and it needs a more substantial rework of the way we handle the cpucap bitmaps and walk over the capability structures. Given that, I'd like to leave this as-is for now, and follow up with the rework for that. Thanks, Mark. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel