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 991ABEB64DA for ; Mon, 10 Jul 2023 13:32:18 +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=iAKkoOsShArj3VW34fqvw5vFNBZcOiACg410ygMm9+Y=; b=naI8hAVC40ODpI 8H3RPoFr7K6gPQ2wSPIONsFmG6CiJjFBcCl88dh/rKRosfdhLP4ZJ2HKmyaCN1nLrDGXkhsfTxrwq mp3EAd/DejRsu+z5OQE4JsF3oOn4Qee+AInfqSw2bKgjRPEpXUjWtfA87Poqlhlc4RR7ulIRbnvbV tdc37fyUNuaRT2CytHyoIsdwigQgth+ESgXkKg7tt9XKNUazuxezXV8yYKEVOHeEaE6zcM353O1Z+ 8sMx2RMdfwi8qdx4OZ/tUYkwj/Dex9IeTZpVpa9Q0uniTh5Rt88QfIrsXXQp7/jdTX5ZAYbR3vQO2 uAnsQRrEJFANvhO+zVnQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1qIqzV-00BlRb-2Q; Mon, 10 Jul 2023 13:31:49 +0000 Received: from dfw.source.kernel.org ([139.178.84.217]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1qIqzT-00BlQT-0T for linux-arm-kernel@lists.infradead.org; Mon, 10 Jul 2023 13:31:48 +0000 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 2B49061000; Mon, 10 Jul 2023 13:31:46 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id EEDCEC433C7; Mon, 10 Jul 2023 13:31:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1688995905; bh=Zae0sXZ1apKn8b44P9R9P2lKldy08yGANk4vIqeZlU0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=TpEBMDbsZ4zuGsGTLnbNkZkxD78Qop9PdG2mTF/3in+XYZINwiy8E3DnGYBxT56uW FlwZUAutSZxHaHaF1bH1+/kdeO+zm2oH7pdw7iGFgDsJiznuRIATXGV6PNA3e+kEFC TpC/CsbKeigp0h5giJ5GNEoojyvUdk+mpZPQE7jU= Date: Mon, 10 Jul 2023 15:31:42 +0200 From: Greg KH To: Will Deacon Cc: Mark Brown , Sasha Levin , linux-kernel@vger.kernel.org, stable@vger.kernel.org, Kristina Martsenko , Catalin Marinas , james.morse@arm.com, mark.rutland@arm.com, amit.kachhap@arm.com, maz@kernel.org, anshuman.khandual@arm.com, joey.gouly@arm.com, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH AUTOSEL 6.4 07/12] arm64: cpufeature: detect FEAT_HCX Message-ID: <2023071024-unpaved-washed-4d7d@gregkh> References: <20230702195057.1787686-1-sashal@kernel.org> <20230702195057.1787686-7-sashal@kernel.org> <20230710094438.GD32673@willie-the-truck> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20230710094438.GD32673@willie-the-truck> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230710_063147_223885_057C8C19 X-CRM114-Status: GOOD ( 25.51 ) 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 Mon, Jul 10, 2023 at 10:44:38AM +0100, Will Deacon wrote: > On Sun, Jul 09, 2023 at 10:13:29PM +0100, Mark Brown wrote: > > On Sun, Jul 09, 2023 at 10:56:13AM -0400, Sasha Levin wrote: > > > On Mon, Jul 03, 2023 at 12:51:57PM +0100, Mark Brown wrote: > > > > On Sun, Jul 02, 2023 at 03:50:52PM -0400, Sasha Levin wrote: > > > > > > > KVM currently relies on the register being present on all CPUs (or > > > > > none), so the kernel will panic if that is not the case. Fortunately no > > > > > such systems currently exist, but this can be revisited if they appear. > > > > > Note that the kernel will not panic if CONFIG_KVM is disabled. > > > > > > This is a new feature, it's not clear why we'd backport it (especially > > > > since it's a new feature which is a dependency for other features rather > > > > than something that people can use outside of the kernel)? > > > > > The second paragraph (above) suggested it should be. > > > > That's saying that the code won't work properly on systems where some > > but not all of the CPUs support the feature. Note that the changelog > > says nothing about fixing any issue here. > > Try reading it like a GPU running an ML model: > > "This is not a new feature, it's especially clear why we'd backport it." > > Makes sense. *sigh* > > We've been considering opting arm64 out of this for a while, but I don't > think we do a great job of CC'ing stable either (I certainly forget to > add it all the time and then hope that the Fixes: tag does the job),so > it's not obviously going to improve things. > > Maybe we just need a commit hook that yells if something with a Fixes: > tag doesn't have a CC: stable on it? I could start doing that, it's going to be really noisy... greg k-h _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel