From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sean Christopherson Date: Thu, 3 Nov 2022 17:44:51 +0000 Subject: [PATCH 36/44] KVM: x86: Do compatibility checks when onlining CPU In-Reply-To: <23bfd709-f99a-5a74-e4b9-1381b88453f1@redhat.com> References: <20221102231911.3107438-1-seanjc@google.com> <20221102231911.3107438-37-seanjc@google.com> <23bfd709-f99a-5a74-e4b9-1381b88453f1@redhat.com> Message-ID: List-Id: To: kvm-riscv@lists.infradead.org MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit On Thu, Nov 03, 2022, Paolo Bonzini wrote: > On 11/3/22 00:19, Sean Christopherson wrote: > > From: Chao Gao > > > > Do compatibility checks when enabling hardware to effectively add > > compatibility checks when onlining a CPU. Abort enabling, i.e. the > > online process, if the (hotplugged) CPU is incompatible with the known > > good setup. > > This paragraph is not true with this patch being before "KVM: Rename and > move CPUHP_AP_KVM_STARTING to ONLINE section". Argh, good eyes. Getting the ordering correct in this series has been quite the struggle. Assuming there are no subtle dependencies between x86 and common KVM, the ordering should be something like this: KVM: Opt out of generic hardware enabling on s390 and PPC KVM: Register syscore (suspend/resume) ops early in kvm_init() KVM: x86: Do compatibility checks when onlining CPU KVM: SVM: Check for SVM support in CPU compatibility checks KVM: VMX: Shuffle support checks and hardware enabling code around KVM: x86: Do VMX/SVM support checks directly in vendor code KVM: x86: Unify pr_fmt to use module name for all KVM modules KVM: x86: Use KBUILD_MODNAME to specify vendor module name KVM: Make hardware_enable_failed a local variable in the "enable all" path KVM: Use a per-CPU variable to track which CPUs have enabled virtualization KVM: Remove on_each_cpu(hardware_disable_nolock) in kvm_exit() KVM: Drop kvm_count_lock and instead protect kvm_usage_count with kvm_lock KVM: Disable CPU hotplug during hardware enabling KVM: Rename and move CPUHP_AP_KVM_STARTING to ONLINE section KVM: Drop kvm_arch_check_processor_compat() hook 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 mm01.cs.columbia.edu (mm01.cs.columbia.edu [128.59.11.253]) by smtp.lore.kernel.org (Postfix) with ESMTP id 82443C4321E for ; Thu, 3 Nov 2022 17:45:01 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id F05044B133; Thu, 3 Nov 2022 13:45:00 -0400 (EDT) X-Virus-Scanned: at lists.cs.columbia.edu Authentication-Results: mm01.cs.columbia.edu (amavisd-new); dkim=softfail (fail, message has been altered) header.i=@google.com Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id bFXhafjYdVb8; Thu, 3 Nov 2022 13:44:59 -0400 (EDT) Received: from mm01.cs.columbia.edu (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id D1AE04B274; Thu, 3 Nov 2022 13:44:59 -0400 (EDT) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 929BA4B0D0 for ; Thu, 3 Nov 2022 13:44:58 -0400 (EDT) X-Virus-Scanned: at lists.cs.columbia.edu Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id Qasc0ehMxVvK for ; Thu, 3 Nov 2022 13:44:57 -0400 (EDT) Received: from mail-pj1-f52.google.com (mail-pj1-f52.google.com [209.85.216.52]) by mm01.cs.columbia.edu (Postfix) with ESMTPS id 728C149F49 for ; Thu, 3 Nov 2022 13:44:57 -0400 (EDT) Received: by mail-pj1-f52.google.com with SMTP id v4-20020a17090a088400b00212cb0ed97eso2485484pjc.5 for ; Thu, 03 Nov 2022 10:44:57 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=cK19xZ8r/JxZ6zrZk59CGRO4XALiFfw/k+DEo690ifc=; b=AMXkMgBJe864E9ylH4eLhcV4DnnmpnUZQciwStcW/fWfVy8vl8xbyLHXqWoh/4n8QF bRAhsfNtOcglKLMhK6Nb/v5AF7HvdYNYuPv80cwXOHPX5E9n4f4rIwmSH2XAdpFIqhuj sSsx/7sAKHM3fmeDS7xyNpoxOPMcbkwOVVWM5XBPQcjHKuBxYoH5JxFh6oDyEgClSLr4 VePL27iqi0rk5/s+JivkXFUi7OtMXJLNacJQMnJ3M4obYSjfplMj8jxI5D4RNhWTNCit VmDRgbq4Pt+ph415Zp0hH77zR2JN9eVpsj1xI6CTZrVgir1QKlQnpGg6QTPI6wKdJ0ls 3hyg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=cK19xZ8r/JxZ6zrZk59CGRO4XALiFfw/k+DEo690ifc=; b=8AGL/PsJDqmkBbWJctJQ5bgh7/DFqzRw/vHpBouVq+OayKYyWsnx2x/E4gWYGvu5NM VuleSbHhj+fv3XwNnuDq8nbjPxCNQGn4AoOXij3M9O4mZEsGWuQ8iSybKM7yZapSIXeA 76Fu0VY3ns/qHr2UjTxcsBnCZm2BmR+A5/gm5eE06RLsObXReQYOudL2pNJ9unT28TCh iRyI7UkHVCrqItIgrmsEWwUJqB3QiEv+87a0whoMjnEU3sk7+apmlBQhwuO91scVozkM 01qHrmXxs8qsmujn5ahzULySkZlu6fToBasMR/WH927YF5K7fwFfGT6YrARhD1eqkcY3 +t/g== X-Gm-Message-State: ACrzQf3WoAi7z+rYzwBaP5b2uE1TQgwH1mKAv9tlQvZj+StlZV9ZjMU4 4WdgRCibC2gcUVL4TuzIJ04MGQ== X-Google-Smtp-Source: AMsMyM7Vi7ErqJmqrzHt1bwsO7Jfw+kVc4w4lCdxf/cK5b8KZHYV39XlOvASF4Eye8GSeC7ZJ2rbFQ== X-Received: by 2002:a17:90a:d24d:b0:213:d3e4:677a with SMTP id o13-20020a17090ad24d00b00213d3e4677amr24629292pjw.101.1667497496277; Thu, 03 Nov 2022 10:44:56 -0700 (PDT) Received: from google.com (7.104.168.34.bc.googleusercontent.com. [34.168.104.7]) by smtp.gmail.com with ESMTPSA id i7-20020a17090332c700b00178aaf6247bsm1004862plr.21.2022.11.03.10.44.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 03 Nov 2022 10:44:55 -0700 (PDT) Date: Thu, 3 Nov 2022 17:44:51 +0000 From: Sean Christopherson To: Paolo Bonzini Subject: Re: [PATCH 36/44] KVM: x86: Do compatibility checks when onlining CPU Message-ID: References: <20221102231911.3107438-1-seanjc@google.com> <20221102231911.3107438-37-seanjc@google.com> <23bfd709-f99a-5a74-e4b9-1381b88453f1@redhat.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <23bfd709-f99a-5a74-e4b9-1381b88453f1@redhat.com> Cc: Matthew Rosato , David Hildenbrand , Yuan Yao , Paul Walmsley , linux-kernel@vger.kernel.org, Michael Ellerman , linux-riscv@lists.infradead.org, Claudio Imbrenda , kvmarm@lists.cs.columbia.edu, linux-s390@vger.kernel.org, Janosch Frank , Marc Zyngier , Huacai Chen , Aleksandar Markovic , Christian Borntraeger , Chao Gao , Eric Farman , Albert Ou , kvm@vger.kernel.org, Atish Patra , kvmarm@lists.linux.dev, Thomas Gleixner , linux-arm-kernel@lists.infradead.org, Isaku Yamahata , Fabiano Rosas , linux-mips@vger.kernel.org, Palmer Dabbelt , kvm-riscv@lists.infradead.org, Vitaly Kuznetsov , linuxppc-dev@lists.ozlabs.org X-BeenThere: kvmarm@lists.cs.columbia.edu X-Mailman-Version: 2.1.14 Precedence: list List-Id: Where KVM/ARM decisions are made List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu On Thu, Nov 03, 2022, Paolo Bonzini wrote: > On 11/3/22 00:19, Sean Christopherson wrote: > > From: Chao Gao > > > > Do compatibility checks when enabling hardware to effectively add > > compatibility checks when onlining a CPU. Abort enabling, i.e. the > > online process, if the (hotplugged) CPU is incompatible with the known > > good setup. > > This paragraph is not true with this patch being before "KVM: Rename and > move CPUHP_AP_KVM_STARTING to ONLINE section". Argh, good eyes. Getting the ordering correct in this series has been quite the struggle. Assuming there are no subtle dependencies between x86 and common KVM, the ordering should be something like this: KVM: Opt out of generic hardware enabling on s390 and PPC KVM: Register syscore (suspend/resume) ops early in kvm_init() KVM: x86: Do compatibility checks when onlining CPU KVM: SVM: Check for SVM support in CPU compatibility checks KVM: VMX: Shuffle support checks and hardware enabling code around KVM: x86: Do VMX/SVM support checks directly in vendor code KVM: x86: Unify pr_fmt to use module name for all KVM modules KVM: x86: Use KBUILD_MODNAME to specify vendor module name KVM: Make hardware_enable_failed a local variable in the "enable all" path KVM: Use a per-CPU variable to track which CPUs have enabled virtualization KVM: Remove on_each_cpu(hardware_disable_nolock) in kvm_exit() KVM: Drop kvm_count_lock and instead protect kvm_usage_count with kvm_lock KVM: Disable CPU hotplug during hardware enabling KVM: Rename and move CPUHP_AP_KVM_STARTING to ONLINE section KVM: Drop kvm_arch_check_processor_compat() hook _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pj1-f48.google.com (mail-pj1-f48.google.com [209.85.216.48]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1011163A0 for ; Thu, 3 Nov 2022 17:44:56 +0000 (UTC) Received: by mail-pj1-f48.google.com with SMTP id gw22so2354458pjb.3 for ; Thu, 03 Nov 2022 10:44:56 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=cK19xZ8r/JxZ6zrZk59CGRO4XALiFfw/k+DEo690ifc=; b=AMXkMgBJe864E9ylH4eLhcV4DnnmpnUZQciwStcW/fWfVy8vl8xbyLHXqWoh/4n8QF bRAhsfNtOcglKLMhK6Nb/v5AF7HvdYNYuPv80cwXOHPX5E9n4f4rIwmSH2XAdpFIqhuj sSsx/7sAKHM3fmeDS7xyNpoxOPMcbkwOVVWM5XBPQcjHKuBxYoH5JxFh6oDyEgClSLr4 VePL27iqi0rk5/s+JivkXFUi7OtMXJLNacJQMnJ3M4obYSjfplMj8jxI5D4RNhWTNCit VmDRgbq4Pt+ph415Zp0hH77zR2JN9eVpsj1xI6CTZrVgir1QKlQnpGg6QTPI6wKdJ0ls 3hyg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=cK19xZ8r/JxZ6zrZk59CGRO4XALiFfw/k+DEo690ifc=; b=5co6LCXtkPVpW38nrOfE9R7FEK5MwUEfsHvYp6QXvFdicBsv2UieH/HEWZCA1sKq9l VET9WTMNS5eeil8HuXGUY2qtMl6hdTNOtkmpT2Tbr1Ltk7GLOpZfl4vX5ZzHTHX9X2cu YCkx5S7dVSK07vs4oBdTpmyJk5eVf6yb2bQV80EEV96YWx9mPgrA2FB0n0ETSfYN6GAi ms5RfRbUlSd/Q4jHPdJAR+jT3n8E40Mtq3y6LBd/mT8PFIWq7IG2a8VNibbHXIo5rt/l EDjn+0AW2XZZ/aq42hy6lT6HTtxjucKGfT/+1bFhwRq01ELRJ2D+rv57+FecmxVKQwTE wH6w== X-Gm-Message-State: ACrzQf1JwEsYbv8ctY1FHpBPnXK2yyUUPnSSJhyYf4S3/SNzG3RZtYrt nNGa1BWik3RZdqUAgE09O90u8g== X-Google-Smtp-Source: AMsMyM7Vi7ErqJmqrzHt1bwsO7Jfw+kVc4w4lCdxf/cK5b8KZHYV39XlOvASF4Eye8GSeC7ZJ2rbFQ== X-Received: by 2002:a17:90a:d24d:b0:213:d3e4:677a with SMTP id o13-20020a17090ad24d00b00213d3e4677amr24629292pjw.101.1667497496277; Thu, 03 Nov 2022 10:44:56 -0700 (PDT) Received: from google.com (7.104.168.34.bc.googleusercontent.com. [34.168.104.7]) by smtp.gmail.com with ESMTPSA id i7-20020a17090332c700b00178aaf6247bsm1004862plr.21.2022.11.03.10.44.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 03 Nov 2022 10:44:55 -0700 (PDT) Date: Thu, 3 Nov 2022 17:44:51 +0000 From: Sean Christopherson To: Paolo Bonzini Cc: Marc Zyngier , Huacai Chen , Aleksandar Markovic , Anup Patel , Paul Walmsley , Palmer Dabbelt , Albert Ou , Christian Borntraeger , Janosch Frank , Claudio Imbrenda , Matthew Rosato , Eric Farman , Vitaly Kuznetsov , James Morse , Alexandru Elisei , Suzuki K Poulose , Oliver Upton , Atish Patra , David Hildenbrand , kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, kvmarm@lists.cs.columbia.edu, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, Isaku Yamahata , Fabiano Rosas , Michael Ellerman , Chao Gao , Thomas Gleixner , Yuan Yao Subject: Re: [PATCH 36/44] KVM: x86: Do compatibility checks when onlining CPU Message-ID: References: <20221102231911.3107438-1-seanjc@google.com> <20221102231911.3107438-37-seanjc@google.com> <23bfd709-f99a-5a74-e4b9-1381b88453f1@redhat.com> Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <23bfd709-f99a-5a74-e4b9-1381b88453f1@redhat.com> Message-ID: <20221103174451.u4ThMi2c3sxKft3XqN4SrD-WqjRnQl68hvu4aXOyWxU@z> On Thu, Nov 03, 2022, Paolo Bonzini wrote: > On 11/3/22 00:19, Sean Christopherson wrote: > > From: Chao Gao > > > > Do compatibility checks when enabling hardware to effectively add > > compatibility checks when onlining a CPU. Abort enabling, i.e. the > > online process, if the (hotplugged) CPU is incompatible with the known > > good setup. > > This paragraph is not true with this patch being before "KVM: Rename and > move CPUHP_AP_KVM_STARTING to ONLINE section". Argh, good eyes. Getting the ordering correct in this series has been quite the struggle. Assuming there are no subtle dependencies between x86 and common KVM, the ordering should be something like this: KVM: Opt out of generic hardware enabling on s390 and PPC KVM: Register syscore (suspend/resume) ops early in kvm_init() KVM: x86: Do compatibility checks when onlining CPU KVM: SVM: Check for SVM support in CPU compatibility checks KVM: VMX: Shuffle support checks and hardware enabling code around KVM: x86: Do VMX/SVM support checks directly in vendor code KVM: x86: Unify pr_fmt to use module name for all KVM modules KVM: x86: Use KBUILD_MODNAME to specify vendor module name KVM: Make hardware_enable_failed a local variable in the "enable all" path KVM: Use a per-CPU variable to track which CPUs have enabled virtualization KVM: Remove on_each_cpu(hardware_disable_nolock) in kvm_exit() KVM: Drop kvm_count_lock and instead protect kvm_usage_count with kvm_lock KVM: Disable CPU hotplug during hardware enabling KVM: Rename and move CPUHP_AP_KVM_STARTING to ONLINE section KVM: Drop kvm_arch_check_processor_compat() hook 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 41B0DC4332F for ; Thu, 3 Nov 2022 17:45:12 +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=gHC6oMiqXiA6siE7m8pgOUY8CsK2FLlxfaW6gl6N9pU=; b=vHFxuNJ9F2yjU9 TWGRgn1ctugCoLokGycsec28pS3/BGenZPh+3So5JsGeYiY/paLuKGqPnm4DjOu+xPGW/+DqE76h3 3m/ER26RS66aewKsoOi+dgMGauHR1nEm0AwHG/l4Y7U5dL9AkAMTzCdZO1c5uCu0IQ90hZ8YHMpqI oOx1EHzp10cFkOLKpm2WMDz12SNQIdhQDR/ot2Bb6s6EDCcLxomP9U72y+Ak0RaTnX1VV6wMlWEJy F+9dZUIe/3YNUwTgNOCM195A0KtvOuCGW8bpwnTVx6oj7XzNcszniiEXfGsQ2pLa3Ib4ulD/EkXsy pBjdEnL9xWYQ1talW7+g==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1oqeH0-0017J5-MX; Thu, 03 Nov 2022 17:45:02 +0000 Received: from mail-pj1-x1036.google.com ([2607:f8b0:4864:20::1036]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1oqeGv-0017G7-Tc for linux-riscv@lists.infradead.org; Thu, 03 Nov 2022 17:45:00 +0000 Received: by mail-pj1-x1036.google.com with SMTP id o7so2367610pjj.1 for ; Thu, 03 Nov 2022 10:44:56 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=cK19xZ8r/JxZ6zrZk59CGRO4XALiFfw/k+DEo690ifc=; b=AMXkMgBJe864E9ylH4eLhcV4DnnmpnUZQciwStcW/fWfVy8vl8xbyLHXqWoh/4n8QF bRAhsfNtOcglKLMhK6Nb/v5AF7HvdYNYuPv80cwXOHPX5E9n4f4rIwmSH2XAdpFIqhuj sSsx/7sAKHM3fmeDS7xyNpoxOPMcbkwOVVWM5XBPQcjHKuBxYoH5JxFh6oDyEgClSLr4 VePL27iqi0rk5/s+JivkXFUi7OtMXJLNacJQMnJ3M4obYSjfplMj8jxI5D4RNhWTNCit VmDRgbq4Pt+ph415Zp0hH77zR2JN9eVpsj1xI6CTZrVgir1QKlQnpGg6QTPI6wKdJ0ls 3hyg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=cK19xZ8r/JxZ6zrZk59CGRO4XALiFfw/k+DEo690ifc=; b=zATlkalcrWkNMYQWzzKfziohVOUm3OLFXJZvSZmnRznNeeYGdcnbG3FVoXY4BeXqfl 6jAA1anhhmYFoyEZwpJVDnwMe8nH02dvPZOidJXQLhWAsHf5AVLfPdqwyJZUsrsh5mEv vpOJzx8wIgrMEdkq52ji84iV9agMcgv/YKA0V+hTNG38lH2lM26VJ391CW4MBOig2Zgb zlzx7lABov5i013VCPEMwEyF15RT86p2StUSPaYSMVzZx+x6W9Pv/nDMubCUpnHgFWye ZtkQtsTmyAyzk3JJqUMYXYSR6cbH1liD+QRlLdzrvOYYj8PIMt1o0Hp0MPoSbeUeZmHD 664Q== X-Gm-Message-State: ACrzQf0AwX0veViEhYbaNFVqcFCTZula9bhEDIbR9yhFFwlZK3+AISM4 8+7cw4KvWipiXUUUFPPDDalv9Q== X-Google-Smtp-Source: AMsMyM7Vi7ErqJmqrzHt1bwsO7Jfw+kVc4w4lCdxf/cK5b8KZHYV39XlOvASF4Eye8GSeC7ZJ2rbFQ== X-Received: by 2002:a17:90a:d24d:b0:213:d3e4:677a with SMTP id o13-20020a17090ad24d00b00213d3e4677amr24629292pjw.101.1667497496277; Thu, 03 Nov 2022 10:44:56 -0700 (PDT) Received: from google.com (7.104.168.34.bc.googleusercontent.com. [34.168.104.7]) by smtp.gmail.com with ESMTPSA id i7-20020a17090332c700b00178aaf6247bsm1004862plr.21.2022.11.03.10.44.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 03 Nov 2022 10:44:55 -0700 (PDT) Date: Thu, 3 Nov 2022 17:44:51 +0000 From: Sean Christopherson To: Paolo Bonzini Cc: Marc Zyngier , Huacai Chen , Aleksandar Markovic , Anup Patel , Paul Walmsley , Palmer Dabbelt , Albert Ou , Christian Borntraeger , Janosch Frank , Claudio Imbrenda , Matthew Rosato , Eric Farman , Vitaly Kuznetsov , James Morse , Alexandru Elisei , Suzuki K Poulose , Oliver Upton , Atish Patra , David Hildenbrand , kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, kvmarm@lists.cs.columbia.edu, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, Isaku Yamahata , Fabiano Rosas , Michael Ellerman , Chao Gao , Thomas Gleixner , Yuan Yao Subject: Re: [PATCH 36/44] KVM: x86: Do compatibility checks when onlining CPU Message-ID: References: <20221102231911.3107438-1-seanjc@google.com> <20221102231911.3107438-37-seanjc@google.com> <23bfd709-f99a-5a74-e4b9-1381b88453f1@redhat.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <23bfd709-f99a-5a74-e4b9-1381b88453f1@redhat.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20221103_104459_552160_BDC8EF4F X-CRM114-Status: GOOD ( 11.26 ) X-BeenThere: linux-riscv@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-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org On Thu, Nov 03, 2022, Paolo Bonzini wrote: > On 11/3/22 00:19, Sean Christopherson wrote: > > From: Chao Gao > > > > Do compatibility checks when enabling hardware to effectively add > > compatibility checks when onlining a CPU. Abort enabling, i.e. the > > online process, if the (hotplugged) CPU is incompatible with the known > > good setup. > > This paragraph is not true with this patch being before "KVM: Rename and > move CPUHP_AP_KVM_STARTING to ONLINE section". Argh, good eyes. Getting the ordering correct in this series has been quite the struggle. Assuming there are no subtle dependencies between x86 and common KVM, the ordering should be something like this: KVM: Opt out of generic hardware enabling on s390 and PPC KVM: Register syscore (suspend/resume) ops early in kvm_init() KVM: x86: Do compatibility checks when onlining CPU KVM: SVM: Check for SVM support in CPU compatibility checks KVM: VMX: Shuffle support checks and hardware enabling code around KVM: x86: Do VMX/SVM support checks directly in vendor code KVM: x86: Unify pr_fmt to use module name for all KVM modules KVM: x86: Use KBUILD_MODNAME to specify vendor module name KVM: Make hardware_enable_failed a local variable in the "enable all" path KVM: Use a per-CPU variable to track which CPUs have enabled virtualization KVM: Remove on_each_cpu(hardware_disable_nolock) in kvm_exit() KVM: Drop kvm_count_lock and instead protect kvm_usage_count with kvm_lock KVM: Disable CPU hotplug during hardware enabling KVM: Rename and move CPUHP_AP_KVM_STARTING to ONLINE section KVM: Drop kvm_arch_check_processor_compat() hook _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv 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 lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (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 26155C433FE for ; Thu, 3 Nov 2022 17:46:32 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4N3B5L4sJbz3dsF for ; Fri, 4 Nov 2022 04:46:30 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=google.com header.i=@google.com header.a=rsa-sha256 header.s=20210112 header.b=AMXkMgBJ; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=google.com (client-ip=2607:f8b0:4864:20::1035; helo=mail-pj1-x1035.google.com; envelope-from=seanjc@google.com; receiver=) Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=google.com header.i=@google.com header.a=rsa-sha256 header.s=20210112 header.b=AMXkMgBJ; dkim-atps=neutral Received: from mail-pj1-x1035.google.com (mail-pj1-x1035.google.com [IPv6:2607:f8b0:4864:20::1035]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4N3B3b2YWzz3cJG for ; Fri, 4 Nov 2022 04:44:58 +1100 (AEDT) Received: by mail-pj1-x1035.google.com with SMTP id d13-20020a17090a3b0d00b00213519dfe4aso2508639pjc.2 for ; Thu, 03 Nov 2022 10:44:58 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=cK19xZ8r/JxZ6zrZk59CGRO4XALiFfw/k+DEo690ifc=; b=AMXkMgBJe864E9ylH4eLhcV4DnnmpnUZQciwStcW/fWfVy8vl8xbyLHXqWoh/4n8QF bRAhsfNtOcglKLMhK6Nb/v5AF7HvdYNYuPv80cwXOHPX5E9n4f4rIwmSH2XAdpFIqhuj sSsx/7sAKHM3fmeDS7xyNpoxOPMcbkwOVVWM5XBPQcjHKuBxYoH5JxFh6oDyEgClSLr4 VePL27iqi0rk5/s+JivkXFUi7OtMXJLNacJQMnJ3M4obYSjfplMj8jxI5D4RNhWTNCit VmDRgbq4Pt+ph415Zp0hH77zR2JN9eVpsj1xI6CTZrVgir1QKlQnpGg6QTPI6wKdJ0ls 3hyg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=cK19xZ8r/JxZ6zrZk59CGRO4XALiFfw/k+DEo690ifc=; b=HAQPieJKFKPuFP6xtDIrbE+rNcsQRLq1gEEEfGGMwTMVOaPZfDm90ezI2yyheCkGAL 75sWkyjsVA0AXmY8Ugvq6Xu/Y5edRb0zao7BgZUs497jgDImt2c+nGer7GnLvve3XkiH 2lpTsioS54+hayvzAbZrAmEOi70LNX/wAuJGGQrqosDfwotNGQM2FBsb3bv6ji7T8Mf7 2kT+MkNskOcCexqnuDHh4qsiqsxND7x3w45oVhkOAlgd6scj2qY0E8vWwWLVS47ID2UM hA7VYqmyreOuhA8CWGoPI58/UkuCayXotrzkuP4cEQiSPw34L8vnc1t6h93zBP0BkId0 Uk1A== X-Gm-Message-State: ACrzQf3AtenrYXfJPMLqW/3/ssgeJNAyJoAX9WEZalGjbqqF54+F/749 k7clQTJVCqWRS4VPtybuLnfJMA== X-Google-Smtp-Source: AMsMyM7Vi7ErqJmqrzHt1bwsO7Jfw+kVc4w4lCdxf/cK5b8KZHYV39XlOvASF4Eye8GSeC7ZJ2rbFQ== X-Received: by 2002:a17:90a:d24d:b0:213:d3e4:677a with SMTP id o13-20020a17090ad24d00b00213d3e4677amr24629292pjw.101.1667497496277; Thu, 03 Nov 2022 10:44:56 -0700 (PDT) Received: from google.com (7.104.168.34.bc.googleusercontent.com. [34.168.104.7]) by smtp.gmail.com with ESMTPSA id i7-20020a17090332c700b00178aaf6247bsm1004862plr.21.2022.11.03.10.44.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 03 Nov 2022 10:44:55 -0700 (PDT) Date: Thu, 3 Nov 2022 17:44:51 +0000 From: Sean Christopherson To: Paolo Bonzini Subject: Re: [PATCH 36/44] KVM: x86: Do compatibility checks when onlining CPU Message-ID: References: <20221102231911.3107438-1-seanjc@google.com> <20221102231911.3107438-37-seanjc@google.com> <23bfd709-f99a-5a74-e4b9-1381b88453f1@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <23bfd709-f99a-5a74-e4b9-1381b88453f1@redhat.com> X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Matthew Rosato , David Hildenbrand , Yuan Yao , Paul Walmsley , linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org, Claudio Imbrenda , kvmarm@lists.cs.columbia.edu, linux-s390@vger.kernel.org, Janosch Frank , Marc Zyngier , Huacai Chen , Aleksandar Markovic , James Morse , Christian Borntraeger , Chao Gao , Eric Farman , Albert Ou , Suzuki K Poulose , kvm@vger.kernel.org, Atish Patra , kvmarm@lists.linux.dev, Thomas Gleixner , Alexandru Elisei , linux-arm-kernel@lists.infradead.org, Isaku Yamahata , Fabiano Rosas , linux-mips@vger.kernel.org, Oliver Upton , Palmer Dabbelt , kvm-riscv@lists.infradead.org, Anup Patel , Vitaly Kuznetsov , linuxppc-dev@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Thu, Nov 03, 2022, Paolo Bonzini wrote: > On 11/3/22 00:19, Sean Christopherson wrote: > > From: Chao Gao > > > > Do compatibility checks when enabling hardware to effectively add > > compatibility checks when onlining a CPU. Abort enabling, i.e. the > > online process, if the (hotplugged) CPU is incompatible with the known > > good setup. > > This paragraph is not true with this patch being before "KVM: Rename and > move CPUHP_AP_KVM_STARTING to ONLINE section". Argh, good eyes. Getting the ordering correct in this series has been quite the struggle. Assuming there are no subtle dependencies between x86 and common KVM, the ordering should be something like this: KVM: Opt out of generic hardware enabling on s390 and PPC KVM: Register syscore (suspend/resume) ops early in kvm_init() KVM: x86: Do compatibility checks when onlining CPU KVM: SVM: Check for SVM support in CPU compatibility checks KVM: VMX: Shuffle support checks and hardware enabling code around KVM: x86: Do VMX/SVM support checks directly in vendor code KVM: x86: Unify pr_fmt to use module name for all KVM modules KVM: x86: Use KBUILD_MODNAME to specify vendor module name KVM: Make hardware_enable_failed a local variable in the "enable all" path KVM: Use a per-CPU variable to track which CPUs have enabled virtualization KVM: Remove on_each_cpu(hardware_disable_nolock) in kvm_exit() KVM: Drop kvm_count_lock and instead protect kvm_usage_count with kvm_lock KVM: Disable CPU hotplug during hardware enabling KVM: Rename and move CPUHP_AP_KVM_STARTING to ONLINE section KVM: Drop kvm_arch_check_processor_compat() hook 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 089F0C433FE for ; Thu, 3 Nov 2022 17:46:18 +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=iW5YExnwRVgqAOEOIyteo0P8Evq8qinsh1WAiqgOe7g=; b=2fNEhhgnga56zP T6XVGt4wddtg+djao15Pq5S5Qc6S/K9xxXBpO+Y8Mc3Dj2LT1MlNZVnG+1cZVzXLVqk01bqeBjX7U FStYnbYal/v8DvL/Qb8usDpfi0p/v9MSl/OGiEM+LpNJirLXe/BYuHeE8eC04z0bC5fqy3ZGrdG19 BvM18Q/iqdmBKk/EstyGdGZ1LvlvIgsv2OGP2R3x7+0ckS44df2X3sseG95rahGFA+8oE7o4EfMza Tq6oQse0r/0qJZtbWI9Q+gY9M1+yWqP9uKdJy25fAChxzHQXapnHuDhy0/1NFrXUAe6MSAAtfZs4S HSmuqG+/y5SrnbZxuP5A==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1oqeH2-0017Jq-Nj; Thu, 03 Nov 2022 17:45:04 +0000 Received: from mail-pj1-x102e.google.com ([2607:f8b0:4864:20::102e]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1oqeGv-0017G6-Td for linux-arm-kernel@lists.infradead.org; Thu, 03 Nov 2022 17:45:00 +0000 Received: by mail-pj1-x102e.google.com with SMTP id h14so2347895pjv.4 for ; Thu, 03 Nov 2022 10:44:56 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=cK19xZ8r/JxZ6zrZk59CGRO4XALiFfw/k+DEo690ifc=; b=AMXkMgBJe864E9ylH4eLhcV4DnnmpnUZQciwStcW/fWfVy8vl8xbyLHXqWoh/4n8QF bRAhsfNtOcglKLMhK6Nb/v5AF7HvdYNYuPv80cwXOHPX5E9n4f4rIwmSH2XAdpFIqhuj sSsx/7sAKHM3fmeDS7xyNpoxOPMcbkwOVVWM5XBPQcjHKuBxYoH5JxFh6oDyEgClSLr4 VePL27iqi0rk5/s+JivkXFUi7OtMXJLNacJQMnJ3M4obYSjfplMj8jxI5D4RNhWTNCit VmDRgbq4Pt+ph415Zp0hH77zR2JN9eVpsj1xI6CTZrVgir1QKlQnpGg6QTPI6wKdJ0ls 3hyg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=cK19xZ8r/JxZ6zrZk59CGRO4XALiFfw/k+DEo690ifc=; b=K/dm6CxBl8p1TA5NLpEDPaTd3l47eCvSMSHsT4h3gP7Zlm5uxGEGHpSWVeB3VZ30BL I9h4zfZUqjRfTONv5ayu7Lo5tQPrr/lAD2WzkAF89aiWNsmeK+jCRXq1vAh70ZENhFPj fPC3kb4SHXdgp7d4+HE+vPTUOQy+UH7dtPmyq76v6QsQgo2a5ZwgUThOCrsh3UouTR/S KuaYOqTbwK8Qt3zm9iO3n5lgTra9GI+sCG4AhT6upSaFZRBpmpRMo0Jb/Wnuf/7dgE3b fl7tOwrVin9IuBEJwzpjN37q5P9Gf5Y/3mgvQd8j56lWkuRITawQJA3ys8Rwh1/GkZTQ zUZQ== X-Gm-Message-State: ACrzQf3V8UM+eK+ELm8qFs2VZ7dENVEeURGNFN8gU8l4IjDuR9X319BY z6zIy3AkPlMQAElxvT5SaXmBUg== X-Google-Smtp-Source: AMsMyM7Vi7ErqJmqrzHt1bwsO7Jfw+kVc4w4lCdxf/cK5b8KZHYV39XlOvASF4Eye8GSeC7ZJ2rbFQ== X-Received: by 2002:a17:90a:d24d:b0:213:d3e4:677a with SMTP id o13-20020a17090ad24d00b00213d3e4677amr24629292pjw.101.1667497496277; Thu, 03 Nov 2022 10:44:56 -0700 (PDT) Received: from google.com (7.104.168.34.bc.googleusercontent.com. [34.168.104.7]) by smtp.gmail.com with ESMTPSA id i7-20020a17090332c700b00178aaf6247bsm1004862plr.21.2022.11.03.10.44.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 03 Nov 2022 10:44:55 -0700 (PDT) Date: Thu, 3 Nov 2022 17:44:51 +0000 From: Sean Christopherson To: Paolo Bonzini Cc: Marc Zyngier , Huacai Chen , Aleksandar Markovic , Anup Patel , Paul Walmsley , Palmer Dabbelt , Albert Ou , Christian Borntraeger , Janosch Frank , Claudio Imbrenda , Matthew Rosato , Eric Farman , Vitaly Kuznetsov , James Morse , Alexandru Elisei , Suzuki K Poulose , Oliver Upton , Atish Patra , David Hildenbrand , kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, kvmarm@lists.cs.columbia.edu, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, Isaku Yamahata , Fabiano Rosas , Michael Ellerman , Chao Gao , Thomas Gleixner , Yuan Yao Subject: Re: [PATCH 36/44] KVM: x86: Do compatibility checks when onlining CPU Message-ID: References: <20221102231911.3107438-1-seanjc@google.com> <20221102231911.3107438-37-seanjc@google.com> <23bfd709-f99a-5a74-e4b9-1381b88453f1@redhat.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <23bfd709-f99a-5a74-e4b9-1381b88453f1@redhat.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20221103_104459_567329_34086759 X-CRM114-Status: GOOD ( 12.73 ) 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, Nov 03, 2022, Paolo Bonzini wrote: > On 11/3/22 00:19, Sean Christopherson wrote: > > From: Chao Gao > > > > Do compatibility checks when enabling hardware to effectively add > > compatibility checks when onlining a CPU. Abort enabling, i.e. the > > online process, if the (hotplugged) CPU is incompatible with the known > > good setup. > > This paragraph is not true with this patch being before "KVM: Rename and > move CPUHP_AP_KVM_STARTING to ONLINE section". Argh, good eyes. Getting the ordering correct in this series has been quite the struggle. Assuming there are no subtle dependencies between x86 and common KVM, the ordering should be something like this: KVM: Opt out of generic hardware enabling on s390 and PPC KVM: Register syscore (suspend/resume) ops early in kvm_init() KVM: x86: Do compatibility checks when onlining CPU KVM: SVM: Check for SVM support in CPU compatibility checks KVM: VMX: Shuffle support checks and hardware enabling code around KVM: x86: Do VMX/SVM support checks directly in vendor code KVM: x86: Unify pr_fmt to use module name for all KVM modules KVM: x86: Use KBUILD_MODNAME to specify vendor module name KVM: Make hardware_enable_failed a local variable in the "enable all" path KVM: Use a per-CPU variable to track which CPUs have enabled virtualization KVM: Remove on_each_cpu(hardware_disable_nolock) in kvm_exit() KVM: Drop kvm_count_lock and instead protect kvm_usage_count with kvm_lock KVM: Disable CPU hotplug during hardware enabling KVM: Rename and move CPUHP_AP_KVM_STARTING to ONLINE section KVM: Drop kvm_arch_check_processor_compat() hook _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel