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([2001:b07:6468:f312:c8dd:75d4:99ab:290a]) by smtp.gmail.com with ESMTPSA id w25sm7281095edi.22.2021.09.20.11.22.51 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 20 Sep 2021 11:22:52 -0700 (PDT) To: Marc Zyngier References: <20210828003558.713983-1-seanjc@google.com> <20210828201336.GD4353@worktop.programming.kicks-ass.net> <662e93f9-e858-689d-d203-742731ecad2c@redhat.com> <87tuifv3mb.wl-maz@kernel.org> <7a5825d1-d6e9-8ac8-5df2-cce693525da7@redhat.com> <87o88nuzzc.wl-maz@kernel.org> From: Paolo Bonzini Subject: Re: [PATCH v2 00/13] perf: KVM: Fix, optimize, and clean up callbacks Message-ID: <0eb2d4b1-23a4-c318-9f91-8dce78c6c8ad@redhat.com> Date: Mon, 20 Sep 2021 20:22:50 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: <87o88nuzzc.wl-maz@kernel.org> Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=pbonzini@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Cc: Wanpeng Li , kvm@vger.kernel.org, Peter Zijlstra , Catalin Marinas , Guo Ren , "H. Peter Anvin" , linux-riscv@lists.infradead.org, Vincent Chen , Jiri Olsa , Boris Ostrovsky , Stefano Stabellini , xen-devel@lists.xenproject.org, Will Deacon , Joerg Roedel , x86@kernel.org, linux-csky@vger.kernel.org, kvmarm@lists.cs.columbia.edu, Alexander Shishkin , Ingo Molnar , Like Xu , Albert Ou , Zhu Lingshan , Arnaldo Carvalho de Melo , Borislav Petkov , Greentime Hu , Paul Walmsley , Namhyung Kim , Thomas Gleixner , Artem Kashkanov , linux-arm-kernel@lists.infradead.org, Jim Mattson , Juergen Gross , Nick Hu , Sean Christopherson , linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, Palmer Dabbelt , Vitaly Kuznetsov 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-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu On 20/09/21 15:40, Marc Zyngier wrote: >>> At least not before we >>> declare the arm64 single kernel image policy to be obsolete. >> >> --verbose please.:) I am sure you're right, but I don't understand >> the link between the two. > > To start making KVM/arm64 modular, you'd have to build it such as > there is no support for the nVHE hypervisor anymore. Which would mean > two different configs (one that can only work with VHE, and one for > the rest) and contradicts the current single kernel image policy. Ah okay, I interpreted the policy as "it's possible to build a single kernel image but it would be possible to build an image for a subset of the features as well". In that case you could have one config that can work either with or without VHE (and supports y/n) and one config that can only work with VHE (and supports y/m/n). The code to enter VHE EL2 would of course always be builtin. > It is bad enough that we have to support 3 sets of page sizes. > Doubling the validation space for the sake of being able to unload KVM > seems a dubious prospect. It's not even a configuration that matches kconfig very well, since it does have a way to build something *only as a module*, but not a way to build something only as built-in. That said, if you had the possibility to unload/reload KVM, you'll quickly become unable to live without it. :) Paolo _______________________________________________ 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 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1FC71C433EF for ; Mon, 20 Sep 2021 18:29:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 048CF60EE7 for ; Mon, 20 Sep 2021 18:29:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1352695AbhITSas (ORCPT ); Mon, 20 Sep 2021 14:30:48 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:60837 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1378306AbhITSYX (ORCPT ); Mon, 20 Sep 2021 14:24:23 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1632162176; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=vRI2avQuBNPO4mZTVFj4yY0DXqukEShEdAk6taZEnJk=; b=cV+rEkxVVpi8hgrpFdw8Oj9BL4m66kM4kVd3EyEFhjQLUr5rb3Se5XI9amNgg5bZPN8AS6 GW5HMHgVscLcHGQERaRfgeuELNomHJxNu4lXg/s2P6om1IgbiZLDJ1/wtAussDC3xFrSST BxwWvG2BpeXuEYebkdWe/9JMTYiKnUg= Received: from mail-ed1-f71.google.com (mail-ed1-f71.google.com [209.85.208.71]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-218-4QYV6KclNCyjusWfoXOolA-1; Mon, 20 Sep 2021 14:22:55 -0400 X-MC-Unique: 4QYV6KclNCyjusWfoXOolA-1 Received: by mail-ed1-f71.google.com with SMTP id l29-20020a50d6dd000000b003d80214566cso12106449edj.21 for ; Mon, 20 Sep 2021 11:22:55 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:to:cc:references:from:subject:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=vRI2avQuBNPO4mZTVFj4yY0DXqukEShEdAk6taZEnJk=; b=CTUMXQ79LprDQilKlvrsLbiyBpomtCJDlbFLb5ezeW5BDHYFEHCf6RRwUtY+D++lV4 1A6LtcViQnRK3q8BKJcm1Qiwzu4d5qTFBX9N+0SnLCqtOfr4zkqpQU+V8fZ93h7wYMb2 tsouv+4EGgcbTaRJcN19vc6IOi9v++u25mjAs9cq9ftrse6k4NA9BtR+kLh0v9nTNJch r+aOY4YrymnXHTYZ8Bjp9/h94jM0nsEhQ9qUQM/UQ/l8XCPnE225M9D8AQ5LECRlf+81 NTJtXTQkitu7DLAweHiYcfRNarP7zI2edEOtJy++5xJ7xqjBRkFaYKjUfWg06ISzDlCf +aog== X-Gm-Message-State: AOAM532WlM8/xon0OLYvg4L1H0UCMfsj8oax0o1cqjJAJ2St3R2O9vEd rUVbyeMlQCP1/NlXXIFuyHCjvq6M4iNmnMvLd9pJ6gUN+rjanesATfEIpTgGJmeTpEFYGWhVKk2 HdkQ1ldNCoMWs5Rgpam2Aq03s X-Received: by 2002:a17:907:76b2:: with SMTP id jw18mr31101768ejc.120.1632162173781; Mon, 20 Sep 2021 11:22:53 -0700 (PDT) X-Google-Smtp-Source: ABdhPJzSoRFsPRM/7K22YQ1jPmATj4IuvLfgFOqCYFtPnEIPU80lrUpqlQ2FpuvfaQh3tH7XvhJmFg== X-Received: by 2002:a17:907:76b2:: with SMTP id jw18mr31101728ejc.120.1632162173428; Mon, 20 Sep 2021 11:22:53 -0700 (PDT) Received: from ?IPv6:2001:b07:6468:f312:c8dd:75d4:99ab:290a? ([2001:b07:6468:f312:c8dd:75d4:99ab:290a]) by smtp.gmail.com with ESMTPSA id w25sm7281095edi.22.2021.09.20.11.22.51 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 20 Sep 2021 11:22:52 -0700 (PDT) To: Marc Zyngier Cc: Peter Zijlstra , Sean Christopherson , Ingo Molnar , Arnaldo Carvalho de Melo , Will Deacon , Mark Rutland , Catalin Marinas , Guo Ren , Nick Hu , Greentime Hu , Vincent Chen , Paul Walmsley , Palmer Dabbelt , Albert Ou , Thomas Gleixner , Borislav Petkov , x86@kernel.org, Boris Ostrovsky , Juergen Gross , Alexander Shishkin , Jiri Olsa , Namhyung Kim , James Morse , Alexandru Elisei , Suzuki K Poulose , "H. Peter Anvin" , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Stefano Stabellini , linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, linux-csky@vger.kernel.org, linux-riscv@lists.infradead.org, kvm@vger.kernel.org, xen-devel@lists.xenproject.org, Artem Kashkanov , Like Xu , Zhu Lingshan References: <20210828003558.713983-1-seanjc@google.com> <20210828201336.GD4353@worktop.programming.kicks-ass.net> <662e93f9-e858-689d-d203-742731ecad2c@redhat.com> <87tuifv3mb.wl-maz@kernel.org> <7a5825d1-d6e9-8ac8-5df2-cce693525da7@redhat.com> <87o88nuzzc.wl-maz@kernel.org> From: Paolo Bonzini Subject: Re: [PATCH v2 00/13] perf: KVM: Fix, optimize, and clean up callbacks Message-ID: <0eb2d4b1-23a4-c318-9f91-8dce78c6c8ad@redhat.com> Date: Mon, 20 Sep 2021 20:22:50 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: <87o88nuzzc.wl-maz@kernel.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 20/09/21 15:40, Marc Zyngier wrote: >>> At least not before we >>> declare the arm64 single kernel image policy to be obsolete. >> >> --verbose please.:) I am sure you're right, but I don't understand >> the link between the two. > > To start making KVM/arm64 modular, you'd have to build it such as > there is no support for the nVHE hypervisor anymore. Which would mean > two different configs (one that can only work with VHE, and one for > the rest) and contradicts the current single kernel image policy. Ah okay, I interpreted the policy as "it's possible to build a single kernel image but it would be possible to build an image for a subset of the features as well". In that case you could have one config that can work either with or without VHE (and supports y/n) and one config that can only work with VHE (and supports y/m/n). The code to enter VHE EL2 would of course always be builtin. > It is bad enough that we have to support 3 sets of page sizes. > Doubling the validation space for the sake of being able to unload KVM > seems a dubious prospect. It's not even a configuration that matches kconfig very well, since it does have a way to build something *only as a module*, but not a way to build something only as built-in. That said, if you had the possibility to unload/reload KVM, you'll quickly become unable to live without it. :) Paolo 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 X-Spam-Level: X-Spam-Status: No, score=-6.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B995DC43219 for ; Mon, 20 Sep 2021 18:23:37 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id 6D07861BC0 for ; Mon, 20 Sep 2021 18:23:37 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 6D07861BC0 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:Content-Type: Content-Transfer-Encoding:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date:Message-ID:Subject: From:References:Cc:To:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=Y1iBfgXQ8RkvGaEMUb1bi+2p+H1+mz1CmMrA4xCNS7w=; b=PlKE9yKYELHDUAdhOalHIpeAfC 4h21TqTCZIARv8aBbK5S3Q+CSeDuIQ5Qc2n58d+jQO+7At+ql+2ZDwKZFZKjbUTzpJrPv8HcoY4dg 1HzZ5X2Qp77d9C1hSdQ+ZFc7xEJoE6K9NdINsOuIcurq24LhPRqBq8ZfIKW4m9TE7+mQi7jS3s54H F05evhmRoMzQPl7rUFZamtgV3wY3iGlmyO9d/e1XNOIHXLf56lCFuqrOM7KQQYU1Px6HA+gBnwWtE d+8nnG00j5BFINswd+zBg5qpPYelP/ITFgguGRiTLIhcq2HfdD96ezopPw1xjXSYn0iNJ76TObgAq vCVl/vqg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1mSNwj-002lfj-2C; Mon, 20 Sep 2021 18:23:17 +0000 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1mSNwR-002le5-84 for linux-riscv@lists.infradead.org; Mon, 20 Sep 2021 18:23:01 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1632162178; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=vRI2avQuBNPO4mZTVFj4yY0DXqukEShEdAk6taZEnJk=; b=QKfpsv+CskZC0k7tcN6emdKmlWaqNvhAps6iyIIecmKzfcpg87kOInNT/MuJW4iMnp1mog ZV1e3RDIP7Ms7bL772mu9T98YBXqg9K3esf0A6qLf5p0LrV26qEPN28MQAOw3xQHVLdvMi 0nluoyfz6ZDgyNETtaeHurCC1JLp+1U= Received: from mail-ed1-f70.google.com (mail-ed1-f70.google.com [209.85.208.70]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-539-AAsJnjAlMdyUcxhAvedtPA-1; Mon, 20 Sep 2021 14:22:55 -0400 X-MC-Unique: AAsJnjAlMdyUcxhAvedtPA-1 Received: by mail-ed1-f70.google.com with SMTP id r23-20020a50d697000000b003d824845066so8061155edi.8 for ; Mon, 20 Sep 2021 11:22:55 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:to:cc:references:from:subject:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=vRI2avQuBNPO4mZTVFj4yY0DXqukEShEdAk6taZEnJk=; b=VZc5o9rKvq5KMcBqsnwHl6WaqvXAX5BU8+XeS99PyOCvaMfyAiVi6oWZ8bGnbCcCGY W4juZ3uQxIMEfW9L004VAr7m9aLzVEbvc/4GIID61QxzzZz3K11aJc6pcWwjr072KZiA Rw2rvcqzOjLjY9YpteMBJtLPgm2DywvTiE72ZkOWZ0CbXOH+/MsxyGKDfnjSbH/nnBl5 KclZg6dulTNN8wPikHLGzn9H3M/eiuAMe1YXEL/O/kzMOqNQ9O/aERWjwcuqZSazPRX6 cAVxGZq8WlhCdNGvqoy5iJ/qzOCV5ya9c8yezVIdK5Hj+cPRy0XtIUjtyPSMkCvtUkWW q9dQ== X-Gm-Message-State: AOAM533E2RIF9qIsOP0uDG3lk6TZ4JyIsoUo5GBN3v1rcbqLaBB4XbUp KW2wwKNawm8Qt6wpW/vWzpqP+IkVqYHTF1llHvknFFrVOcvbsDEyEaTnUltpKuPZvMsAM1TOOs1 sUsNWFDGIzZI0aSEbT7IlaTQFpyaW X-Received: by 2002:a17:907:76b2:: with SMTP id jw18mr31101776ejc.120.1632162173782; Mon, 20 Sep 2021 11:22:53 -0700 (PDT) X-Google-Smtp-Source: ABdhPJzSoRFsPRM/7K22YQ1jPmATj4IuvLfgFOqCYFtPnEIPU80lrUpqlQ2FpuvfaQh3tH7XvhJmFg== X-Received: by 2002:a17:907:76b2:: with SMTP id jw18mr31101728ejc.120.1632162173428; Mon, 20 Sep 2021 11:22:53 -0700 (PDT) Received: from ?IPv6:2001:b07:6468:f312:c8dd:75d4:99ab:290a? ([2001:b07:6468:f312:c8dd:75d4:99ab:290a]) by smtp.gmail.com with ESMTPSA id w25sm7281095edi.22.2021.09.20.11.22.51 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 20 Sep 2021 11:22:52 -0700 (PDT) To: Marc Zyngier Cc: Peter Zijlstra , Sean Christopherson , Ingo Molnar , Arnaldo Carvalho de Melo , Will Deacon , Mark Rutland , Catalin Marinas , Guo Ren , Nick Hu , Greentime Hu , Vincent Chen , Paul Walmsley , Palmer Dabbelt , Albert Ou , Thomas Gleixner , Borislav Petkov , x86@kernel.org, Boris Ostrovsky , Juergen Gross , Alexander Shishkin , Jiri Olsa , Namhyung Kim , James Morse , Alexandru Elisei , Suzuki K Poulose , "H. Peter Anvin" , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Stefano Stabellini , linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, linux-csky@vger.kernel.org, linux-riscv@lists.infradead.org, kvm@vger.kernel.org, xen-devel@lists.xenproject.org, Artem Kashkanov , Like Xu , Zhu Lingshan References: <20210828003558.713983-1-seanjc@google.com> <20210828201336.GD4353@worktop.programming.kicks-ass.net> <662e93f9-e858-689d-d203-742731ecad2c@redhat.com> <87tuifv3mb.wl-maz@kernel.org> <7a5825d1-d6e9-8ac8-5df2-cce693525da7@redhat.com> <87o88nuzzc.wl-maz@kernel.org> From: Paolo Bonzini Subject: Re: [PATCH v2 00/13] perf: KVM: Fix, optimize, and clean up callbacks Message-ID: <0eb2d4b1-23a4-c318-9f91-8dce78c6c8ad@redhat.com> Date: Mon, 20 Sep 2021 20:22:50 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: <87o88nuzzc.wl-maz@kernel.org> Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=pbonzini@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210920_112259_401611_2A008D88 X-CRM114-Status: GOOD ( 20.94 ) 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-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org On 20/09/21 15:40, Marc Zyngier wrote: >>> At least not before we >>> declare the arm64 single kernel image policy to be obsolete. >> >> --verbose please.:) I am sure you're right, but I don't understand >> the link between the two. > > To start making KVM/arm64 modular, you'd have to build it such as > there is no support for the nVHE hypervisor anymore. Which would mean > two different configs (one that can only work with VHE, and one for > the rest) and contradicts the current single kernel image policy. Ah okay, I interpreted the policy as "it's possible to build a single kernel image but it would be possible to build an image for a subset of the features as well". In that case you could have one config that can work either with or without VHE (and supports y/n) and one config that can only work with VHE (and supports y/m/n). The code to enter VHE EL2 would of course always be builtin. > It is bad enough that we have to support 3 sets of page sizes. > Doubling the validation space for the sake of being able to unload KVM > seems a dubious prospect. It's not even a configuration that matches kconfig very well, since it does have a way to build something *only as a module*, but not a way to build something only as built-in. That said, if you had the possibility to unload/reload KVM, you'll quickly become unable to live without it. :) Paolo _______________________________________________ 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 X-Spam-Level: X-Spam-Status: No, score=-6.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 66BFDC433F5 for ; Mon, 20 Sep 2021 18:24:47 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id 2B1AA61A8C for ; Mon, 20 Sep 2021 18:24:47 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 2B1AA61A8C Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:Content-Type: Content-Transfer-Encoding:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date:Message-ID:Subject: From:References:Cc:To:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=hDEdd3Dcrl3AuwaZpeMTTJSQLBd/UDhQaatEOBes7/c=; b=WFbq8oMPlDpsbG+87ktLNgMTnf mNnSMddf6TIjOftjc6Oo4H7Hdg0ZwS+wZzUUtWaP2y1hTE23ZMJn2RMzC7BTkPmSNP9HSNH4JMcu0 746TdYtg/TktOE7/ucrfpjIhgt7BahGIRO/kIHg0zYVS8uiap2cxKrXFUmP7V+9jyCttK0Ihp3gG5 711Hxt3PWJb/5taC7qCIhBWL5GAJGKOn+zPW5YpQG13MM/Yx71PfqX61SsjoScV/WymqUbzof8CJo nRQH4BTNqm2JkGS9infLaYGi9d0p7eB/9ekzcO8XAybYjgl5MxB2Y7ni2EXuwGfo0MwegLAj9iU3y CkCibBJQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1mSNwY-002lf3-Ux; Mon, 20 Sep 2021 18:23:07 +0000 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1mSNwQ-002ldJ-4K for linux-arm-kernel@lists.infradead.org; Mon, 20 Sep 2021 18:22:59 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1632162176; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=vRI2avQuBNPO4mZTVFj4yY0DXqukEShEdAk6taZEnJk=; b=cV+rEkxVVpi8hgrpFdw8Oj9BL4m66kM4kVd3EyEFhjQLUr5rb3Se5XI9amNgg5bZPN8AS6 GW5HMHgVscLcHGQERaRfgeuELNomHJxNu4lXg/s2P6om1IgbiZLDJ1/wtAussDC3xFrSST BxwWvG2BpeXuEYebkdWe/9JMTYiKnUg= Received: from mail-ed1-f72.google.com (mail-ed1-f72.google.com [209.85.208.72]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-539-Xxy89-I0MDibpuTYjNYaww-1; Mon, 20 Sep 2021 14:22:55 -0400 X-MC-Unique: Xxy89-I0MDibpuTYjNYaww-1 Received: by mail-ed1-f72.google.com with SMTP id s12-20020a05640217cc00b003cde58450f1so16556972edy.9 for ; Mon, 20 Sep 2021 11:22:55 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:to:cc:references:from:subject:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=vRI2avQuBNPO4mZTVFj4yY0DXqukEShEdAk6taZEnJk=; b=R6lxgUSfWSMb3sb09g5VDrC9xn0UC/Xv/atdThyGeSGxyocUZu5Z+jybXCgiQMOZwk /QoaxeYHcZzlG7Fk3+zlc0UoLJRSUCkI9aQVIqhQHeEuMpgeNXS13ZZvObOmVIWX6URD hNTx5ue/i5i69jBcDGU0UjU213yIZegircBpXIfMvl5kkOdSURVTWs1h5kF56Kfxboj/ H0C8AZKUlB4wIMjAwFzXxOGHDOKUO6+XaiwmSqWmdn7ByRl2m2iRZUF+c88j9HNlbbGm BkfTnu0t78kKqiUv5lqKxYhW4mF/vtdgUduJDkuu35I5ZDlKids6y+ixj4AEp3NaalWi /Oyg== X-Gm-Message-State: AOAM532h5ZMnDz1k7BkYfS/6qZQmmxPNOTYTPS973CtTDrEwZWZKr4Sv 7+o7LlncRZSqYoK1+GkevWsFph7f6kdyFwP0tMTWVjqPCeNeMROXIp2GBvUSBKBctKAJWHLrHno U1j0Leb3/ZXtnwYxtRzTZxNaXTsBDxXBc3m4= X-Received: by 2002:a17:907:76b2:: with SMTP id jw18mr31101800ejc.120.1632162173790; Mon, 20 Sep 2021 11:22:53 -0700 (PDT) X-Google-Smtp-Source: ABdhPJzSoRFsPRM/7K22YQ1jPmATj4IuvLfgFOqCYFtPnEIPU80lrUpqlQ2FpuvfaQh3tH7XvhJmFg== X-Received: by 2002:a17:907:76b2:: with SMTP id jw18mr31101728ejc.120.1632162173428; Mon, 20 Sep 2021 11:22:53 -0700 (PDT) Received: from ?IPv6:2001:b07:6468:f312:c8dd:75d4:99ab:290a? ([2001:b07:6468:f312:c8dd:75d4:99ab:290a]) by smtp.gmail.com with ESMTPSA id w25sm7281095edi.22.2021.09.20.11.22.51 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 20 Sep 2021 11:22:52 -0700 (PDT) To: Marc Zyngier Cc: Peter Zijlstra , Sean Christopherson , Ingo Molnar , Arnaldo Carvalho de Melo , Will Deacon , Mark Rutland , Catalin Marinas , Guo Ren , Nick Hu , Greentime Hu , Vincent Chen , Paul Walmsley , Palmer Dabbelt , Albert Ou , Thomas Gleixner , Borislav Petkov , x86@kernel.org, Boris Ostrovsky , Juergen Gross , Alexander Shishkin , Jiri Olsa , Namhyung Kim , James Morse , Alexandru Elisei , Suzuki K Poulose , "H. Peter Anvin" , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Stefano Stabellini , linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, linux-csky@vger.kernel.org, linux-riscv@lists.infradead.org, kvm@vger.kernel.org, xen-devel@lists.xenproject.org, Artem Kashkanov , Like Xu , Zhu Lingshan References: <20210828003558.713983-1-seanjc@google.com> <20210828201336.GD4353@worktop.programming.kicks-ass.net> <662e93f9-e858-689d-d203-742731ecad2c@redhat.com> <87tuifv3mb.wl-maz@kernel.org> <7a5825d1-d6e9-8ac8-5df2-cce693525da7@redhat.com> <87o88nuzzc.wl-maz@kernel.org> From: Paolo Bonzini Subject: Re: [PATCH v2 00/13] perf: KVM: Fix, optimize, and clean up callbacks Message-ID: <0eb2d4b1-23a4-c318-9f91-8dce78c6c8ad@redhat.com> Date: Mon, 20 Sep 2021 20:22:50 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: <87o88nuzzc.wl-maz@kernel.org> Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=pbonzini@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210920_112258_298135_9CBEF6C2 X-CRM114-Status: GOOD ( 22.56 ) 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-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 20/09/21 15:40, Marc Zyngier wrote: >>> At least not before we >>> declare the arm64 single kernel image policy to be obsolete. >> >> --verbose please.:) I am sure you're right, but I don't understand >> the link between the two. > > To start making KVM/arm64 modular, you'd have to build it such as > there is no support for the nVHE hypervisor anymore. Which would mean > two different configs (one that can only work with VHE, and one for > the rest) and contradicts the current single kernel image policy. Ah okay, I interpreted the policy as "it's possible to build a single kernel image but it would be possible to build an image for a subset of the features as well". In that case you could have one config that can work either with or without VHE (and supports y/n) and one config that can only work with VHE (and supports y/m/n). The code to enter VHE EL2 would of course always be builtin. > It is bad enough that we have to support 3 sets of page sizes. > Doubling the validation space for the sake of being able to unload KVM > seems a dubious prospect. It's not even a configuration that matches kconfig very well, since it does have a way to build something *only as a module*, but not a way to build something only as built-in. That said, if you had the possibility to unload/reload KVM, you'll quickly become unable to live without it. :) Paolo _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel