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=-4.0 required=3.0 tests=BAYES_00,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 66B6AC433F5 for ; Mon, 20 Sep 2021 13:40:47 +0000 (UTC) Received: from mm01.cs.columbia.edu (mm01.cs.columbia.edu [128.59.11.253]) by mail.kernel.org (Postfix) with ESMTP id DACB26108E for ; Mon, 20 Sep 2021 13:40:46 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org DACB26108E Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=lists.cs.columbia.edu Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 6BAA3406E7; Mon, 20 Sep 2021 09:40:46 -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 ptlem9EHfWrq; Mon, 20 Sep 2021 09:40:45 -0400 (EDT) Received: from mm01.cs.columbia.edu (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 5AEE34A534; Mon, 20 Sep 2021 09:40:45 -0400 (EDT) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 82DE64079D for ; Mon, 20 Sep 2021 09:40:44 -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 7fnlpuf1uJ2B for ; Mon, 20 Sep 2021 09:40:43 -0400 (EDT) Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by mm01.cs.columbia.edu (Postfix) with ESMTPS id 596D9406E7 for ; Mon, 20 Sep 2021 09:40:43 -0400 (EDT) Received: from disco-boy.misterjones.org (disco-boy.misterjones.org [51.254.78.96]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 32B9260F21; Mon, 20 Sep 2021 13:40:42 +0000 (UTC) Received: from sofa.misterjones.org ([185.219.108.64] helo=why.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1mSJXE-00Bm01-5z; Mon, 20 Sep 2021 14:40:40 +0100 Date: Mon, 20 Sep 2021 14:40:39 +0100 Message-ID: <87o88nuzzc.wl-maz@kernel.org> From: Marc Zyngier To: Paolo Bonzini Subject: Re: [PATCH v2 00/13] perf: KVM: Fix, optimize, and clean up callbacks In-Reply-To: <7a5825d1-d6e9-8ac8-5df2-cce693525da7@redhat.com> 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> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/27.1 (x86_64-pc-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: pbonzini@redhat.com, peterz@infradead.org, seanjc@google.com, mingo@redhat.com, acme@kernel.org, will@kernel.org, mark.rutland@arm.com, catalin.marinas@arm.com, guoren@kernel.org, nickhu@andestech.com, green.hu@gmail.com, deanbo422@gmail.com, paul.walmsley@sifive.com, palmer@dabbelt.com, aou@eecs.berkeley.edu, tglx@linutronix.de, bp@alien8.de, x86@kernel.org, boris.ostrovsky@oracle.com, jgross@suse.com, alexander.shishkin@linux.intel.com, jolsa@redhat.com, namhyung@kernel.org, james.morse@arm.com, alexandru.elisei@arm.com, suzuki.poulose@arm.com, hpa@zytor.com, vkuznets@redhat.com, wanpengli@tencent.com, jmattson@google.com, joro@8bytes.org, sstabellini@kernel.org, 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@intel.com, like.xu.linux@gmail.com, lingsha n.zhu@intel.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false 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-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 Mon, 20 Sep 2021 14:18:30 +0100, Paolo Bonzini wrote: > > On 20/09/21 14:22, Marc Zyngier wrote: > >> I think that's only ARM, and even then it is only because of > >> limitations of the hardware which mostly apply only if VHE is not in > >> use. > >> > >> If anything, it's ARM that should support module build in VHE mode > >> (Linux would still need to know whether it will be running at EL1 or > >> EL2, but KVM's functionality is as self-contained as on x86 in the VHE > >> case). > > I don't see this happening anytime soon. 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. 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. M. -- Without deviation from the norm, progress is not possible. _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm