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 25AACC46467 for ; Tue, 3 Jan 2023 14:25:59 +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:MIME-Version:References:In-Reply-To: Subject:Cc:To:From:Message-ID:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=7Or+ZboKo2msJ1d5yhcH9Xr8RZFLXoe/iRzuvoDXu4A=; b=AGJnMKKR6sMRt/ 3cuEL5LQ144MCrILlWtS3XQ8UZU6fIO1Tplp3MJ2nl8mU2gerAMPztw3mNGiwEAMkkmJzZgGMDmUR mThwUnjS7nz+jCMsTBtz+mblx0O6gWun7IrmqCFhv4IRmcJ7vXX9f3Qao+jA6NX+C57SP1kzWQVpu fxfJgRRuYKEX/ibQ7NG9T8AqKTpNV5dAn9cFChClEGAixRHXFWVIOQFefrRNoYdhHaU7CB/wqco80 Xn9UYC14BaPolIwq+iEa3y8cqJ8UNNyXfebj8YyZSoYJe1wOPUSzVE/o84sMfFIfJ8tPA8dBh7DEo cj5TywUsVeNi98jITwnA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1pCiDD-001w9J-BN; Tue, 03 Jan 2023 14:24:20 +0000 Received: from ams.source.kernel.org ([145.40.68.75]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1pCghQ-001L8s-4E for linux-arm-kernel@lists.infradead.org; Tue, 03 Jan 2023 12:47:25 +0000 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id C27C7B80E50; Tue, 3 Jan 2023 12:47:22 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8AF2DC433EF; Tue, 3 Jan 2023 12:47:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1672750041; bh=fmL8KjCcvKRY2xHo4keozvHeaPX7SCsSBhRNSxlj99U=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=M0G1INN85CDvLDcTCnOedHctGvxW1od+1e0XGvX9RwTKH4oagjlWh0ZHc+B5J6Mnr bxV8YCFXhzzEj+XKdxj0LHNIsQ6bktT0Ch1ybgKkd+5HR0C8J8rSzFK0F4p+ANKop2 WIfheMQFG1O2oNCdRANO66mwoHoBDtchkV3ria5qRJwAPXoTdpKPe1wrhxLylcb9sE teUJaPSaJiTSrKDtWw++g/Cikbpq9nGuz3NJjUfH+ItoEkiQFOI4LjI0WAFzZeoBJy bFmMDgBDjeLX4rEx9mT17SuIGqVxoeVDWnue8QAzZ7y5qbWorLywMqSmYEl38D6q0x 0xP/kS2KaYUFA== Received: from sofa.misterjones.org ([185.219.108.64] helo=goblin-girl.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.95) (envelope-from ) id 1pCghL-00GVWW-7K; Tue, 03 Jan 2023 12:47:19 +0000 Date: Tue, 03 Jan 2023 12:47:18 +0000 Message-ID: <86y1qj7pk9.wl-maz@kernel.org> From: Marc Zyngier To: Jonathan Cameron Cc: Reiji Watanabe , , , , , James Morse , Alexandru Elisei , Suzuki K Poulose , Paolo Bonzini , "Ricardo\ Koller" , Oliver Upton , "Jing\ Zhang" , Raghavendra Rao Anata Subject: Re: [PATCH 0/7] KVM: arm64: PMU: Allow userspace to limit the number of PMCs on vCPU In-Reply-To: <20230103124034.000027aa@Huawei.com> References: <20221230035928.3423990-1-reijiw@google.com> <20230103124034.000027aa@Huawei.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/28.2 (aarch64-unknown-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: Jonathan.Cameron@Huawei.com, reijiw@google.com, kvmarm@lists.cs.columbia.edu, kvmarm@lists.linux.dev, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, james.morse@arm.com, alexandru.elisei@arm.com, suzuki.poulose@arm.com, pbonzini@redhat.com, ricarkol@google.com, oliver.upton@linux.dev, jingzhangos@google.com, rananta@google.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230103_044724_365836_F8F3BFC6 X-CRM114-Status: GOOD ( 20.42 ) 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 Tue, 03 Jan 2023 12:40:34 +0000, Jonathan Cameron wrote: > > On Thu, 29 Dec 2022 19:59:21 -0800 > Reiji Watanabe wrote: > > > The goal of this series is to allow userspace to limit the number > > of PMU event counters on the vCPU. > > Hi Rieji, > > Why do you want to do this? > > I can conjecture a bunch of possible reasons, but they may not > match up with your use case. It would be useful to have that information > in the cover letter. The most obvious use case is to support migration across systems that implement different numbers of counters. Similar reasoning could also apply to the debug infrastructure (watchpoints, breakpoints). In any case, being able to decouple the VM from the underlying HW within the extent that the architecture permits it seems like a valuable goal. Thanks, M. -- Without deviation from the norm, progress is not possible. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel