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 93D3CC43217 for ; Sun, 6 Nov 2022 12:49:52 +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=QKUiQqsMNwz8KNn73uN7I8lMrATxXSBiK8SzUrGQbKc=; b=Dw7FTMQt7DFl0U sr6xTxa5ySg8HCYl5AoArQFi54DIeKSIKPX0RqhcWH3MKqslhoKgMUXcE4uBSc7oblTjmgrKiQKNO Mx44BwerJ2/DXopdL7dCp6MPUyRnTA6OgAKBua51+rfCxLWexE6i4+sNobnR31doEiMjbevXf9icc JZ2JLP+QJeJgLv8qublBFOXKNwsemXJCLMC2UIFm/ffxddOEbu3ZY6tjLtYJjfSj63ma9aURKydHo FXiFThpT1yk6Qy5Jgdos3Lb4Ua/UcT0V0ZiWxzk5TjVmPSSNEfDrE1TR0zx4xzZIlIYAhsuQYzuO2 CkT+E6G9OzP+6GZ6WwSA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1orf4d-008Ejh-B5; Sun, 06 Nov 2022 12:48:27 +0000 Received: from dfw.source.kernel.org ([2604:1380:4641:c500::1]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1orf4a-008Eif-UK for linux-arm-kernel@lists.infradead.org; Sun, 06 Nov 2022 12:48:26 +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 dfw.source.kernel.org (Postfix) with ESMTPS id 5CDD760C55; Sun, 6 Nov 2022 12:48:24 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C4003C433C1; Sun, 6 Nov 2022 12:48:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1667738903; bh=lPkPvrrBnX0tum9Cs3g5MY8Kww2Y8rLfZv7Bw6QwLPo=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=udADkqfFCiPrepd+awS0kdEUSpM4CSqvKYWb4KpnEjs0g7posfsFPHGk/F9jsOHFB OqjBk7SxbzdbZ62rG+SlefchxqEmpvELaOL6wVJbRrU9vNX1WuJh6HWuZjXWSEoHfA 6MprE1Q+rA+Y0VyUdoaESSebGwvvvKuGPnDYS3edysTb4pqd4ItIKInmvc7axnpt0A D56kId2qZgbyru0Fj5j99yPAh1abjuiVn1r1pJus8b/n6C3aZcCr4ny+kwsTXIyzX9 VRtA/llZrAVwBYAiUBEgJbVYC6uFtYgE0VxMa38CutaDvd+lAui2bB1Jflcw/TVIX8 Ds8sfYS6qEd8g== Received: from sofa.misterjones.org ([185.219.108.64] helo=wait-a-minute.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 1orf4X-004CH5-FR; Sun, 06 Nov 2022 12:48:21 +0000 Date: Sun, 06 Nov 2022 12:47:54 +0000 Message-ID: <87pme0fdvp.wl-maz@kernel.org> From: Marc Zyngier To: Reiji Watanabe Cc: linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvmarm@lists.linux.dev, kvm@vger.kernel.org, James Morse , Suzuki K Poulose , Alexandru Elisei , Oliver Upton , Ricardo Koller Subject: Re: [PATCH v2 11/14] KVM: arm64: PMU: Allow ID_AA64DFR0_EL1.PMUver to be set from userspace In-Reply-To: References: <20221028105402.2030192-1-maz@kernel.org> <20221028105402.2030192-12-maz@kernel.org> <87tu3gfi8u.wl-maz@kernel.org> <86bkpmrjv8.wl-maz@kernel.org> 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: reijiw@google.com, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvmarm@lists.linux.dev, kvm@vger.kernel.org, james.morse@arm.com, suzuki.poulose@arm.com, alexandru.elisei@arm.com, oliver.upton@linux.dev, ricarkol@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-20221106_044825_036403_0A62587A X-CRM114-Status: GOOD ( 17.28 ) 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 Hi Reiji, On Fri, 04 Nov 2022 15:53:21 +0000, Reiji Watanabe wrote: > > BTW, if we have no intention of supporting a mix of vCPUs with and > without PMU, I think it would be nice if we have a clear comment on > that in the code. Or I'm hoping to disallow it if possible though. I'm not sure we're in a position to do this right now. The current API has always (for good or bad reasons) been per-vcpu as it is tied to the vcpu initialisation. However, once we move to a sysreg-based API to control the vcpu features, we can revisit this and say that some features have a VM-wide effect if the vcpus have been created with some special flag (or some other TBD mechanism). 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