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=-4.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT 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 4A33FC2BA83 for ; Fri, 14 Feb 2020 18:36:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1718024654 for ; Fri, 14 Feb 2020 18:36:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1581705392; bh=T+ilQI9wpmnmJVmL5LiaSl2V8wIK4X9cI78O+ANnNOE=; h=From:To:Cc:Subject:Date:List-ID:From; b=odgWRLYle70my7LJeMa5nZ/L48ZYoyX+dcrzZ1WMwmuEpDngyuP4YBFmfLTu/y/Zd EGowMCAagOcBdY5CP0U0e+ZINkwbif8V0v83Mkak9J9Ysdt++8JKtKX3M4DJef3rzU 86hhZ7OMxXYRSXvSWr7xFBWZEIGMzyuweuKcPm6M= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729760AbgBNSgb (ORCPT ); Fri, 14 Feb 2020 13:36:31 -0500 Received: from mail.kernel.org ([198.145.29.99]:37376 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728239AbgBNSga (ORCPT ); Fri, 14 Feb 2020 13:36:30 -0500 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 BEBCD20848; Fri, 14 Feb 2020 18:36:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1581705389; bh=T+ilQI9wpmnmJVmL5LiaSl2V8wIK4X9cI78O+ANnNOE=; h=From:To:Cc:Subject:Date:From; b=IlBTVTsHr/G7gWRjLL220TV6NPEbmZBkt9QuKo/4Rpgju5AedYJhyRse2UusxxeJZ zzQOay2oAzn6jKo984xRFeUNONIWdX8k3ofL0/Ht5Z6qAuuwpqXhUf2Vr9Bvb8Mum0 iOe4t7QGTnK4VAYcCWHOKefn2AH6GdhFEEE6YaWo= Received: from 78.163-31-62.static.virginmediabusiness.co.uk ([62.31.163.78] helo=why.lan) by disco-boy.misterjones.org with esmtpsa (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1j2fpE-005J5c-2m; Fri, 14 Feb 2020 18:36:28 +0000 From: Marc Zyngier To: linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org Cc: James Morse , Julien Thierry , Suzuki K Poulose Subject: [PATCH 0/2] KVM: arm64: Filtering PMU events Date: Fri, 14 Feb 2020 18:36:13 +0000 Message-Id: <20200214183615.25498-1-maz@kernel.org> X-Mailer: git-send-email 2.20.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-SA-Exim-Connect-IP: 62.31.163.78 X-SA-Exim-Rcpt-To: linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, james.morse@arm.com, julien.thierry.kdev@gmail.com, suzuki.poulose@arm.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org It is at times necessary to prevent a guest from being able to sample certain events if multiple CPUs share resources such as a cache level. In this case, it would be interesting if the VMM could simply prevent certain events from being counted instead of simply not exposing a PMU. Given that most events are not architected, there is no easy way to designate which events shouldn't be counted other than specifying the raw event number. Since I have no idea whether it is better to use an event whitelist or blacklist, the proposed API takes a cue from the x86 version and allows either allowing or denying counting of ranges of events. The event space being pretty large (16bits on ARMv8.1), the default policy is set by the first filter that gets installed (default deny if we first allow, default allow if we first deny). The filter state is global to the guest, despite the PMU being per CPU. I'm not sure whether it would be worth it making it CPU-private. Anyway, I'd be interesting in comments on how people would use this. I'll try to push a patch against kvmtool that implement this shortly (what I have currently is a harcoded set of hacks). Marc Zyngier (2): KVM: arm64: Add PMU event filtering infrastructure KVM: arm64: Document PMU filtering API Documentation/virt/kvm/devices/vcpu.txt | 28 +++++++++ arch/arm64/include/asm/kvm_host.h | 6 ++ arch/arm64/include/uapi/asm/kvm.h | 16 ++++++ virt/kvm/arm/arm.c | 2 + virt/kvm/arm/pmu.c | 76 +++++++++++++++++++++---- 5 files changed, 116 insertions(+), 12 deletions(-) -- 2.20.1