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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,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 51B8FC43603 for ; Fri, 20 Dec 2019 18:10:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 35AF820866 for ; Fri, 20 Dec 2019 18:10:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727514AbfLTSKE (ORCPT ); Fri, 20 Dec 2019 13:10:04 -0500 Received: from foss.arm.com ([217.140.110.172]:53916 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727404AbfLTSKE (ORCPT ); Fri, 20 Dec 2019 13:10:04 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id B45D61FB; Fri, 20 Dec 2019 10:10:03 -0800 (PST) Received: from lakrids.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 7A1F73F67D; Fri, 20 Dec 2019 10:10:02 -0800 (PST) Date: Fri, 20 Dec 2019 18:10:00 +0000 From: Mark Rutland To: Andrew Murray Cc: Marc Zyngier , Catalin Marinas , Will Deacon , Sudeep Holla , kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 15/18] perf: arm_spe: Handle guest/host exclusion flags Message-ID: <20191220180959.GF25258@lakrids.cambridge.arm.com> References: <20191220143025.33853-1-andrew.murray@arm.com> <20191220143025.33853-16-andrew.murray@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191220143025.33853-16-andrew.murray@arm.com> User-Agent: Mutt/1.11.1+11 (2f07cb52) (2018-12-01) Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Fri, Dec 20, 2019 at 02:30:22PM +0000, Andrew Murray wrote: > A side effect of supporting the SPE in guests is that we prevent the > host from collecting data whilst inside a guest thus creating a black-out > window. This occurs because instead of emulating the SPE, we share it > with our guests. We used to permit this; do we know if anyone is using it? Thanks, Mark. > Let's accurately describe our capabilities by using the perf exclude > flags to prevent !exclude_guest and exclude_host flags from being used. > > Signed-off-by: Andrew Murray > --- > drivers/perf/arm_spe_pmu.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/drivers/perf/arm_spe_pmu.c b/drivers/perf/arm_spe_pmu.c > index 2d24af4cfcab..3703dbf459de 100644 > --- a/drivers/perf/arm_spe_pmu.c > +++ b/drivers/perf/arm_spe_pmu.c > @@ -679,6 +679,9 @@ static int arm_spe_pmu_event_init(struct perf_event *event) > if (attr->exclude_idle) > return -EOPNOTSUPP; > > + if (!attr->exclude_guest || attr->exclude_host) > + return -EOPNOTSUPP; > + > /* > * Feedback-directed frequency throttling doesn't work when we > * have a buffer of samples. We'd need to manually count the > -- > 2.21.0 >