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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3B721E95A8E for ; Mon, 9 Oct 2023 08:59:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345594AbjJII7Z (ORCPT ); Mon, 9 Oct 2023 04:59:25 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41778 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234477AbjJII7W (ORCPT ); Mon, 9 Oct 2023 04:59:22 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 1466FAB for ; Mon, 9 Oct 2023 01:59:20 -0700 (PDT) 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 4AF5B1FB; Mon, 9 Oct 2023 02:00:00 -0700 (PDT) Received: from [192.168.1.3] (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id ECB173F7A6; Mon, 9 Oct 2023 01:59:18 -0700 (PDT) Message-ID: Date: Mon, 9 Oct 2023 09:59:19 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.15.1 Subject: Re: [PATCH] driver: perf: arm_pmuv3: Read PMMIR_EL1 unconditionally To: Anshuman Khandual , linux-arm-kernel@lists.infradead.org, zhangshaokun@hisilicon.com Cc: Will Deacon , Mark Rutland , linux-kernel@vger.kernel.org References: <20231009075631.193208-1-anshuman.khandual@arm.com> Content-Language: en-US From: James Clark In-Reply-To: <20231009075631.193208-1-anshuman.khandual@arm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09/10/2023 08:56, Anshuman Khandual wrote: > PMMIR_EL1 needs to be captured in 'armpmu->reg_pmmir', for all appropriate > PMU version implementations where the register is available and reading it > is valid . Hence checking for bus slot event presence is redundant and can > be dropped. > > Cc: Will Deacon > Cc: Mark Rutland > Cc: linux-arm-kernel@lists.infradead.org > Cc: linux-kernel@vger.kernel.org > Signed-off-by: Anshuman Khandual > --- > This applies on v6.6-rc5. > > drivers/perf/arm_pmuv3.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/perf/arm_pmuv3.c b/drivers/perf/arm_pmuv3.c > index 1e72b486c033..9fc1b6da5106 100644 > --- a/drivers/perf/arm_pmuv3.c > +++ b/drivers/perf/arm_pmuv3.c > @@ -1129,7 +1129,7 @@ static void __armv8pmu_probe_pmu(void *info) > pmceid, ARMV8_PMUV3_MAX_COMMON_EVENTS); > > /* store PMMIR register for sysfs */ > - if (is_pmuv3p4(pmuver) && (pmceid_raw[1] & BIT(31))) > + if (is_pmuv3p4(pmuver)) > cpu_pmu->reg_pmmir = read_pmmir(); > else > cpu_pmu->reg_pmmir = 0; This does have the side effect of showing non-zero values in caps/slots even when the STALL_SLOT event isn't implemented. I think that's the scenario that the original commit (f5be3a61fd) was trying to avoid: /sys/bus/event_source/devices/armv8_pmuv3_0/caps/slots is exposed under sysfs. [If] Both ARMv8.4-PMU and STALL_SLOT event are implemented, it returns the slots from PMMIR_EL1, otherwise it will return 0. I can't really think of a scenario where that would be an issue, and the availability of the STALL_SLOT event is already discoverable from userspace through the events folder, so it's probably fine. Adding the original author just in case. But otherwise: Reviewed-by: James Clark