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 C1B37E77197 for ; Tue, 7 Jan 2025 17:50:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=/EYC0T76ByQZcJbAbKWoZkjglkyUuah6iWq4ib5v/LA=; b=tnnkQ3UO4gHb8OhMYllu/OCd9c YPno2uQvi+XMQOipTuPPGTMmPov7Fr5lzWG/6gsuun0qJ2z69aTq1WS/pLDiEarYKk1FaJw5bsGjj uCa7XentzSyYiqeb4EsIG+HzsT3CYXo18dmPwaR9ce4+7yDDG1aTt639o7sQRBdcpxIl3W8gjK//s jxIXsmyAsa1yStjJSU/KxYurN8NrEVI63xTGxLHsqmukhurl/ahk9YXm7924Udvr5GttkwUq1b2Cs DPE5QBS2HfYNu0v76OLXi7meRxBz+HZ64xkNHmoBjuCajafjvCsp75h2/rhfYOMHolabRCq+wB1Oy +OGy+90g==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1tVDiB-00000005ujq-3W5T; Tue, 07 Jan 2025 17:49:51 +0000 Received: from nyc.source.kernel.org ([147.75.193.91]) by bombadil.infradead.org with esmtps (Exim 4.98 #2 (Red Hat Linux)) id 1tVDYd-00000005tOK-0GV0 for linux-arm-kernel@lists.infradead.org; Tue, 07 Jan 2025 17:40:00 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by nyc.source.kernel.org (Postfix) with ESMTP id 63F7FA41B1F; Tue, 7 Jan 2025 17:38:09 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3C8E2C4CED6; Tue, 7 Jan 2025 17:39:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1736271597; bh=bC0Vjd7rRZHPln6p604z6wqdtBBsP1GgN3w/1l4oKoA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=aqyVLnXjjRsPz9sT60cqkyLe+0aJppf2xeVF2/aVlPTMNpSIhwmUZ/l2TpHI7LM9b m0IeLxWD7yTzJZmPzOPOR2jT3O3QwhxAqapmFHtVHW0QRx71zyV7TgDSXtRpTiWqIV eXAFymlyfpJe5JQ33ms2SwdjgVGfTKrlF4QgEsbLGCz1bDVH4OkBZ5ZxiCwazuIaiE QtOejTF/pF7IOJQTDk3NMh548h/uYHrRrosK7Ntd+anHvU2HON2QGBZDm5XkahhfVx FpeU36MT4cbyVKbCVCIRdzpd96w+CxYVgRGwZylpK7TFypf9JpjGtoyKhvTu42qteE GK3qykviouzAA== Date: Tue, 7 Jan 2025 17:39:51 +0000 From: Will Deacon To: James Clark Cc: linux-arm-kernel@lists.infradead.org, linux-perf-users@vger.kernel.org, irogers@google.com, yeoreum.yun@arm.com, mark.rutland@arm.com, robh@kernel.org, Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Namhyung Kim , Alexander Shishkin , Jiri Olsa , Adrian Hunter , "Liang, Kan" , John Garry , Mike Leach , Leo Yan , Graham Woodward , linux-kernel@vger.kernel.org, bpf@vger.kernel.org Subject: Re: [PATCH v2 1/5] perf: arm_spe: Add format option for discard mode Message-ID: <20250107173950.GA8111@willie-the-truck> References: <20241224104414.179365-1-james.clark@linaro.org> <20241224104414.179365-2-james.clark@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20241224104414.179365-2-james.clark@linaro.org> User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250107_093959_232419_03636509 X-CRM114-Status: GOOD ( 22.12 ) 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: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, Dec 24, 2024 at 10:44:08AM +0000, James Clark wrote: > FEAT_SPEv1p2 (optional from Armv8.6) adds a discard mode that allows all > SPE data to be discarded rather than written to memory. Add a format > bit for this mode. > > If the mode isn't supported, the format bit isn't published and attempts > to use it will result in -EOPNOTSUPP. Allocating an aux buffer is still > allowed even though it won't be written to so that old tools continue to > work, but updated tools can choose to skip this step. > > Reviewed-by: Yeoreum Yun > Signed-off-by: James Clark > --- > drivers/perf/arm_spe_pmu.c | 23 +++++++++++++++++++++++ > 1 file changed, 23 insertions(+) > > diff --git a/drivers/perf/arm_spe_pmu.c b/drivers/perf/arm_spe_pmu.c > index fd5b78732603..9aaf3f98e6f5 100644 > --- a/drivers/perf/arm_spe_pmu.c > +++ b/drivers/perf/arm_spe_pmu.c > @@ -193,6 +193,9 @@ static const struct attribute_group arm_spe_pmu_cap_group = { > #define ATTR_CFG_FLD_store_filter_CFG config /* PMSFCR_EL1.ST */ > #define ATTR_CFG_FLD_store_filter_LO 34 > #define ATTR_CFG_FLD_store_filter_HI 34 > +#define ATTR_CFG_FLD_discard_CFG config /* PMBLIMITR_EL1.FM = DISCARD */ > +#define ATTR_CFG_FLD_discard_LO 35 > +#define ATTR_CFG_FLD_discard_HI 35 > > #define ATTR_CFG_FLD_event_filter_CFG config1 /* PMSEVFR_EL1 */ > #define ATTR_CFG_FLD_event_filter_LO 0 > @@ -216,6 +219,7 @@ GEN_PMU_FORMAT_ATTR(store_filter); > GEN_PMU_FORMAT_ATTR(event_filter); > GEN_PMU_FORMAT_ATTR(inv_event_filter); > GEN_PMU_FORMAT_ATTR(min_latency); > +GEN_PMU_FORMAT_ATTR(discard); > > static struct attribute *arm_spe_pmu_formats_attr[] = { > &format_attr_ts_enable.attr, > @@ -228,9 +232,15 @@ static struct attribute *arm_spe_pmu_formats_attr[] = { > &format_attr_event_filter.attr, > &format_attr_inv_event_filter.attr, > &format_attr_min_latency.attr, > + &format_attr_discard.attr, > NULL, > }; > > +static bool discard_unsupported(struct arm_spe_pmu *spe_pmu) > +{ > + return spe_pmu->pmsver < ID_AA64DFR0_EL1_PMSVer_V1P2; > +} Why not add a new SPE_PMU_FEAT_* for this and handle it in a similar way to other optional hardware features? Will