From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 5799432A3CC; Fri, 29 Aug 2025 16:39:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756485568; cv=none; b=VWJndUzrV/QjsPchPOAe63B8Ru3iJxnm1u2Vrvde/oht5aQ1ckQE0+BZxWkwVIa/YLbKlhzt7J7NTn511S9CTvsukNgPFyJojN+jmgsKq9GmC6zlxWpCMwGQbSuM812nb6C7Ckxzuk0izzMIClPU3bDL9HLFoL7W+lhVKyRvQ+w= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756485568; c=relaxed/simple; bh=LiufvYLN3N0v9a6NqAyygZVjAXotK4sKZTliv0DtNZQ=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=F/ZXgyZChVgiESJxAVweC6MAnTzeJglP1z1+LTMzHOtA0WwI+QEKBmHizJutEva3d8CceE76LCEXw/7z6CReCTs9k2Rge16+7+ckzD+nLJt0docsbhYddbw8+4PhBC5lOKheuQpzoUSrsNngL/1nrsQ+1lMnDJXHgHU84+iqE/w= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com 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 158C519F0; Fri, 29 Aug 2025 09:39:17 -0700 (PDT) Received: from [10.1.196.46] (e134344.arm.com [10.1.196.46]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 4DBEB3F694; Fri, 29 Aug 2025 09:39:20 -0700 (PDT) Message-ID: Date: Fri, 29 Aug 2025 17:39:18 +0100 Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 30/33] arm_mpam: Use long MBWU counters if supported To: James Morse , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-acpi@vger.kernel.org, devicetree@vger.kernel.org Cc: shameerali.kolothum.thodi@huawei.com, D Scott Phillips OS , carl@os.amperecomputing.com, lcherian@marvell.com, bobo.shaobowang@huawei.com, tan.shaopeng@fujitsu.com, baolin.wang@linux.alibaba.com, Jamie Iles , Xin Hao , peternewman@google.com, dfustini@baylibre.com, amitsinght@marvell.com, David Hildenbrand , Rex Nie , Dave Martin , Koba Ko , Shanker Donthineni , fenghuay@nvidia.com, baisheng.gao@unisoc.com, Jonathan Cameron , Rob Herring , Rohit Mathew , Rafael Wysocki , Len Brown , Lorenzo Pieralisi , Hanjun Guo , Sudeep Holla , Krzysztof Kozlowski , Conor Dooley , Catalin Marinas , Will Deacon , Greg Kroah-Hartman , Danilo Krummrich References: <20250822153048.2287-1-james.morse@arm.com> <20250822153048.2287-31-james.morse@arm.com> From: Ben Horgan Content-Language: en-US In-Reply-To: <20250822153048.2287-31-james.morse@arm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Hi James, On 8/22/25 16:30, James Morse wrote: > From: Rohit Mathew > > If the 44 bit (long) or 63 bit (LWD) counters are detected on probing > the RIS, use long/LWD counter instead of the regular 31 bit mbwu > counter. > > Only 32bit accesses to the MSC are required to be supported by the > spec, but these registers are 64bits. The lower half may overflow > into the higher half between two 32bit reads. To avoid this, use > a helper that reads the top half multiple times to check for overflow. > > Signed-off-by: Rohit Mathew > [morse: merged multiple patches from Rohit] > Signed-off-by: James Morse > --- > Changes since RFC: > * Commit message wrangling. > * Refer to 31 bit counters as opposed to 32 bit (registers). > --- > drivers/resctrl/mpam_devices.c | 89 ++++++++++++++++++++++++++++++---- > 1 file changed, 80 insertions(+), 9 deletions(-) > Looks good to me. Reviewed-by: Ben Horgan > diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/mpam_devices.c > index 2ab7f127baaa..8fbcf6eb946a 100644 > --- a/drivers/resctrl/mpam_devices.c > +++ b/drivers/resctrl/mpam_devices.c > @@ -1002,6 +1002,48 @@ struct mon_read { > int err; > }; > > +static bool mpam_ris_has_mbwu_long_counter(struct mpam_msc_ris *ris) > +{ > + return (mpam_has_feature(mpam_feat_msmon_mbwu_63counter, &ris->props) || > + mpam_has_feature(mpam_feat_msmon_mbwu_44counter, &ris->props)); > +} > + > +static u64 mpam_msc_read_mbwu_l(struct mpam_msc *msc) > +{ > + int retry = 3; > + u32 mbwu_l_low; > + u64 mbwu_l_high1, mbwu_l_high2; > + > + mpam_mon_sel_lock_held(msc); > + > + WARN_ON_ONCE((MSMON_MBWU_L + sizeof(u64)) > msc->mapped_hwpage_sz); > + WARN_ON_ONCE(!cpumask_test_cpu(smp_processor_id(), &msc->accessibility)); > + > + mbwu_l_high2 = __mpam_read_reg(msc, MSMON_MBWU_L + 4); > + do { > + mbwu_l_high1 = mbwu_l_high2; > + mbwu_l_low = __mpam_read_reg(msc, MSMON_MBWU_L); > + mbwu_l_high2 = __mpam_read_reg(msc, MSMON_MBWU_L + 4); > + > + retry--; > + } while (mbwu_l_high1 != mbwu_l_high2 && retry > 0); > + > + if (mbwu_l_high1 == mbwu_l_high2) > + return (mbwu_l_high1 << 32) | mbwu_l_low; > + return MSMON___NRDY_L; > +} > + > +static void mpam_msc_zero_mbwu_l(struct mpam_msc *msc) > +{ > + mpam_mon_sel_lock_held(msc); > + > + WARN_ON_ONCE((MSMON_MBWU_L + sizeof(u64)) > msc->mapped_hwpage_sz); > + WARN_ON_ONCE(!cpumask_test_cpu(smp_processor_id(), &msc->accessibility)); > + > + __mpam_write_reg(msc, MSMON_MBWU_L, 0); > + __mpam_write_reg(msc, MSMON_MBWU_L + 4, 0); > +} > + > static void gen_msmon_ctl_flt_vals(struct mon_read *m, u32 *ctl_val, > u32 *flt_val) > { > @@ -1058,6 +1100,7 @@ static void read_msmon_ctl_flt_vals(struct mon_read *m, u32 *ctl_val, > static void clean_msmon_ctl_val(u32 *cur_ctl) > { > *cur_ctl &= ~MSMON_CFG_x_CTL_OFLOW_STATUS; > + *cur_ctl &= ~MSMON_CFG_MBWU_CTL_OFLOW_STATUS_L; I observe that this bit is res0, in the CSU case, and so the clearing is ok. > } > > static void write_msmon_ctl_flt_vals(struct mon_read *m, u32 ctl_val, > @@ -1080,7 +1123,11 @@ static void write_msmon_ctl_flt_vals(struct mon_read *m, u32 ctl_val, > case mpam_feat_msmon_mbwu: > mpam_write_monsel_reg(msc, CFG_MBWU_FLT, flt_val); > mpam_write_monsel_reg(msc, CFG_MBWU_CTL, ctl_val); > - mpam_write_monsel_reg(msc, MBWU, 0); > + if (mpam_ris_has_mbwu_long_counter(m->ris)) > + mpam_msc_zero_mbwu_l(m->ris->vmsc->msc); > + else > + mpam_write_monsel_reg(msc, MBWU, 0); > + > mpam_write_monsel_reg(msc, CFG_MBWU_CTL, ctl_val | MSMON_CFG_x_CTL_EN); > > mbwu_state = &m->ris->mbwu_state[m->ctx->mon]; > @@ -1095,8 +1142,13 @@ static void write_msmon_ctl_flt_vals(struct mon_read *m, u32 ctl_val, > > static u64 mpam_msmon_overflow_val(struct mpam_msc_ris *ris) > { > - /* TODO: scaling, and long counters */ > - return GENMASK_ULL(30, 0); > + /* TODO: implement scaling counters */ > + if (mpam_has_feature(mpam_feat_msmon_mbwu_63counter, &ris->props)) > + return GENMASK_ULL(62, 0); > + else if (mpam_has_feature(mpam_feat_msmon_mbwu_44counter, &ris->props)) > + return GENMASK_ULL(43, 0); > + else > + return GENMASK_ULL(30, 0); > } > > /* Call with MSC lock held */ > @@ -1138,10 +1190,24 @@ static void __ris_msmon_read(void *arg) > now = FIELD_GET(MSMON___VALUE, now); > break; > case mpam_feat_msmon_mbwu: > - now = mpam_read_monsel_reg(msc, MBWU); > - if (mpam_has_feature(mpam_feat_msmon_mbwu_hw_nrdy, rprops)) > - nrdy = now & MSMON___NRDY; > - now = FIELD_GET(MSMON___VALUE, now); > + /* > + * If long or lwd counters are supported, use them, else revert > + * to the 31 bit counter. > + */ > + if (mpam_ris_has_mbwu_long_counter(ris)) { > + now = mpam_msc_read_mbwu_l(msc); > + if (mpam_has_feature(mpam_feat_msmon_mbwu_hw_nrdy, rprops)) > + nrdy = now & MSMON___NRDY_L; > + if (mpam_has_feature(mpam_feat_msmon_mbwu_63counter, rprops)) > + now = FIELD_GET(MSMON___LWD_VALUE, now); > + else > + now = FIELD_GET(MSMON___L_VALUE, now); > + } else { > + now = mpam_read_monsel_reg(msc, MBWU); > + if (mpam_has_feature(mpam_feat_msmon_mbwu_hw_nrdy, rprops)) > + nrdy = now & MSMON___NRDY; > + now = FIELD_GET(MSMON___VALUE, now); > + } > > if (nrdy) > break; > @@ -1433,8 +1499,13 @@ static int mpam_save_mbwu_state(void *arg) > cur_ctl = mpam_read_monsel_reg(msc, CFG_MBWU_CTL); > mpam_write_monsel_reg(msc, CFG_MBWU_CTL, 0); > > - val = mpam_read_monsel_reg(msc, MBWU); > - mpam_write_monsel_reg(msc, MBWU, 0); > + if (mpam_ris_has_mbwu_long_counter(ris)) { > + val = mpam_msc_read_mbwu_l(msc); > + mpam_msc_zero_mbwu_l(msc); > + } else { > + val = mpam_read_monsel_reg(msc, MBWU); > + mpam_write_monsel_reg(msc, MBWU, 0); > + } > > cfg->mon = i; > cfg->pmg = FIELD_GET(MSMON_CFG_MBWU_FLT_PMG, cur_flt); -- Thanks, Ben