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[175.34.8.244]) by smtp.gmail.com with ESMTPSA id a92af1059eb24-13cd432f1cesm10234714c88.11.2026.07.15.21.50.02 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 15 Jul 2026 21:50:05 -0700 (PDT) Message-ID: Date: Thu, 16 Jul 2026 14:49:59 +1000 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v1 06/11] arm_mpam: Use __ris_msmon_read() for saving MBWU state To: Ben Horgan Cc: james.morse@arm.com, reinette.chatre@intel.com, fenghuay@nvidia.com, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, dave.martin@arm.com, andre.przywara@arm.com References: <20260710115546.29644-1-ben.horgan@arm.com> <20260710115546.29644-7-ben.horgan@arm.com> Content-Language: en-US From: Gavin Shan In-Reply-To: <20260710115546.29644-7-ben.horgan@arm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 7/10/26 9:55 PM, Ben Horgan wrote: > mbwu_save_mbwu_state() reads the MBWU counters and adds that to a saved > correction value. However, the type of counter to read is determined by the > RIS rather than the class and overflow is not taken into account. Fix this > and mitigate against further divergence by using the same helper as used > for user reads, __ris_msmon_read(). > > Fixes: 41e8a14950e1 ("arm_mpam: Track bandwidth counter state for power management") > Signed-off-by: Ben Horgan > --- > drivers/resctrl/mpam_devices.c | 33 +++++++++++++++++++++------------ > 1 file changed, 21 insertions(+), 12 deletions(-) > > diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/mpam_devices.c > index 222fc248067e..a49f426aefc0 100644 > --- a/drivers/resctrl/mpam_devices.c > +++ b/drivers/resctrl/mpam_devices.c > @@ -1029,12 +1029,6 @@ struct mon_read { > bool waited_timeout; > }; > > -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; > @@ -1687,6 +1681,7 @@ static int mpam_save_mbwu_state(void *arg) > struct mpam_msc_ris *ris = arg; > struct msmon_mbwu_state *mbwu_state; > struct mpam_msc *msc = ris->vmsc->msc; > + struct mpam_class *class = ris->vmsc->comp->class; > > for (i = 0; i < ris->props.num_mbwu_mon; i++) { > mbwu_state = &ris->mbwu_state[i]; > @@ -1702,18 +1697,32 @@ static int mpam_save_mbwu_state(void *arg) > cur_flt = mpam_read_monsel_reg(msc, CFG_MBWU_FLT); > cur_ctl = mpam_read_monsel_reg(msc, CFG_MBWU_CTL); > > - if (mpam_ris_has_mbwu_long_counter(ris)) > - val = mpam_msc_read_mbwu_l(msc); > - else > - val = mpam_read_monsel_reg(msc, MBWU); > - > cfg->mon = i; > cfg->pmg = FIELD_GET(MSMON_CFG_x_FLT_PMG, cur_flt); > cfg->match_pmg = FIELD_GET(MSMON_CFG_x_CTL_MATCH_PMG, cur_ctl); > cfg->partid = FIELD_GET(MSMON_CFG_x_FLT_PARTID, cur_flt); > - mbwu_state->correction += val; > mbwu_state->enabled = FIELD_GET(MSMON_CFG_x_CTL_EN, cur_ctl); > mpam_mon_sel_unlock(msc); > + > + if (mbwu_state->enabled) { > + struct mon_read mbwu_arg = { > + mbwu_arg.ris = ris, > + mbwu_arg.ctx = cfg, > + mbwu_arg.type = mpam_msmon_choose_counter(class), > + mbwu_arg.val = &val, > + }; > + > + val = 0; > + __ris_msmon_read(&mbwu_arg); > + > + if (WARN_ON_ONCE(!mpam_mon_sel_lock(msc))) > + return -EIO; > + > + mbwu_state->reset_on_next_read = true; > + if (!mbwu_arg.err) > + mbwu_state->correction = val; > + mpam_mon_sel_unlock(msc); > + } > } The unnecessary nested conditional statement can be avoided by skipping the disabled MBWU state. if (!mbwu_state->enabled) { mpam_mon_sel_unlock(msc); continue; } mpam_mon_sel_unlock(msc); val = 0; mbwu_arg.ris = ris; mbwu_arg.ctx = cfg; mbwu_arg.type = mpam_msmon_choose_counter(class); mbwu_arg.val = &val __ris_msmon_read(&mbwu_arg); : : > > return 0; Thanks, Gavin