linux-kernel - Re: [PATCH 28/33] arm_mpam: Track bandwidth counter state for overflow and power management

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <1a571086-4165-4c94-a834-bd7b92a31b0d@arm.com>
Date: Wed, 10 Sep 2025 20:29:42 +0100
From: James Morse <james.morse@....com>
To: Fenghua Yu <fenghuay@...dia.com>, linux-kernel@...r.kernel.org,
 linux-arm-kernel@...ts.infradead.org, linux-acpi@...r.kernel.org,
 devicetree@...r.kernel.org
Cc: shameerali.kolothum.thodi@...wei.com,
 D Scott Phillips OS <scott@...amperecomputing.com>,
 carl@...amperecomputing.com, lcherian@...vell.com,
 bobo.shaobowang@...wei.com, tan.shaopeng@...itsu.com,
 baolin.wang@...ux.alibaba.com, Jamie Iles <quic_jiles@...cinc.com>,
 Xin Hao <xhao@...ux.alibaba.com>, peternewman@...gle.com,
 dfustini@...libre.com, amitsinght@...vell.com,
 David Hildenbrand <david@...hat.com>, Rex Nie <rex.nie@...uarmicro.com>,
 Dave Martin <dave.martin@....com>, Koba Ko <kobak@...dia.com>,
 Shanker Donthineni <sdonthineni@...dia.com>, baisheng.gao@...soc.com,
 Jonathan Cameron <jonathan.cameron@...wei.com>, Rob Herring
 <robh@...nel.org>, Rohit Mathew <rohit.mathew@....com>,
 Rafael Wysocki <rafael@...nel.org>, Len Brown <lenb@...nel.org>,
 Lorenzo Pieralisi <lpieralisi@...nel.org>, Hanjun Guo
 <guohanjun@...wei.com>, Sudeep Holla <sudeep.holla@....com>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley
 <conor+dt@...nel.org>, Catalin Marinas <catalin.marinas@....com>,
 Will Deacon <will@...nel.org>,
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
 Danilo Krummrich <dakr@...nel.org>
Subject: Re: [PATCH 28/33] arm_mpam: Track bandwidth counter state for
 overflow and power management

Hi Fenghua,

On 28/08/2025 01:58, Fenghua Yu wrote:
> On 8/22/25 08:30, James Morse wrote:
>> Bandwidth counters need to run continuously to correctly reflect the
>> bandwidth.
>>
>> The value read may be lower than the previous value read in the case
>> of overflow and when the hardware is reset due to CPU hotplug.
>>
>> Add struct mbwu_state to track the bandwidth counter to allow overflow
>> and power management to be handled.

>> @@ -2291,11 +2395,35 @@ static void mpam_unregister_irqs(void)
>>     static void __destroy_component_cfg(struct mpam_component *comp)
>>   {
>> +    struct mpam_msc *msc;
>> +    struct mpam_vmsc *vmsc;
>> +    struct mpam_msc_ris *ris;
>> +
>> +    lockdep_assert_held(&mpam_list_lock);
>> +
>>       add_to_garbage(comp->cfg);
>> +    list_for_each_entry(vmsc, &comp->vmsc, comp_list) {
>> +        msc = vmsc->msc;
>> +
>> +        mpam_mon_sel_outer_lock(msc);
>> +        if (mpam_mon_sel_inner_lock(msc)) {
>> +            list_for_each_entry(ris, &vmsc->ris, vmsc_list)
>> +                add_to_garbage(ris->mbwu_state);
>> +            mpam_mon_sel_inner_unlock(msc);
>> +        }
>> +        mpam_mon_sel_outer_lock(msc);
> 
> s/mpam_mon_sel_outer_lock(msc);/mpam_mon_sel_outer_unlock(msc);/
> 
> Or this will hit a dead lock.

Heh, that's a good typo. Thanks!

James