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: <b2fb792f-92ba-4bee-8a2a-e434405653e9@nvidia.com>
Date: Wed, 27 Aug 2025 17:58:26 -0700
From: Fenghua Yu <fenghuay@...dia.com>
To: James Morse <james.morse@....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, James,

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.
>
> Signed-off-by: James Morse <james.morse@....com>
[SNIP]
> @@ -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.

[SNIP]

Thanks.

-Fenghua