linux-kernel - Re: [PATCH 11/33] arm_mpam: Add support for memory controller MSC on DT platforms

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: <25e99137-54ee-434d-8777-a771798e9da1@arm.com>
Date: Wed, 10 Sep 2025 20:31:28 +0100
From: James Morse <james.morse@....com>
To: "Shaopeng Tan (Fujitsu)" <tan.shaopeng@...itsu.com>,
 "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
 "linux-arm-kernel@...ts.infradead.org"
 <linux-arm-kernel@...ts.infradead.org>,
 "linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
 "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>
Cc: "shameerali.kolothum.thodi@...wei.com"
 <shameerali.kolothum.thodi@...wei.com>,
 D Scott Phillips OS <scott@...amperecomputing.com>,
 "carl@...amperecomputing.com" <carl@...amperecomputing.com>,
 "lcherian@...vell.com" <lcherian@...vell.com>,
 "bobo.shaobowang@...wei.com" <bobo.shaobowang@...wei.com>,
 "baolin.wang@...ux.alibaba.com" <baolin.wang@...ux.alibaba.com>,
 Jamie Iles <quic_jiles@...cinc.com>, Xin Hao <xhao@...ux.alibaba.com>,
 "peternewman@...gle.com" <peternewman@...gle.com>,
 "dfustini@...libre.com" <dfustini@...libre.com>,
 "amitsinght@...vell.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>,
 "fenghuay@...dia.com" <fenghuay@...dia.com>,
 "baisheng.gao@...soc.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 11/33] arm_mpam: Add support for memory controller MSC on
 DT platforms

Hi Shaopeng,

On 09/09/2025 08:11, Shaopeng Tan (Fujitsu) wrote:
>> From: Shanker Donthineni <sdonthineni@...dia.com>
>>
>> The device-tree binding has two examples for MSC associated with memory
>> controllers. Add the support to discover the component_id from the device-tree
>> and create 'memory' RIS.

>> diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/mpam_devices.c
>> index a0d9a699a6e7..71a1fb1a9c75 100644
>> --- a/drivers/resctrl/mpam_devices.c
>> +++ b/drivers/resctrl/mpam_devices.c
>> @@ -62,41 +62,63 @@ static int mpam_dt_parse_resource(struct mpam_msc
>> *msc, struct device_node *np,
>>  				  u32 ris_idx)
>>  {
>>  	int err = 0;
>> -	u32 level = 0;
>> -	unsigned long cache_id;
>> -	struct device_node *cache;
>> +	u32 class_id = 0, component_id = 0;
>> +	struct device_node *cache = NULL, *memory = NULL;
>> +	enum mpam_class_types type = MPAM_CLASS_UNKNOWN;
>>
>>  	do {
>> +		/* What kind of MSC is this? */
>>  		if (of_device_is_compatible(np, "arm,mpam-cache")) {
>>  			cache = of_parse_phandle(np, "arm,mpam-device",
>> 0);
>>  			if (!cache) {
>>  				pr_err("Failed to read phandle\n");
>>  				break;
>>  			}
>> +			type = MPAM_CLASS_CACHE;
>>  		} else if (of_device_is_compatible(np->parent, "cache")) {
>>  			cache = of_node_get(np->parent);
>> +			type = MPAM_CLASS_CACHE;
>> +		} else if (of_device_is_compatible(np, "arm,mpam-memory"))
>> {
>> +			memory = of_parse_phandle(np, "arm,mpam-device",
>> 0);
>> +			if (!memory) {
>> +				pr_err("Failed to read phandle\n");
>> +				break;
>> +			}
>> +			type = MPAM_CLASS_MEMORY;
>> +		} else if (of_device_is_compatible(np,
>> "arm,mpam-memory-controller-msc")) {
>> +			memory = of_node_get(np->parent);
>> +			type = MPAM_CLASS_MEMORY;
>>  		} else {
>> -			/* For now, only caches are supported */
>> -			cache = NULL;
>> +			/*
>> +			 * For now, only caches and memory controllers are
>> +			 * supported.
>> +			 */
>>  			break;
>>  		}

> There is no need "{}" here.

Sure, but its more than one line, and all the previous parts of this else-if tree have
them. Keeping this here make it much easier to read.


Thanks,

James