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Message-ID: <tencent_594804A808BD93A4EBF50A994F228E3A7F07@qq.com>
From:   Pu Wen <pu_wen@foxmail.com>
Subject: Re: [patch V3a 30/40] x86/cpu: Provide an AMD/HYGON specific topology
 parser
To:     Thomas Gleixner <tglx@linutronix.de>, Pu Wen <puwen@hygon.cn>,
        LKML <linux-kernel@vger.kernel.org>
Cc:     x86@kernel.org, Tom Lendacky <thomas.lendacky@amd.com>,
        Andrew Cooper <andrew.cooper3@citrix.com>,
        Arjan van de Ven <arjan@linux.intel.com>,
        Huang Rui <ray.huang@amd.com>, Juergen Gross <jgross@suse.com>,
        Dimitri Sivanich <dimitri.sivanich@hpe.com>,
        Michael Kelley <mikelley@microsoft.com>,
        Wei Liu <wei.liu@kernel.org>
References: <20230802101635.459108805@linutronix.de>
 <20230802101934.418143974@linutronix.de> <87il9xjk95.ffs@tglx>
 <tencent_3C08D6938E6BD58AACCF018E0A7F3B848807@qq.com> <87jzu1h5cm.ffs@tglx>
Date:   Sat, 12 Aug 2023 11:58:59 +0800
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On 2023/8/12 1:11, Thomas Gleixner wrote:
> On Fri, Aug 11 2023 at 20:58, Pu Wen wrote:
>> On 2023/8/3 3:51, Thomas Gleixner wrote:
>>> +	if (tscan->c->x86_vendor == X86_VENDOR_AMD) {
>>> +		if (tscan->c->x86 == 0x15)
>>> +			tscan->c->topo.cu_id = leaf.cuid;
>>> +
>>> +		cacheinfo_amd_init_llc_id(tscan->c, leaf.nodeid);
>>> +	} else {
>>> +		/*
>>> +		 * Package ID is ApicId[6..] on Hygon CPUs. See commit
>>> +		 * e0ceeae708ce for explanation. The topology info is
>>> +		 * screwed up: The package shift is always 6 and the node
>>> +		 * ID is bit [4:5]. Don't touch the latter without
>>> +		 * confirmation from the Hygon developers.
>>> +		 */
>>> +		topology_set_dom(tscan, TOPO_CORE_DOMAIN, 6, tscan->dom_ncpus[TOPO_CORE_DOMAIN]);
>>
>> Hygon updated CPUs will not always shift 6, and shift 6 is not good for
>> running guests.
>> So suggest to modify like this:
>>       if (!boot_cpu_has(X86_FEATURE_HYPERVISOR) && tscan->c->x86_model <=
>> 0x3)
>>           topology_set_dom(tscan, TOPO_CORE_DOMAIN, 6,
>> tscan->dom_ncpus[TOPO_CORE_DOMAIN]);
> 
> This is exactly what the existing code does today. Can you please send a
> delta patch on top of this with a proper explanation?

Will.

And I think it's better to send a prerequisite patch(is attached) after
patch 02 of this series. Since it can be individually back-ported to the
stable releases.

-- 
Regards,
Pu Wen


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