Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Subject: Re: [PATCH RFC 0/3] Support CPU hotplug for ARM64
To:     Jia He <hejianet@gmail.com>, <rjw@rjwysocki.net>,
        <catalin.marinas@arm.com>, <james.morse@arm.com>
CC:     <linux-acpi@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        <linux-arm-kernel@lists.infradead.org>, <guohanjun@huawei.com>,
        <xiexiuqi@huawei.com>, <huawei.libin@huawei.com>,
        <john.garry@huawei.com>, <jonathan.cameron@huawei.com>
References: <1561720392-45907-1-git-send-email-wangxiongfeng2@huawei.com>
 <2b22cf4d-9646-9f20-41ae-cceb83d9791b@gmail.com>
From:   Xiongfeng Wang <wangxiongfeng2@huawei.com>
Message-ID: <135ee490-a5a6-46c9-208e-81849b20d6b6@huawei.com>
Date:   Thu, 4 Jul 2019 11:26:16 +0800
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101
 Thunderbird/52.6.0
MIME-Version: 1.0
In-Reply-To: <2b22cf4d-9646-9f20-41ae-cceb83d9791b@gmail.com>
Content-Type: text/plain; charset="utf-8"
Content-Language: en-US
Content-Transfer-Encoding: 8bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Hi Justin,

On 2019/7/4 11:00, Jia He wrote:
> Hi Xiongfeng
> 
> It is a little bit awkful that I am also  investigating acpi based cpu hotplug issue silimar with
> 
> your idea. My question is your purpose to implement the vcpu hotplug in arm64 qemu?

Yes, my purpose is to implement the vcpu hotplug in arm64 qemu. So that I can add or remove vcpu
without shutting down the Guest OS.

Thanks,
Xiongfeng

> 
> Thanks for the ellaboration
> 
> ---
> Cheers,
> Justin (Jia He)
> 
> On 2019/6/28 19:13, Xiongfeng Wang wrote:
>> This patchset mark all the GICC node in MADT as possible CPUs even though it
>> is disabled. But only those enabled GICC node are marked as present CPUs.
>> So that kernel will initialize some CPU related data structure in advance before
>> the CPU is actually hot added into the system. This patchset also implement
>> 'acpi_(un)map_cpu()' and 'arch_(un)register_cpu()' for ARM64. These functions are
>> needed to enable CPU hotplug.
>>
>> To support CPU hotplug, we need to add all the possible GICC node in MADT
>> including those CPUs that are not present but may be hot added later. Those
>> CPUs are marked as disabled in GICC nodes.
>>
>> Xiongfeng Wang (3):
>>    ACPI / scan: evaluate _STA for processors declared via ASL Device
>>      statement
>>    arm64: mark all the GICC nodes in MADT as possible cpu
>>    arm64: Add CPU hotplug support
>>
>>   arch/arm64/kernel/acpi.c  | 22 ++++++++++++++++++++++
>>   arch/arm64/kernel/setup.c | 19 ++++++++++++++++++-
>>   arch/arm64/kernel/smp.c   | 11 +++++------
>>   drivers/acpi/scan.c       | 12 ++++++++++++
>>   4 files changed, 57 insertions(+), 7 deletions(-)
>>
> 
> .
>