From: Sourabh Jain <sourabhjain@linux.ibm.com>
To: Baoquan He <bhe@redhat.com>
Cc: Eric DeVolder <eric.devolder@oracle.com>,
linux-kernel@vger.kernel.org, x86@kernel.org,
kexec@lists.infradead.org, ebiederm@xmission.com,
dyoung@redhat.com, vgoyal@redhat.com, tglx@linutronix.de,
mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com,
hpa@zytor.com, nramas@linux.microsoft.com,
thomas.lendacky@amd.com, robh@kernel.org, efault@gmx.de,
rppt@kernel.org, david@redhat.com, konrad.wilk@oracle.com,
boris.ostrovsky@oracle.com
Subject: Re: [PATCH v7 4/8] crash: add generic infrastructure for crash hotplug support
Date: Thu, 5 May 2022 15:29:19 +0530 [thread overview]
Message-ID: <e677f11b-32f9-0c89-9592-b987b00c4353@linux.ibm.com> (raw)
In-Reply-To: <YnNkgfnHlUTky0lt@MiWiFi-R3L-srv>
On 05/05/22 11:15, Baoquan He wrote:
> On 04/28/22 at 10:48am, Sourabh Jain wrote:
>> Hi Baoquan,
>>
>> On 26/04/22 10:52, Baoquan He wrote:
>>> On 04/26/22 at 09:36am, Sourabh Jain wrote:
>>>> On 15/04/22 03:59, Eric DeVolder wrote:
> ......
>
>>>>>>> +#if defined(CONFIG_MEMORY_HOTPLUG)
>>>>>>> +static int crash_memhp_notifier(struct notifier_block *nb,
>>>>>>> + unsigned long val, void *v)
>>>>>>> +{
>>>>>>> + struct memory_notify *mhp = v;
>>>>>>> +
>>>>>>> + switch (val) {
>>>>>>> + case MEM_ONLINE:
>>>>>>> + crash_hotplug_handler(KEXEC_CRASH_HP_ADD_MEMORY, -1U);
>>>>>> We don't differentiate the memory add/remove, cpu add, except of cpu
>>>>>> remove. Means the hp_action only differentiate cpu remove from the other
>>>>>> action. Maybe only making two types?
>>>>>>
>>>>>> #define KEXEC_CRASH_HP_REMOVE_CPU 0
>>>>>> #define KEXEC_CRASH_HP_UPDATE_OTHER 1
>>>>>>
>>>>> Sourabh Jain's work with PPC uses REMOVE_CPU, REMOVE_MEMORY, and
>>>>> ADD_MEMORY.
>>>>> Do you still want to consolidate these?
>>>> On PowerPC different actions are needed for CPU add and memory add/remove.
>>>> For CPU add case only FDT is updated whereas for the memory hotplug we will
>>>> be
>>>> updating FDT and elfcorehdr.
>>> I don't understand. For elfcorehdr updating, we only need regenerate it.
>>> Do you update them different for memory add/remove?
>> We have different actions for cpu remove, CPU add and memory add/remove
>> case.
>>
>> CPU remove: no action
>> CPU add: update flattened device tree (FDT)
>> memory add/remove: update FDT and regenerate/update elfcorehdr
>>
>> Since memory add/remove action is same we can have common hp_action for
>> them.
> For memory hot add/remove, we need rengereate elfcorehdr, and add the
> new elfcorehdr into fdt. Except of this, FDT need to know the hp_action
> and the hot added/removed memory region, namely the start and end, e.g
> [start, end]?
>
> I checked arm64 kexec code, seems we only need to know if mem hotplug
> event happened, then regenerate elfcorehdr and embed the new elfcorehdr
> into fdt. Then we don't know pass the [start, end] info into the
> handler. Please tell if ppc is different or I missed anything.
Yes we don't need start and end info as such but we expect arch
handler to have info about which hotplug action is performed.
It is just that I don't see an significant advantage of consolidation of
CPU ADD, memory ADD and Memory REMOVE in one hp_action as
KEXEC_CRASH_HP_UPDATE_OTHER.
> If I am right, I would like the handler interface as Boris has made
> in his draft patch.
>
> void __weak arch_crash_handle_hotplug_event(struct kimage *image, unsigned int hp_action,
> unsigned int cpu)
>
> static void handle_hotplug_event(unsigned int hp_action, unsigned int cpu)
The above template works fine for PowerPC as long we have four different
hp_action
to indicate CPU add/remove and memory add/remove.
Thanks,
Sourabh Jain
next prev parent reply other threads:[~2022-05-05 10:00 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-13 16:42 [PATCH v7 0/8] crash: Kernel handling of CPU and memory hot un/plug Eric DeVolder
2022-04-13 16:42 ` [PATCH v7 1/8] x86/crash: fix minor typo/bug in debug message Eric DeVolder
2022-04-13 17:52 ` [tip: x86/kdump] x86/crash: Fix " tip-bot2 for Eric DeVolder
2022-04-28 9:49 ` [PATCH v7 1/8] x86/crash: fix " David Hildenbrand
2022-04-13 16:42 ` [PATCH v7 2/8] x86/crash: Introduce new options to support cpu and memory hotplug Eric DeVolder
2022-04-14 13:59 ` Borislav Petkov
2022-04-18 22:03 ` Eric DeVolder
2022-04-19 10:32 ` Borislav Petkov
2022-04-19 21:58 ` Eric DeVolder
2022-04-25 19:25 ` Borislav Petkov
2022-04-26 20:08 ` Eric DeVolder
2022-04-27 10:48 ` Borislav Petkov
2022-04-26 4:21 ` Sourabh Jain
2022-04-26 14:39 ` Eric DeVolder
2022-04-29 6:41 ` Sourabh Jain
2022-05-05 16:31 ` Eric DeVolder
2022-04-13 16:42 ` [PATCH v7 3/8] crash: prototype change for crash_prepare_elf64_headers Eric DeVolder
2022-04-13 16:42 ` [PATCH v7 4/8] crash: add generic infrastructure for crash hotplug support Eric DeVolder
2022-04-14 2:45 ` Baoquan He
2022-04-14 22:29 ` Eric DeVolder
2022-04-18 3:17 ` Baoquan He
2022-04-26 4:06 ` Sourabh Jain
2022-04-26 5:22 ` Baoquan He
2022-04-28 5:18 ` Sourabh Jain
2022-05-04 18:11 ` Eric DeVolder
2022-05-05 5:45 ` Baoquan He
2022-05-05 9:59 ` Sourabh Jain [this message]
2022-05-05 11:04 ` Baoquan He
2022-05-05 13:35 ` Eric DeVolder
2022-04-13 16:42 ` [PATCH v7 5/8] kexec: exclude elfcorehdr from the segment digest Eric DeVolder
2022-04-13 16:42 ` [PATCH v7 6/8] kexec: exclude hot remove cpu from elfcorehdr notes Eric DeVolder
2022-04-14 2:48 ` Baoquan He
2022-04-14 22:31 ` Eric DeVolder
2022-04-13 16:42 ` [PATCH v7 7/8] x86/crash: Add x86 crash hotplug support for kexec_file_load Eric DeVolder
2022-04-14 2:52 ` Baoquan He
2022-04-14 22:32 ` Eric DeVolder
2022-04-13 16:42 ` [PATCH v7 8/8] x86/crash: Add x86 crash hotplug support for kexec_load Eric DeVolder
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