linux-kernel - Re: [PATCH v8 0/2] x86: vmclear vmcss on all cpus when doing kdump if necessary

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Date:	Mon, 26 Nov 2012 09:50:05 +0800
From:	Zhang Yanfei <zhangyanfei@...fujitsu.com>
To:	Gleb Natapov <gleb@...hat.com>
CC:	"x86@...nel.org" <x86@...nel.org>,
	"kexec@...ts.infradead.org" <kexec@...ts.infradead.org>,
	Marcelo Tosatti <mtosatti@...hat.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"kvm@...r.kernel.org" <kvm@...r.kernel.org>
Subject: Re: [PATCH v8 0/2] x86: vmclear vmcss on all cpus when doing kdump
 if necessary

于 2012年11月25日 22:26, Gleb Natapov 写道:
> On Thu, Nov 22, 2012 at 04:22:26PM +0800, Zhang Yanfei wrote:
>> Currently, kdump just makes all the logical processors leave VMX operation by
>> executing VMXOFF instruction, so any VMCSs active on the logical processors may
>> be corrupted. But, sometimes, we need the VMCSs to debug guest images contained
>> in the host vmcore. To prevent the corruption, we should VMCLEAR the VMCSs before
>> executing the VMXOFF instruction.
>>
>> The patch set provides a way to VMCLEAR vmcss related to guests on all cpus before
>> executing the VMXOFF when doing kdump. This is used to ensure the VMCSs in the
>> vmcore updated and non-corrupted.
>>
> Looks fine to me, but kexec part should get acks from exec maintainers.

Thanks. I will ask the exec maintainer.

> 
>> Changelog from v7 to v8:
>> 1. KEXEC: regression for using name crash_notifier_list
>>    and remove comments related to KVM
>>    and just call function atomic_notifier_call_chain directly.
>>
>> Changelog from v6 to v7:
>> 1. KVM-INTEL: in hardware_disable, we needn't disable the
>>    vmclear, so remove it.
>>
>> Changelog from v5 to v6:
>> 1. KEXEC: the atomic notifier list renamed:
>>    crash_notifier_list --> vmclear_notifier_list
>> 2. KVM-INTEL: provide empty functions if CONFIG_KEXEC is
>>    not defined and remove unnecessary #ifdef's.
>>
>> Changelog from v4 to v5:
>> 1. use an atomic notifier instead of function call, so
>>    have all the vmclear codes in vmx.c.
>>
>> Changelog from v3 to v4:
>> 1. add a new percpu variable vmclear_skipped to skip
>>    vmclear in kdump in some conditions.
>>
>> Changelog from v2 to v3:
>> 1. remove unnecessary conditions in function
>>    cpu_emergency_clear_loaded_vmcss as Marcelo suggested.
>>
>> Changelog from v1 to v2:
>> 1. remove the sysctl and clear VMCSs unconditionally.
>>
>> Zhang Yanfei (2):
>>   x86/kexec: add a new atomic notifier list for kdump
>>   KVM-INTEL: add a notifier and a bitmap to support VMCLEAR in kdump
>>
>>  arch/x86/include/asm/kexec.h |    2 +
>>  arch/x86/kernel/crash.c      |    9 +++++
>>  arch/x86/kvm/vmx.c           |   70 ++++++++++++++++++++++++++++++++++++++++++
>>  3 files changed, 81 insertions(+), 0 deletions(-)
> 
> --
> 			Gleb.
> 

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