linux-kernel - Re: [PATCH 2/4] KVM: VMX: Add functions to fill VMCSINFO

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Date:	Wed, 11 Apr 2012 18:34:36 +0800
From:	zhangyanfei <zhangyanfei@...fujitsu.com>
To:	Avi Kivity <avi@...hat.com>
CC:	mtosatti@...hat.com, ebiederm@...ssion.com, luto@....edu,
	joerg.roedel@....com, dzickus@...hat.com,
	paul.gortmaker@...driver.com, gregkh@...e.de,
	ludwig.nussel@...e.de, linux-kernel@...r.kernel.org,
	kvm@...r.kernel.org, kexec@...ts.infradead.org
Subject: Re: [PATCH 2/4] KVM: VMX: Add functions to fill VMCSINFO

于 2012年04月11日 16:48, Avi Kivity 写道:
> On 04/11/2012 04:50 AM, zhangyanfei wrote:
>> This patch is to implement the feature that at initialization of
>> kvm_intel module, fills VMCSINFO with a VMCS revision identifier,
>> and encoded offsets of VMCS fields. The reason why we put the
>> VMCSINFO processing at the initialization of kvm_intel module
>> is that it's dangerous to rob VMX resources while kvm module is
>> loaded.
> 
> Maybe it should be done by a separate module.
> 

If we put vmcsinfo processing at the initialization of kvm_intel module,
as soon as the kvm_intel module is loaded, VMCSINFO is filled. And it is
because vmcsinfo processing is at the initialization of kvm_intel module,
no kvm guests are running, so it will not rob any VMX resources.

If it is done by a separate module, I am afraid this module may not be
loaded when the kernel needs VMCSINFO.

>> +
>> +	kvm_cpu_vmxon(__pa(per_cpu(vmxarea, raw_smp_processor_id())));
>> +	vmcs_load(vmcs);
> 
> Should do this after writing into the vmcs directly (vmcs_load() may
> cache some information for vmcs_read()).
>

Hmm, thanks for pointing this.

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