linux-kernel - Re: [PATCH 7/7] kvm x86: report 1GB page support to userspace

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Message-ID: <20090329124548.GG31080@8bytes.org>
Date:	Sun, 29 Mar 2009 14:45:48 +0200
From:	Joerg Roedel <joro@...tes.org>
To:	Avi Kivity <avi@...hat.com>
Cc:	Joerg Roedel <joerg.roedel@....com>,
	Marcelo Tosatti <mtosatti@...hat.com>, kvm@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 7/7] kvm x86: report 1GB page support to userspace

On Sun, Mar 29, 2009 at 02:54:31PM +0300, Avi Kivity wrote:
> Joerg Roedel wrote:
>> If userspace knows that the kernel part supports 1GB pages it can enable
>> the corresponding cpuid bit so that guests actually use GB pages.
>>   
>
>> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
>> index a1df2a3..6593198 100644
>> --- a/arch/x86/include/asm/kvm_host.h
>> +++ b/arch/x86/include/asm/kvm_host.h
>> @@ -542,6 +542,8 @@ struct kvm_x86_ops {
>>  	int (*set_tss_addr)(struct kvm *kvm, unsigned int addr);
>>  	int (*get_tdp_level)(void);
>>  	int (*get_mt_mask_shift)(void);
>> +
>> +	bool (*gb_page_enable)(void);
>>  };
>>   
>
> Should enable unconditionally.  Of course we need to find the shadow bug  
> first, may be the has_wrprotected thingy.

This was the original plan. But how about VMX with EPT enabled? I am not
sure but I think this configuration will not support gbpages?

	Joerg
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