From mboxrd@z Thu Jan  1 00:00:00 1970
From: Andrew Cooper <andrew.cooper3@citrix.com>
Subject: Re: [v3] libxc: Expose the 1GB pages cpuid flag to guest
Date: Fri, 28 Nov 2014 10:32:20 +0000
Message-ID: <54784F34.2000900@citrix.com>
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To: "Li, Liang Z" <liang.z.li@intel.com>, Jan Beulich <JBeulich@suse.com>
Cc: "wei.liu2@citrix.com" <wei.liu2@citrix.com>, "ian.campbell@citrix.com" <ian.campbell@citrix.com>, "stefano.stabellini@eu.citrix.com" <stefano.stabellini@eu.citrix.com>, "tim@xen.org" <tim@xen.org>, "ian.jackson@eu.citrix.com" <ian.jackson@eu.citrix.com>, "xen-devel@lists.xen.org" <xen-devel@lists.xen.org>, "Zhang,
	Yang Z" <yang.z.zhang@intel.com>
List-Id: xen-devel@lists.xenproject.org

On 28/11/14 10:29, Li, Liang Z wrote:
>>> -        if (!hvm_pse1gb_supported(d))
>>> +        if (!hvm_pse1gb_supported(d) || paging_mode_shadow(d))
>>>              *edx &= ~cpufeat_mask(X86_FEATURE_PAGE1GB);
>> With
>>
>> #define hvm_pse1gb_supported(d) \
>>    (cpu_has_page1gb && paging_mode_hap(d))
>> the change above is pointless. While, considering this, comments on
>> v2 may have been misleading, you should have simply updated the patch description instead to clarify why the v2 change was okay even for the shadow mode case.
> I checked the code and found that for a normal guest can only be in hap mode or shadow mode before I sending the patch, but I am not share if it's true for dom0. 
>
> Liang

Dom0 may either be PV (in which case neither hap nor shadow, and cant
use 1GB pages anyway), or experimentally PVH which is currently
restricted to hap.

~Andrew