From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Chen, Tiejun" <tiejun.chen@intel.com>
Subject: Re: [v4][PATCH 03/19] xen/vtd: create RMRR mapping
Date: Wed, 24 Jun 2015 09:11:41 +0800
Message-ID: <558A03CD.3090206@intel.com>
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To: Jan Beulich <JBeulich@suse.com>
Cc: Yang Zhang <yang.z.zhang@intel.com>, Kevin Tian <kevin.tian@intel.com>, Tim Deegan <tim@xen.org>, xen-devel@lists.xen.org
List-Id: xen-devel@lists.xenproject.org

On 2015/6/23 18:12, Jan Beulich wrote:
>>>> On 23.06.15 at 11:57, <tiejun.chen@intel.com> wrote:
>> --- a/xen/drivers/passthrough/vtd/iommu.c
>> +++ b/xen/drivers/passthrough/vtd/iommu.c
>> @@ -1839,7 +1839,7 @@ static int rmrr_identity_mapping(struct domain *d, bool_t map,
>>
>>               while ( base_pfn < end_pfn )
>>               {
>> -                if ( intel_iommu_unmap_page(d, base_pfn) )
>> +                if ( guest_physmap_remove_page(d, base_pfn, base_pfn, 0) )

Yeah, I also thought this may bring some confusions in this context.

>>                       ret = -ENXIO;
>>                   base_pfn++;
>>               }
>> @@ -1855,8 +1855,7 @@ static int rmrr_identity_mapping(struct domain *d, bool_t map,
>>
>>       while ( base_pfn < end_pfn )
>>       {
>> -        int err = intel_iommu_map_page(d, base_pfn, base_pfn,
>> -                                       IOMMUF_readable|IOMMUF_writable);
>> +        int err = set_identity_p2m_entry(d, base_pfn, p2m_access_rw);
>
> Shouldn't the two continue to be the inverse of one another?

Initially, instead of using guest_physmap_remove_page, I was trying to 
introduce a new, clear_identity_p2m_entry, which can wrapper 
p2m_remove_page().

But Tim just thought we'd better avoid duplicating code,

http://lists.xenproject.org/archives/html/xen-devel/2015-06/msg02970.html

> Maybe guest_physmap_remove_page() does what you want,

Note actually we just need p2m_remove_page() to unmap these mapping on 
both ept and vt-d sides, and guest_physmap_remove_page is really a 
wrapper of p2m_remove_page().

Thanks
Tiejun