From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Chen, Tiejun" <tiejun.chen@intel.com>
Subject: Re: [PATCH 1/1] xen:vtd: missing RMRR mapping while
 share EPT
Date: Thu, 24 Jul 2014 16:28:03 +0800
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To: Jan Beulich <JBeulich@suse.com>
Cc: yang.z.zhang@intel.com, kevin.tian@intel.com, xen-devel@lists.xen.org
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On 2014/7/24 15:45, Jan Beulich wrote:
>>>> On 24.07.14 at 09:00, <tiejun.chen@intel.com> wrote:
>> On 2014/7/24 14:14, Jan Beulich wrote:
>>>>>> On 24.07.14 at 03:23, <tiejun.chen@intel.com> wrote:
>>>> @@ -1867,7 +1869,21 @@ static int rmrr_identity_mapping(struct domain *d,
>>>>
>>>>         while ( base_pfn < end_pfn )
>>>>         {
>>>> -        if ( intel_iommu_map_page(d, base_pfn, base_pfn,
>>>> +        if ( iommu_use_hap_pt(d) )
>>>
>>> Don't you, btw, need to extend this condition by
>>> && (!iommu_passthrough || !is_hardware_domain(d))?
>>
>> Why do we need these checks here?
>
> At least for documentation purposes: It would be wrong to try to
> establish these mappings. I reckon iommu_use_hap_pt() implies the
> combined other condition, so an ASSERT() would presumably be fine
> as well (and get even closer to the intended documentation purpose).
>

I think if() should be reasonable here. Because

intel_iommu_map_page()
{
	...
     /* do nothing if dom0 and iommu supports pass thru */
     if ( iommu_passthrough && is_hardware_domain(d) )
         return 0;

We just do nothing to return simply. But if ASSERT will cause abort.

Thanks
Tiejun