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 17:56:02 +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 17:41, Jan Beulich wrote:
>>>> On 24.07.14 at 10:28, <tiejun.chen@intel.com> wrote:
>> 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.
>
> Then tell me the scenario where iommu_use_hap_pt(d) is true and
> both iommu_passthrough and is_hardware_domain(d) are true too.

Then HVM?

Anyway I did a test like this,

	if (iommu_use_hap_pt(d))
	{
		ASSERT (iommu_passthrough && is_hardware_domain(d));

Then Xen really reboot.

Thanks
Tiejun

> Remember that for Dom0 iommu_use_hap_pt() can be true only for
> PVH, and PVH implies !iommu_passthrough.
>
> Jan
>
>
>