Re: [Xen-devel] [RFC][PATCH 4/5] tools:firmware:hvmloader: reserve RMRR mappings in e820

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 12.08.14 at 12:56, <tiejun.chen@xxxxxxxxx> wrote:
> On 2014/8/11 14:53, Jan Beulich wrote:
>>>>> On 08.08.14 at 23:47, <kevin.tian@xxxxxxxxx> wrote:
>>>>   From: Chen, Tiejun
>>>> Sent: Thursday, August 07, 2014 4:03 AM
>>>>
>>>> We need to reserve all RMRR mappings in e820 to avoid any
>>>> potential guest memory conflict.
>>>
>>> strictly speaking besides reserving in e820, you should also poke later
>>> MMIO BAR allocations to avoid confliction too. Currently it's relative
>>> to low_mem_pgend, which is likely to be different from host layout
>>> so it's still possible to see a virtual MMIO bar base conflicting to the
>>> RMRR ranges which are supposed to be sparse.
>>
>> Correct. And what's worse: Possible collisions between RMRRs and
>> the BIOS we place into the VM need to be taken care of, which may
>> turn out rather tricky.
> 
> Looks BIOS itself ranges is covered with a e820 entry, so I think the 
> codes to sort all entries can check this thing as well.

Hmm, just like said in the reply sent to patch 3 a minute ago -
please don't mix up the host's and guest's E820 maps.

Jan


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