RE: [Xen-ia64-devel] [PATCH]Fix the logic when deassign the mmio ranges for vti-domain.

["Zhang, Xiantao" <xiantao.zhang@xxxxxxxxx>]

Isaku Yamahata wrote:
> On Wed, Mar 04, 2009 at 05:26:41PM +0800, Zhang, Xiantao wrote:
>> So far, we just found the msi-x case. Maybe we will add msi-x
>> support later, so this fix is also required. 
> 
> Okay, makes sense.
> 
>>>>> And why GPFN_LOW_MMIO independently of addr? Shouldn't it be aware
>>>>> of io_ranges[]?
>>>> 
>>>> For the low mmio ranges (3G-3.5G), we can use the fixed mfn
>>>> GPFN_LOW_MMIO combined with ASSIGN_io to indicate whether the p2m
>>>> entries are mmio ranges.   You may refer to io_ranges and it also
>>>> use the fixed GPFN_LOW_MMIO to intialize p2m entries for low mmio
>>>> range.
>>> 
>>> Hmm, there are two cases to call
>>> xc_domain_mempry_mapping(DPCI_REMOVE_MAPPING). - Just to remove the
>>>   entry. zap_domain_page_one() is wanted.
>> 
>> Why remove the entries ?  For hvm domain, I think the entires should
>> always exists during the lift of the guests. 
>> You may refer to the call vmx_build_io_physmap_table, and these
>> entries are created at the initialization time of the domain. 
>> 
>>>   the one in pt_iomem_map() and remove_msix_mapping() excpet called
>>>   by pt_iomem_map()
>> 
>>> 
>>> - mmio on the area should be rounted to qemu-dm
>>>   GPFN_LOW_MMIO and ASSIGN_io are wanted.
>>> 
>>>   remove_msix_mapping() which is called by pt_iomem_map().
>>> 
>>> Is there a way to distinguish them.
>> 
>> We don't need to distinguish them, and instead of we should keep
>> these entires in two cases consistent with the values which is
>> initilized by vmx_build_io_physmap_table.  
> 
> The current x86 implementation mmio which isn't handled by xen VMM
> are passed to qemu-dm.
> On the other hand, the current xen/ia64 check _PAGE_IO and
> if _PAGE_IO it is passed to qemu-dm, otherwise panic_domain()
> So the behaviour should be changed such that if load/store on
> the unpresent p2m entry is passed to qemu-dm like x86. 

That may change much logic.  For hvm/ia64, we have the assumption that all p2m 
entries  for mmio range should exist, and use the
_PAGE_IO to identify its type. 

Xiantao



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