Re: [Xen-ia64-devel] PV-on-HVM driver for IPF

[Doi.Tsunehisa@xxxxxxxxxxxxxx]

Hi,

You (Tristan.Gingold) said:
>>>>   I will post patches of PV-on-HVM for IPF.
>>>>
>>>>   We wrote the patch under this consideration:
>>>>
>>>>    * Expand hvm_op hypercall
>>>>      + Introduce HVMOP_setup_shared_info_page
>>>>        - A page allocated on HVM-guest OS is swapped original
>>>> shared_info page with this hypercall.
>>>>        - In x86 code, original shared_info page is used after pv-on-hvm
>>>>          setup with remapping feature in arch depend
>>>> HYPERVISOR_memory_op. But, we can't implement same feature for IPF, thus
>>>> we select to implement with this method.
>>>
>>> Can you explain why you can't reuse the HYPERVISOR_memory_op hcall ?
>>> It isn't clear for me.
>>
>>   In x86 code (xen/arch/x86/mm.c), it uses only virtual space of page frame
>> allocated by GuestOS, and remaps the vitual space to original share_info
>> page frame. But, we can't find same method for IPF.
>>
>>   Can you suggest us about the remapping method ?
> I simply wonder why did you create a new hypercall.  You could have reuse the 
> same hypercall, using a slighly different semantic.  But it doesn't really 
> matter.

  I think that the functions which have diffect semantic should be called
with the different names.

>>> +            if (likely(IS_XEN_HEAP_FRAME(virt_to_page(pgaddr)))) {
>>> +                free_domheap_page(virt_to_page(pgaddr));
>>> +                free_xenheap_page((void *)pgaddr);
>>> +            }
>>> +            else {
>>> +                put_page(virt_to_page(pgaddr));
>>> +            }
>>> May create a function to be called by gnttab_setup_table and
>>> setup_shared_info_page.
>>
>>   I think that these function are for only VT-i domain, thus I used
>> vmx_ prefix. What do you think about it ?
> Sorry I was not clear enough.
> This block appears in both function.  I'd suggest to create a function to 
> avoid duplicating code.

  Sorry, I had misunderstood your suggestion.

  I agree. I'll correct it.

Thanks,
-- Tsunehisa Doi

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