RE: [Xen-ia64-devel] a potential issue in set/get-rse-reg function

["Xu, Anthony" <anthony.xu@xxxxxxxxx>]

>As far as I know, existing processor implementations (i.e. Itanium 1
>& Itanium 2) only implement lazy mode.  Is this no longer true...?
Sorry, I don't know the answer, the Montecito I used only implement lazy mode 
from the result of pal call(RSE_INFO), but for software implementation, we must 
support eager mode.

>-----Original Message-----
>From: Matt Chapman [mailto:matthewc@xxxxxxxxxxxxxxx]
>Sent: 2005年9月13日 17:38
>To: Xu, Anthony
>Cc: Magenheimer, Dan (HP Labs Fort Collins);
>xen-ia64-devel@xxxxxxxxxxxxxxxxxxx
>Subject: Re: [Xen-ia64-devel] a potential issue in set/get-rse-reg function
>
>Anthony,
>
>As far as I know, existing processor implementations (i.e. Itanium 1
>& Itanium 2) only implement lazy mode.  Is this no longer true...?
>
>Matt
>
>
>On Tue, Sep 13, 2005 at 05:07:36PM +0800, Xu, Anthony wrote:
>> Dan,
>>
>> In current implementation, Guest stack register of current guest
>> function can be saved in hypervisor backing store or/and guest backing
>> store, if some saved in guest backing store, set/get-rse-reg will
>> directly access guest backing store, at this time, tlb miss may happen.
>> But tlb miss handler only search guest vhpt not guest page table, that
>> means it is possible hypervisor can't handle this tlb miss and inject
>> tlb miss to guest kernel, at this situation, I think hypervisor can't
>> inject tlb miss to guest kernel.
>> One explicit solution is in ivt.S set rse to lazy mode before do 'cover'
>> to make sure guest stack register of current guest function are all
>> saved in hypervisor backing store. Yes this solution will penalize
>> performance, but just a little, because there are only about ten
>> assembly instructions between 'cover' and 'mov ar.rse=0' in current
>> implementation.
>> What's your opinion?
>>
>> Thanks
>> Anthony.
>>
>> _______________________________________________
>> Xen-ia64-devel mailing list
>> Xen-ia64-devel@xxxxxxxxxxxxxxxxxxx
>> http://lists.xensource.com/xen-ia64-devel

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