Re: [Xen-devel] [PATCH RFC v2 1/4] x86/mm: Shadow and p2m changes for PV mem_access

["Aravindh Puthiyaparambil (aravindp)" <aravindp@xxxxxxxxx>]

>>>> Good point. The only other thing I can think of to get around this
>>>> issue is to pause the domain during these writes and unpause it on the
>>>> way out of the guest access functions.
>>>
>>>If that's tolerable guest-performance-wise...
>>
>> It would be for the use cases we. The performance hit would only be for
>> users who want to watch for writes to memory that is shared between Xen
>and
>> the guest. Given that which variant would you prefer between the CR0.WP
>and
>> pagetable methods?
>
>Since the page table one has the overall smaller window of reduced
>protection, I think I'd prefer that one. However, judging the overhead
>acceptability by just the specific use case you have is perhaps
>insufficient for including your changes in the public tree, especially
>with no clear perspective of how to reduce it if someone indeed cared.

I am a little lost by your statement about specific use case. People using 
mem_access typically use it for security and guest inspection purposes. They 
are aware of the performance hits that come along with that. Given that use 
case, would you please reconsider including these changes? Or were you talking 
about other use cases?

Aravindh


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