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

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

>Please find below a POC patch that includes pausing and unpausing the
>domain during the Xen writes to guest memory. I have it on top of the patch
>that was using CR0.WP to highlight the difference. Please take a look and let
>me know if this solution is acceptable.
>>
>> PS: I do realize whatever I do to create_bounce_frame() will have to be
>reflected in the compat version. If this is correct approach I will do the same
>there too.
>>
>> Thanks,
>> Aravindh
>
>I am concerned with the addition of a the vcpu specifics to
>shadow_write_entries().  Most of the shadow code is already vcpu centric
>where it should be domain centric, and steps are being made to alleviate
>these problems.  

All the call sites of shadow_write_entries() are vcpu specific which I why I 
thought it was OK to extend this to shadow_write_entries(). What are the steps 
being taken to alleviate the problems? Maybe I can piggy back on them?

>Any access in from a toolstack/device model hypercall
>will probably be using vcpu[0], which will cause this logic to be
>applied in an erroneous context.

If the access from a toolstack/device model hypercall causes a Xen write to 
guest memory, it will be recorded for vcpu[0]. So won't it be ok?

Thanks,
Aravindh


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