Re: [Xen-devel] Is this a data corruption bug for p2m_ram_shared page in hvm_hap_nested_page_fault()

[Tim Deegan <tim@xxxxxxx>]

At 18:25 +0800 on 02 Feb (1328207143), nai.xia wrote:
> On 2012???02???02??? 18:17, nai.xia wrote:
> >In hvm_hap_nested_page_fault(), it seems that all valid write faults are 
> >now handled
> >by p2m_mem_access_check(), right? Then when will mem_sharing_unshare_page()
> >be called? And if p2m->access_required == false, the access restrictions 
> >is cleared
> 
> Oh, sorry, I notice that with p2m_ram_shared, the write permissions is
> always cleared.  But, still, this seems cannot lead to the call of
> mem_sharing_unshare_page() and this write fault will happen again and
> again?

There's an explicit call of mem_sharing_unshare_page() in
hvm_hap_nested_page_fault(); the only thing that will skip that is if
the fault is caused by a p2m_access violation, in which case 
we report the fault on the p2m_access ring and wait for the consumer of
that ring to fix the problem. 

Cheers,

Tim.

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