Re: [Xen-devel] [PATCH] mem_access: Use monitor_traps instead of mem_access_send_req

[Julien Grall <julien.grall@xxxxxxx>]

Hello Tamas,

On 29/07/16 23:26, Tamas K Lengyel wrote:
> However, as this patch really only touches
> things that belong to mem_access/monitor components maybe we should
> split these from the generic ARM code altogether to avoid such
> conflicts in the future.
I am not against moving part of mem_access outside of the P2M. However, 
the ARM (32-bit and 64-bit) code needs a lot more attention to make it 
work in *all* the case. I was able to break memaccess quite easily on 
various platform (include models).
For instance p2m_mem_access_check_and_get_page is using the hardware to 
translate a VA to an IPA. This only works if the memory where the 
stage-1 page tables reside is not protected. The upcoming support of 
altp2m will make things trickier.
The interface of p2m_mem_access_check_and_get_page should also be 
updated to take a VCPU in parameter.
Lastly getting/setting access in the the mem_access_settings radix tree 
should stay in the p2m code as it is tight to stage-2 page table 
implementation.
Regards,

--
Julien Grall

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