Re: [Xen-devel] [PATCH v2 00/25] arm/altp2m: Introducing altp2m to ARM.

[Julien Grall <julien.grall@xxxxxxx>]

On 02/08/16 17:00, Tamas K Lengyel wrote:
> On Tue, Aug 2, 2016 at 1:38 AM, Julien Grall <julien.grall@xxxxxxx> wrote:
> Hi Julien,
> as I said our use-case is purely external so I don't have an actual
> use-case for anything being accessible from within the guest. However,
> I could imagine the gfn remapping be used to protect kernel memory
> areas against information disclosure by only switching to the
> accessible mapping
> when certain conditions are met. Also, I had been able to use
> mem_access from domUs with the use of XSM so I believe it would be
> possible for a domain to enable mem_access on itself that way and thus
> not having to implement #VE exactly the way x86 does and still have
> feature parity.
I believe that your suggestion does not currently work. memaccess will 
pause the current vCPU whilst the introspection app will handle the 
access (see p2m_mem_access_check). How can the guest handle the event if 
the vCPU has been paused?
Regards,

--
Julien Grall

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