Re: [Xen-devel] [PATCH v3 1/2] x86/mm: Change default value for suppress #VE in set_mem_access()

[George Dunlap <George.Dunlap@xxxxxxxxxxxxx>]

On Wed, Jul 19, 2017 at 7:24 PM, Tamas K Lengyel <tamas@xxxxxxxxxxxxx> wrote:
>> I think the issue would be whether to allow a domain to set/clear the
>> suppress #VE bit for its pages by calling the new HVMOP on itself.
>
> This problem is not limited to setting the SVE bit. It also applies to
> swapping altp2m views. Pretty much all altp2m HVMOPs can be issued
> from a user-space program without any way to check whether that
> process is allowed to do that or not. If you don't think it is safe
> for a domain to set SVE, the none of the altp2m ops are safe for the
> domain to issue on itself. If we could say ensure only the kernel can
> issue the hvmops, that would be OK. But that's not possible at the
> moment AFAICT.

Wait, is that right?  I think we normally restrict hypercalls to only
being made from the guest kernel, don't we?

 -George

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