Re: [Xen-devel] [PATCH v1] Fix p2m_set_suppress_ve

[Razvan Cojocaru <rcojocaru@xxxxxxxxxxxxxxx>]

On 4/3/19 7:16 PM, Tamas K Lengyel wrote:
> It is right to fully populate a slot when for example we want
> different mem_access permissions in different altp2m views. We can't
> wait for the domain to on-demand populate the altp2m view because we
> don't know when (and if) that will actually happen. So
> p2m_set_altp2m_mem_access already copies the entry over from the
> hostp2m to the altp2m and then applies the requested mem_access
> setting. This is done even if the mem_access setting is the same as it
> was in the hostp2m.
> 
> Doing the same behavior for p2m_set_suppress_ve I think is consistent,
> albeit you could easily overcome the issue by first simply setting a
> mem_access permission on the gfn to trigger the aforementioned copy to
> the altp2m before you try to set the ve settings.

That's what we're doing now, but it wasn't at all intuitive to figure it
out. I'd expect that setting the SVE bit simply works without
maneuvering something else in place first.


Thanks,
Razvan

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