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

[Tamas K Lengyel <tamas.k.lengyel@xxxxxxxxx>]

On Wed, Apr 3, 2019 at 11:08 AM Razvan Cojocaru
<rcojocaru@xxxxxxxxxxxxxxx> wrote:
>
> 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.

Yeap, makes sense to me :)

Tamas

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