Re: [Xen-devel] [PATCH V6] x86/altp2m: Hypercall to set altp2m view visibility

[Jan Beulich <jbeulich@xxxxxxxx>]

On 03.03.2020 13:23, Alexandru Stefan ISAILA wrote:
> At this moment a guest can call vmfunc to change the altp2m view. This
> should be limited in order to avoid any unwanted view switch.
> 
> The new xc_altp2m_set_visibility() solves this by making views invisible
> to vmfunc.
> This is done by having a separate arch.altp2m_working_eptp that is
> populated and made invalid in the same places as altp2m_eptp. This is
> written to EPTP_LIST_ADDR.
> The views are made in/visible by marking them with INVALID_MFN or
> copying them back from altp2m_eptp.
> To have consistency the visibility also applies to
> p2m_switch_domain_altp2m_by_id().
> 
> Note: If altp2m mode is set to mixed the guest is able to change the view
> visibility and then call vmfunc.
> 
> Signed-off-by: Alexandru Isaila <aisaila@xxxxxxxxxxxxxxx>

Hypervisor parts
Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>

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