Re: [PATCH V7] x86/altp2m: Hypercall to set altp2m view visibility

[Jan Beulich <jbeulich@xxxxxxxx>]

On 30.03.2020 08:54, Alexandru 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().
> 
> The usage of this hypercall is aimed at dom0 having a logic with a number of 
> views
> created and at some time there is a need to be sure that only some of the 
> views
> can be switched, saving the rest and making them visible when the time
> is right.
> 
> 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>

For v6 I did provide a hypervisor side R-b; I didn't think ...

> Changes since V6:
>       - Update commit message.

... this alone would have warranted to drop it?

Jan