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RE: [PATCH] VMX: use a single, global APIC access page
- To: Jan Beulich <jbeulich@xxxxxxxx>, "Cooper, Andrew" <andrew.cooper3@xxxxxxxxxx>
- From: "Tian, Kevin" <kevin.tian@xxxxxxxxx>
- Date: Mon, 1 Mar 2021 02:08:48 +0000
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- Cc: Julien Grall <julien@xxxxxxx>, Wei Liu <wl@xxxxxxx>, Roger Pau Monné <roger.pau@xxxxxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxxx>
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- Thread-topic: [PATCH] VMX: use a single, global APIC access page
> From: Jan Beulich <jbeulich@xxxxxxxx>
> Sent: Thursday, February 11, 2021 1:04 AM
>
> On 10.02.2021 18:00, Andrew Cooper wrote:
> > On 10/02/2021 16:48, Jan Beulich wrote:
> >> The address of this page is used by the CPU only to recognize when to
> >> instead access the virtual APIC page instead. No accesses would ever go
> >> to this page. It only needs to be present in the (CPU) page tables so
> >> that address translation will produce its address as result for
> >> respective accesses.
> >>
> >> By making this page global, we also eliminate the need to refcount it,
> >> or to assign it to any domain in the first place.
> >>
> >> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
> >
> > How certain are you about this?
>
> The documentation (I'm inclined to say: unexpectedly) is very
> clear about this; I don't think it had been this clear back at
> the time. I'm hoping for Kevin to shout if he's aware of issues
> here.
>
No, I didn't see an issue here.
Thanks
Kevin
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