Re: [Xen-devel] [PATCH] x86/EPT: defer enabling of A/D maintenance until PML get enabled

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 14.10.15 at 11:08, <kai.huang@xxxxxxxxxxxxxxx> wrote:
> After some thinking, just set/clear p2m->ept.ept_ad is not enough -- we 
> also need to __vmwrite it to VMCS's EPTP, and then call ept_sync_domain. 

Ah, yes, this makes sense of course.

> I have verified attached patch can work.

Thanks!

> Which implementation would you prefer, existing code or with attached 
> patch? If you prefer the latter, please provide comments.

I think it's marginal whether to flip the bit in ept_{en,dis}able_pml()
or vmx_domain_{en,dis}able_pml(); the former would seem slightly
more logical.

There's one possible problem with the patch though: Deferring the
sync from the vcpu to the domain function is fine when the domain
function is the caller, but what about the calls out of vmx.c? The
calls look safe as the domain isn't running (yet or anymore) at that
point, but the respective comments may need adjustment (and
the disable one should also refer to vmx_domain_disable_pml()),
in order to avoid confusing future readers. Also you'd need to fix
coding style of these new comments.

Jan


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