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

[Kai Huang <kai.huang@xxxxxxxxxxxxxxx>]

Hi Jan,

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. 
I have verified attached patch can work.
Which implementation would you prefer, existing code or with attached 
patch? If you prefer the latter, please provide comments.
Thanks,
-Kai

On 10/14/2015 09:19 AM, Kai Huang wrote:
> Hi Jan,
>
> Our QA tested this patch but this patch broke PML. Neither GUI display 
> (video ram tracking also uses PML) nor live migration works. I'll 
> investigate what's wrong and get back to you.
> Thanks,
> -Kai
>
> On 09/30/2015 08:45 PM, Kai Huang wrote:
> > On Wed, Sep 30, 2015 at 5:54 PM, Jan Beulich <JBeulich@xxxxxxxx> wrote:
> > > > > > On 30.09.15 at 10:58, <kaih.linux@xxxxxxxxx> wrote:
> > > > Good to me, if you have tested it. Sorry I cannot test it as I am
> > > > taking vacation  until Oct.8.
> > > Note how I asked for help with testing ...
> > >
> > > > On Mon, Sep 28, 2015 at 10:42 PM, Jan Beulich <JBeulich@xxxxxxxx> 
> > > > wrote:
> > > > > There's no point in enabling the extra feature for every domain when
> > > > > we're not meaning to use it (yet). Just setting the flag should be
> > > > > sufficient - the domain is required to be paused for PML enabling
> > > > > anyway, i.e. hardware will pick up the new setting the next time
> > > > > each vCPU of the guest gets scheduled.
> > > > >
> > > > > Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
> > > > > Cc: Kai Huang <kai.huang@xxxxxxxxxxxxxxx>
> > > > > ---
> > > > > VT-x maintainers, Kai: Me lacking the hardware to test this, may I 
> > > > > ask
> > > > > for your help here?
> > > ... here. This patch can certainly wait until you get back from
> > > vacation.
> > Thanks. I'll test it or ask someone has machine to test it after I 
> > get back.
> > Thanks,
> > -Kai
> > > Jan
>
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Attachment: 0001-x86-ept-defer-enabling-EPT-A-D-bit-until-PML-is-enab.patch
Description: Text Data

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