Re: [Xen-devel] [RFC PATCH 00/84] Remove direct map from Xen

[Julien Grall <julien.grall@xxxxxxx>]

Hi,

On 9/26/19 11:33 AM, hongyax@xxxxxxxxxx wrote:
> On 26/09/2019 11:21, Julien Grall wrote:
> > Hi,
> >
> > Thank you for posting the series.
> >
> > On 9/26/19 10:45 AM, hongyax@xxxxxxxxxx wrote:
> > > From: Hongyan Xia <hongyax@xxxxxxxxxx>
> > >
> > > Previously, Wei Liu has created the patch series to switch to
> > > alloc/map/unmap/free APIs for Xen page tables so that Xen page tables
> > > are mapped with map_domain_page(). This is the first step towards
> > > removing the direct map. I implemented patches on top of Wei's to remove
> > > the direct map completely.
> > >
> > > In addition to Wei's, my patches:
> > > - (Wei) implement a proper PMAP infrastructure for bootstrapping
> > > - remove direct map code in map_domain_page() and use mapcache, use PMAP
> > >   when mapcache not ready
> > > - map/unmap xenheap allocations to the direct map region so that va<->pa
> > >   macros still work
> > > - install dummy mappings (no permissions, INVALID_MFN) instead of actual
> > >   1:1 mappings during boot, so the direct map no longer exists
> > > - fix many places where code incorrectly assumes a direct map
> > I am a bit confused. Are your patches fixing bug from Wei's series?
> The goal is to remove the direct map completely from Xen. Wei's series 
> has done the first step but was not complete. My additional patches 
> finished the remaining steps and removed the direct map.
So I understand this correctly, Wei's series has no bug in it and could 
be committed as is without breaking Xen. Am I correct?
The reason I am asking that if you have a few patches that say fix 
leak/bug. If they are bug in Wei's series, then they should be squashed 
in patches introducing them.
> > > I have moderately tested the patches. I am able to boot into dom0,
> > > create/destroy PV/HVM guests and run XTF tests. Personally, I find it
> > > difficult to discover all places where it incorrectly assumes a direct
> > > map, so reviews and further testing are more than welcome.
> > Do you have a branch with this series applied?
> I am setting this up. Will send out the link to the branch soon.
Thank you.

Cheers,

--
Julien Grall

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