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


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?

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?


Julien Grall

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