Re: [Xen-devel] [PATCH v2 00/55] Switch to domheap for Xen PTEs

[Wei Liu <wl@xxxxxxx>]

On Mon, Sep 30, 2019 at 11:32:52AM +0100, Hongyan Xia wrote:
> This series is mostly Wei's effort to switch from xenheap to domheap for
> Xen page tables. In addition, I have also merged several bug fixes from
> my "Remove direct map from Xen" series [1]. As the title suggests, this
> series switches from xenheap to domheap for Xen PTEs.
> 
> This is needed to achieve the ultimate goal of removing the
> always-mapped direct map from Xen. To work without an always-mapped
> direct map, Xen PTE manipulations themselves must not rely on it.
> Unfortunately, PTE APIs currently use the xenheap that does not work
> without the direct map. By switching to domheap APIs, it is much easier
> for us to break the reliance on the direct map later on, not only for
> PTEs but for all other memory allocations as well.
> 
> I have broken down the direct map removal series into two. This series
> is the first batch. The patches change the life cycle of Xen PTEs from
> alloc-free to alloc-map-unmap-free, which means PTEs must be explicitly
> mapped and unmapped. This also makes sense to be the first batch from a
> stability PoV, since this is just an API change and the direct map has
> not been actually removed. Further, the map and unmap in the release
> build use the direct map as a fast path, so there is also no performance
> degredation in a release build.
> 
> I have tested both debug and release build on bare-metal and nested
> virtualisation. I am able to run PV and HVM guests and XTF tests without
> crashes so far on x86. I am able to build on AArch64.
> 
> This series is at https://xenbits.xen.org/git-http/people/hx242/xen.git,
> xen_pte_map branch.
> 
> ---
> Changed since v1:
> - squash some commits
> - merge bug fixes into this first batch
> - rebase against latest master

FYI in the future it is better to rebase against staging.

Wei.

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