Re: [PATCH for-4.19 v3 0/3] xen/x86: support foreign mappings for HVM/PVH

[Jan Beulich <jbeulich@xxxxxxxx>]

On 17.05.2024 15:33, Roger Pau Monne wrote:
> Hello,
> 
> The following series attempts to solve a shortcoming of HVM/PVH guests
> with the lack of support for foreign mappings.  Such lack of support
> prevents using PVH based guests as stubdomains for example.
> 
> Add support in a way similar to how it's done on Arm, by iterating over
> the p2m based on the maximum gfn.
> 
> Patch 2 is not strictly needed.  Moving the enablement of altp2m from an
> HVM param to a create domctl flag avoids any possible race with the HVM
> param changing after it's been evaluated.  Note the param can only be
> set by the control domain, and libxl currently sets it at domain
> create.  Also altp2m enablement is different from activation, as
> activation does happen during runtime of the domain.
> 
> Thanks, Roger.
> 
> Roger Pau Monne (3):
>   xen/x86: account number of foreign mappings in the p2m
>   xen/x86: enable altp2m at create domain domctl
>   xen/x86: remove foreign mappings from the p2m on teardown

Here, too, I'd like to ask whether to keep this as a candidate for 4.19, or
whether to postpone. Afaict what's still missing are Arm and tool chain acks
on patch 2.

Jan

>  CHANGELOG.md                        |  1 +
>  tools/libs/light/libxl_create.c     | 23 +++++++++-
>  tools/libs/light/libxl_x86.c        | 26 +++++------
>  tools/ocaml/libs/xc/xenctrl_stubs.c |  2 +-
>  xen/arch/arm/domain.c               |  6 +++
>  xen/arch/x86/domain.c               | 28 ++++++++++++
>  xen/arch/x86/hvm/hvm.c              | 23 +++++++++-
>  xen/arch/x86/include/asm/p2m.h      | 32 +++++++++-----
>  xen/arch/x86/mm/p2m-basic.c         | 18 ++++++++
>  xen/arch/x86/mm/p2m.c               | 68 +++++++++++++++++++++++++++--
>  xen/include/public/domctl.h         | 20 ++++++++-
>  xen/include/public/hvm/params.h     |  9 +---
>  12 files changed, 215 insertions(+), 41 deletions(-)
>