Re: [PATCH v4 0/7] Static shared memory followup v2 - pt2

["Oleksii K." <oleksii.kurochko@xxxxxxxxx>]

On Tue, 2024-06-11 at 12:35 +0000, Luca Fancellu wrote:
> + Oleksii
> 
> > On 24 May 2024, at 13:40, Luca Fancellu <Luca.Fancellu@xxxxxxx>
> > wrote:
> > 
> > This serie is a partial rework of this other serie:
> > https://patchwork.kernel.org/project/xen-devel/cover/20231206090623.1932275-1-Penny.Zheng@xxxxxxx/
> > 
> > The original serie is addressing an issue of the static shared
> > memory feature
> > that impacts the memory footprint of other component when the
> > feature is
> > enabled, another issue impacts the device tree generation for the
> > guests when
> > the feature is enabled and used and the last one is a missing
> > feature that is
> > the option to have a static shared memory region that is not from
> > the host
> > address space.
> > 
> > This serie is handling some comment on the original serie and it is
> > splitting
> > the rework in two part, this first part is addressing the memory
> > footprint issue
> > and the device tree generation and currently is fully merged
> > (
> > https://patchwork.kernel.org/project/xen-devel/cover/20240418073652.3622828-1-luca.fancellu@xxxxxxx
> > /),
> > this serie is addressing the static shared memory allocation from
> > the Xen heap.
> > 
> > Luca Fancellu (5):
> >  xen/arm: Lookup bootinfo shm bank during the mapping
> >  xen/arm: Wrap shared memory mapping code in one function
> >  xen/arm: Parse xen,shared-mem when host phys address is not
> > provided
> >  xen/arm: Rework heap page allocation outside allocate_bank_memory
> >  xen/arm: Implement the logic for static shared memory from Xen
> > heap
> > 
> > Penny Zheng (2):
> >  xen/p2m: put reference for level 2 superpage
> >  xen/docs: Describe static shared memory when host address is not
> >    provided
> > 
> > docs/misc/arm/device-tree/booting.txt   |  52 ++-
> > xen/arch/arm/arm32/mmu/mm.c             |  11 +-
> > xen/arch/arm/dom0less-build.c           |   4 +-
> > xen/arch/arm/domain_build.c             |  84 +++--
> > xen/arch/arm/include/asm/domain_build.h |   9 +-
> > xen/arch/arm/mmu/p2m.c                  |  82 +++--
> > xen/arch/arm/setup.c                    |  14 +-
> > xen/arch/arm/static-shmem.c             | 432 +++++++++++++++++----
> > ---
> > 8 files changed, 502 insertions(+), 186 deletions(-)
> > 
> > -- 
> > 2.34.1
> > 
> > 
> 
> Hi,
> 
> We would like this serie to be in Xen 4.19, there was a
> misunderstanding on our side because we thought
> that since the serie was sent before the last posting date, it could
> have been a candidate for merging in the
> new release, instead after speaking with Julien and Oleksii we are
> now aware that we need to provide a
> justification for its presence.
> 
> Pros to this serie is that we are closing the circle for static
> shared memory, allowing it to use memory from
> the host or from Xen, it is also a feature that is not enabled by
> default, so it should not cause too much
> disruption in case of any bugs that escaped the review, however we’ve
> tested many configurations for that
> with/without enabling the feature if that can be an additional value.
> 
> Cons: we are touching some common code related to p2m, but also there
> the impact should be minimal because
> the new code is subject to l2 foreign mapping (to be confirmed maybe
> from a p2m expert like Julien).
> 
> The comments on patch 3 of this serie are addressed by this patch:
> https://patchwork.kernel.org/project/xen-devel/patch/20240528125603.2467640-1-luca.fancellu@xxxxxxx/
> And the serie is fully reviewed.
> 
> So our request is to allow this serie in 4.19, Oleksii, ARM
> maintainers, do you agree on that?
Considering that it is not enabled by default and affect on common code
is minimal we should consider this patch series in 4.19:
 Release-Acked-by: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>

~ Oleksii