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Re: [PATCH for-4.22 v2 0/2] xen/arm: validate hwdom first bank boot placement
- To: "Orzel, Michal" <michal.orzel@xxxxxxx>, Mykola Kvach <xakep.amatop@xxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxxx
- From: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>
- Date: Fri, 5 Jun 2026 10:26:28 +0200
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- Cc: Mykola Kvach <mykola_kvach@xxxxxxxx>, Stefano Stabellini <sstabellini@xxxxxxxxxx>, Julien Grall <julien@xxxxxxx>, Bertrand Marquis <bertrand.marquis@xxxxxxx>, Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>, Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, Anthony PERARD <anthony.perard@xxxxxxxxxx>, Jan Beulich <jbeulich@xxxxxxxx>, Roger Pau Monné <roger.pau@xxxxxxxxxx>
- Delivery-date: Fri, 05 Jun 2026 08:26:45 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On 6/5/26 10:03 AM, Orzel, Michal wrote:
On 05-Jun-26 10:00, Oleksii Kurochko wrote:
Hello Mykola,
On 6/5/26 7:19 AM, Mykola Kvach wrote:
From: Mykola Kvach <mykola_kvach@xxxxxxxx>
Just out of curiosity, is it okay that the email address listed here
differs from the one you're using to send patches? (By the way, nice
email address ;))
With LLC coloring enabled, the hardware domain memory is allocated by
allocate_hwdom_memory() instead of relying on the fixed direct-map
layout. Since de99f3263555 ("device-tree: Improve hwdom memory
allocation for DMA"), the allocator prefers lower host regions, but the
first-bank filter still only enforces the old 128MB heuristic.
A low candidate bank can satisfy that heuristic while still being
unsuitable for the Arm kernel/DTB/initrd placement rules. Split the Arm
placement logic into reusable helpers first, then validate the candidate
hardware-domain bank 0 against those helpers before allocating it.
Changes in v2:
- Split the previous single patch into a behavior-preserving Arm
placement refactoring and a separate hardware-domain first-bank fix.
- Rename find_module_placement() and place_modules() to use DTB/initrd
terminology.
- Pass ramend to find_dtb_initrd_placement().
- Update the stale tools/libs/guest/xg_dom_arm.c reference.
Link to v1:
https://patchew.org/Xen/4f862bb2dc323914b8120b0f16af7516140cf42b.1780065103.git.mykola._5Fkvach@xxxxxxxx/
I would like to clarify whether my understanding is correct.
With LLC coloring enabled on ARM, the allocator could assign the
hardware domain a bank 0 that passes the size check but is unsuitable
for kernel/DTB/initrd placement. As a result, the hardware domain may
fail to boot or could silently corrupt memory if the images are placed
in an incorrect location.
Is my understanding correct?
Yes, Xen would fail to boot such domain. On Arm we carry a lot of placement
logic we need to deal with...
Thanks for confirming. Then for this patch series:
Release-Acked-by: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>
~ Oleksii
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