Xen 4.21 Development Update [June-July]

[Oleksii Kurochko]

Hello everyone,

This email only tracks big items for xen.git tree. Please reply for 
items you
would like to see in 4.21 so that people have an idea what is going on and
prioritise accordingly.
You're welcome to provide description and use cases of the feature you're
working on.

= Timeline =

The current release schedule could be found here:
  https://wiki.xenproject.org/wiki/Xen_Project_X.YY_Release_Notes

And as a reminder I would like to remind at the of this week we will have
Last posting date (Fri Aug 08, 2025).

= Updates =

The following items ( the links for them could be found int the list below )
were moved to completed:
  [since Jun2 - Aug5]:
   Added some tags: [4.21], [next-rel(s)] to the list "Full list of items"
   below.
   * x86:
    - kexec: add kexec support to Mini-OS.
    - x86: memcpy() / memset() (non-)ERMS flavors plus fallout
   * Arm:
    - SMMU handling for PCIe Passthrough on ARM.
    - Add support for R-Car Gen4 PCI host controller.
    - First chunk for Arm R82 and MPU support.
    - Enable R52 support for the first chunk of MPU support
    - ARM split hardware and control domains.
   * RISC-V:
    - Introduce basic UART support and interrupts for hypervisor mode.

  [since May 6 - Jun2]:
    * Hypervisor:
      - tools: remove qemu-traditional
    * Arm:
      - PCI devices passthrough on Arm, part 3
    * x86:
      - xen: cache control improvements
  [since 4.20 relese - May 6]:
    * Hypervisor:
      - Move parts of Arm's Dom0less to common code
      - remove libxenctrl usage from xenstored
    * Arm:
      - Enable early bootup of Armv8-R AArch32 systems
    * x86:
      - x86/HVM: emulation (MMIO) improvements
    * RISC-V:
      - RISC-V some preinit calls.
      - Fixes for UBSAN & GCOV support for RISC-V.

Some new items added:
 [since May]
    * x86:
     - Allow x86 to unflatten DTs
     - hyperlaunch: move remaining pvh dom0 construction
     - x86/hyperlaunch: introduce concept of core domains
     - Confidential computing and AMD SEV support
    * Arm:
     - SMMU handling for PCIe Passthrough on ARM
     - xen/arm: scmi: introduce SCI SCMI SMC multi-agent support
     - Add initial Xen Suspend-to-RAM support on ARM64
    * RISC-V:
     - introduce p2m functionality
 [since 4.20 release]
    * Hypervisor:
      - tools: remove qemu-traditional
      - Physical address hypercall ABI ("HVMv2")
      - xen: Untangle mm.h
      - xen: introduce CONFIG_SYSCTL
      - Add support for exact-node memory claims
      - Several CI cleanups and improvements, plus yet another new runner
    * x86:
      - x86/EFI: prevent write-execute sections
      - x86: Trenchboot Secure Launch DRTM (Xen)
      - Hyperlaunch device tree for dom0 (v6)
      - amd-cppc CPU Performance Scaling Driver (v4)
      - Hyperlaunch domain builder
      - kexec: add kexec support to Mini-OS
      - xen: cache control improvements (should be moved to "Hypervisor"?)
      - x86: generate xen.efi image with no write-execute sections
      - x86/asm: cleanups after toolchain baseline upgrade
    * Arm:
      - Add support for R-Car Gen4 PCI host controller (v4)
      - FF-A VM to VM support (v5)
      - First chunk for Arm R82 and MPU support (v4)
      - ARM split hardware and control domains (v5)
      - MPU mm subsistem skeleton
    * RISC-V:
      - introduce basic UART support and interrupts for hypervisor mode

* Full list of items : *

= Projects =

== Hypervisor ==

* [4.21] xen/console: cleanup console input switch logic (v5)
  - Denis Mukhin
  - 
https://lore.kernel.org/xen-devel/20250530231841.73386-1-dmuk...@ford.com/

* [4.21] xen: introduce CONFIG_SYSCTL (v4 -> v8)
  -  Penny Zheng
  - 
https://lore.kernel.org/xen-devel/20250711043158.2566880-1-penny.zh...@amd.com/

* [4.21] Several CI cleanups and improvements, plus yet another new runner
  - Marek Marczykowski-Górecki
  - 
https://lore.kernel.org/xen-devel/cover.7da1777882774486a13e6f39ff4a2096f6b7901e.1744028549.git-series.marma...@invisiblethingslab.com/
  - 
https://patchew.org/Xen/cover.7da1777882774486a13e6f39ff4a2096f6b7901e.1744028549.git-series.marma...@invisiblethingslab.com/

* [4.21] automation: Refresh the remaining Debian containers (v2)
  -  Javi Merino
  - 
https://lore.kernel.org/xen-devel/cover.1730743077.git.javi.mer...@cloud.com/T/#m5d9acb7cf5db3c2be3d6527de14b69b07812314e

* [4.21] MSI-X support with qemu in stubdomain, and other related 
changes (v8)
  -  Marek Marczykowski-Górecki
  - 
https://lore.kernel.org/xen-devel/cover.33fb4385b7dd6c53bda4acf0a9e91748b3d7b1f7.1715313192.git-series.marma...@invisiblethingslab.com/
  -  Only automation patch left to be reviewed/merged.

* [next-rel(s)] Physical address hypercall ABI ("HVMv2")
  - Teddy Astie
  - 
https://lore.kernel.org/xen-devel/cover.1744981654.git.teddy.as...@vates.tech/

* [next-rel(s)] xen: Untangle mm.h
  -  Andrew Cooper
  - 
https://lore.kernel.org/xen-devel/20250312174513.4075066-1-andrew.coop...@citrix.com/
  - 
https://patchew.org/Xen/20250312174513.4075066-1-andrew.coop...@citrix.com/

* [next-rel(s)] Add support for exact-node memory claims
  -  Alejandro Vallejo
  - 
https://lore.kernel.org/xen-devel/20250314172502.53498-1-alejandro.vall...@cloud.com/
  - 
https://patchew.org/Xen/20250314172502.53498-1-alejandro.vall...@cloud.com/

* [next-rel(s)] Remove the directmap (v5)
  -  Alejandro Vallejo
  - 
https://lore.kernel.org/xen-devel/20250108151822.16030-1-alejandro.vall...@cloud.com/
  - 
https://patchew.org/Xen/20250108151822.16030-1-alejandro.vall...@cloud.com/

* [next-rel(s)] GRUB: Supporting Secure Boot of xen.gz (v1)
  -  Ross Lagerwall
  - 
https://patchew.org/Xen/20240313150748.791236-1-ross.lagerw...@citrix.com/

* [next-rel(s)] Introduce xenbindgen to autogen hypercall structs (v1)
  -  Alejandro Vallejo
  - 
https://patchew.org/Xen/20241115115200.2824-1-alejandro.vall...@cloud.com/

* [next-rel(s)] Introduce NS8250 UART emulator (v2)
  -  Denis Mukhin
  - 
https://patchew.org/Xen/20241205-vuart-ns8250-v1-0-e9aa92312...@ford.com/

* [next-rel(s)] xen: framework for UART emulators
  - Denis Mukhin
  - 
https://lore.kernel.org/xen-devel/20250624035443.344099-1-dmuk...@ford.com/

=== x86 ===
* [4.21] x86/asm: cleanups after toolchain baseline upgrade (v1 -> v2)
  - Denis Mukhin
  - 
https://lore.kernel.org/xen-devel/20250403182250.3329498-1-dmuk...@ford.com/
  - https://patchew.org/Xen/20250403182250.3329498-1-dmuk...@ford.com/

* [4.21?] x86/efi: Fix booting when NX is disabled (v1 -> v2)
  - Andrew Cooper
  - 
https://patchew.org/Xen/20240722101838.3946983-1-andrew.coop...@citrix.com/
  - 
https://lore.kernel.org/xen-devel/20240722101838.3946983-1-andrew.coop...@citrix.com/

* [4.21?] Hyperlaunch device tree for dom0 (v6)
  - Alejandro Vallejo
  - https://patchew.org/Xen/20250429123629.20839-1-agarc...@amd.com/
  - 
https://lore.kernel.org/xen-devel/20250429123629.20839-1-agarc...@amd.com/

*  [4.21?] Boot modules for Hyperlaunch (v9)
  -  Daniel P. Smith
  - 
https://lore.kernel.org/xen-devel/20241115131204.32135-1-dpsm...@apertussolutions.com/
  - 
https://patchew.org/Xen/20241115131204.32135-1-dpsm...@apertussolutions.com/

*  [4.21?] Address Space Isolation FPU preparations (v2->v3)
  -  Alejandro Vallejo
  - 
https://patchew.org/Xen/20250110132823.24348-1-alejandro.vall...@cloud.com/

* [next-rel(s)] Hyperlaunch domain builder
  - Daniel P. Smith
  - 
https://lore.kernel.org/xen-devel/20250515131744.3843-1-dpsm...@apertussolutions.com/

* [next-rel(s)] Confidential computing and AMD SEV support
  - Teddy Astie
  - https://patchew.org/Xen/cover.1747312394.git.teddy.as...@vates.tech/
  - 
https://lore.kernel.org/xen-devel/cover.1747312394.git.teddy.as...@vates.tech/

* [next-rel(s)] amd-cppc CPU Performance Scaling Driver (v5 -> v6)
  - Penny Zheng
  - 
https://lore.kernel.org/xen-devel/20250711035106.2540522-1-penny.zh...@amd.com/

* [next-rel(s)] x86: Trenchboot Secure Launch DRTM (Xen) (v1 -> v3)
  - Sergii Dmytruk
  - https://patchew.org/Xen/cover.1745172094.git.sergii.dmyt...@3mdeb.com/
  - 
https://lore.kernel.org/xen-devel/cover.1748611041.git.sergii.dmyt...@3mdeb.com/

* [next-rel(s)] x86/EFI: prevent write-execute sections
  - Roger Pau Monne <roger....@citrix.com>
  - 
https://lore.kernel.org/xen-devel/20250401130840.72119-1-roger....@citrix.com/

* [next-rel(s)] x86: generate xen.efi image with no write-execute sections
  - Roger Pau Monne
  - 
https://lore.kernel.org/xen-devel/20250318173547.59475-1-roger....@citrix.com/

*  [next-rel(s)] Expose consistent topology to guests (v7)
  -  Alejandro Vallejo
  - 
https://patchew.org/Xen/20241021154600.11745-1-alejandro.vall...@cloud.com/

*  [next-rel(s)] x86/alternatives: Adjust all insn-relative fields (v2)
  -  Andrew Cooper
  - 
https://lore.kernel.org/xen-devel/20241002152725.1841575-1-andrew.coop...@citrix.com/T/#mac2deaea7e02a343210d61887486433d946ad129

*  [next-rel(s)] x86emul: misc additions (v7)
  -  Jan Beulich
  - https://patchew.org/Xen/3a25cd59-e1cb-4bfc-b868-fb11599d2...@suse.com/

*  [next-rel(s)] x86: support AVX10 (v3)
  -  Jan Beulich
  - 
https://lore.kernel.org/xen-devel/516b7f9a-048e-409d-8a4e-89aeb8ffa...@suse.com/
  - https://patchew.org/Xen/516b7f9a-048e-409d-8a4e-89aeb8ffa...@suse.com/

*  [next-rel(s)] VT-d: SATC handling; ATS: tidying (v2)
  -  Jan Beulich
  - https://patchew.org/Xen/64b028be-2197-4951-ae5b-32f9eabfa...@suse.com/

*  [next-rel(s)] x86: parallelize AP bring-up during boot (v1)
  -  Krystian Hebel
  - 
https://lore.kernel.org/xen-devel/cover.1699982111.git.krystian.he...@3mdeb.com/

*  [next-rel(s)] x86/spec-ctrl: IBPB improvements (v4)
  -  Jan Beulich
  - https://patchew.org/Xen/06591b64-2f05-a4cc-a2f3-a74c3c4a7...@suse.com/

*  [next-rel(s)] Move some boot code from assembly to C (v2)
  -  Frediano Ziglio
  - 
https://lore.kernel.org/xen-devel/20241122093358.478774-1-frediano.zig...@cloud.com/
  - 
https://patchew.org/Xen/20241122093358.478774-1-frediano.zig...@cloud.com/

*  [next-rel(s)]amd-pstate CPU Performance Scaling Driver (v1)
  -  Penny Zheng
  - https://patchew.org/Xen/20241203081111.463400-1-penny.zh...@amd.com/
  - 
https://lore.kernel.org/xen-devel/593baee2-9bf1-4db4-86e8-015cae48d...@suse.com/

* [next-rel(s)] x86: adventures in Address Space Isolation
  - Roger Pau Monne <roger....@citrix.com>
  - 
https://lore.kernel.org/xen-devel/20250108142659.99490-1-roger....@citrix.com/

=== ARM ===

* [4.21?] MPU mm subsistem skeleton
  - Luca Fancellu
  - 
https://lore.kernel.org/xen-devel/20250312135258.1815706-1-luca.fance...@arm.com/
  - https://patchew.org/Xen/20250312135258.1815706-1-luca.fance...@arm.com/

* [4.21?] Add initial Xen Suspend-to-RAM support on ARM64 (v4)
  - Mykola Kvach
  - 
https://lore.kernel.org/xen-devel/cover.1748848482.git.mykola_kv...@epam.com/

* [4.21?] xen/arm: scmi: introduce SCI SCMI SMC multi-agent support (->v4)
  - Oleksii Moisieiev
  - 
https://lore.kernel.org/xen-devel/cover.1753184487.git.oleksii_moisie...@epam.com/

* [next-rel(s)] FF-A VM to VM support (v6)
  - Bertrand Marquis <bertrand.marq...@arm.com>
  - 
https://lore.kernel.org/xen-devel/cover.1747925287.git.bertrand.marq...@arm.com/
  - https://patchew.org/Xen/cover.1747925287.git.bertrand.marq...@arm.com/

*  [next-rel(s)] Add Virtio-PCI for dom0less on ARM (v1)
  -  Edgar E. Iglesias
  - 
https://lore.kernel.org/xen-devel/20240924162359.1390487-1-edgar.igles...@gmail.com/T/#mfa148991b9408f223a079d4cef610244d5b04c2b
  - 
https://patchew.org/Xen/20240924162359.1390487-1-edgar.igles...@gmail.com/

*  [next-rel(s)] DOMCTL-based guest magic region allocation for 11 domUs 
(v4)
  -  Henry Wang
  - https://patchew.org/Xen/20240409045357.236802-1-xin.wa...@amd.com/

=== RISCV ===

* [4.21] xen/riscv: introduce p2m functionality (v1->v3)
  - Oleksii Kurochko
  - 
https://lore.kernel.org/xen-devel/cover.1753973161.git.oleksii.kuroc...@gmail.com/T/#t

=== PPC ===

*  Early Boot Allocation on Power (v5)
  -  Shawn Anastasio
  - 
https://lore.kernel.org/xen-devel/cover.1727388925.git.sanasta...@raptorengineering.com/T/#m8cac91a93b56a359fa2d5f08596c4be61dca290d
  - 
https://patchew.org/Xen/cover.1727388925.git.sanasta...@raptorengineering.com/

== Completed ==

=== Hypervisor ===

* tools: remove qemu-traditional
  - Juergen Gross <jgr...@suse.com>
  - https://lore.kernel.org/xen-devel/20250527132035.985-1-jgr...@suse.com/

*  remove libxenctrl usage from xenstored (v8)
  -  Juergen Gross
  - 
https://lore.kernel.org/xen-devel/20250204113407.16839-1-jgr...@suse.com/

* xen/config.h: Move BITS_PER_* definitions from asm/config.h to 
xen/config.h
  - Oleksii Kurochko
  - 
https://lore.kernel.org/xen-devel/6b21fb046cf1c8ca760f5ad72fa3cc13b59c4069.1743092485.git.oleksii.kuroc...@gmail.com/

* Move parts of Arm's Dom0less to common code
  - Oleksii Kurochko
  - 
https://patchew.org/Xen/cover.1746468003.git.oleksii.kuroc...@gmail.com/
  - 
https://lore.kernel.org/xen-devel/cover.1746468003.git.oleksii.kuroc...@gmail.com/T/#t

=== x86 ===

*  x86: memcpy() / memset() (non-)ERMS flavors plus fallout (v4 -> v5)
  -  Jan Beulich
  - https://patchew.org/Xen/14b65231-b83b-43fb-bbcf-dec5c07d2...@suse.com/

* kexec: add kexec support to Mini-OS (v1 -> v2)
  - Juergen Gross <jgr...@suse.com>
  - 
https://lore.kernel.org/xen-devel/20250616084619.11112-1-jgr...@suse.com/

* [4.21] Allow x86 to unflatten DTs (v8)
  - Alejandro Vallejo
  - 
https://lore.kernel.org/xen-devel/20250722000525.7247-1-alejandro.garciavall...@amd.com/#t

* xen: cache control improvements
  - Roger Pau Monne
  - 
https://lore.kernel.org/xen-devel/20250506083148.34963-1-roger....@citrix.com/

*  x86/HVM: emulation (MMIO) improvements (v3)
  -  Jan Beulich
  - https://patchew.org/Xen/729f7896-55b7-4b5b-a7e9-6eb0420e0...@suse.com/

=== ARM ===

* Enable R52 support for the first chunk of MPU support
 -  Ayan Kumar Halder
 - 
https://lore.kernel.org/xen-devel/20250619113152.2723066-1-ayan.kumar.hal...@amd.com/

* ARM split hardware and control domains (v5)
  - Jason Andryuk
  - 
https://lore.kernel.org/xen-devel/20250416212911.410946-1-jason.andr...@amd.com/
  - https://patchew.org/Xen/20250416212911.410946-1-jason.andr...@amd.com/

* First chunk for Arm R82 and MPU support (v4 -> v6)
  - Luca Fancellu
  - 
https://lore.kernel.org/xen-devel/20250523065406.3795420-1-luca.fance...@arm.com/
  - https://patchew.org/Xen/20250523065406.3795420-1-luca.fance...@arm.com/

* Add support for R-Car Gen4 PCI host controller (v4 -> v5)
  - Mykyta Poturai
  - 
https://lore.kernel.org/xen-devel/cover.1747820844.git.mykyta_potu...@epam.com/
  - 
https://patchew.org/Xen/cover.1747820844.git.mykyta._5fpotu...@epam.com/

* SMMU handling for PCIe Passthrough on ARM (v11 -> v12)
  - Mykyta Poturai
  - 
https://lore.kernel.org/xen-devel/cover.1751439885.git.mykyta_potu...@epam.com/

*  PCI devices passthrough on Arm, part 3 (v16->v20->v21)
  -  Stewart Hildebrand
  - 
https://patchew.org/Xen/20250508104608.531079-1-stewart.hildebr...@amd.com/
  - 
https://lore.kernel.org/xen-devel/20250508104608.531079-1-stewart.hildebr...@amd.com/

* Enable early bootup of Armv8-R AArch32 systems
  - Ayan Kumar Halder
  - 
https://lore.kernel.org/xen-devel/20250414164514.588373-1-ayan.kumar.hal...@amd.com/
  - 
https://patchew.org/Xen/20250414164514.588373-1-ayan.kumar.hal...@amd.com/

=== RISC-V ===

* riscv: introduce basic UART support and interrupts for hypervisor mode 
(v2 -> v3)
  -  Oleksii Kurochko
  - 
https://lore.kernel.org/xen-devel/cover.1747843009.git.oleksii.kuroc...@gmail.com/
  - 
https://patchew.org/Xen/cover.1747843009.git.oleksii.kuroc...@gmail.com/

* RISC-V some preinit calls:
  -  Oleksii Kurochko
  - 
https://lore.kernel.org/xen-devel/4ddde60347edf6740fbc69b5739d099616f5b5ff.1743165791.git.oleksii.kuroc...@gmail.com/

* Fixes for UBSAN & GCOV support for RISC-V:
  -  Oleksii Kurochko
  - 
https://lore.kernel.org/xen-devel/9fbb5e1389b84bed2e95f99e4c383d0215c7a524.1744889185.git.oleksii.kuroc...@gmail.com/

Have a good week!

Best regards,
 Oleksii