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From: Fiona Ebner <f.ebner@proxmox.com>
To: pve-devel@lists.proxmox.com
Subject: [PATCH-SERIES qemu-server v2 0/3] cpu config: disable APICv for Windows 11/2022/2025 to mitigate issues with VBS
Date: Mon, 13 Jul 2026 14:40:14 +0200	[thread overview]
Message-ID: <20260713124025.121154-1-f.ebner@proxmox.com> (raw)

Changes in v2:
* Disable MBEC by default for machine versions < 11.0 for backwards
  compat with older kernel and QEMU.

As reported in the community forum [0] and enterprise support, Windows
with MBEC and VBS can have issues on certain Intel CPUs, leading to
guest freezes and 100% CPU usage. The detection/enabling of APICv
support in Windows was determined to be related. Disabling
vmx-apicv-vid and/or vmx-apicv-register mitigates the issue. Disable
both flags starting with a bumped 11.0+pve2 machine version for
consistency.

[0]: https://forum.proxmox.com/threads/184178

qemu-server:

Fiona Ebner (3):
  cpu config: disable vmx-mbec flag for machine versions < 11.0
  cpu config: use $version_guard rather than passing $machine_version
  cpu config: disable APICv for Windows 11/2022/2025 to mitigate issues
    with VBS

 src/PVE/QemuServer.pm                         |  2 +-
 src/PVE/QemuServer/CPUConfig.pm               | 46 +++++++++++++++----
 src/PVE/QemuServer/Machine.pm                 |  3 +-
 src/test/cfg2cmd/cpu-level.conf.cmd           |  2 +-
 src/test/cfg2cmd/win11-host-11.0+pve2.conf    |  4 ++
 .../cfg2cmd/win11-host-11.0+pve2.conf.cmd     | 26 +++++++++++
 6 files changed, 70 insertions(+), 13 deletions(-)
 create mode 100644 src/test/cfg2cmd/win11-host-11.0+pve2.conf
 create mode 100644 src/test/cfg2cmd/win11-host-11.0+pve2.conf.cmd


Summary over all repositories:
  6 files changed, 70 insertions(+), 13 deletions(-)

-- 
Generated by git-murpp 0.5.0




             reply	other threads:[~2026-07-13 12:41 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-07-13 12:40 Fiona Ebner [this message]
2026-07-13 12:40 ` [PATCH qemu-server v2 1/3] cpu config: disable vmx-mbec flag for machine versions < 11.0 Fiona Ebner
2026-07-13 12:46   ` Friedrich Weber
2026-07-13 12:48     ` Fiona Ebner
2026-07-13 12:40 ` [PATCH qemu-server v2 2/3] cpu config: use $version_guard rather than passing $machine_version Fiona Ebner
2026-07-13 12:40 ` [PATCH qemu-server v2 3/3] cpu config: disable APICv for Windows 11/2022/2025 to mitigate issues with VBS Fiona Ebner
2026-07-15  8:21 ` superseded: [PATCH-SERIES qemu-server v2 0/3] " Fiona Ebner

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