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From: Fiona Ebner <f.ebner@proxmox.com>
To: pve-devel@lists.proxmox.com
Subject: [PATCH-SERIES qemu-server v3 0/4] cpu config: enable hv-evmcs for Windows 11/2022/2025 to mitigate issues with VBS
Date: Tue, 14 Jul 2026 12:41:47 +0200	[thread overview]
Message-ID: <20260714104201.71308-1-f.ebner@proxmox.com> (raw)

Changes in v3:
* Improve commit message in patch 1.
* Different approach, enable recommended hv-evmcs flag instead of
  disabling apicv flags.
* Mock host CPU vendor in tests.

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. With hv_emcs, that
feature is not used in Windows anymore. The flag is also recommended
in the QEMU documentation [1], so start using it with a bumped
11.0+pve2 machine version.

[0]: https://forum.proxmox.com/threads/184178
[1]: https://www.qemu.org/docs/master/system/i386/hyperv.html#recommendations

qemu-server:

Fiona Ebner (4):
  cpu config: disable vmx-mbec flag for machine versions < 11.0
  cpu config: use $version_guard rather than passing $machine_version
  cpu config: enable hv-evmcs for Windows 11/2022/2025 to mitigate
    issues with VBS
  test: cfg2cmd: allow setting host CPU vendor for a given test

 src/PVE/QemuServer.pm                         |  2 +-
 src/PVE/QemuServer/CPUConfig.pm               | 40 ++++++++++++++-----
 src/PVE/QemuServer/Machine.pm                 |  3 +-
 src/test/cfg2cmd/cpu-level.conf.cmd           |  2 +-
 .../cfg2cmd/win11-amd-host-11.0+pve2.conf     |  5 +++
 .../cfg2cmd/win11-amd-host-11.0+pve2.conf.cmd | 26 ++++++++++++
 src/test/cfg2cmd/win11-host-11.0+pve2.conf    |  4 ++
 .../cfg2cmd/win11-host-11.0+pve2.conf.cmd     | 26 ++++++++++++
 src/test/run_config2command_tests.pl          | 17 ++++++++
 9 files changed, 112 insertions(+), 13 deletions(-)
 create mode 100644 src/test/cfg2cmd/win11-amd-host-11.0+pve2.conf
 create mode 100644 src/test/cfg2cmd/win11-amd-host-11.0+pve2.conf.cmd
 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:
  9 files changed, 112 insertions(+), 13 deletions(-)

-- 
Generated by git-murpp 0.5.0




             reply	other threads:[~2026-07-14 10:42 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-07-14 10:41 Fiona Ebner [this message]
2026-07-14 10:41 ` [PATCH qemu-server v3 1/4] cpu config: disable vmx-mbec flag for machine versions < 11.0 Fiona Ebner
2026-07-14 10:41 ` [PATCH qemu-server v3 2/4] cpu config: use $version_guard rather than passing $machine_version Fiona Ebner
2026-07-14 10:41 ` [PATCH qemu-server v3 3/4] cpu config: enable hv-evmcs for Windows 11/2022/2025 to mitigate issues with VBS Fiona Ebner
2026-07-14 10:41 ` [PATCH qemu-server v3 4/4] test: cfg2cmd: allow setting host CPU vendor for a given test Fiona Ebner

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