From: Jonas Theisen <j.theisen@proxmox.com>
To: Fiona Ebner <f.ebner@proxmox.com>
Cc: pve-devel@lists.proxmox.com
Subject: Re: [PATCH-SERIES qemu-server v3 0/4] cpu config: enable hv-evmcs for Windows 11/2022/2025 to mitigate issues with VBS
Date: Wed, 15 Jul 2026 14:20:52 +0200 [thread overview]
Message-ID: <c879aebb-fb47-4442-9d51-b7b9c84ce84b@proxmox.com> (raw)
In-Reply-To: <20260714104201.71308-1-f.ebner@proxmox.com>
On 7/14/26 12:41, Fiona Ebner wrote:
> 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
>
> [...]
Tested the patch on an affected Intel machine with q35 Windows Server
2025 VMs.
Bumping the machine version to 11.0-pve2 fixes the issue while the
previously available 11.0-pve1 stays unchanged.
Tested-by: Jonas Theisen <j.theisen@proxmox.com>
next prev parent reply other threads:[~2026-07-15 12:20 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-07-14 10:41 [PATCH-SERIES qemu-server v3 0/4] 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 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
2026-07-15 11:46 ` [PATCH-SERIES qemu-server v3 0/4] cpu config: enable hv-evmcs for Windows 11/2022/2025 to mitigate issues with VBS Maximiliano Sandoval
2026-07-15 12:20 ` Jonas Theisen [this message]
2026-07-15 12:42 ` applied: " Thomas Lamprecht
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