[Devel] [PATCH hci-8.0/hci-8.1 4/6] i386: keep bus-lock-detect for AMD guests on vz machine types up to vz9.2.0 #VSTOR-152291

[no-reply at sashiko.virtuozzo.com]

> From: Denis V. Lunev <den at openvz.org>
> 
> Since kernel commit 54950bfe2b69 KVM on AMD no longer offers
> bus-lock-detect. A Zen 5 guest started under an older kernel has it in
> its CPUID, and QEMU filters it on the new host, so migration, restore
> and snapshot revert fail (VSTOR-152291).
> 
> Add x-bus-lock-detect-compat and turn it on in pc_vz_9_2_compat: an
> AMD guest keeps a requested bus-lock-detect. The guest loses nothing
> it had: bus lock detection did not work under KVM on AMD before kernel
> commit 62ad461079e7, DR6 bit 11 stays fixed, and a Linux 6.13 or newer
> guest only logs one "unchecked MSR access" warning when it brings a
> vCPU online.
> 
> Signed-off-by: Denis V. Lunev <den at openvz.org>

Sashiko has reviewed this patch and found no issues. It looks great!

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