[PATCH docs] qm: document potential host cpu type drawback

[PATCH docs] qm: document potential host cpu type drawback

[Maximiliano Sandoval]

Signed-off-by: Maximiliano Sandoval <m.sandoval@proxmox.com>
---

Notes:
    This happened for example on Kernel 7.0.0 where the vmx-mbec is now enabled.

 qm.adoc | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/qm.adoc b/qm.adoc
index 96ba68b..bca5792 100644
--- a/qm.adoc
+++ b/qm.adoc
@@ -482,6 +482,10 @@ cluster, choose the lowest compatible virtual QEMU CPU type.
 
 NOTE: Live migrations between Intel and AMD host CPUs have no guarantee to work.
 
+WARNING: The 'host' CPU type can potentially enable new CPU features for the
+guest when the guest is restarted after a system upgrade. This can result in
+unexpected consequences.
+
 See also
 xref:chapter_qm_vcpu_list[List of AMD and Intel CPU Types as Defined in QEMU].
 
-- 
2.47.3

Re: [PATCH docs] qm: document potential host cpu type drawback

[Jonas Theisen]

On 7/15/26 15:01, Maximiliano Sandoval wrote:
> Signed-off-by: Maximiliano Sandoval <m.sandoval@proxmox.com>
> ---
>
> Notes:
>      This happened for example on Kernel 7.0.0 where the vmx-mbec is now enabled.
>
>   qm.adoc | 4 ++++
>   1 file changed, 4 insertions(+)
>
> diff --git a/qm.adoc b/qm.adoc
> index 96ba68b..bca5792 100644
> --- a/qm.adoc
> +++ b/qm.adoc
> @@ -482,6 +482,10 @@ cluster, choose the lowest compatible virtual QEMU CPU type.
>   
>   NOTE: Live migrations between Intel and AMD host CPUs have no guarantee to work.
>   
> +WARNING: The 'host' CPU type can potentially enable new CPU features for the
> +guest when the guest is restarted after a system upgrade. This can result in
> +unexpected consequences.
> +
>   See also
>   xref:chapter_qm_vcpu_list[List of AMD and Intel CPU Types as Defined in QEMU].
>   
Gentle ping.
I personally would like to see this mentioned in the docs, since this
is and will stay a potential problem / hazard to be aware of with
this CPU type.

So consider this:
Reviewed-by: Jonas Theisen <j.theisen@proxmox.com>