Re: [PATCH pve-qemu] parse-cpu-flags: stop filtering out 'pmu'

[Fiona Ebner <f.ebner@proxmox.com>]

Am 13.10.26 um 10:32 AM schrieb Arthur Bied-Charreton:
> 'pmu' was excluded from the list of flags in the custom CPU flag dialog
> because it is not a CPUID flag (not part of '-cpu help' output).
> However, it is a plain boolean property so it fits the [+-]<flag> syntax
> from the custom CPU config, and QEMU accepts it when set manually via
> '+pmu'.

What I wanted to write: if it's not a CPUID flag, wouldn't it be better
to expose it as a separate property? I.e. add to the $cpu_fmt schema and
have a separate checkbox in the UI?

But then I looked into the implementation and the 'pmu' property is very
closely related to the CPUID_EXT_PDCM flag, so it makes a lot of sense
if it goes through the same "on which nodes is it supported" checks and
if we treat it as a flag.

Could you adapt the commit message to reflect this? IMHO the argument
with QEMU accepting the same syntax is rather weak. There has to be
conceptual similarity too, which there is :)

> 
> Windows guests using VBS need a virtual PMU, which is not enabled by
> default on many models (EPYC-Turin, EPYC-Genoa, SapphireRapids, and
> presumably others I have not tested). This currently requires users to
> edit the config by hand since the flag cannot be selected in the UI.
> 
> Remove 'pmu' from the blacklist so it shows up in the generated flag
> list.
> 
> Reported-by: David Riley <d.riley@proxmox.com>
> Signed-off-by: Arthur Bied-Charreton <a.bied-charreton@proxmox.com>
> ---
>  debian/parse-cpu-flags.pl | 1 -
>  1 file changed, 1 deletion(-)
> 
> diff --git a/debian/parse-cpu-flags.pl b/debian/parse-cpu-flags.pl
> index e680f99..e1af0e8 100755
> --- a/debian/parse-cpu-flags.pl
> +++ b/debian/parse-cpu-flags.pl
> @@ -66,7 +66,6 @@ my $filtered_props = {
>          'legacy-multi-node' => 1,
>          lmce => 1,
>          migratable => 1,
> -        pmu => 1,
>          realized => 1,
>          'start-powered-off' => 1,
>          'tcg-cpuid' => 1,

Note: you also need to add it to debian/recognized-CPUID-flags-x86_64