Re: [PATCH] EDAC/mce_amd: Reduce unnecessary spew in dmesg if SMCA feature bit is not exposed

[Borislav Petkov]

On Mon, Jun 14, 2021 at 04:21:29PM -0500, Smita Koralahalli wrote:
> The SMCA feature bit is not exposed on the guest.
> 
> This causes a lot of noise in dmesg as the warning is printed for each
> logical CPU.
> 
> $ dmesg |grep -i family
> 
> [    0.031000] smpboot: CPU0: AMD EPYC-Milan Processor (family: 0x19, model: 0x1, stepping: 0x1)
> [    4.653422] Huh? What family is it: 0x19?!
> [    4.720732] Huh? What family is it: 0x19?!
> [    6.171028] Huh? What family is it: 0x19?!
> [    6.766552] Huh? What family is it: 0x19?!
> [    6.811119] Huh? What family is it: 0x19?!
> [    6.839855] Huh? What family is it: 0x19?!
> 
> Give these messages debug severity and output once as it is mostly useful
> for module developers and just noise for users.

I'm getting a patch like that on a pretty regular basis and each time I
tell people simply not to load the module in guests. Hypervisors do not
support SMCA...

But apparently those wrong error messages bug people on a regular basis
and I'm tired of typing this each time so I'll take a different version
of this patch: check X86_FEATURE_HYPERVISOR on entry in mce_amd_init()
and return -ENODEV if set.

So that this is done once and for all.

Thx.

-- 
Regards/Gruss,
    Boris.

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