linux-kernel - Re: [PATCH] EDAC/Intel: Do not load EDAC driver when running as a guest

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Date:   Tue, 15 Jun 2021 19:00:20 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     "Luck, Tony" <tony.luck@...el.com>
Cc:     Yazen Ghannam <yazen.ghannam@....com>,
        Smita Koralahalli <Smita.KoralahalliChannabasappa@....com>,
        "x86@...nel.org" <x86@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-edac@...r.kernel.org" <linux-edac@...r.kernel.org>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        James Morse <james.morse@....com>,
        Robert Richter <rric@...nel.org>
Subject: Re: [PATCH] EDAC/Intel: Do not load EDAC driver when running as a
 guest

On Tue, Jun 15, 2021 at 09:45:25AM -0700, Luck, Tony wrote:
> There's little to no point in loading an EDAC driver running in a guest:
> 1) The CPU model reported by CPUID may not represent actual h/w
> 2) The hypervisor likely does not pass in access to memory controller devices
> 3) Hypervisors generally do not pass corrected error details to guests
> 
> Add a check in each of the Intel EDAC drivers for X86_FEATURE_HYPERVISOR
> and simply return -ENODEV in the init routine.
> 
> Signed-off-by: Tony Luck <tony.luck@...el.com>
> ---
>  drivers/edac/i10nm_base.c | 3 +++
>  drivers/edac/pnd2_edac.c  | 3 +++
>  drivers/edac/sb_edac.c    | 3 +++
>  drivers/edac/skx_base.c   | 3 +++
>  4 files changed, 12 insertions(+)

If you insist... I mean, those drivers won't load for other reasons but
sure.

> diff --git a/drivers/edac/i10nm_base.c b/drivers/edac/i10nm_base.c
> index 238a4ad1e526..fa08622ff2a8 100644
> --- a/drivers/edac/i10nm_base.c
> +++ b/drivers/edac/i10nm_base.c
> @@ -278,6 +278,9 @@ static int __init i10nm_init(void)
>  	if (owner && strncmp(owner, EDAC_MOD_STR, sizeof(EDAC_MOD_STR)))
>  		return -EBUSY;
>  
> +	if (boot_cpu_has(X86_FEATURE_HYPERVISOR))

Can you change that to cpu_feature_enabled() everywhere pls?

We're going to use that single API for checking CPU features from now on
and slowly move away from the others to simplify things.

With that changed you can add:

Acked-by: Borislav Petkov <bp@...e.de>

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette