Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Tue, 26 Oct 2021 19:15:24 +0200
From:   Borislav Petkov <bp@alien8.de>
To:     "Koralahalli Channabasappa, Smita" <skoralah@amd.com>
Cc:     Smita Koralahalli <Smita.KoralahalliChannabasappa@amd.com>,
        x86@kernel.org, linux-edac@vger.kernel.org,
        linux-kernel@vger.kernel.org, Tony Luck <tony.luck@intel.com>,
        "H . Peter Anvin" <hpa@zytor.com>, yazen.ghannam@amd.com
Subject: Re: [PATCH v2 2/5] x86/mce/inject: Warn the user on a not set valid
 bit in MCA_STATUS
Message-ID: <YXg3rIump+CAtgs6@zn.tnic>
References: <20211019233641.140275-1-Smita.KoralahalliChannabasappa@amd.com>
 <20211019233641.140275-3-Smita.KoralahalliChannabasappa@amd.com>
 <YXfSGW1i5dLsiX84@zn.tnic>
 <00f4a0ab-f241-6674-f37f-623f3d9a8337@amd.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
In-Reply-To: <00f4a0ab-f241-6674-f37f-623f3d9a8337@amd.com>
Precedence: bulk

On Tue, Oct 26, 2021 at 11:58:58AM -0500, Koralahalli Channabasappa, Smita wrote:
> Like how it was done here?
> https://lkml.kernel.org/r/20210915232739.6367-3-Smita.KoralahalliChannabasappa@amd.com

Whoops, sorry about that.

So let's analyze this properly - there are two cases:

1. warn if VAL=0: what does that bring us? The person doing the injection
will simply have to set the valid bit and repeat the injection.

I guess "maybe the user wants to inject with Val not set" doesn't make a
whole lot of sense because nothing will happen - error will get ignored.

So we can do all the warning we want - it will be useless and in some
cases the user might not even see it.

So it sounds to me like setting the valid bit directly makes a lot more
sense.

2. Automatically set VAL=1 to correct any VAL=0 injections.

Yes, we force the VAL bit to 1 and that is not what the user injected
but the user injecting with VAL=0 will get ignored, i.e., it will be
pointless.

So we "help" here and set the valid bit.

Anything else I'm missing?

Sorry again for being back'n'forth on this.

-- 
Regards/Gruss,
    Boris.

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