linux-kernel - Re: [PATCH 1/5] x86/mce/inject: Check if a bank is unpopulated before error simulation

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Date:   Mon, 27 Sep 2021 16:56:17 -0500
From:   Smita Koralahalli Channabasappa <skoralah@....com>
To:     Borislav Petkov <bp@...en8.de>
Cc:     Smita Koralahalli <Smita.KoralahalliChannabasappa@....com>,
        x86@...nel.org, linux-edac@...r.kernel.org,
        linux-kernel@...r.kernel.org, Tony Luck <tony.luck@...el.com>,
        "H . Peter Anvin" <hpa@...or.com>, yazen.ghannam@....com
Subject: Re: [PATCH 1/5] x86/mce/inject: Check if a bank is unpopulated before
 error simulation

On 9/27/21 3:15 PM, Borislav Petkov wrote:

> On Mon, Sep 27, 2021 at 02:51:56PM -0500, Smita Koralahalli Channabasappa wrote:
>> Can you please elaborate on this? I'm not sure if I understood this
>> right. Should I read the ipid file to verify that the user has input
>> proper ipid? If ipid file reads zero then do rdmsrl_on_cpu?
> No, on a write to the ipid file you should do that checking and write if
> the bank is populated or fail the write otherwise. And you should put
> all that code in inj_bank_set() - that's why I say "on a write to the
> ipid file".
>
> And instead of boot_cpu_has() you should use cpu_feature_enabled().
>
> Makes sense?

Yes, this makes sense to me now. But you meant to say inj_ipid_set()
instead of inj_bank_set()..?

Something like this:

-MCE_INJECT_SET(ipid)

+static int inj_ipid_set(void *data, u64 val)
+{
+	struct mce *m = (struct mce*)data;

+	if cpu_feature_enabled(X86_FEATURE_SMCA)) {

+		rdmsrl_on_cpu(..
		..
		..
+	m->ipid = val;
+	..
+}

Thanks,