linux-kernel - Re: [PATCH v3 5/6] x86/MCE: Save MCA control bits that get set in hardware

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Date:   Fri, 17 May 2019 10:26:49 -0700
From:   "Luck, Tony" <tony.luck@...el.com>
To:     Borislav Petkov <bp@...en8.de>
Cc:     "Ghannam, Yazen" <Yazen.Ghannam@....com>,
        "linux-edac@...r.kernel.org" <linux-edac@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "x86@...nel.org" <x86@...nel.org>
Subject: Re: [PATCH v3 5/6] x86/MCE: Save MCA control bits that get set in
 hardware

On Fri, May 17, 2019 at 06:37:29PM +0200, Borislav Petkov wrote:
> Now, the
> 
> 	wrmsrl(msr_ops.ctl(i), -1)
> 	rdmsrl(msr_ops.ctl(i), val);
> 
> method of throwing all 1s to see what sticks is what Intel wants, as
> Tony said. Is that going to be a problem on AMD?

It is what we want in general ...  but there is this:

        if (c->x86_vendor == X86_VENDOR_INTEL) {
                /*
                 * SDM documents that on family 6 bank 0 should not be written
                 * because it aliases to another special BIOS controlled
                 * register.
                 * But it's not aliased anymore on model 0x1a+
                 * Don't ignore bank 0 completely because there could be a
                 * valid event later, merely don't write CTL0.
                 */

                if (c->x86 == 6 && c->x86_model < 0x1A && cfg->banks > 0)
                        mce_banks[0].init = 0;

Which is a quirk for some models where we don't want to do
the "write all 1s and see what sticks"

-Tony