linux-kernel - RE: [tip: ras/core] x86/mce: Enable additional error logging on certain Intel CPUs

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Message-ID: <a22b5468e1c94906b72c4d8bc83c0f64@intel.com>
Date:   Mon, 9 Nov 2020 22:57:35 +0000
From:   "Luck, Tony" <tony.luck@...el.com>
To:     Jim Mattson <jmattson@...gle.com>
CC:     Qian Cai <cai@...hat.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-tip-commits@...r.kernel.org" 
        <linux-tip-commits@...r.kernel.org>, Boris Petkov <bp@...en8.de>,
        "Borislav Petkov" <bp@...e.de>, x86 <x86@...nel.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>
Subject: RE: [tip: ras/core] x86/mce: Enable additional error logging on
 certain Intel CPUs

> I thought Linux had long ago gone the route of turning rdmsr/wrmsr
> into rdmsr_safe/wrmsr_safe, so that the guest would ignore the #GPs on
> writes and return zero to the caller for #GPs on reads.

Linux just switched that around for the machine check banks ... if they #GP
fault, then something is seriously wrong.

Maybe that isn't a general change of direction though. Perhaps I
should either use rdmsrl_safe() in this code. Or (better?) add

	if (boot_cpu_has(X86_FEATURE_HYPERVISOR))
		return;

to the start of intel_imc_init().

-Tony