linux-kernel - Re: [PATCH v2 5/5] x86/pti: Do not enable PTI on fixed Intel processors

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Message-ID: <1516822667.13558.178.camel@infradead.org>
Date:   Wed, 24 Jan 2018 19:37:47 +0000
From:   David Woodhouse <dwmw2@...radead.org>
To:     Alan Cox <gnomes@...rguk.ukuu.org.uk>
Cc:     Dave Hansen <dave.hansen@...ux.intel.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 5/5] x86/pti: Do not enable PTI on fixed Intel
 processors

How about...

static const __initdata struct x86_cpu_id cpu_no_speculation[] = {
	{ X86_VENDOR_INTEL, 6, INTEL_FAM6_ATOM_CEDARVIEW, X86_FEATURE_ANY },
	{ X86_VENDOR_INTEL, 6, INTEL_FAM6_ATOM_CLOVERVIEW, X86_FEATURE_ANY },
	{ X86_VENDOR_INTEL, 6, INTEL_FAM6_ATOM_LINCROFT, X86_FEATURE_ANY },
	{ X86_VENDOR_INTEL, 6, INTEL_FAM6_ATOM_PENWELL, X86_FEATURE_ANY },
	{ X86_VENDOR_INTEL, 6, INTEL_FAM6_ATOM_PINEVIEW, X86_FEATURE_ANY },
	{ X86_VENDOR_INTEL, 5 },
	{ X86_VENDOR_CENTAUR, 5 },
	{ X86_VENDOR_ANY, 4 },
	{}
};

static const __initdata struct x86_cpu_id cpu_no_meltdown[] = {
	{ X86_VENDOR_AMD },
	{}
};

static bool __init early_cpu_vulnerable_meltdown(struct cpuinfo_x86 *c)
{
	u64 ia32_cap = 0;

	if (x86_match_cpu(cpu_no_meltdown))
                return false;

	if (cpu_has(c, X86_FEATURE_ARCH_CAPABILITIES))
		rdmsrl(MSR_IA32_ARCH_CAPABILITIES, ia32_cap);

	/* Rogue Data Cache Load? No! */
	if (ia32_cap & ARCH_CAP_RDCL_NO)
		return false;

	return true;
}

...



	if (!x86_match_cpu(cpu_no_speculation)) {
		if (early_cpu_vulnerable_meltdown(c))
			setup_force_cpu_bug(X86_BUG_CPU_MELTDOWN);
		setup_force_cpu_bug(X86_BUG_SPECTRE_V1);
		setup_force_cpu_bug(X86_BUG_SPECTRE_V2);
	}
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