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x86/speculation: Simplify the CPU bug detection logic

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commit 8ecc4979b1bd9c94168e6fc92960033b7a951336 upstream.

Only CPUs which speculate can speculate. Therefore, it seems prudent
to test for cpu_no_speculation first and only then determine whether
a specific speculating CPU is susceptible to store bypass speculation.
This is underlined by all CPUs currently listed in cpu_no_speculation
were present in cpu_no_spec_store_bypass as well.

Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: bp@suse.de
Cc: konrad.wilk@oracle.com
Link: https://lkml.kernel.org/r/20180522090539.GA24668@light.dominikbrodowski.net
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Dominik Brodowski 2018-05-22 11:05:39 +02:00 • committed by Greg Kroah-Hartman
parent efcb85dd26
commit 2b8e34665e
1 changed files with 7 additions and 15 deletions
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22
arch/x86/kernel/cpu/common.c
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@ -859,12 +859,8 @@ static const __initconst struct x86_cpu_id cpu_no_meltdown[] = {
{}
};
/* Only list CPUs which speculate but are non susceptible to SSB */
static const __initconst struct x86_cpu_id cpu_no_spec_store_bypass[] = {
{ X86_VENDOR_INTEL, 6, INTEL_FAM6_ATOM_PINEVIEW },
{ X86_VENDOR_INTEL, 6, INTEL_FAM6_ATOM_LINCROFT },
{ X86_VENDOR_INTEL, 6, INTEL_FAM6_ATOM_PENWELL },
{ X86_VENDOR_INTEL, 6, INTEL_FAM6_ATOM_CLOVERVIEW },
{ X86_VENDOR_INTEL, 6, INTEL_FAM6_ATOM_CEDARVIEW },
{ X86_VENDOR_INTEL, 6, INTEL_FAM6_ATOM_SILVERMONT1 },
{ X86_VENDOR_INTEL, 6, INTEL_FAM6_ATOM_AIRMONT },
{ X86_VENDOR_INTEL, 6, INTEL_FAM6_ATOM_SILVERMONT2 },
@ -872,14 +868,10 @@ static const __initconst struct x86_cpu_id cpu_no_spec_store_bypass[] = {
{ X86_VENDOR_INTEL, 6, INTEL_FAM6_CORE_YONAH },
{ X86_VENDOR_INTEL, 6, INTEL_FAM6_XEON_PHI_KNL },
{ X86_VENDOR_INTEL, 6, INTEL_FAM6_XEON_PHI_KNM },
{ X86_VENDOR_CENTAUR, 5, },
{ X86_VENDOR_INTEL, 5, },
{ X86_VENDOR_NSC, 5, },
{ X86_VENDOR_AMD, 0x12, },
{ X86_VENDOR_AMD, 0x11, },
{ X86_VENDOR_AMD, 0x10, },
{ X86_VENDOR_AMD, 0xf, },
{ X86_VENDOR_ANY, 4, },
{}
};
@ -902,6 +894,12 @@ static void __init cpu_set_bug_bits(struct cpuinfo_x86 *c)
{
u64 ia32_cap = 0;
if (x86_match_cpu(cpu_no_speculation))
return;
setup_force_cpu_bug(X86_BUG_SPECTRE_V1);
setup_force_cpu_bug(X86_BUG_SPECTRE_V2);
if (cpu_has(c, X86_FEATURE_ARCH_CAPABILITIES))
rdmsrl(MSR_IA32_ARCH_CAPABILITIES, ia32_cap);
@ -909,12 +907,6 @@ static void __init cpu_set_bug_bits(struct cpuinfo_x86 *c)
!(ia32_cap & ARCH_CAP_SSB_NO))
setup_force_cpu_bug(X86_BUG_SPEC_STORE_BYPASS);
if (x86_match_cpu(cpu_no_speculation))
return;
setup_force_cpu_bug(X86_BUG_SPECTRE_V1);
setup_force_cpu_bug(X86_BUG_SPECTRE_V2);
if (ia32_cap & ARCH_CAP_IBRS_ALL)
setup_force_cpu_cap(X86_FEATURE_IBRS_ENHANCED);