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authorDominik Brodowski <linux@dominikbrodowski.net>2018-05-22 11:05:39 +0200
committerThomas Gleixner <tglx@linutronix.de>2018-05-23 10:55:52 +0200
commit8ecc4979b1bd9c94168e6fc92960033b7a951336 (patch)
tree61f642b529c1bc721adb23818d5c289924d9c5fb /arch
parent0aa48468d00959c8a37cd3ac727284f4f7359151 (diff)
downloadlinux-8ecc4979b1bd9c94168e6fc92960033b7a951336.tar.bz2
x86/speculation: Simplify the CPU bug detection logic
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
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/kernel/cpu/common.c22
1 files changed, 7 insertions, 15 deletions
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 78decc3e3067..38276f58d3bf 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -942,12 +942,8 @@ 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 },
@@ -955,14 +951,10 @@ 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, },
{}
};
@@ -970,6 +962,12 @@ 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);
@@ -977,12 +975,6 @@ 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 (x86_match_cpu(cpu_no_meltdown))
return;