Also, for CPUs which don't speculate at all, don't report that they're
vulnerable to the Spectre variants either.
Leave the cpu_no_meltdown[] match table with just X86_VENDOR_AMD in it
for now, even though that could be done with a simple comparison, on the
assumption that we'll have more to add.
Based on suggestions from Dave Hansen and Alan Cox.
Signed-off-by: David Woodhouse <d...@amazon.co.uk>
Reviewed-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
arch/x86/kernel/cpu/common.c | 48 +++++++++++++++++++++++++++++++++++++++-----
1 file changed, 43 insertions(+), 5 deletions(-)
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index e5d66e9..32650c7 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -47,6 +47,8 @@
#include <asm/pat.h>
#include <asm/microcode.h>
#include <asm/microcode_intel.h>
+#include <asm/intel-family.h>
+#include <asm/cpu_device_id.h>
#ifdef CONFIG_X86_LOCAL_APIC
#include <asm/uv/uv.h>
@@ -853,6 +855,41 @@ static void identify_cpu_without_cpuid(struct cpuinfo_x86
*c)
#endif
}
+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_CENTAUR, 5 },
+ { X86_VENDOR_INTEL, 5 },
+ { X86_VENDOR_NSC, 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;
+}
+
/*
* Do minimum CPU detection early.
* Fields really needed: vendor, cpuid_level, family, model, mask,
@@ -900,11 +937,12 @@ static void __init early_identify_cpu(struct cpuinfo_x86
*c)
setup_force_cpu_cap(X86_FEATURE_ALWAYS);
- if (c->x86_vendor != X86_VENDOR_AMD)
- setup_force_cpu_bug(X86_BUG_CPU_MELTDOWN);
-
- setup_force_cpu_bug(X86_BUG_SPECTRE_V1);
- setup_force_cpu_bug(X86_BUG_SPECTRE_V2);
+ 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);
+ }
fpu__init_system(c);
--
2.7.4
