x86/cpufeature: Blacklist SPEC_CTRL/PRED_CMD on early Spectre v2 microcodes

(cherry picked from commit a5b2966364538a0e68c9fa29bc0a3a1651799035)

This doesn't refuse to load the affected microcodes; it just refuses to
use the Spectre v2 mitigation features if they're detected, by clearing
the appropriate feature bits.

The AMD CPUID bits are handled here too, because hypervisors *may* have
been exposing those bits even on Intel chips, for fine-grained control
of what's available.

It is non-trivial to use x86_match_cpu() for this table because that
doesn't handle steppings. And the approach taken in commit bd9240a18
almost made me lose my lunch.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: gnomes@lxorguk.ukuu.org.uk
Cc: ak@linux.intel.com
Cc: ashok.raj@intel.com
Cc: dave.hansen@intel.com
Cc: karahmed@amazon.de
Cc: arjan@linux.intel.com
Cc: torvalds@linux-foundation.org
Cc: peterz@infradead.org
Cc: bp@alien8.de
Cc: pbonzini@redhat.com
Cc: tim.c.chen@linux.intel.com
Cc: gregkh@linux-foundation.org
Link: https://lkml.kernel.org/r/1516896855-7642-7-git-send-email-dwmw@amazon.co.uk
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Srivatsa S. Bhat <srivatsa@csail.mit.edu>
Reviewed-by: Matt Helsley (VMware) <matt.helsley@gmail.com>
Reviewed-by: Alexey Makhalov <amakhalov@vmware.com>
Reviewed-by: Bo Gan <ganb@vmware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/x86/include/asm/intel-family.h b/arch/x86/include/asm/intel-family.h
index 6999f7d01a0d12cb890b9dceef23fcb85734b940..12fa187865c26bd5e0f68ed736736c226c4adf88 100644 (file)
--- a/arch/x86/include/asm/intel-family.h
+++ b/arch/x86/include/asm/intel-family.h
@@ -12,6 +12,7 @@
  */
 
 #define INTEL_FAM6_CORE_YONAH          0x0E
+
 #define INTEL_FAM6_CORE2_MEROM         0x0F
 #define INTEL_FAM6_CORE2_MEROM_L       0x16
 #define INTEL_FAM6_CORE2_PENRYN                0x17
@@ -20,6 +21,7 @@
 #define INTEL_FAM6_NEHALEM             0x1E
 #define INTEL_FAM6_NEHALEM_EP          0x1A
 #define INTEL_FAM6_NEHALEM_EX          0x2E
+
 #define INTEL_FAM6_WESTMERE            0x25
 #define INTEL_FAM6_WESTMERE2           0x1F
 #define INTEL_FAM6_WESTMERE_EP         0x2C
@@ -36,9 +38,9 @@
 #define INTEL_FAM6_HASWELL_GT3E                0x46
 
 #define INTEL_FAM6_BROADWELL_CORE      0x3D
-#define INTEL_FAM6_BROADWELL_XEON_D    0x56
 #define INTEL_FAM6_BROADWELL_GT3E      0x47
 #define INTEL_FAM6_BROADWELL_X         0x4F
+#define INTEL_FAM6_BROADWELL_XEON_D    0x56
 
 #define INTEL_FAM6_SKYLAKE_MOBILE      0x4E
 #define INTEL_FAM6_SKYLAKE_DESKTOP     0x5E
@@ -60,6 +62,7 @@
 #define INTEL_FAM6_ATOM_MERRIFIELD2    0x5A /* Annidale */
 #define INTEL_FAM6_ATOM_GOLDMONT       0x5C
 #define INTEL_FAM6_ATOM_DENVERTON      0x5F /* Goldmont Microserver */
+#define INTEL_FAM6_ATOM_GEMINI_LAKE    0x7A
 
 /* Xeon Phi */
 

diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c
index 9299e3bdfad6bacf4a8d8341567e79682b67f241..23ba9cc0cc0d68ab2b385985f0286cfb8c4686f8 100644 (file)
--- a/arch/x86/kernel/cpu/intel.c
+++ b/arch/x86/kernel/cpu/intel.c
@@ -13,6 +13,7 @@
 #include <asm/msr.h>
 #include <asm/bugs.h>
 #include <asm/cpu.h>
+#include <asm/intel-family.h>
 
 #ifdef CONFIG_X86_64
 #include <linux/topology.h>
@@ -25,6 +26,59 @@
 #include <asm/apic.h>
 #endif
 
+/*
+ * Early microcode releases for the Spectre v2 mitigation were broken.
+ * Information taken from;
+ * - https://newsroom.intel.com/wp-content/uploads/sites/11/2018/01/microcode-update-guidance.pdf
+ * - https://kb.vmware.com/s/article/52345
+ * - Microcode revisions observed in the wild
+ * - Release note from 20180108 microcode release
+ */
+struct sku_microcode {
+       u8 model;
+       u8 stepping;
+       u32 microcode;
+};
+static const struct sku_microcode spectre_bad_microcodes[] = {
+       { INTEL_FAM6_KABYLAKE_DESKTOP,  0x0B,   0x84 },
+       { INTEL_FAM6_KABYLAKE_DESKTOP,  0x0A,   0x84 },
+       { INTEL_FAM6_KABYLAKE_DESKTOP,  0x09,   0x84 },
+       { INTEL_FAM6_KABYLAKE_MOBILE,   0x0A,   0x84 },
+       { INTEL_FAM6_KABYLAKE_MOBILE,   0x09,   0x84 },
+       { INTEL_FAM6_SKYLAKE_X,         0x03,   0x0100013e },
+       { INTEL_FAM6_SKYLAKE_X,         0x04,   0x0200003c },
+       { INTEL_FAM6_SKYLAKE_MOBILE,    0x03,   0xc2 },
+       { INTEL_FAM6_SKYLAKE_DESKTOP,   0x03,   0xc2 },
+       { INTEL_FAM6_BROADWELL_CORE,    0x04,   0x28 },
+       { INTEL_FAM6_BROADWELL_GT3E,    0x01,   0x1b },
+       { INTEL_FAM6_BROADWELL_XEON_D,  0x02,   0x14 },
+       { INTEL_FAM6_BROADWELL_XEON_D,  0x03,   0x07000011 },
+       { INTEL_FAM6_BROADWELL_X,       0x01,   0x0b000025 },
+       { INTEL_FAM6_HASWELL_ULT,       0x01,   0x21 },
+       { INTEL_FAM6_HASWELL_GT3E,      0x01,   0x18 },
+       { INTEL_FAM6_HASWELL_CORE,      0x03,   0x23 },
+       { INTEL_FAM6_HASWELL_X,         0x02,   0x3b },
+       { INTEL_FAM6_HASWELL_X,         0x04,   0x10 },
+       { INTEL_FAM6_IVYBRIDGE_X,       0x04,   0x42a },
+       /* Updated in the 20180108 release; blacklist until we know otherwise */
+       { INTEL_FAM6_ATOM_GEMINI_LAKE,  0x01,   0x22 },
+       /* Observed in the wild */
+       { INTEL_FAM6_SANDYBRIDGE_X,     0x06,   0x61b },
+       { INTEL_FAM6_SANDYBRIDGE_X,     0x07,   0x712 },
+};
+
+static bool bad_spectre_microcode(struct cpuinfo_x86 *c)
+{
+       int i;
+
+       for (i = 0; i < ARRAY_SIZE(spectre_bad_microcodes); i++) {
+               if (c->x86_model == spectre_bad_microcodes[i].model &&
+                   c->x86_mask == spectre_bad_microcodes[i].stepping)
+                       return (c->microcode <= spectre_bad_microcodes[i].microcode);
+       }
+       return false;
+}
+
 static void early_init_intel(struct cpuinfo_x86 *c)
 {
        u64 misc_enable;
@@ -51,6 +105,19 @@ static void early_init_intel(struct cpuinfo_x86 *c)
                rdmsr(MSR_IA32_UCODE_REV, lower_word, c->microcode);
        }
 
+       if ((cpu_has(c, X86_FEATURE_SPEC_CTRL) ||
+            cpu_has(c, X86_FEATURE_STIBP) ||
+            cpu_has(c, X86_FEATURE_AMD_SPEC_CTRL) ||
+            cpu_has(c, X86_FEATURE_AMD_PRED_CMD) ||
+            cpu_has(c, X86_FEATURE_AMD_STIBP)) && bad_spectre_microcode(c)) {
+               pr_warn("Intel Spectre v2 broken microcode detected; disabling SPEC_CTRL\n");
+               clear_cpu_cap(c, X86_FEATURE_SPEC_CTRL);
+               clear_cpu_cap(c, X86_FEATURE_STIBP);
+               clear_cpu_cap(c, X86_FEATURE_AMD_SPEC_CTRL);
+               clear_cpu_cap(c, X86_FEATURE_AMD_PRED_CMD);
+               clear_cpu_cap(c, X86_FEATURE_AMD_STIBP);
+       }
+
        /*
         * Atom erratum AAE44/AAF40/AAG38/AAH41:
         *