diff options
Diffstat (limited to 'common/recipes-kernel/linux/linux-yocto-4.9.21/0018-x86-cpufeatures-Clean-up-Spectre-v2-related-CPUID-fl.patch')
| -rw-r--r-- | common/recipes-kernel/linux/linux-yocto-4.9.21/0018-x86-cpufeatures-Clean-up-Spectre-v2-related-CPUID-fl.patch | 181 |
1 files changed, 181 insertions, 0 deletions
diff --git a/common/recipes-kernel/linux/linux-yocto-4.9.21/0018-x86-cpufeatures-Clean-up-Spectre-v2-related-CPUID-fl.patch b/common/recipes-kernel/linux/linux-yocto-4.9.21/0018-x86-cpufeatures-Clean-up-Spectre-v2-related-CPUID-fl.patch new file mode 100644 index 00000000..09e6e0ce --- /dev/null +++ b/common/recipes-kernel/linux/linux-yocto-4.9.21/0018-x86-cpufeatures-Clean-up-Spectre-v2-related-CPUID-fl.patch @@ -0,0 +1,181 @@ +From 9d680bb2dea42b419a94a55a4b65afb1b785b307 Mon Sep 17 00:00:00 2001 +From: David Woodhouse <dwmw@amazon.co.uk> +Date: Sat, 27 Jan 2018 16:24:32 +0000 +Subject: [PATCH 18/42] x86/cpufeatures: Clean up Spectre v2 related CPUID + flags + +(cherry picked from commit 2961298efe1ea1b6fc0d7ee8b76018fa6c0bcef2) + +We want to expose the hardware features simply in /proc/cpuinfo as "ibrs", +"ibpb" and "stibp". Since AMD has separate CPUID bits for those, use them +as the user-visible bits. + +When the Intel SPEC_CTRL bit is set which indicates both IBRS and IBPB +capability, set those (AMD) bits accordingly. Likewise if the Intel STIBP +bit is set, set the AMD STIBP that's used for the generic hardware +capability. + +Hide the rest from /proc/cpuinfo by putting "" in the comments. Including +RETPOLINE and RETPOLINE_AMD which shouldn't be visible there. There are +patches to make the sysfs vulnerabilities information non-readable by +non-root, and the same should apply to all information about which +mitigations are actually in use. Those *shouldn't* appear in /proc/cpuinfo. + +The feature bit for whether IBPB is actually used, which is needed for +ALTERNATIVEs, is renamed to X86_FEATURE_USE_IBPB. + +Originally-by: Borislav Petkov <bp@suse.de> +Signed-off-by: David Woodhouse <dwmw@amazon.co.uk> +Signed-off-by: Thomas Gleixner <tglx@linutronix.de> +Cc: ak@linux.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/1517070274-12128-2-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> +--- + arch/x86/include/asm/cpufeatures.h | 18 +++++++++--------- + arch/x86/include/asm/nospec-branch.h | 2 +- + arch/x86/kernel/cpu/bugs.c | 7 +++---- + arch/x86/kernel/cpu/intel.c | 31 +++++++++++++++++++++---------- + 4 files changed, 34 insertions(+), 24 deletions(-) + +diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h +index 3901545..8eb23f5 100644 +--- a/arch/x86/include/asm/cpufeatures.h ++++ b/arch/x86/include/asm/cpufeatures.h +@@ -194,15 +194,15 @@ + #define X86_FEATURE_HW_PSTATE ( 7*32+ 8) /* AMD HW-PState */ + #define X86_FEATURE_PROC_FEEDBACK ( 7*32+ 9) /* AMD ProcFeedbackInterface */ + +-#define X86_FEATURE_RETPOLINE ( 7*32+12) /* Generic Retpoline mitigation for Spectre variant 2 */ +-#define X86_FEATURE_RETPOLINE_AMD ( 7*32+13) /* AMD Retpoline mitigation for Spectre variant 2 */ ++#define X86_FEATURE_RETPOLINE ( 7*32+12) /* "" Generic Retpoline mitigation for Spectre variant 2 */ ++#define X86_FEATURE_RETPOLINE_AMD ( 7*32+13) /* "" AMD Retpoline mitigation for Spectre variant 2 */ + +-#define X86_FEATURE_RSB_CTXSW ( 7*32+19) /* Fill RSB on context switches */ ++#define X86_FEATURE_RSB_CTXSW ( 7*32+19) /* "" Fill RSB on context switches */ + + /* Because the ALTERNATIVE scheme is for members of the X86_FEATURE club... */ + #define X86_FEATURE_KAISER ( 7*32+31) /* CONFIG_PAGE_TABLE_ISOLATION w/o nokaiser */ + +-#define X86_FEATURE_IBPB ( 7*32+21) /* Indirect Branch Prediction Barrier enabled*/ ++#define X86_FEATURE_USE_IBPB ( 7*32+21) /* "" Indirect Branch Prediction Barrier enabled */ + + /* Virtualization flags: Linux defined, word 8 */ + #define X86_FEATURE_TPR_SHADOW ( 8*32+ 0) /* Intel TPR Shadow */ +@@ -260,9 +260,9 @@ + /* AMD-defined CPU features, CPUID level 0x80000008 (ebx), word 13 */ + #define X86_FEATURE_CLZERO (13*32+0) /* CLZERO instruction */ + #define X86_FEATURE_IRPERF (13*32+1) /* Instructions Retired Count */ +-#define X86_FEATURE_AMD_PRED_CMD (13*32+12) /* Prediction Command MSR (AMD) */ +-#define X86_FEATURE_AMD_SPEC_CTRL (13*32+14) /* Speculation Control MSR only (AMD) */ +-#define X86_FEATURE_AMD_STIBP (13*32+15) /* Single Thread Indirect Branch Predictors (AMD) */ ++#define X86_FEATURE_IBPB (13*32+12) /* Indirect Branch Prediction Barrier */ ++#define X86_FEATURE_IBRS (13*32+14) /* Indirect Branch Restricted Speculation */ ++#define X86_FEATURE_STIBP (13*32+15) /* Single Thread Indirect Branch Predictors */ + + /* Thermal and Power Management Leaf, CPUID level 0x00000006 (eax), word 14 */ + #define X86_FEATURE_DTHERM (14*32+ 0) /* Digital Thermal Sensor */ +@@ -301,8 +301,8 @@ + /* Intel-defined CPU features, CPUID level 0x00000007:0 (EDX), word 18 */ + #define X86_FEATURE_AVX512_4VNNIW (18*32+ 2) /* AVX-512 Neural Network Instructions */ + #define X86_FEATURE_AVX512_4FMAPS (18*32+ 3) /* AVX-512 Multiply Accumulation Single precision */ +-#define X86_FEATURE_SPEC_CTRL (18*32+26) /* Speculation Control (IBRS + IBPB) */ +-#define X86_FEATURE_STIBP (18*32+27) /* Single Thread Indirect Branch Predictors */ ++#define X86_FEATURE_SPEC_CTRL (18*32+26) /* "" Speculation Control (IBRS + IBPB) */ ++#define X86_FEATURE_INTEL_STIBP (18*32+27) /* "" Single Thread Indirect Branch Predictors */ + #define X86_FEATURE_ARCH_CAPABILITIES (18*32+29) /* IA32_ARCH_CAPABILITIES MSR (Intel) */ + + /* +diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h +index 865192a..19ecb54 100644 +--- a/arch/x86/include/asm/nospec-branch.h ++++ b/arch/x86/include/asm/nospec-branch.h +@@ -225,7 +225,7 @@ static inline void indirect_branch_prediction_barrier(void) + "movl %[val], %%eax\n\t" + "movl $0, %%edx\n\t" + "wrmsr", +- X86_FEATURE_IBPB) ++ X86_FEATURE_USE_IBPB) + : : [msr] "i" (MSR_IA32_PRED_CMD), + [val] "i" (PRED_CMD_IBPB) + : "eax", "ecx", "edx", "memory"); +diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c +index efe55c5..3a06718 100644 +--- a/arch/x86/kernel/cpu/bugs.c ++++ b/arch/x86/kernel/cpu/bugs.c +@@ -272,9 +272,8 @@ static void __init spectre_v2_select_mitigation(void) + } + + /* Initialize Indirect Branch Prediction Barrier if supported */ +- if (boot_cpu_has(X86_FEATURE_SPEC_CTRL) || +- boot_cpu_has(X86_FEATURE_AMD_PRED_CMD)) { +- setup_force_cpu_cap(X86_FEATURE_IBPB); ++ if (boot_cpu_has(X86_FEATURE_IBPB)) { ++ setup_force_cpu_cap(X86_FEATURE_USE_IBPB); + pr_info("Enabling Indirect Branch Prediction Barrier\n"); + } + } +@@ -307,7 +306,7 @@ ssize_t cpu_show_spectre_v2(struct device *dev, + return sprintf(buf, "Not affected\n"); + + return sprintf(buf, "%s%s%s\n", spectre_v2_strings[spectre_v2_enabled], +- boot_cpu_has(X86_FEATURE_IBPB) ? ", IBPB" : "", ++ boot_cpu_has(X86_FEATURE_USE_IBPB) ? ", IBPB" : "", + spectre_v2_module_string()); + } + #endif +diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c +index 4d23d78..2e257f8 100644 +--- a/arch/x86/kernel/cpu/intel.c ++++ b/arch/x86/kernel/cpu/intel.c +@@ -140,17 +140,28 @@ 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); ++ /* ++ * The Intel SPEC_CTRL CPUID bit implies IBRS and IBPB support, ++ * and they also have a different bit for STIBP support. Also, ++ * a hypervisor might have set the individual AMD bits even on ++ * Intel CPUs, for finer-grained selection of what's available. ++ */ ++ if (cpu_has(c, X86_FEATURE_SPEC_CTRL)) { ++ set_cpu_cap(c, X86_FEATURE_IBRS); ++ set_cpu_cap(c, X86_FEATURE_IBPB); ++ } ++ if (cpu_has(c, X86_FEATURE_INTEL_STIBP)) ++ set_cpu_cap(c, X86_FEATURE_STIBP); ++ ++ /* Now if any of them are set, check the blacklist and clear the lot */ ++ if ((cpu_has(c, X86_FEATURE_IBRS) || cpu_has(c, X86_FEATURE_IBPB) || ++ cpu_has(c, X86_FEATURE_STIBP)) && bad_spectre_microcode(c)) { ++ pr_warn("Intel Spectre v2 broken microcode detected; disabling Speculation Control\n"); ++ clear_cpu_cap(c, X86_FEATURE_IBRS); ++ clear_cpu_cap(c, X86_FEATURE_IBPB); + 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); ++ clear_cpu_cap(c, X86_FEATURE_SPEC_CTRL); ++ clear_cpu_cap(c, X86_FEATURE_INTEL_STIBP); + } + + /* +-- +2.7.4 + |