This is a note to let you know that I've just added the patch titled
x86/speculation: Add basic IBPB (Indirect Branch Prediction Barrier) support
to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
x86-speculation-add-basic-ibpb-indirect-branch-prediction-barrier-support.patch
and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Thu Feb 8 03:30:27 CET 2018
From: David Woodhouse <dwmw@xxxxxxxxxxxx>
Date: Thu, 25 Jan 2018 16:14:15 +0000
Subject: x86/speculation: Add basic IBPB (Indirect Branch Prediction Barrier) support
From: David Woodhouse <dwmw@xxxxxxxxxxxx>
(cherry picked from commit 20ffa1caecca4db8f79fe665acdeaa5af815a24d)
Expose indirect_branch_prediction_barrier() for use in subsequent patches.
[ tglx: Add IBPB status to spectre_v2 sysfs file ]
Co-developed-by: KarimAllah Ahmed <karahmed@xxxxxxxxx>
Signed-off-by: KarimAllah Ahmed <karahmed@xxxxxxxxx>
Signed-off-by: David Woodhouse <dwmw@xxxxxxxxxxxx>
Cc: gnomes@xxxxxxxxxxxxxxxxxxx
Cc: ak@xxxxxxxxxxxxxxx
Cc: ashok.raj@xxxxxxxxx
Cc: dave.hansen@xxxxxxxxx
Cc: arjan@xxxxxxxxxxxxxxx
Cc: torvalds@xxxxxxxxxxxxxxxxxxxx
Cc: peterz@xxxxxxxxxxxxx
Cc: bp@xxxxxxxxx
Cc: pbonzini@xxxxxxxxxx
Cc: tim.c.chen@xxxxxxxxxxxxxxx
Cc: gregkh@xxxxxxxxxxxxxxxxxxxx
Link: https://lkml.kernel.org/r/1516896855-7642-8-git-send-email-dwmw@xxxxxxxxxxxx
Signed-off-by: David Woodhouse <dwmw@xxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/include/asm/cpufeatures.h | 2 ++
arch/x86/include/asm/nospec-branch.h | 13 +++++++++++++
arch/x86/kernel/cpu/bugs.c | 10 +++++++++-
3 files changed, 24 insertions(+), 1 deletion(-)
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -202,6 +202,8 @@
/* 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*/
+
/* Virtualization flags: Linux defined, word 8 */
#define X86_FEATURE_TPR_SHADOW ( 8*32+ 0) /* Intel TPR Shadow */
#define X86_FEATURE_VNMI ( 8*32+ 1) /* Intel Virtual NMI */
--- a/arch/x86/include/asm/nospec-branch.h
+++ b/arch/x86/include/asm/nospec-branch.h
@@ -218,5 +218,18 @@ static inline void vmexit_fill_RSB(void)
#endif
}
+static inline void indirect_branch_prediction_barrier(void)
+{
+ asm volatile(ALTERNATIVE("",
+ "movl %[msr], %%ecx\n\t"
+ "movl %[val], %%eax\n\t"
+ "movl $0, %%edx\n\t"
+ "wrmsr",
+ X86_FEATURE_IBPB)
+ : : [msr] "i" (MSR_IA32_PRED_CMD),
+ [val] "i" (PRED_CMD_IBPB)
+ : "eax", "ecx", "edx", "memory");
+}
+
#endif /* __ASSEMBLY__ */
#endif /* __NOSPEC_BRANCH_H__ */
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -262,6 +262,13 @@ retpoline_auto:
setup_force_cpu_cap(X86_FEATURE_RSB_CTXSW);
pr_info("Filling RSB on context switch\n");
}
+
+ /* 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);
+ pr_info("Enabling Indirect Branch Prediction Barrier\n");
+ }
}
#undef pr_fmt
@@ -291,7 +298,8 @@ ssize_t cpu_show_spectre_v2(struct devic
if (!boot_cpu_has_bug(X86_BUG_SPECTRE_V2))
return sprintf(buf, "Not affected\n");
- return sprintf(buf, "%s%s\n", spectre_v2_strings[spectre_v2_enabled],
+ return sprintf(buf, "%s%s%s\n", spectre_v2_strings[spectre_v2_enabled],
+ boot_cpu_has(X86_FEATURE_IBPB) ? ", IPBP" : "",
spectre_v2_bad_module ? " - vulnerable module loaded" : "");
}
#endif
Patches currently in stable-queue which might be from dwmw@xxxxxxxxxxxx are
queue-4.9/x86-entry-64-push-extra-regs-right-away.patch
queue-4.9/kvm-vmx-introduce-alloc_loaded_vmcs.patch
queue-4.9/kvm-nvmx-eliminate-vmcs02-pool.patch
queue-4.9/kvm-vmx-allow-direct-access-to-msr_ia32_spec_ctrl.patch
queue-4.9/kvm-x86-add-ibpb-support.patch
queue-4.9/kvm-svm-allow-direct-access-to-msr_ia32_spec_ctrl.patch
queue-4.9/x86-cpufeatures-add-intel-feature-bits-for-speculation-control.patch
queue-4.9/x86-retpoline-simplify-vmexit_fill_rsb.patch
queue-4.9/x86-paravirt-remove-noreplace-paravirt-cmdline-option.patch
queue-4.9/x86-cpufeatures-clean-up-spectre-v2-related-cpuid-flags.patch
queue-4.9/documentation-document-array_index_nospec.patch
queue-4.9/x86-usercopy-replace-open-coded-stac-clac-with-__uaccess_-begin-end.patch
queue-4.9/x86-asm-move-status-from-thread_struct-to-thread_info.patch
queue-4.9/x86-cpufeatures-add-cpuid_7_edx-cpuid-leaf.patch
queue-4.9/kvm-x86-make-indirect-calls-in-emulator-speculation-safe.patch
queue-4.9/x86-entry-64-remove-the-syscall64-fast-path.patch
queue-4.9/x86-cpufeature-blacklist-spec_ctrl-pred_cmd-on-early-spectre-v2-microcodes.patch
queue-4.9/x86-nospec-fix-header-guards-names.patch
queue-4.9/x86-retpoline-avoid-retpolines-for-built-in-__init-functions.patch
queue-4.9/vfs-fdtable-prevent-bounds-check-bypass-via-speculative-execution.patch
queue-4.9/x86-uaccess-use-__uaccess_begin_nospec-and-uaccess_try_nospec.patch
queue-4.9/x86-cpu-bugs-make-retpoline-module-warning-conditional.patch
queue-4.9/x86-spectre-check-config_retpoline-in-command-line-parser.patch
queue-4.9/x86-implement-array_index_mask_nospec.patch
queue-4.9/x86-alternative-print-unadorned-pointers.patch
queue-4.9/x86-cpuid-fix-up-virtual-ibrs-ibpb-stibp-feature-bits-on-intel.patch
queue-4.9/array_index_nospec-sanitize-speculative-array-de-references.patch
queue-4.9/kvm-vmx-make-indirect-call-speculation-safe.patch
queue-4.9/x86-cpufeatures-add-amd-feature-bits-for-speculation-control.patch
queue-4.9/x86-spectre-fix-spelling-mistake-vunerable-vulnerable.patch
queue-4.9/module-retpoline-warn-about-missing-retpoline-in-module.patch
queue-4.9/x86-kvm-update-spectre-v1-mitigation.patch
queue-4.9/x86-get_user-use-pointer-masking-to-limit-speculation.patch
queue-4.9/x86-syscall-sanitize-syscall-table-de-references-under-speculation.patch
queue-4.9/kvm-nvmx-vmx_complete_nested_posted_interrupt-can-t-fail.patch
queue-4.9/x86-spectre-simplify-spectre_v2-command-line-parsing.patch
queue-4.9/x86-msr-add-definitions-for-new-speculation-control-msrs.patch
queue-4.9/x86-pti-make-unpoison-of-pgd-for-trusted-boot-work-for-real.patch
queue-4.9/kvm-vmx-make-msr-bitmaps-per-vcpu.patch
queue-4.9/x86-speculation-add-basic-ibpb-indirect-branch-prediction-barrier-support.patch
queue-4.9/kvm-nvmx-mark-vmcs12-pages-dirty-on-l2-exit.patch
queue-4.9/x86-pti-mark-constant-arrays-as-__initconst.patch
queue-4.9/x86-speculation-fix-typo-ibrs_att-which-should-be-ibrs_all.patch
queue-4.9/x86-spectre-report-get_user-mitigation-for-spectre_v1.patch
queue-4.9/x86-introduce-barrier_nospec.patch
queue-4.9/kvm-vmx-emulate-msr_ia32_arch_capabilities.patch
queue-4.9/x86-bugs-drop-one-mitigation-from-dmesg.patch
queue-4.9/x86-retpoline-remove-the-esp-rsp-thunk.patch
queue-4.9/x86-pti-do-not-enable-pti-on-cpus-which-are-not-vulnerable-to-meltdown.patch
queue-4.9/x86-introduce-__uaccess_begin_nospec-and-uaccess_try_nospec.patch
queue-4.9/nl80211-sanitize-array-index-in-parse_txq_params.patch