[PATCH 08/13] x86/bhi: Define SPEC_CTRL_BHI_DIS_S
Stefan Bader
stefan.bader at canonical.com
Tue Apr 16 14:53:20 UTC 2024
From: Daniel Sneddon <daniel.sneddon at linux.intel.com>
commit 0f4a837615ff925ba62648d280a861adf1582df7 upstream.
Newer processors supports a hardware control BHI_DIS_S to mitigate
Branch History Injection (BHI). Setting BHI_DIS_S protects the kernel
from userspace BHI attacks without having to manually overwrite the
branch history.
Define MSR_SPEC_CTRL bit BHI_DIS_S and its enumeration CPUID.BHI_CTRL.
Mitigation is enabled later.
Signed-off-by: Daniel Sneddon <daniel.sneddon at linux.intel.com>
Signed-off-by: Pawan Gupta <pawan.kumar.gupta at linux.intel.com>
Signed-off-by: Daniel Sneddon <daniel.sneddon at linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx at linutronix.de>
Reviewed-by: Alexandre Chartre <alexandre.chartre at oracle.com>
Reviewed-by: Josh Poimboeuf <jpoimboe at kernel.org>
Signed-off-by: Daniel Sneddon <daniel.sneddon at linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
CVE-2024-2201
(cherry picked from commit a9ca0e34a406b5e122ad1e9b7e12a4281fccfca1 linux-5.15.y)
Signed-off-by: Stefan Bader <stefan.bader at canonical.com>
---
arch/x86/include/asm/cpufeatures.h | 1 +
arch/x86/include/asm/msr-index.h | 5 ++++-
arch/x86/kernel/cpu/scattered.c | 1 +
arch/x86/kvm/reverse_cpuid.h | 3 ++-
4 files changed, 8 insertions(+), 2 deletions(-)
diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
index 7c47e6aa9ea1..8edb74b8e3e6 100644
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -432,6 +432,7 @@
* Reuse free bits when adding new feature flags!
*/
#define X86_FEATURE_CLEAR_BHB_LOOP (21*32+ 1) /* "" Clear branch history at syscall entry using SW loop */
+#define X86_FEATURE_BHI_CTRL (21*32+ 2) /* "" BHI_DIS_S HW control available */
/*
* BUG word(s)
diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h
index dc7fa0aa0a8e..cee413b8927a 100644
--- a/arch/x86/include/asm/msr-index.h
+++ b/arch/x86/include/asm/msr-index.h
@@ -53,10 +53,13 @@
#define SPEC_CTRL_SSBD BIT(SPEC_CTRL_SSBD_SHIFT) /* Speculative Store Bypass Disable */
#define SPEC_CTRL_RRSBA_DIS_S_SHIFT 6 /* Disable RRSBA behavior */
#define SPEC_CTRL_RRSBA_DIS_S BIT(SPEC_CTRL_RRSBA_DIS_S_SHIFT)
+#define SPEC_CTRL_BHI_DIS_S_SHIFT 10 /* Disable Branch History Injection behavior */
+#define SPEC_CTRL_BHI_DIS_S BIT(SPEC_CTRL_BHI_DIS_S_SHIFT)
/* A mask for bits which the kernel toggles when controlling mitigations */
#define SPEC_CTRL_MITIGATIONS_MASK (SPEC_CTRL_IBRS | SPEC_CTRL_STIBP | SPEC_CTRL_SSBD \
- | SPEC_CTRL_RRSBA_DIS_S)
+ | SPEC_CTRL_RRSBA_DIS_S \
+ | SPEC_CTRL_BHI_DIS_S)
#define MSR_IA32_PRED_CMD 0x00000049 /* Prediction Command */
#define PRED_CMD_IBPB BIT(0) /* Indirect Branch Prediction Barrier */
diff --git a/arch/x86/kernel/cpu/scattered.c b/arch/x86/kernel/cpu/scattered.c
index 06bfef1c4175..0f5211087810 100644
--- a/arch/x86/kernel/cpu/scattered.c
+++ b/arch/x86/kernel/cpu/scattered.c
@@ -27,6 +27,7 @@ static const struct cpuid_bit cpuid_bits[] = {
{ X86_FEATURE_APERFMPERF, CPUID_ECX, 0, 0x00000006, 0 },
{ X86_FEATURE_EPB, CPUID_ECX, 3, 0x00000006, 0 },
{ X86_FEATURE_RRSBA_CTRL, CPUID_EDX, 2, 0x00000007, 2 },
+ { X86_FEATURE_BHI_CTRL, CPUID_EDX, 4, 0x00000007, 2 },
{ X86_FEATURE_CQM_LLC, CPUID_EDX, 1, 0x0000000f, 0 },
{ X86_FEATURE_CQM_OCCUP_LLC, CPUID_EDX, 0, 0x0000000f, 1 },
{ X86_FEATURE_CQM_MBM_TOTAL, CPUID_EDX, 1, 0x0000000f, 1 },
diff --git a/arch/x86/kvm/reverse_cpuid.h b/arch/x86/kvm/reverse_cpuid.h
index 7c8e2b20a13b..0af89eede626 100644
--- a/arch/x86/kvm/reverse_cpuid.h
+++ b/arch/x86/kvm/reverse_cpuid.h
@@ -42,7 +42,7 @@ enum kvm_only_cpuid_leafs {
#define X86_FEATURE_IPRED_CTRL KVM_X86_FEATURE(CPUID_7_2_EDX, 1)
#define KVM_X86_FEATURE_RRSBA_CTRL KVM_X86_FEATURE(CPUID_7_2_EDX, 2)
#define X86_FEATURE_DDPD_U KVM_X86_FEATURE(CPUID_7_2_EDX, 3)
-#define X86_FEATURE_BHI_CTRL KVM_X86_FEATURE(CPUID_7_2_EDX, 4)
+#define KVM_X86_FEATURE_BHI_CTRL KVM_X86_FEATURE(CPUID_7_2_EDX, 4)
#define X86_FEATURE_MCDT_NO KVM_X86_FEATURE(CPUID_7_2_EDX, 5)
struct cpuid_reg {
@@ -104,6 +104,7 @@ static __always_inline u32 __feature_translate(int x86_feature)
KVM_X86_TRANSLATE_FEATURE(SGX1);
KVM_X86_TRANSLATE_FEATURE(SGX2);
KVM_X86_TRANSLATE_FEATURE(RRSBA_CTRL);
+ KVM_X86_TRANSLATE_FEATURE(BHI_CTRL);
default:
return x86_feature;
}
--
2.34.1
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