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| author | Linus Torvalds <torvalds@linux-foundation.org> | 2024-04-09 06:07:51 +0300 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2024-04-09 06:07:51 +0300 |
| commit | 2bb69f5fc72183e1c62547d900f560d0e9334925 (patch) | |
| tree | ce019218c8853bc4012bed9a208eec4648a0a7ae /arch/x86/kvm | |
| parent | 20cb38a7af88dc40095da7c2c9094da3873fea23 (diff) | |
| parent | ed2e8d49b54d677f3123668a21a57822d679651f (diff) | |
| download | linux-2bb69f5fc72183e1c62547d900f560d0e9334925.tar.xz | |
Merge tag 'nativebhi' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 mitigations from Thomas Gleixner:
"Mitigations for the native BHI hardware vulnerabilty:
Branch History Injection (BHI) attacks may allow a malicious
application to influence indirect branch prediction in kernel by
poisoning the branch history. eIBRS isolates indirect branch targets
in ring0. The BHB can still influence the choice of indirect branch
predictor entry, and although branch predictor entries are isolated
between modes when eIBRS is enabled, the BHB itself is not isolated
between modes.
Add mitigations against it either with the help of microcode or with
software sequences for the affected CPUs"
[ This also ends up enabling the full mitigation by default despite the
system call hardening, because apparently there are other indirect
calls that are still sufficiently reachable, and the 'auto' case just
isn't hardened enough.
We'll have some more inevitable tweaking in the future - Linus ]
* tag 'nativebhi' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
KVM: x86: Add BHI_NO
x86/bhi: Mitigate KVM by default
x86/bhi: Add BHI mitigation knob
x86/bhi: Enumerate Branch History Injection (BHI) bug
x86/bhi: Define SPEC_CTRL_BHI_DIS_S
x86/bhi: Add support for clearing branch history at syscall entry
x86/syscall: Don't force use of indirect calls for system calls
x86/bugs: Change commas to semicolons in 'spectre_v2' sysfs file
Diffstat (limited to 'arch/x86/kvm')
| -rw-r--r-- | arch/x86/kvm/reverse_cpuid.h | 3 | ||||
| -rw-r--r-- | arch/x86/kvm/vmx/vmenter.S | 2 | ||||
| -rw-r--r-- | arch/x86/kvm/x86.c | 2 |
3 files changed, 5 insertions, 2 deletions
diff --git a/arch/x86/kvm/reverse_cpuid.h b/arch/x86/kvm/reverse_cpuid.h index 58ac8d69c94b..2f4e155080ba 100644 --- a/arch/x86/kvm/reverse_cpuid.h +++ b/arch/x86/kvm/reverse_cpuid.h @@ -52,7 +52,7 @@ 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) /* CPUID level 0x80000007 (EDX). */ @@ -128,6 +128,7 @@ static __always_inline u32 __feature_translate(int x86_feature) KVM_X86_TRANSLATE_FEATURE(CONSTANT_TSC); KVM_X86_TRANSLATE_FEATURE(PERFMON_V2); KVM_X86_TRANSLATE_FEATURE(RRSBA_CTRL); + KVM_X86_TRANSLATE_FEATURE(BHI_CTRL); default: return x86_feature; } diff --git a/arch/x86/kvm/vmx/vmenter.S b/arch/x86/kvm/vmx/vmenter.S index 2bfbf758d061..f6986dee6f8c 100644 --- a/arch/x86/kvm/vmx/vmenter.S +++ b/arch/x86/kvm/vmx/vmenter.S @@ -275,6 +275,8 @@ SYM_INNER_LABEL_ALIGN(vmx_vmexit, SYM_L_GLOBAL) call vmx_spec_ctrl_restore_host + CLEAR_BRANCH_HISTORY_VMEXIT + /* Put return value in AX */ mov %_ASM_BX, %_ASM_AX diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 47d9f03b7778..984ea2089efc 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -1621,7 +1621,7 @@ static bool kvm_is_immutable_feature_msr(u32 msr) ARCH_CAP_PSCHANGE_MC_NO | ARCH_CAP_TSX_CTRL_MSR | ARCH_CAP_TAA_NO | \ ARCH_CAP_SBDR_SSDP_NO | ARCH_CAP_FBSDP_NO | ARCH_CAP_PSDP_NO | \ ARCH_CAP_FB_CLEAR | ARCH_CAP_RRSBA | ARCH_CAP_PBRSB_NO | ARCH_CAP_GDS_NO | \ - ARCH_CAP_RFDS_NO | ARCH_CAP_RFDS_CLEAR) + ARCH_CAP_RFDS_NO | ARCH_CAP_RFDS_CLEAR | ARCH_CAP_BHI_NO) static u64 kvm_get_arch_capabilities(void) { |