On 8 January 2018 at 21:31, Shanker Donthineni <shankerd@xxxxxxxxxxxxxx> wrote: > Falkor is susceptible to branch predictor aliasing and can > theoretically be attacked by malicious code. This patch > implements a mitigation for these attacks, preventing any > malicious entries from affecting other victim contexts. > > Signed-off-by: Shanker Donthineni <shankerd@xxxxxxxxxxxxxx> > --- > Changes since v1: > Corrected typo to fix the compilation errors if HARDEN_BRANCH_PREDICTOR=n > > This patch requires FALKOR MIDR which is available in upstream v4.15-rc7 > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/arch/arm64?h=v4.15-rc7&id=c622cc013cece073722592cff1ac6643a33b1622 ans also > attached this v2 patch series. > > arch/arm64/include/asm/cpucaps.h | 3 ++- > arch/arm64/include/asm/kvm_asm.h | 2 ++ > arch/arm64/kernel/bpi.S | 8 +++++++ > arch/arm64/kernel/cpu_errata.c | 49 ++++++++++++++++++++++++++++++++++++++-- > arch/arm64/kvm/hyp/entry.S | 12 ++++++++++ > arch/arm64/kvm/hyp/switch.c | 10 ++++++++ > 6 files changed, 81 insertions(+), 3 deletions(-) > > diff --git a/arch/arm64/include/asm/cpucaps.h b/arch/arm64/include/asm/cpucaps.h > index 51616e7..7049b48 100644 > --- a/arch/arm64/include/asm/cpucaps.h > +++ b/arch/arm64/include/asm/cpucaps.h > @@ -43,7 +43,8 @@ > #define ARM64_SVE 22 > #define ARM64_UNMAP_KERNEL_AT_EL0 23 > #define ARM64_HARDEN_BRANCH_PREDICTOR 24 > +#define ARM64_HARDEN_BP_POST_GUEST_EXIT 25 > > -#define ARM64_NCAPS 25 > +#define ARM64_NCAPS 26 > > #endif /* __ASM_CPUCAPS_H */ > diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h > index ab4d0a9..24961b7 100644 > --- a/arch/arm64/include/asm/kvm_asm.h > +++ b/arch/arm64/include/asm/kvm_asm.h > @@ -68,6 +68,8 @@ > > extern u32 __init_stage2_translation(void); > > +extern void __qcom_hyp_sanitize_btac_predictors(void); > + > #endif > > #endif /* __ARM_KVM_ASM_H__ */ > diff --git a/arch/arm64/kernel/bpi.S b/arch/arm64/kernel/bpi.S > index 2b10d52..44ffcda 100644 > --- a/arch/arm64/kernel/bpi.S > +++ b/arch/arm64/kernel/bpi.S > @@ -77,3 +77,11 @@ ENTRY(__psci_hyp_bp_inval_start) > ldp x2, x3, [sp], #16 > ldp x0, x1, [sp], #16 > ENTRY(__psci_hyp_bp_inval_end) > + > +ENTRY(__qcom_hyp_sanitize_link_stack_start) > + stp x29, x30, [sp, #-16]! > + .rept 16 > + bl . + 4 > + .endr > + ldp x29, x30, [sp], #16 > +ENTRY(__qcom_hyp_sanitize_link_stack_end) > diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c > index cb0fb37..9ee9d2e 100644 > --- a/arch/arm64/kernel/cpu_errata.c > +++ b/arch/arm64/kernel/cpu_errata.c > @@ -54,6 +54,8 @@ static int cpu_enable_trap_ctr_access(void *__unused) > > #ifdef CONFIG_KVM > extern char __psci_hyp_bp_inval_start[], __psci_hyp_bp_inval_end[]; > +extern char __qcom_hyp_sanitize_link_stack_start[]; > +extern char __qcom_hyp_sanitize_link_stack_end[]; > > static void __copy_hyp_vect_bpi(int slot, const char *hyp_vecs_start, > const char *hyp_vecs_end) > @@ -96,8 +98,10 @@ static void __install_bp_hardening_cb(bp_hardening_cb_t fn, > spin_unlock(&bp_lock); > } > #else > -#define __psci_hyp_bp_inval_start NULL > -#define __psci_hyp_bp_inval_end NULL > +#define __psci_hyp_bp_inval_start NULL > +#define __psci_hyp_bp_inval_end NULL > +#define __qcom_hyp_sanitize_link_stack_start NULL > +#define __qcom_hyp_sanitize_link_stack_end NULL > > static void __install_bp_hardening_cb(bp_hardening_cb_t fn, > const char *hyp_vecs_start, > @@ -138,6 +142,29 @@ static int enable_psci_bp_hardening(void *data) > > return 0; > } > + > +static void qcom_link_stack_sanitization(void) > +{ > + u64 tmp; > + > + asm volatile("mov %0, x30 \n" > + ".rept 16 \n" > + "bl . + 4 \n" > + ".endr \n" > + "mov x30, %0 \n" > + : "=&r" (tmp)); > +} > + Couldn't you just add x30 to the clobber list here? > +static int qcom_enable_link_stack_sanitization(void *data) > +{ > + const struct arm64_cpu_capabilities *entry = data; > + > + install_bp_hardening_cb(entry, qcom_link_stack_sanitization, > + __qcom_hyp_sanitize_link_stack_start, > + __qcom_hyp_sanitize_link_stack_end); > + > + return 0; > +} > #endif /* CONFIG_HARDEN_BRANCH_PREDICTOR */ > > #define MIDR_RANGE(model, min, max) \ > @@ -302,6 +329,24 @@ static int enable_psci_bp_hardening(void *data) > MIDR_ALL_VERSIONS(MIDR_CORTEX_A75), > .enable = enable_psci_bp_hardening, > }, > + { > + .capability = ARM64_HARDEN_BRANCH_PREDICTOR, > + MIDR_ALL_VERSIONS(MIDR_QCOM_FALKOR_V1), > + .enable = qcom_enable_link_stack_sanitization, > + }, > + { > + .capability = ARM64_HARDEN_BRANCH_PREDICTOR, > + MIDR_ALL_VERSIONS(MIDR_QCOM_FALKOR), > + .enable = qcom_enable_link_stack_sanitization, > + }, > + { > + .capability = ARM64_HARDEN_BP_POST_GUEST_EXIT, > + MIDR_ALL_VERSIONS(MIDR_QCOM_FALKOR_V1), > + }, > + { > + .capability = ARM64_HARDEN_BP_POST_GUEST_EXIT, > + MIDR_ALL_VERSIONS(MIDR_QCOM_FALKOR), > + }, > #endif > { > } > diff --git a/arch/arm64/kvm/hyp/entry.S b/arch/arm64/kvm/hyp/entry.S > index 12ee62d..9c45c6a 100644 > --- a/arch/arm64/kvm/hyp/entry.S > +++ b/arch/arm64/kvm/hyp/entry.S > @@ -196,3 +196,15 @@ alternative_endif > > eret > ENDPROC(__fpsimd_guest_restore) > + > +ENTRY(__qcom_hyp_sanitize_btac_predictors) > + /** > + * Call SMC64 with Silicon provider serviceID 23<<8 (0xc2001700) > + * 0xC2000000-0xC200FFFF: assigned to SiP Service Calls > + * b15-b0: contains SiP functionID > + */ > + movz x0, #0x1700 > + movk x0, #0xc200, lsl #16 > + smc #0 > + ret > +ENDPROC(__qcom_hyp_sanitize_btac_predictors) > diff --git a/arch/arm64/kvm/hyp/switch.c b/arch/arm64/kvm/hyp/switch.c > index 4d273f6..7e37379 100644 > --- a/arch/arm64/kvm/hyp/switch.c > +++ b/arch/arm64/kvm/hyp/switch.c > @@ -406,6 +406,16 @@ int __hyp_text __kvm_vcpu_run(struct kvm_vcpu *vcpu) > /* 0 falls through to be handled out of EL2 */ > } > > + if (cpus_have_const_cap(ARM64_HARDEN_BP_POST_GUEST_EXIT)) { > + u32 midr = read_cpuid_id(); > + > + /* Apply BTAC predictors mitigation to all Falkor chips */ > + if (((midr & MIDR_CPU_MODEL_MASK) == MIDR_QCOM_FALKOR) || > + ((midr & MIDR_CPU_MODEL_MASK) == MIDR_QCOM_FALKOR_V1)) { > + __qcom_hyp_sanitize_btac_predictors(); > + } > + } > + > fp_enabled = __fpsimd_enabled(); > > __sysreg_save_guest_state(guest_ctxt); > -- > Qualcomm Datacenter Technologies, Inc. on behalf of the Qualcomm Technologies, Inc. > Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project. > > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@xxxxxxxxxxxxxxxxxxx > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
