4.15-stable review patch. If anyone has any objections, please let me know.
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From: Shanker Donthineni shankerd@codeaurora.org
Commit ec82b567a74f upstream.
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@codeaurora.org [will: fix label name when !CONFIG_KVM and remove references to MIDR_FALKOR] Signed-off-by: Will Deacon will.deacon@arm.com
Signed-off-by: Catalin Marinas catalin.marinas@arm.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- 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 | 40 +++++++++++++++++++++++++++++++++++++-- arch/arm64/kvm/hyp/entry.S | 12 +++++++++++ arch/arm64/kvm/hyp/switch.c | 8 +++++++ 6 files changed, 70 insertions(+), 3 deletions(-)
--- 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 */ --- a/arch/arm64/include/asm/kvm_asm.h +++ b/arch/arm64/include/asm/kvm_asm.h @@ -68,6 +68,8 @@ extern u32 __kvm_get_mdcr_el2(void);
extern u32 __init_stage2_translation(void);
+extern void __qcom_hyp_sanitize_btac_predictors(void); + #endif
#endif /* __ARM_KVM_ASM_H__ */ --- a/arch/arm64/kernel/bpi.S +++ b/arch/arm64/kernel/bpi.S @@ -77,3 +77,11 @@ ENTRY(__psci_hyp_bp_inval_start) ldp x0, x1, [sp, #(16 * 8)] add sp, sp, #(8 * 18) 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) --- a/arch/arm64/kernel/cpu_errata.c +++ b/arch/arm64/kernel/cpu_errata.c @@ -68,6 +68,8 @@ DEFINE_PER_CPU_READ_MOSTLY(struct bp_har
#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) @@ -110,8 +112,10 @@ static void __install_bp_hardening_cb(bp 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, @@ -152,6 +156,29 @@ static int enable_psci_bp_hardening(void
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)); +} + +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) \ @@ -323,6 +350,15 @@ const struct arm64_cpu_capabilities arm6 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_BP_POST_GUEST_EXIT, + MIDR_ALL_VERSIONS(MIDR_QCOM_FALKOR_V1), + }, #endif { } --- 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) --- a/arch/arm64/kvm/hyp/switch.c +++ b/arch/arm64/kvm/hyp/switch.c @@ -393,6 +393,14 @@ again: /* 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_V1) + __qcom_hyp_sanitize_btac_predictors(); + } + fp_enabled = __fpsimd_enabled();
__sysreg_save_guest_state(guest_ctxt);