From patchwork Wed Apr 6 16:45:42 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: James Morse X-Patchwork-Id: 558552 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 08600C433EF for ; Wed, 6 Apr 2022 18:08:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240201AbiDFSKD (ORCPT ); Wed, 6 Apr 2022 14:10:03 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58020 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240105AbiDFSIz (ORCPT ); Wed, 6 Apr 2022 14:08:55 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id E95171A4D6D; Wed, 6 Apr 2022 09:46:36 -0700 (PDT) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id D01D41516; Wed, 6 Apr 2022 09:46:36 -0700 (PDT) Received: from eglon.cambridge.arm.com (eglon.cambridge.arm.com [10.1.196.218]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 2EE443F73B; Wed, 6 Apr 2022 09:46:36 -0700 (PDT) From: James Morse To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: James Morse , Catalin Marinas Subject: [stable:PATCH v4.9.309 39/43] KVM: arm64: Add templates for BHB mitigation sequences Date: Wed, 6 Apr 2022 17:45:42 +0100 Message-Id: <20220406164546.1888528-39-james.morse@arm.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20220406164546.1888528-1-james.morse@arm.com> References: <0220406164217.1888053-1-james.morse@arm.com> <20220406164546.1888528-1-james.morse@arm.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org KVM writes the Spectre-v2 mitigation template at the beginning of each vector when a CPU requires a specific sequence to run. Because the template is copied, it can not be modified by the alternatives at runtime. As the KVM template code is intertwined with the bp-hardening callbacks, all templates must have a bp-hardening callback. Add templates for calling ARCH_WORKAROUND_3 and one for each value of K in the brancy-loop. Identify these sequences by a new parameter template_start, and add a copy of install_bp_hardening_cb() that is able to install them. Signed-off-by: James Morse --- arch/arm64/include/asm/cpucaps.h | 3 +- arch/arm64/include/asm/kvm_mmu.h | 2 +- arch/arm64/include/asm/mmu.h | 6 +++ arch/arm64/kernel/bpi.S | 50 ++++++++++++++++++++++ arch/arm64/kernel/cpu_errata.c | 71 +++++++++++++++++++++++++++++++- 5 files changed, 128 insertions(+), 4 deletions(-) diff --git a/arch/arm64/include/asm/cpucaps.h b/arch/arm64/include/asm/cpucaps.h index d4a46764c1ad..9935e55a3cc7 100644 --- a/arch/arm64/include/asm/cpucaps.h +++ b/arch/arm64/include/asm/cpucaps.h @@ -39,7 +39,8 @@ #define ARM64_SSBD 18 #define ARM64_MISMATCHED_CACHE_TYPE 19 #define ARM64_WORKAROUND_1188873 20 +#define ARM64_SPECTRE_BHB 21 -#define ARM64_NCAPS 21 +#define ARM64_NCAPS 22 #endif /* __ASM_CPUCAPS_H */ diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h index ff721659eb94..4a2c95854856 100644 --- a/arch/arm64/include/asm/kvm_mmu.h +++ b/arch/arm64/include/asm/kvm_mmu.h @@ -362,7 +362,7 @@ static inline void *kvm_get_hyp_vector(void) struct bp_hardening_data *data = arm64_get_bp_hardening_data(); void *vect = kvm_ksym_ref(__kvm_hyp_vector); - if (data->fn) { + if (data->template_start) { vect = __bp_harden_hyp_vecs_start + data->hyp_vectors_slot * SZ_2K; diff --git a/arch/arm64/include/asm/mmu.h b/arch/arm64/include/asm/mmu.h index 5eff1c49270d..f4377b005cba 100644 --- a/arch/arm64/include/asm/mmu.h +++ b/arch/arm64/include/asm/mmu.h @@ -45,6 +45,12 @@ typedef void (*bp_hardening_cb_t)(void); struct bp_hardening_data { int hyp_vectors_slot; bp_hardening_cb_t fn; + + /* + * template_start is only used by the BHB mitigation to identify the + * hyp_vectors_slot sequence. + */ + const char *template_start; }; #ifdef CONFIG_HARDEN_BRANCH_PREDICTOR diff --git a/arch/arm64/kernel/bpi.S b/arch/arm64/kernel/bpi.S index dc4eb154e33b..313f2b59eef9 100644 --- a/arch/arm64/kernel/bpi.S +++ b/arch/arm64/kernel/bpi.S @@ -73,3 +73,53 @@ ENTRY(__smccc_workaround_1_smc_end) ENTRY(__smccc_workaround_1_hvc_start) smccc_workaround_1 hvc ENTRY(__smccc_workaround_1_hvc_end) + +ENTRY(__smccc_workaround_3_smc_start) + sub sp, sp, #(8 * 4) + stp x2, x3, [sp, #(8 * 0)] + stp x0, x1, [sp, #(8 * 2)] + mov w0, #ARM_SMCCC_ARCH_WORKAROUND_3 + smc #0 + ldp x2, x3, [sp, #(8 * 0)] + ldp x0, x1, [sp, #(8 * 2)] + add sp, sp, #(8 * 4) +ENTRY(__smccc_workaround_3_smc_end) + +ENTRY(__spectre_bhb_loop_k8_start) + sub sp, sp, #(8 * 2) + stp x0, x1, [sp, #(8 * 0)] + mov x0, #8 +2: b . + 4 + subs x0, x0, #1 + b.ne 2b + dsb nsh + isb + ldp x0, x1, [sp, #(8 * 0)] + add sp, sp, #(8 * 2) +ENTRY(__spectre_bhb_loop_k8_end) + +ENTRY(__spectre_bhb_loop_k24_start) + sub sp, sp, #(8 * 2) + stp x0, x1, [sp, #(8 * 0)] + mov x0, #24 +2: b . + 4 + subs x0, x0, #1 + b.ne 2b + dsb nsh + isb + ldp x0, x1, [sp, #(8 * 0)] + add sp, sp, #(8 * 2) +ENTRY(__spectre_bhb_loop_k24_end) + +ENTRY(__spectre_bhb_loop_k32_start) + sub sp, sp, #(8 * 2) + stp x0, x1, [sp, #(8 * 0)] + mov x0, #32 +2: b . + 4 + subs x0, x0, #1 + b.ne 2b + dsb nsh + isb + ldp x0, x1, [sp, #(8 * 0)] + add sp, sp, #(8 * 2) +ENTRY(__spectre_bhb_loop_k32_end) diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c index 0d08249cbdab..acccc685b670 100644 --- a/arch/arm64/kernel/cpu_errata.c +++ b/arch/arm64/kernel/cpu_errata.c @@ -74,6 +74,14 @@ extern char __smccc_workaround_1_smc_start[]; extern char __smccc_workaround_1_smc_end[]; extern char __smccc_workaround_1_hvc_start[]; extern char __smccc_workaround_1_hvc_end[]; +extern char __smccc_workaround_3_smc_start[]; +extern char __smccc_workaround_3_smc_end[]; +extern char __spectre_bhb_loop_k8_start[]; +extern char __spectre_bhb_loop_k8_end[]; +extern char __spectre_bhb_loop_k24_start[]; +extern char __spectre_bhb_loop_k24_end[]; +extern char __spectre_bhb_loop_k32_start[]; +extern char __spectre_bhb_loop_k32_end[]; static void __copy_hyp_vect_bpi(int slot, const char *hyp_vecs_start, const char *hyp_vecs_end) @@ -87,12 +95,14 @@ static void __copy_hyp_vect_bpi(int slot, const char *hyp_vecs_start, flush_icache_range((uintptr_t)dst, (uintptr_t)dst + SZ_2K); } +static DEFINE_SPINLOCK(bp_lock); +static int last_slot = -1; + static void __install_bp_hardening_cb(bp_hardening_cb_t fn, const char *hyp_vecs_start, const char *hyp_vecs_end) { - static int last_slot = -1; - static DEFINE_SPINLOCK(bp_lock); + int cpu, slot = -1; spin_lock(&bp_lock); @@ -113,6 +123,7 @@ static void __install_bp_hardening_cb(bp_hardening_cb_t fn, __this_cpu_write(bp_hardening_data.hyp_vectors_slot, slot); __this_cpu_write(bp_hardening_data.fn, fn); + __this_cpu_write(bp_hardening_data.template_start, hyp_vecs_start); spin_unlock(&bp_lock); } #else @@ -544,3 +555,59 @@ const struct arm64_cpu_capabilities arm64_errata[] = { { } }; + +#ifdef CONFIG_KVM +static const char *kvm_bhb_get_vecs_end(const char *start) +{ + if (start == __smccc_workaround_3_smc_start) + return __smccc_workaround_3_smc_end; + else if (start == __spectre_bhb_loop_k8_start) + return __spectre_bhb_loop_k8_end; + else if (start == __spectre_bhb_loop_k24_start) + return __spectre_bhb_loop_k24_end; + else if (start == __spectre_bhb_loop_k32_start) + return __spectre_bhb_loop_k32_end; + + return NULL; +} + +void kvm_setup_bhb_slot(const char *hyp_vecs_start) +{ + int cpu, slot = -1; + const char *hyp_vecs_end; + + if (!IS_ENABLED(CONFIG_KVM) || !is_hyp_mode_available()) + return; + + hyp_vecs_end = kvm_bhb_get_vecs_end(hyp_vecs_start); + if (WARN_ON_ONCE(!hyp_vecs_start || !hyp_vecs_end)) + return; + + spin_lock(&bp_lock); + for_each_possible_cpu(cpu) { + if (per_cpu(bp_hardening_data.template_start, cpu) == hyp_vecs_start) { + slot = per_cpu(bp_hardening_data.hyp_vectors_slot, cpu); + break; + } + } + + if (slot == -1) { + last_slot++; + BUG_ON(((__bp_harden_hyp_vecs_end - __bp_harden_hyp_vecs_start) + / SZ_2K) <= last_slot); + slot = last_slot; + __copy_hyp_vect_bpi(slot, hyp_vecs_start, hyp_vecs_end); + } + + __this_cpu_write(bp_hardening_data.hyp_vectors_slot, slot); + __this_cpu_write(bp_hardening_data.template_start, hyp_vecs_start); + spin_unlock(&bp_lock); +} +#else +#define __smccc_workaround_3_smc_start NULL +#define __spectre_bhb_loop_k8_start NULL +#define __spectre_bhb_loop_k24_start NULL +#define __spectre_bhb_loop_k32_start NULL + +void kvm_setup_bhb_slot(const char *hyp_vecs_start) { }; +#endif