linux-kernel - [PATCH 4.9 28/66] arm64: KVM: Use per-CPU vector when BP hardening is enabled

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Message-Id: <20180417155647.089298589@linuxfoundation.org>
Date:   Tue, 17 Apr 2018 17:59:01 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Marc Zyngier <marc.zyngier@....com>,
        Will Deacon <will.deacon@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Greg Hackmann <ghackmann@...gle.com>,
        Mark Rutland <mark.rutland@....com>
Subject: [PATCH 4.9 28/66] arm64: KVM: Use per-CPU vector when BP hardening is enabled

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Mark Rutland <mark.rutland@....com>


From: Marc Zyngier <marc.zyngier@....com>

commit 6840bdd73d07216ab4bc46f5a8768c37ea519038 upstream.

Now that we have per-CPU vectors, let's plug then in the KVM/arm64 code.

Signed-off-by: Marc Zyngier <marc.zyngier@....com>
Signed-off-by: Will Deacon <will.deacon@....com>
Signed-off-by: Catalin Marinas <catalin.marinas@....com>
[v4.9: account for files moved to virt/ upstream, use cpus_have_cap()]
Signed-off-by: Mark Rutland <mark.rutland@....com> [v4.9 backport]
Tested-by: Greg Hackmann <ghackmann@...gle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 arch/arm/include/asm/kvm_mmu.h   |   10 ++++++++++
 arch/arm/kvm/arm.c               |    9 ++++++++-
 arch/arm64/include/asm/kvm_mmu.h |   38 ++++++++++++++++++++++++++++++++++++++
 arch/arm64/kvm/hyp/switch.c      |    2 +-
 4 files changed, 57 insertions(+), 2 deletions(-)

--- a/arch/arm/include/asm/kvm_mmu.h
+++ b/arch/arm/include/asm/kvm_mmu.h
@@ -223,6 +223,16 @@ static inline unsigned int kvm_get_vmid_
 	return 8;
 }
 
+static inline void *kvm_get_hyp_vector(void)
+{
+	return kvm_ksym_ref(__kvm_hyp_vector);
+}
+
+static inline int kvm_map_vectors(void)
+{
+	return 0;
+}
+
 #endif	/* !__ASSEMBLY__ */
 
 #endif /* __ARM_KVM_MMU_H__ */
--- a/arch/arm/kvm/arm.c
+++ b/arch/arm/kvm/arm.c
@@ -1088,7 +1088,7 @@ static void cpu_init_hyp_mode(void *dumm
 	pgd_ptr = kvm_mmu_get_httbr();
 	stack_page = __this_cpu_read(kvm_arm_hyp_stack_page);
 	hyp_stack_ptr = stack_page + PAGE_SIZE;
-	vector_ptr = (unsigned long)kvm_ksym_ref(__kvm_hyp_vector);
+	vector_ptr = (unsigned long)kvm_get_hyp_vector();
 
 	__cpu_init_hyp_mode(pgd_ptr, hyp_stack_ptr, vector_ptr);
 	__cpu_init_stage2();
@@ -1345,6 +1345,13 @@ static int init_hyp_mode(void)
 		goto out_err;
 	}
 
+
+	err = kvm_map_vectors();
+	if (err) {
+		kvm_err("Cannot map vectors\n");
+		goto out_err;
+	}
+
 	/*
 	 * Map the Hyp stack pages
 	 */
--- a/arch/arm64/include/asm/kvm_mmu.h
+++ b/arch/arm64/include/asm/kvm_mmu.h
@@ -313,5 +313,43 @@ static inline unsigned int kvm_get_vmid_
 	return (cpuid_feature_extract_unsigned_field(reg, ID_AA64MMFR1_VMIDBITS_SHIFT) == 2) ? 16 : 8;
 }
 
+#ifdef CONFIG_HARDEN_BRANCH_PREDICTOR
+#include <asm/mmu.h>
+
+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) {
+		vect = __bp_harden_hyp_vecs_start +
+		       data->hyp_vectors_slot * SZ_2K;
+
+		if (!cpus_have_cap(ARM64_HAS_VIRT_HOST_EXTN))
+			vect = lm_alias(vect);
+	}
+
+	return vect;
+}
+
+static inline int kvm_map_vectors(void)
+{
+	return create_hyp_mappings(kvm_ksym_ref(__bp_harden_hyp_vecs_start),
+				   kvm_ksym_ref(__bp_harden_hyp_vecs_end),
+				   PAGE_HYP_EXEC);
+}
+
+#else
+static inline void *kvm_get_hyp_vector(void)
+{
+	return kvm_ksym_ref(__kvm_hyp_vector);
+}
+
+static inline int kvm_map_vectors(void)
+{
+	return 0;
+}
+#endif
+
 #endif /* __ASSEMBLY__ */
 #endif /* __ARM64_KVM_MMU_H__ */
--- a/arch/arm64/kvm/hyp/switch.c
+++ b/arch/arm64/kvm/hyp/switch.c
@@ -50,7 +50,7 @@ static void __hyp_text __activate_traps_
 	val &= ~CPACR_EL1_FPEN;
 	write_sysreg(val, cpacr_el1);
 
-	write_sysreg(__kvm_hyp_vector, vbar_el1);
+	write_sysreg(kvm_get_hyp_vector(), vbar_el1);
 }
 
 static void __hyp_text __activate_traps_nvhe(void)