[PATCH v2 08/11] arm64: KVM: Use per-CPU vector when BP hardening is enabled

Will Deacon
2018-01-05T13:12:38Z

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

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

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
---
arch/arm/include/asm/kvm_mmu.h | 10 ++++++++++
arch/arm64/include/asm/kvm_mmu.h | 38 ++++++++++++++++++++++++++++++++++++++
arch/arm64/kvm/hyp/switch.c | 2 +-
virt/kvm/arm/arm.c | 8 +++++++-
4 files changed, 56 insertions(+), 2 deletions(-)

diff --git a/arch/arm/include/asm/kvm_mmu.h b/arch/arm/include/asm/kvm_mmu.h
index fa6f2174276b..eb46fc81a440 100644
--- a/arch/arm/include/asm/kvm_mmu.h
+++ b/arch/arm/include/asm/kvm_mmu.h
@@ -221,6 +221,16 @@ static inline unsigned int kvm_get_vmid_bits(void)
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__ */
diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h
index 672c8684d5c2..2d6d4bd9de52 100644
--- a/arch/arm64/include/asm/kvm_mmu.h
+++ b/arch/arm64/include/asm/kvm_mmu.h
@@ -309,5 +309,43 @@ static inline unsigned int kvm_get_vmid_bits(void)
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 (!has_vhe())
+ 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__ */
diff --git a/arch/arm64/kvm/hyp/switch.c b/arch/arm64/kvm/hyp/switch.c
index f7c651f3a8c0..8d4f3c9d6dc4 100644
--- a/arch/arm64/kvm/hyp/switch.c
+++ b/arch/arm64/kvm/hyp/switch.c
@@ -52,7 +52,7 @@ static void __hyp_text __activate_traps_vhe(void)
val &= ~(CPACR_EL1_FPEN | CPACR_EL1_ZEN);
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)
diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c
index 6b60c98a6e22..1c9fdb6db124 100644
--- a/virt/kvm/arm/arm.c
+++ b/virt/kvm/arm/arm.c
@@ -1158,7 +1158,7 @@ static void cpu_init_hyp_mode(void *dummy)
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();
@@ -1403,6 +1403,12 @@ 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
*/
--
2.1.4