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