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    Subject[RFC 39/55] KVM: arm/arm64: Add mmu context for the nesting
    Date
    Add the shadow stage-2 MMU context to be used for the nesting, but don't
    do anything with it yet.

    The host hypervisor maintains mmu structures for each nested VM. When
    entering a nested VM, the host hypervisor searches for the nested VM's
    mmu using vmid as a key. Note that this vmid is from the guest
    hypervisor's point of view.

    Signed-off-by: Jintack Lim <jintack@cs.columbia.edu>
    ---
    arch/arm/include/asm/kvm_host.h | 3 ++
    arch/arm/kvm/arm.c | 1 +
    arch/arm64/include/asm/kvm_emulate.h | 13 ++++-----
    arch/arm64/include/asm/kvm_host.h | 19 +++++++++++++
    arch/arm64/include/asm/kvm_mmu.h | 31 ++++++++++++++++++++
    arch/arm64/kvm/Makefile | 1 +
    arch/arm64/kvm/context.c | 2 +-
    arch/arm64/kvm/mmu-nested.c | 55 ++++++++++++++++++++++++++++++++++++
    8 files changed, 116 insertions(+), 9 deletions(-)
    create mode 100644 arch/arm64/kvm/mmu-nested.c

    diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h
    index da45394..fbde48d 100644
    --- a/arch/arm/include/asm/kvm_host.h
    +++ b/arch/arm/include/asm/kvm_host.h
    @@ -82,6 +82,9 @@ struct kvm_arch {
    * here.
    */

    + /* Never used on arm but added to be compatible with arm64 */
    + struct list_head nested_mmu_list;
    +
    /* Interrupt controller */
    struct vgic_dist vgic;
    int max_vcpus;
    diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
    index 371b38e7..147df97 100644
    --- a/arch/arm/kvm/arm.c
    +++ b/arch/arm/kvm/arm.c
    @@ -146,6 +146,7 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
    /* Mark the initial VMID generation invalid */
    kvm->arch.mmu.vmid.vmid_gen = 0;
    kvm->arch.mmu.el2_vmid.vmid_gen = 0;
    + INIT_LIST_HEAD(&kvm->arch.nested_mmu_list);

    /* The maximum number of VCPUs is limited by the host's GIC model */
    kvm->arch.max_vcpus = vgic_present ?
    diff --git a/arch/arm64/include/asm/kvm_emulate.h b/arch/arm64/include/asm/kvm_emulate.h
    index 94068e7..abad676 100644
    --- a/arch/arm64/include/asm/kvm_emulate.h
    +++ b/arch/arm64/include/asm/kvm_emulate.h
    @@ -183,6 +183,11 @@ static inline bool vcpu_el2_imo_is_set(const struct kvm_vcpu *vcpu)
    return (vcpu_el2_reg(vcpu, HCR_EL2) & HCR_IMO);
    }

    +static inline bool vcpu_nested_stage2_enabled(const struct kvm_vcpu *vcpu)
    +{
    + return (vcpu_el2_reg(vcpu, HCR_EL2) & HCR_VM);
    +}
    +
    static inline u32 kvm_vcpu_get_hsr(const struct kvm_vcpu *vcpu)
    {
    return vcpu->arch.fault.esr_el2;
    @@ -363,12 +368,4 @@ static inline unsigned long vcpu_data_host_to_guest(struct kvm_vcpu *vcpu,
    return data; /* Leave LE untouched */
    }

    -static inline struct kvm_s2_vmid *vcpu_get_active_vmid(struct kvm_vcpu *vcpu)
    -{
    - if (unlikely(vcpu_mode_el2(vcpu)))
    - return &vcpu->kvm->arch.mmu.el2_vmid;
    -
    - return &vcpu->kvm->arch.mmu.vmid;
    -}
    -
    #endif /* __ARM64_KVM_EMULATE_H__ */
    diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
    index b33d35d..23e2267 100644
    --- a/arch/arm64/include/asm/kvm_host.h
    +++ b/arch/arm64/include/asm/kvm_host.h
    @@ -65,6 +65,22 @@ struct kvm_s2_mmu {
    pgd_t *pgd;
    };

    +/* Per nested VM mmu structure */
    +struct kvm_nested_s2_mmu {
    + struct kvm_s2_mmu mmu;
    +
    + /*
    + * The vttbr value set by the guest hypervisor for this nested VM.
    + * vmid field is used as a key to search for this mmu structure among
    + * all nested VM mmu structures by the host hypervisor.
    + * baddr field is used to determine if we need to unmap stage 2
    + * shadow page tables.
    + */
    + u64 virtual_vttbr;
    +
    + struct list_head list;
    +};
    +
    struct kvm_arch {
    /* Stage 2 paging state for the VM */
    struct kvm_s2_mmu mmu;
    @@ -80,6 +96,9 @@ struct kvm_arch {

    /* Timer */
    struct arch_timer_kvm timer;
    +
    + /* Stage 2 shadow paging contexts for nested L2 VM */
    + struct list_head nested_mmu_list;
    };

    #define KVM_NR_MEM_OBJS 40
    diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h
    index a504162..d1ef650 100644
    --- a/arch/arm64/include/asm/kvm_mmu.h
    +++ b/arch/arm64/include/asm/kvm_mmu.h
    @@ -112,6 +112,7 @@
    #include <asm/cacheflush.h>
    #include <asm/mmu_context.h>
    #include <asm/pgtable.h>
    +#include <asm/kvm_emulate.h>

    static inline unsigned long __kern_hyp_va(unsigned long v)
    {
    @@ -323,6 +324,21 @@ 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_KVM_ARM_NESTED_HYP
    +struct kvm_nested_s2_mmu *get_nested_mmu(struct kvm_vcpu *vcpu, u64 vttbr);
    +struct kvm_s2_mmu *vcpu_get_active_s2_mmu(struct kvm_vcpu *vcpu);
    +#else
    +static inline struct kvm_nested_s2_mmu *get_nested_mmu(struct kvm_vcpu *vcpu,
    + u64 vttbr)
    +{
    + return NULL;
    +}
    +static inline struct kvm_s2_mmu *vcpu_get_active_s2_mmu(struct kvm_vcpu *vcpu)
    +{
    + return &vcpu->kvm->arch.mmu;
    +}
    +#endif
    +
    static inline u64 kvm_get_vttbr(struct kvm_s2_vmid *vmid,
    struct kvm_s2_mmu *mmu)
    {
    @@ -334,5 +350,20 @@ static inline u64 kvm_get_vttbr(struct kvm_s2_vmid *vmid,
    return baddr | vmid_field;
    }

    +static inline u64 get_vmid(u64 vttbr)
    +{
    + return (vttbr & VTTBR_VMID_MASK(get_kvm_vmid_bits()))>>VTTBR_VMID_SHIFT;
    +}
    +
    +static inline struct kvm_s2_vmid *vcpu_get_active_vmid(struct kvm_vcpu *vcpu)
    +{
    + struct kvm_s2_mmu *mmu = vcpu_get_active_s2_mmu(vcpu);
    +
    + if (unlikely(vcpu_mode_el2(vcpu)))
    + return &mmu->el2_vmid;
    + else
    + return &mmu->vmid;
    +}
    +
    #endif /* __ASSEMBLY__ */
    #endif /* __ARM64_KVM_MMU_H__ */
    diff --git a/arch/arm64/kvm/Makefile b/arch/arm64/kvm/Makefile
    index 8573faf..b0b1074 100644
    --- a/arch/arm64/kvm/Makefile
    +++ b/arch/arm64/kvm/Makefile
    @@ -36,5 +36,6 @@ kvm-$(CONFIG_KVM_ARM_HOST) += $(KVM)/arm/arch_timer.o
    kvm-$(CONFIG_KVM_ARM_PMU) += $(KVM)/arm/pmu.o

    kvm-$(CONFIG_KVM_ARM_NESTED_HYP) += handle_exit_nested.o
    +kvm-$(CONFIG_KVM_ARM_NESTED_HYP) += mmu-nested.o
    kvm-$(CONFIG_KVM_ARM_NESTED_HYP) += emulate-nested.o
    kvm-$(CONFIG_KVM_ARM_NESTED_HYP) += $(KVM)/arm/vgic/vgic-v2-nested.o
    diff --git a/arch/arm64/kvm/context.c b/arch/arm64/kvm/context.c
    index b2c0220..9ebc38f 100644
    --- a/arch/arm64/kvm/context.c
    +++ b/arch/arm64/kvm/context.c
    @@ -91,7 +91,7 @@ static void create_shadow_el1_sysregs(struct kvm_vcpu *vcpu)

    static void setup_s2_mmu(struct kvm_vcpu *vcpu)
    {
    - struct kvm_s2_mmu *mmu = &vcpu->kvm->arch.mmu;
    + struct kvm_s2_mmu *mmu = vcpu_get_active_s2_mmu(vcpu);
    struct kvm_s2_vmid *vmid = vcpu_get_active_vmid(vcpu);

    vcpu->arch.hw_vttbr = kvm_get_vttbr(vmid, mmu);
    diff --git a/arch/arm64/kvm/mmu-nested.c b/arch/arm64/kvm/mmu-nested.c
    new file mode 100644
    index 0000000..d52078f
    --- /dev/null
    +++ b/arch/arm64/kvm/mmu-nested.c
    @@ -0,0 +1,55 @@
    +/*
    + * Copyright (C) 2016 - Columbia University
    + * Author: Jintack Lim <jintack@cs.columbia.edu>
    + *
    + * This program is free software; you can redistribute it and/or modify
    + * it under the terms of the GNU General Public License version 2 as
    + * published by the Free Software Foundation.
    + *
    + * This program is distributed in the hope that it will be useful,
    + * but WITHOUT ANY WARRANTY; without even the implied warranty of
    + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    + * GNU General Public License for more details.
    + *
    + * You should have received a copy of the GNU General Public License
    + * along with this program. If not, see <http://www.gnu.org/licenses/>.
    + */
    +
    +#include <linux/kvm_host.h>
    +
    +#include <asm/kvm_arm.h>
    +#include <asm/kvm_emulate.h>
    +#include <asm/kvm_mmu.h>
    +#include <asm/kvm_nested.h>
    +
    +struct kvm_nested_s2_mmu *get_nested_mmu(struct kvm_vcpu *vcpu, u64 vttbr)
    +{
    + struct kvm_nested_s2_mmu *mmu;
    + u64 target_vmid = get_vmid(vttbr);
    + struct list_head *nested_mmu_list = &vcpu->kvm->arch.nested_mmu_list;
    +
    + list_for_each_entry_rcu(mmu, nested_mmu_list, list) {
    + u64 vmid = get_vmid(mmu->virtual_vttbr);
    +
    + if (target_vmid == vmid)
    + return mmu;
    + }
    + return NULL;
    +}
    +
    +struct kvm_s2_mmu *vcpu_get_active_s2_mmu(struct kvm_vcpu *vcpu)
    +{
    + struct kvm_nested_s2_mmu *nested_mmu;
    +
    + /* If we are NOT entering the nested VM, return mmu in kvm_arch */
    + if (vcpu_mode_el2(vcpu) || !vcpu_nested_stage2_enabled(vcpu))
    + return &vcpu->kvm->arch.mmu;
    +
    + /* Otherwise, search for nested_mmu in the list */
    + nested_mmu = get_nested_mmu(vcpu, vcpu_el2_reg(vcpu, VTTBR_EL2));
    +
    + /* When this function is called, nested_mmu should be in the list */
    + BUG_ON(!nested_mmu);
    +
    + return &nested_mmu->mmu;
    +}
    --
    1.9.1

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