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    Subject[RFC PATCH v5 038/104] KVM: x86/mmu: Allow per-VM override of the TDP max page level
    Date
    From: Sean Christopherson <sean.j.christopherson@intel.com>

    In the existing x86 KVM MMU code, there is already max_level member in
    struct kvm_page_fault with KVM_MAX_HUGEPAGE_LEVEL initial value. The KVM
    page fault handler denies page size larger than max_level.

    Add per-VM member to indicate the allowed maximum page size with
    KVM_MAX_HUGEPAGE_LEVEL as default value and initialize max_level in struct
    kvm_page_fault with it.

    For the guest TD, the set per-VM value for allows maximum page size to 4K
    page size. Then only allowed page size is 4K. It means large page is
    disabled.

    Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
    Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
    ---
    arch/x86/include/asm/kvm_host.h | 1 +
    arch/x86/kvm/mmu.h | 2 +-
    arch/x86/kvm/mmu/mmu.c | 2 ++
    3 files changed, 4 insertions(+), 1 deletion(-)

    diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
    index d8b78d6abc10..d33d79f2af2d 100644
    --- a/arch/x86/include/asm/kvm_host.h
    +++ b/arch/x86/include/asm/kvm_host.h
    @@ -1053,6 +1053,7 @@ struct kvm_arch {
    unsigned long n_requested_mmu_pages;
    unsigned long n_max_mmu_pages;
    unsigned int indirect_shadow_pages;
    + int tdp_max_page_level;
    u8 mmu_valid_gen;
    struct hlist_head mmu_page_hash[KVM_NUM_MMU_PAGES];
    struct list_head active_mmu_pages;
    diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h
    index 0ae91b8b25df..650989c37f2e 100644
    --- a/arch/x86/kvm/mmu.h
    +++ b/arch/x86/kvm/mmu.h
    @@ -192,7 +192,7 @@ static inline int kvm_mmu_do_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
    .is_tdp = likely(vcpu->arch.mmu->page_fault == kvm_tdp_page_fault),
    .nx_huge_page_workaround_enabled = is_nx_huge_page_enabled(),

    - .max_level = KVM_MAX_HUGEPAGE_LEVEL,
    + .max_level = vcpu->kvm->arch.tdp_max_page_level,
    .req_level = PG_LEVEL_4K,
    .goal_level = PG_LEVEL_4K,
    };
    diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
    index a474f2e76d78..e9212394a530 100644
    --- a/arch/x86/kvm/mmu/mmu.c
    +++ b/arch/x86/kvm/mmu/mmu.c
    @@ -5782,6 +5782,8 @@ void kvm_mmu_init_vm(struct kvm *kvm)
    node->track_write = kvm_mmu_pte_write;
    node->track_flush_slot = kvm_mmu_invalidate_zap_pages_in_memslot;
    kvm_page_track_register_notifier(kvm, node);
    +
    + kvm->arch.tdp_max_page_level = KVM_MAX_HUGEPAGE_LEVEL;
    }

    void kvm_mmu_uninit_vm(struct kvm *kvm)
    --
    2.25.1
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