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    Subject[PATCH v2 08/11] KVM: x86/MMU: Track NX hugepages on a per-VM basis
    From
    Track whether NX hugepages are enabled on a per-VM basis instead of as a
    host-wide setting. With this commit, the per-VM state will always be the
    same as the host-wide setting, but in future commits, it will be allowed
    to differ.

    No functional change intended.

    Signed-off-by: Ben Gardon <bgardon@google.com>
    ---
    arch/x86/include/asm/kvm_host.h | 2 ++
    arch/x86/kvm/mmu.h | 8 ++++----
    arch/x86/kvm/mmu/mmu.c | 7 +++++--
    arch/x86/kvm/mmu/spte.c | 7 ++++---
    arch/x86/kvm/mmu/spte.h | 3 ++-
    arch/x86/kvm/mmu/tdp_mmu.c | 3 ++-
    6 files changed, 19 insertions(+), 11 deletions(-)

    diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
    index f72e80178ffc..0a0c54639dd8 100644
    --- a/arch/x86/include/asm/kvm_host.h
    +++ b/arch/x86/include/asm/kvm_host.h
    @@ -1240,6 +1240,8 @@ struct kvm_arch {
    hpa_t hv_root_tdp;
    spinlock_t hv_root_tdp_lock;
    #endif
    +
    + bool nx_huge_pages;
    };

    struct kvm_vm_stat {
    diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h
    index bf8dbc4bb12a..dd28fe8d13ae 100644
    --- a/arch/x86/kvm/mmu.h
    +++ b/arch/x86/kvm/mmu.h
    @@ -173,9 +173,9 @@ struct kvm_page_fault {
    int kvm_tdp_page_fault(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault);

    extern int nx_huge_pages;
    -static inline bool is_nx_huge_page_enabled(void)
    +static inline bool is_nx_huge_page_enabled(struct kvm *kvm)
    {
    - return READ_ONCE(nx_huge_pages);
    + return READ_ONCE(kvm->arch.nx_huge_pages);
    }

    static inline int kvm_mmu_do_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
    @@ -191,8 +191,8 @@ static inline int kvm_mmu_do_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
    .user = err & PFERR_USER_MASK,
    .prefetch = prefetch,
    .is_tdp = likely(vcpu->arch.mmu->page_fault == kvm_tdp_page_fault),
    - .nx_huge_page_workaround_enabled = is_nx_huge_page_enabled(),
    -
    + .nx_huge_page_workaround_enabled =
    + is_nx_huge_page_enabled(vcpu->kvm),
    .max_level = KVM_MAX_HUGEPAGE_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 1b59b56642f1..dc9672f70468 100644
    --- a/arch/x86/kvm/mmu/mmu.c
    +++ b/arch/x86/kvm/mmu/mmu.c
    @@ -6195,8 +6195,10 @@ static void __set_nx_huge_pages(bool val)
    nx_huge_pages = itlb_multihit_kvm_mitigation = val;
    }

    -static int kvm_update_nx_huge_pages(struct kvm *kvm)
    +static void kvm_update_nx_huge_pages(struct kvm *kvm)
    {
    + kvm->arch.nx_huge_pages = nx_huge_pages;
    +
    mutex_lock(&kvm->slots_lock);
    kvm_mmu_zap_all_fast(kvm);
    mutex_unlock(&kvm->slots_lock);
    @@ -6227,7 +6229,7 @@ static int set_nx_huge_pages(const char *val, const struct kernel_param *kp)
    mutex_lock(&kvm_lock);

    list_for_each_entry(kvm, &vm_list, vm_list)
    - kvm_set_nx_huge_pages(kvm);
    + kvm_update_nx_huge_pages(kvm);
    mutex_unlock(&kvm_lock);
    }

    @@ -6448,6 +6450,7 @@ int kvm_mmu_post_init_vm(struct kvm *kvm)
    {
    int err;

    + kvm->arch.nx_huge_pages = READ_ONCE(nx_huge_pages);
    err = kvm_vm_create_worker_thread(kvm, kvm_nx_lpage_recovery_worker, 0,
    "kvm-nx-lpage-recovery",
    &kvm->arch.nx_lpage_recovery_thread);
    diff --git a/arch/x86/kvm/mmu/spte.c b/arch/x86/kvm/mmu/spte.c
    index 4739b53c9734..877ad30bc7ad 100644
    --- a/arch/x86/kvm/mmu/spte.c
    +++ b/arch/x86/kvm/mmu/spte.c
    @@ -116,7 +116,7 @@ bool make_spte(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
    spte |= spte_shadow_accessed_mask(spte);

    if (level > PG_LEVEL_4K && (pte_access & ACC_EXEC_MASK) &&
    - is_nx_huge_page_enabled()) {
    + is_nx_huge_page_enabled(vcpu->kvm)) {
    pte_access &= ~ACC_EXEC_MASK;
    }

    @@ -215,7 +215,8 @@ static u64 make_spte_executable(u64 spte)
    * This is used during huge page splitting to build the SPTEs that make up the
    * new page table.
    */
    -u64 make_huge_page_split_spte(u64 huge_spte, int huge_level, int index)
    +u64 make_huge_page_split_spte(struct kvm *kvm, u64 huge_spte, int huge_level,
    + int index)
    {
    u64 child_spte;
    int child_level;
    @@ -243,7 +244,7 @@ u64 make_huge_page_split_spte(u64 huge_spte, int huge_level, int index)
    * When splitting to a 4K page, mark the page executable as the
    * NX hugepage mitigation no longer applies.
    */
    - if (is_nx_huge_page_enabled())
    + if (is_nx_huge_page_enabled(kvm))
    child_spte = make_spte_executable(child_spte);
    }

    diff --git a/arch/x86/kvm/mmu/spte.h b/arch/x86/kvm/mmu/spte.h
    index 73f12615416f..e4142caff4b1 100644
    --- a/arch/x86/kvm/mmu/spte.h
    +++ b/arch/x86/kvm/mmu/spte.h
    @@ -415,7 +415,8 @@ bool make_spte(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
    unsigned int pte_access, gfn_t gfn, kvm_pfn_t pfn,
    u64 old_spte, bool prefetch, bool can_unsync,
    bool host_writable, u64 *new_spte);
    -u64 make_huge_page_split_spte(u64 huge_spte, int huge_level, int index);
    +u64 make_huge_page_split_spte(struct kvm *kvm, u64 huge_spte, int huge_level,
    + int index);
    u64 make_nonleaf_spte(u64 *child_pt, bool ad_disabled);
    u64 make_mmio_spte(struct kvm_vcpu *vcpu, u64 gfn, unsigned int access);
    u64 mark_spte_for_access_track(u64 spte);
    diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
    index af60922906ef..98a45a87f0b2 100644
    --- a/arch/x86/kvm/mmu/tdp_mmu.c
    +++ b/arch/x86/kvm/mmu/tdp_mmu.c
    @@ -1466,7 +1466,8 @@ static int tdp_mmu_split_huge_page(struct kvm *kvm, struct tdp_iter *iter,
    * not been linked in yet and thus is not reachable from any other CPU.
    */
    for (i = 0; i < PT64_ENT_PER_PAGE; i++)
    - sp->spt[i] = make_huge_page_split_spte(huge_spte, level, i);
    + sp->spt[i] = make_huge_page_split_spte(kvm, huge_spte,
    + level, i);

    /*
    * Replace the huge spte with a pointer to the populated lower level
    --
    2.35.1.894.gb6a874cedc-goog
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