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    Subject[RFC PATCH 13/67] KVM: VMX: Explicitly check for hv_remote_flush_tlb when loading pgd()
    Date
    From: Sean Christopherson <sean.j.christopherson@intel.com>

    Explicitly check that kvm_x86_ops.tlb_remote_flush() points at Hyper-V's
    implementation for PV flushing instead of assuming that a non-NULL
    implemenation means running on Hyper-V. Wrap the related logic in
    ifdeffery as hv_remote_flush_tlb() is defined iff CONFIG_HYPERV!=n.

    Short term, the explicit check makes it more obvious why a non-NULL
    tlb_remote_flush() triggers EPTP shenanigans. Long term, this will
    allow TDX to define its own implementation of tlb_remote_flush() without
    running afoul of Hyper-V.

    Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
    ---
    arch/x86/kvm/vmx/vmx.c | 7 +++++--
    arch/x86/kvm/vmx/vmx.h | 2 ++
    2 files changed, 7 insertions(+), 2 deletions(-)

    diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
    index 1c9ad3103c87..0703d82e7bad 100644
    --- a/arch/x86/kvm/vmx/vmx.c
    +++ b/arch/x86/kvm/vmx/vmx.c
    @@ -3072,14 +3072,15 @@ static void vmx_load_mmu_pgd(struct kvm_vcpu *vcpu, unsigned long pgd,
    eptp = construct_eptp(vcpu, pgd, pgd_level);
    vmcs_write64(EPT_POINTER, eptp);

    - if (kvm_x86_ops.tlb_remote_flush) {
    +#if IS_ENABLED(CONFIG_HYPERV)
    + if (kvm_x86_ops.tlb_remote_flush == hv_remote_flush_tlb) {
    spin_lock(&to_kvm_vmx(kvm)->ept_pointer_lock);
    to_vmx(vcpu)->ept_pointer = eptp;
    to_kvm_vmx(kvm)->ept_pointers_match
    = EPT_POINTERS_CHECK;
    spin_unlock(&to_kvm_vmx(kvm)->ept_pointer_lock);
    }
    -
    +#endif
    if (!enable_unrestricted_guest && !is_paging(vcpu))
    guest_cr3 = to_kvm_vmx(kvm)->ept_identity_map_addr;
    else if (test_bit(VCPU_EXREG_CR3, (ulong *)&vcpu->arch.regs_avail))
    @@ -6970,7 +6971,9 @@ static int vmx_create_vcpu(struct kvm_vcpu *vcpu)

    static int vmx_vm_init(struct kvm *kvm)
    {
    +#if IS_ENABLED(CONFIG_HYPERV)
    spin_lock_init(&to_kvm_vmx(kvm)->ept_pointer_lock);
    +#endif

    if (!ple_gap)
    kvm->arch.pause_in_guest = true;
    diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h
    index f6f66e5c6510..e9cdb0fb7f56 100644
    --- a/arch/x86/kvm/vmx/vmx.h
    +++ b/arch/x86/kvm/vmx/vmx.h
    @@ -301,8 +301,10 @@ struct kvm_vmx {
    bool ept_identity_pagetable_done;
    gpa_t ept_identity_map_addr;

    +#if IS_ENABLED(CONFIG_HYPERV)
    enum ept_pointers_status ept_pointers_match;
    spinlock_t ept_pointer_lock;
    +#endif
    };

    bool nested_vmx_allowed(struct kvm_vcpu *vcpu);
    --
    2.17.1
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