Re: [PATCH v2 08/10] KVM: VMX: Define Hyper-V paravirt TLB flush fields iff Hyper-V is enabled

From: Vitaly Kuznetsov
Date: Wed Oct 21 2020 - 10:20:35 EST


Sean Christopherson <sean.j.christopherson@xxxxxxxxx> writes:

> Ifdef away the Hyper-V specific fields in structs kvm_vmx and vcpu_vmx
> as each field has only a single reference outside of the struct itself
> that isn't already wrapped in ifdeffery (and both are initialization).
>
> vcpu_vmx.ept_pointer in particular should be wrapped as it is valid if
> and only if Hyper-v is active, i.e. non-Hyper-V code cannot rely on it
> to actually track the current EPTP (without additional code changes).
>
> Signed-off-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
> ---
> arch/x86/kvm/vmx/vmx.c | 5 ++++-
> arch/x86/kvm/vmx/vmx.h | 4 ++++
> 2 files changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index 55d6b699d8e3..a45a90d44d24 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -6933,8 +6933,9 @@ static int vmx_create_vcpu(struct kvm_vcpu *vcpu)
> vmx->pi_desc.nv = POSTED_INTR_VECTOR;
> vmx->pi_desc.sn = 1;
>
> +#if IS_ENABLED(CONFIG_HYPERV)
> vmx->ept_pointer = INVALID_PAGE;
> -
> +#endif
> return 0;
>
> free_vmcs:
> @@ -6951,7 +6952,9 @@ 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 e8d7d07b2020..1b8c08e483cd 100644
> --- a/arch/x86/kvm/vmx/vmx.h
> +++ b/arch/x86/kvm/vmx/vmx.h
> @@ -276,7 +276,9 @@ struct vcpu_vmx {
> */
> u64 msr_ia32_feature_control;
> u64 msr_ia32_feature_control_valid_bits;
> +#if IS_ENABLED(CONFIG_HYPERV)
> u64 ept_pointer;
> +#endif
>
> struct pt_desc pt_desc;
>
> @@ -295,8 +297,10 @@ struct kvm_vmx {
> bool ept_identity_pagetable_done;
> gpa_t ept_identity_map_addr;
>
> +#if IS_ENABLED(CONFIG_HYPERV)
> hpa_t hv_tlb_eptp;
> spinlock_t ept_pointer_lock;
> +#endif
> };
>
> bool nested_vmx_allowed(struct kvm_vcpu *vcpu);

Assuming this compiles without CONFIG_HYPERV,

Reviewed-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>

--
Vitaly