linux-kernel - Re: [PATCH v3 09/11] KVM: VMX: Define Hyper-V paravirt TLB flush fields iff Hyper-V is enabled

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Message-ID: <87361ezw21.fsf@vitty.brq.redhat.com>
Date:   Thu, 12 Nov 2020 11:52:38 +0100
From:   Vitaly Kuznetsov <vkuznets@...hat.com>
To:     Sean Christopherson <sean.j.christopherson@...el.com>
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 09/11] KVM: VMX: Define Hyper-V paravirt TLB flush
 fields iff Hyper-V is enabled

Sean Christopherson <sean.j.christopherson@...el.com> 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@...el.com>
> ---
>  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 b684f45d6a78..5b7c5b2fd2c7 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -6955,8 +6955,9 @@ 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:
> @@ -6973,7 +6974,9 @@ 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 cecc2a641e19..2bd86d8b2f4b 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);

Reviewed-by: Vitaly Kuznetsov <vkuznets@...hat.com>

-- 
Vitaly