linux-kernel - Re: [PATCH v2 2/3] KVM: VMX: Fold loaded_vmcs_init() into alloc_loaded

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Date:   Sun, 22 Mar 2020 14:08:13 +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 v2 2/3] KVM: VMX: Fold loaded_vmcs_init() into alloc_loaded_vmcs()

Sean Christopherson <sean.j.christopherson@...el.com> writes:

> Subsume loaded_vmcs_init() into alloc_loaded_vmcs(), its only remaining
> caller, and drop the VMCLEAR on the shadow VMCS, which is guaranteed to
> be NULL.  loaded_vmcs_init() was previously used by loaded_vmcs_clear(),
> but loaded_vmcs_clear() also subsumed loaded_vmcs_init() to properly
> handle smp_wmb() with respect to VMCLEAR.
>
> Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
> ---
>  arch/x86/kvm/vmx/vmx.c | 14 ++++----------
>  arch/x86/kvm/vmx/vmx.h |  1 -
>  2 files changed, 4 insertions(+), 11 deletions(-)
>
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index efaca09455bf..07634caa560d 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -653,15 +653,6 @@ static int vmx_set_guest_msr(struct vcpu_vmx *vmx, struct shared_msr_entry *msr,
>  	return ret;
>  }
>  
> -void loaded_vmcs_init(struct loaded_vmcs *loaded_vmcs)
> -{
> -	vmcs_clear(loaded_vmcs->vmcs);
> -	if (loaded_vmcs->shadow_vmcs && loaded_vmcs->launched)
> -		vmcs_clear(loaded_vmcs->shadow_vmcs);
> -	loaded_vmcs->cpu = -1;
> -	loaded_vmcs->launched = 0;
> -}
> -
>  #ifdef CONFIG_KEXEC_CORE
>  static void crash_vmclear_local_loaded_vmcss(void)
>  {
> @@ -2555,9 +2546,12 @@ int alloc_loaded_vmcs(struct loaded_vmcs *loaded_vmcs)
>  	if (!loaded_vmcs->vmcs)
>  		return -ENOMEM;
>  
> +	vmcs_clear(loaded_vmcs->vmcs);
> +
>  	loaded_vmcs->shadow_vmcs = NULL;
>  	loaded_vmcs->hv_timer_soft_disabled = false;
> -	loaded_vmcs_init(loaded_vmcs);
> +	loaded_vmcs->cpu = -1;
> +	loaded_vmcs->launched = 0;
>  
>  	if (cpu_has_vmx_msr_bitmap()) {
>  		loaded_vmcs->msr_bitmap = (unsigned long *)
> diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h
> index be93d597306c..79d38f41ef7a 100644
> --- a/arch/x86/kvm/vmx/vmx.h
> +++ b/arch/x86/kvm/vmx/vmx.h
> @@ -492,7 +492,6 @@ struct vmcs *alloc_vmcs_cpu(bool shadow, int cpu, gfp_t flags);
>  void free_vmcs(struct vmcs *vmcs);
>  int alloc_loaded_vmcs(struct loaded_vmcs *loaded_vmcs);
>  void free_loaded_vmcs(struct loaded_vmcs *loaded_vmcs);
> -void loaded_vmcs_init(struct loaded_vmcs *loaded_vmcs);
>  void loaded_vmcs_clear(struct loaded_vmcs *loaded_vmcs);
>  
>  static inline struct vmcs *alloc_vmcs(bool shadow)

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

-- 
Vitaly