linux-kernel - Re: [RFC PATCH 2/2] KVM: x86: use __kvm_guest

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Message-ID: <jpgbn3023p3.fsf@linux.bootlegged.copy>
Date:	Thu, 16 Jun 2016 18:01:44 -0400
From:	Bandan Das <bsd@...hat.com>
To:	Paolo Bonzini <pbonzini@...hat.com>
Cc:	linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
	rkrcmar@...hat.com
Subject: Re: [RFC PATCH 2/2] KVM: x86: use __kvm_guest_exit

...
>  static bool vmx_has_high_real_mode_segbase(void)
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 7e3041ef050f..cc741b68139c 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -6706,21 +6706,13 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
>  
>  	kvm_put_guest_xcr0(vcpu);
>  
> -	/* Interrupt is enabled by handle_external_intr() */
>  	kvm_x86_ops->handle_external_intr(vcpu);
>  
>  	++vcpu->stat.exits;
>  
> -	/*
> -	 * We must have an instruction between local_irq_enable() and
> -	 * kvm_guest_exit(), so the timer interrupt isn't delayed by
> -	 * the interrupt shadow.  The stat.exits increment will do nicely.
> -	 * But we need to prevent reordering, hence this barrier():
> -	 */
> -	barrier();
> -
> -	kvm_guest_exit();
> +	__kvm_guest_exit();

kvm_guest_exit has no more callers and so can be removed.

Bandan

> +	local_irq_enable();
>  	preempt_enable();
>  
>  	vcpu->srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);