linux-kernel - Re: [PATCH v2] KVM: x86: Unconditionally call x86 ops that are always implemented

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Date:   Fri, 2 Aug 2019 15:48:27 -0700
From:   Krish Sadhukhan <krish.sadhukhan@...cle.com>
To:     Sean Christopherson <sean.j.christopherson@...el.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] KVM: x86: Unconditionally call x86 ops that are always
 implemented



On 08/02/2019 03:06 PM, Sean Christopherson wrote:
> Remove a few stale checks for non-NULL ops now that the ops in question
> are implemented by both VMX and SVM.
>
> Note, this is **not** stable material, the Fixes tags are there purely
> to show when a particular op was first supported by both VMX and SVM.
>
> Fixes: 74f169090b6f ("kvm/svm: Setup MCG_CAP on AMD properly")
> Fixes: b31c114b82b2 ("KVM: X86: Provide a capability to disable PAUSE intercepts")
> Fixes: 411b44ba80ab ("svm: Implements update_pi_irte hook to setup posted interrupt")
> Cc: Krish Sadhukhan <krish.sadhukhan@...cle.com>
> Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
> ---
>
> v2: Give update_pi_iret the same treatment [Krish].
>
>   arch/x86/kvm/x86.c | 13 +++----------
>   1 file changed, 3 insertions(+), 10 deletions(-)
>
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 01e18caac825..e7c993f0cbed 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -3506,8 +3506,7 @@ static int kvm_vcpu_ioctl_x86_setup_mce(struct kvm_vcpu *vcpu,
>   	for (bank = 0; bank < bank_num; bank++)
>   		vcpu->arch.mce_banks[bank*4] = ~(u64)0;
>   
> -	if (kvm_x86_ops->setup_mce)
> -		kvm_x86_ops->setup_mce(vcpu);
> +	kvm_x86_ops->setup_mce(vcpu);
>   out:
>   	return r;
>   }
> @@ -9313,10 +9312,7 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
>   	kvm_page_track_init(kvm);
>   	kvm_mmu_init_vm(kvm);
>   
> -	if (kvm_x86_ops->vm_init)
> -		return kvm_x86_ops->vm_init(kvm);
> -
> -	return 0;
> +	return kvm_x86_ops->vm_init(kvm);
>   }
>   
>   static void kvm_unload_vcpu_mmu(struct kvm_vcpu *vcpu)
> @@ -9992,7 +9988,7 @@ EXPORT_SYMBOL_GPL(kvm_arch_has_noncoherent_dma);
>   
>   bool kvm_arch_has_irq_bypass(void)

Now that this is returning true always and that this is called only in 
kvm_irqfd_assign(), this can perhaps be removed altogether ?

>   {
> -	return kvm_x86_ops->update_pi_irte != NULL;
> +	return true;
>   }
>   
>   int kvm_arch_irq_bypass_add_producer(struct irq_bypass_consumer *cons,
> @@ -10032,9 +10028,6 @@ void kvm_arch_irq_bypass_del_producer(struct irq_bypass_consumer *cons,
>   int kvm_arch_update_irqfd_routing(struct kvm *kvm, unsigned int host_irq,
>   				   uint32_t guest_irq, bool set)
>   {
> -	if (!kvm_x86_ops->update_pi_irte)
> -		return -EINVAL;
> -
>   	return kvm_x86_ops->update_pi_irte(kvm, host_irq, guest_irq, set);
>   }
>   

Reviewed-by: Krish Sadhukhan <krish.sadhukhan@...cle.com>