linux-kernel - Re: [PATCH v7 10/14] KVM: s390: Refactor absolute vm mem

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Date:   Tue, 7 Feb 2023 14:17:34 +0100
From:   Janosch Frank <frankja@...ux.ibm.com>
To:     Janis Schoetterl-Glausch <scgl@...ux.ibm.com>,
        Christian Borntraeger <borntraeger@...ux.ibm.com>,
        Claudio Imbrenda <imbrenda@...ux.ibm.com>,
        Heiko Carstens <hca@...ux.ibm.com>,
        Vasily Gorbik <gor@...ux.ibm.com>,
        Alexander Gordeev <agordeev@...ux.ibm.com>
Cc:     David Hildenbrand <david@...hat.com>,
        Jonathan Corbet <corbet@....net>, kvm@...r.kernel.org,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-kselftest@...r.kernel.org, linux-s390@...r.kernel.org,
        Paolo Bonzini <pbonzini@...hat.com>,
        Shuah Khan <shuah@...nel.org>,
        Sven Schnelle <svens@...ux.ibm.com>,
        Thomas Huth <thuth@...hat.com>
Subject: Re: [PATCH v7 10/14] KVM: s390: Refactor absolute vm mem_op function

On 2/6/23 17:45, Janis Schoetterl-Glausch wrote:
> Remove code duplication with regards to the CHECK_ONLY flag.
> Decrease the number of indents.
> No functional change indented.
> 
> Suggested-by: Janosch Frank <frankja@...ux.ibm.com>
> Signed-off-by: Janis Schoetterl-Glausch <scgl@...ux.ibm.com>
> Reviewed-by: Thomas Huth <thuth@...hat.com>

Reviewed-by: Janosch Frank <frankja@...ux.ibm.com>

> ---
> 
> 
> Cosmetic only, can be dropped
> 
> 
>   arch/s390/kvm/kvm-s390.c | 43 +++++++++++++++++-----------------------
>   1 file changed, 18 insertions(+), 25 deletions(-)
> 
> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
> index 707967a296f1..1f94b18f1cb5 100644
> --- a/arch/s390/kvm/kvm-s390.c
> +++ b/arch/s390/kvm/kvm-s390.c
> @@ -2782,6 +2782,7 @@ static int mem_op_validate_common(struct kvm_s390_mem_op *mop, u64 supported_fla
>   static int kvm_s390_vm_mem_op_abs(struct kvm *kvm, struct kvm_s390_mem_op *mop)
>   {
>   	void __user *uaddr = (void __user *)mop->buf;
> +	enum gacc_mode acc_mode;
>   	void *tmpbuf = NULL;
>   	int r, srcu_idx;
>   
> @@ -2803,33 +2804,25 @@ static int kvm_s390_vm_mem_op_abs(struct kvm *kvm, struct kvm_s390_mem_op *mop)
>   		goto out_unlock;
>   	}
>   
> -	switch (mop->op) {
> -	case KVM_S390_MEMOP_ABSOLUTE_READ: {
> -		if (mop->flags & KVM_S390_MEMOP_F_CHECK_ONLY) {
> -			r = check_gpa_range(kvm, mop->gaddr, mop->size, GACC_FETCH, mop->key);
> -		} else {
> -			r = access_guest_abs_with_key(kvm, mop->gaddr, tmpbuf,
> -						      mop->size, GACC_FETCH, mop->key);
> -			if (r == 0) {
> -				if (copy_to_user(uaddr, tmpbuf, mop->size))
> -					r = -EFAULT;
> -			}
> -		}
> -		break;
> +	acc_mode = mop->op == KVM_S390_MEMOP_ABSOLUTE_READ ? GACC_FETCH : GACC_STORE;
> +	if (mop->flags & KVM_S390_MEMOP_F_CHECK_ONLY) {
> +		r = check_gpa_range(kvm, mop->gaddr, mop->size, acc_mode, mop->key);
> +		goto out_unlock;
>   	}
> -	case KVM_S390_MEMOP_ABSOLUTE_WRITE: {
> -		if (mop->flags & KVM_S390_MEMOP_F_CHECK_ONLY) {
> -			r = check_gpa_range(kvm, mop->gaddr, mop->size, GACC_STORE, mop->key);
> -		} else {
> -			if (copy_from_user(tmpbuf, uaddr, mop->size)) {
> -				r = -EFAULT;
> -				break;
> -			}
> -			r = access_guest_abs_with_key(kvm, mop->gaddr, tmpbuf,
> -						      mop->size, GACC_STORE, mop->key);
> +	if (acc_mode == GACC_FETCH) {
> +		r = access_guest_abs_with_key(kvm, mop->gaddr, tmpbuf,
> +					      mop->size, GACC_FETCH, mop->key);
> +		if (r)
> +			goto out_unlock;
> +		if (copy_to_user(uaddr, tmpbuf, mop->size))
> +			r = -EFAULT;
> +	} else {
> +		if (copy_from_user(tmpbuf, uaddr, mop->size)) {
> +			r = -EFAULT;
> +			goto out_unlock;
>   		}
> -		break;
> -	}
> +		r = access_guest_abs_with_key(kvm, mop->gaddr, tmpbuf,
> +					      mop->size, GACC_STORE, mop->key);
>   	}
>   
>   out_unlock: