Re: [PATCH v7 08/14] KVM: s390: Move common code of mem_op functions into function

[Janosch Frank]

On 2/6/23 17:45, Janis Schoetterl-Glausch wrote:
> The vcpu and vm mem_op ioctl implementations share some functionality.
> Move argument checking into a function and call it from both
> implementations. This allows code reuse in case of additional future
> mem_op operations.
>
> Suggested-by: Janosch Frank <frankja@xxxxxxxxxxxxx>
> Signed-off-by: Janis Schoetterl-Glausch <scgl@xxxxxxxxxxxxx>

Reviewed-by: Janosch Frank <frankja@xxxxxxxxxxxxx>

> ---
>   arch/s390/kvm/kvm-s390.c | 52 +++++++++++++++++++---------------------
>   1 file changed, 24 insertions(+), 28 deletions(-)
>
> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
> index e4890e04b210..0367c1a7e69a 100644
> --- a/arch/s390/kvm/kvm-s390.c
> +++ b/arch/s390/kvm/kvm-s390.c
> @@ -2764,24 +2764,32 @@ static int kvm_s390_handle_pv(struct kvm *kvm, struct kvm_pv_cmd *cmd)
>   	return r;
>   }
>   
> -static bool access_key_invalid(u8 access_key)
> +static int mem_op_validate_common(struct kvm_s390_mem_op *mop, u64 supported_flags)
>   {
> -	return access_key > 0xf;
> +	if (mop->flags & ~supported_flags || !mop->size)
> +		return -EINVAL;
> +	if (mop->size > MEM_OP_MAX_SIZE)
> +		return -E2BIG;
> +	if (mop->flags & KVM_S390_MEMOP_F_SKEY_PROTECTION) {
> +		if (mop->key > 0xf)
> +			return -EINVAL;
> +	} else {
> +		mop->key = 0;
> +	}
> +	return 0;
>   }
>   
>   static int kvm_s390_vm_mem_op(struct kvm *kvm, struct kvm_s390_mem_op *mop)
>   {
>   	void __user *uaddr = (void __user *)mop->buf;
> -	u64 supported_flags;
>   	void *tmpbuf = NULL;
>   	int r, srcu_idx;
>   
> -	supported_flags = KVM_S390_MEMOP_F_SKEY_PROTECTION
> -			  | KVM_S390_MEMOP_F_CHECK_ONLY;
> -	if (mop->flags & ~supported_flags || !mop->size)
> -		return -EINVAL;
> -	if (mop->size > MEM_OP_MAX_SIZE)
> -		return -E2BIG;
> +	r = mem_op_validate_common(mop, KVM_S390_MEMOP_F_SKEY_PROTECTION |
> +					KVM_S390_MEMOP_F_CHECK_ONLY);
> +	if (r)
> +		return r;
> +
>   	/*
>   	 * This is technically a heuristic only, if the kvm->lock is not
>   	 * taken, it is not guaranteed that the vm is/remains non-protected.
> @@ -2793,12 +2801,6 @@ static int kvm_s390_vm_mem_op(struct kvm *kvm, struct kvm_s390_mem_op *mop)
>   	 */
>   	if (kvm_s390_pv_get_handle(kvm))
>   		return -EINVAL;
> -	if (mop->flags & KVM_S390_MEMOP_F_SKEY_PROTECTION) {
> -		if (access_key_invalid(mop->key))
> -			return -EINVAL;
> -	} else {
> -		mop->key = 0;
> -	}
>   	if (!(mop->flags & KVM_S390_MEMOP_F_CHECK_ONLY)) {
>   		tmpbuf = vmalloc(mop->size);
>   		if (!tmpbuf)
> @@ -5250,23 +5252,17 @@ static long kvm_s390_vcpu_mem_op(struct kvm_vcpu *vcpu,
>   {
>   	void __user *uaddr = (void __user *)mop->buf;
>   	void *tmpbuf = NULL;
> -	int r = 0;
> -	const u64 supported_flags = KVM_S390_MEMOP_F_INJECT_EXCEPTION
> -				    | KVM_S390_MEMOP_F_CHECK_ONLY
> -				    | KVM_S390_MEMOP_F_SKEY_PROTECTION;
> +	int r;
>   
> -	if (mop->flags & ~supported_flags || mop->ar >= NUM_ACRS || !mop->size)
> +	r = mem_op_validate_common(mop, KVM_S390_MEMOP_F_INJECT_EXCEPTION |
> +					KVM_S390_MEMOP_F_CHECK_ONLY |
> +					KVM_S390_MEMOP_F_SKEY_PROTECTION);
> +	if (r)
> +		return r;
> +	if (mop->ar >= NUM_ACRS)
>   		return -EINVAL;
> -	if (mop->size > MEM_OP_MAX_SIZE)
> -		return -E2BIG;
>   	if (kvm_s390_pv_cpu_is_protected(vcpu))
>   		return -EINVAL;
> -	if (mop->flags & KVM_S390_MEMOP_F_SKEY_PROTECTION) {
> -		if (access_key_invalid(mop->key))
> -			return -EINVAL;
> -	} else {
> -		mop->key = 0;
> -	}
>   	if (!(mop->flags & KVM_S390_MEMOP_F_CHECK_ONLY)) {
>   		tmpbuf = vmalloc(mop->size);
>   		if (!tmpbuf)