Re: [PATCH v6 10/14] KVM: s390: Refactor absolute vm mem_op function

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On 1/25/23 22:26, 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@xxxxxxxxxxxxx>
Signed-off-by: Janis Schoetterl-Glausch <scgl@xxxxxxxxxxxxx>
---


Cosmetic only, can be dropped.


  arch/s390/kvm/kvm-s390.c | 43 ++++++++++++++++------------------------
  1 file changed, 17 insertions(+), 26 deletions(-)

diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 588cf70dc81e..cfd09cb43ef6 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -2794,6 +2794,7 @@ static void *mem_op_alloc_buf(struct kvm_s390_mem_op *mop)
  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;
@@ -2813,33 +2814,23 @@ 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;
-	}
-	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);
+	acc_mode = mop->op == KVM_S390_MEMOP_ABSOLUTE_READ ? GACC_FETCH : GACC_STORE;

Would the line be too long if that variable would be initialized where it's defined?

+	if (mop->flags & KVM_S390_MEMOP_F_CHECK_ONLY) {
+		r = check_gpa_range(kvm, mop->gaddr, mop->size, acc_mode, mop->key);

We should early return i.e. goto out_unlock.

IMHO else if, else patterns should either be switches (testing the same variable) or kept as short as possible / be avoided.

+	} else if (acc_mode == GACC_FETCH) {
+		r = access_guest_abs_with_key(kvm, mop->gaddr, tmpbuf,
+					      mop->size, GACC_FETCH, mop->key);

I'd guess it's personal taste whether you use GACC_FETCH or access_mode but if you don't use it here then we can remove the variable all together, no?

+		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:




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