KVM: ARM/arm64: return -EFAULT if copy_from_user fails in set_timer_reg

We currently return the number of bytes not copied if set_timer_reg
fails, which is almost certainly not what userspace would like.

This patch returns -EFAULT instead.

Cc: Christoffer Dall <christoffer.dall@linaro.org>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>

arch/arm/kvm/guest.c

@@ -163,7 +163,7 @@ static int set_timer_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
 
 	ret = copy_from_user(&val, uaddr, KVM_REG_SIZE(reg->id));
 	if (ret != 0)
-		return ret;
+		return -EFAULT;
 
 	return kvm_arm_timer_set_reg(vcpu, reg->id, val);
 }

arch/arm64/kvm/guest.c

@@ -174,7 +174,7 @@ static int set_timer_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
 
 	ret = copy_from_user(&val, uaddr, KVM_REG_SIZE(reg->id));
 	if (ret != 0)
-		return ret;
+		return -EFAULT;
 
 	return kvm_arm_timer_set_reg(vcpu, reg->id, val);
 }