Messages in this thread | | | Date | Thu, 26 Jan 2023 07:48:46 +0100 | From | Thomas Huth <> | Subject | Re: [PATCH v6 08/14] KVM: s390: Move common code of mem_op functions into functions |
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On 25/01/2023 22.26, Janis Schoetterl-Glausch wrote: > The vcpu and vm mem_op ioctl implementations share some functionality. > Move argument checking and buffer allocation into functions and call > them from both implementations. > This allows code reuse in case of additional future mem_op operations. > > Suggested-by: Janosch Frank <frankja@linux.ibm.com> > Signed-off-by: Janis Schoetterl-Glausch <scgl@linux.ibm.com> > --- > arch/s390/kvm/kvm-s390.c | 80 +++++++++++++++++++++------------------- > 1 file changed, 42 insertions(+), 38 deletions(-) > > diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c > index e4890e04b210..e0dfaa195949 100644 > --- a/arch/s390/kvm/kvm-s390.c > +++ b/arch/s390/kvm/kvm-s390.c > @@ -2764,24 +2764,44 @@ 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 void *mem_op_alloc_buf(struct kvm_s390_mem_op *mop) > +{ > + void *buf; > + > + if (mop->flags & KVM_S390_MEMOP_F_CHECK_ONLY) > + return NULL; > + buf = vmalloc(mop->size); > + if (!buf) > + return ERR_PTR(-ENOMEM); > + return buf; > } > > 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;
You likely can now remove the "= NULL" here, I guess?
> 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. > @@ -2793,17 +2813,9 @@ 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) > - return -ENOMEM; > - } > + tmpbuf = mem_op_alloc_buf(mop); > + if (IS_ERR(tmpbuf)) > + return PTR_ERR(tmpbuf); > > srcu_idx = srcu_read_lock(&kvm->srcu); > > @@ -5250,28 +5262,20 @@ static long kvm_s390_vcpu_mem_op(struct kvm_vcpu *vcpu, > { > void __user *uaddr = (void __user *)mop->buf; > void *tmpbuf = NULL;
... and here, too.
But I have to admit that I'm also not sure whether I like the mem_op_alloc_buf() part or not (the mem_op_validate_common() part looks fine to me) : mem_op_alloc_buf() is a new function with 11 lines of code, and the old spots that allocate memory were only 5 lines of code each, so you now increased the LoC count and additionally have to fiddly with IS_ERR and PTR_ERR which is always a little bit ugly in my eyes ... IMHO I'd rather keep the old code here. But that's just my 0.02 €, if you think it's nicer with mem_op_alloc_buf(), I won't insist on keeping the old code.
Thomas
> - 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) > - return -ENOMEM; > - } > + tmpbuf = mem_op_alloc_buf(mop); > + if (IS_ERR(tmpbuf)) > + return PTR_ERR(tmpbuf); > > switch (mop->op) { > case KVM_S390_MEMOP_LOGICAL_READ:
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