On Thu, 2023-01-26 at 14:02 +0100, Janosch Frank wrote:
On 1/26/23 07:48, Thomas Huth wrote:
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);@@ -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
I've done a PoC that has a **buff argument and combines the check with the alloc.
I just didn't like that much because it felt like an unspecific memop_do_things function.