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@xxxxxxxxxxxxx>
Signed-off-by: Janis Schoetterl-Glausch <scgl@xxxxxxxxxxxxx>
---
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
I've done a PoC that has a **buff argument and combines the check with
the alloc.
@Nina: Any reason why this was split up?
