KVM: selftests: Fix typos and stale comments in kvm_util

Fix minor documentation errors in `kvm_util.h` and `kvm_util.c`.

- Correct the argument description for `vcpu_args_set` in `kvm_util.h`,
  which incorrectly listed `vm` instead of `vcpu`.
- Fix a typo in the comment for `kvm_selftest_arch_init` ("exeucting" ->
  "executing").
- Correct the return value description for `vm_vaddr_unused_gap` in
  `kvm_util.c` to match the implementation, which returns an address "at
  or above" `vaddr_min`, not "at or below".

No functional change intended.

Reviewed-by: Andrew Jones <andrew.jones@linux.dev>
Signed-off-by: Fuad Tabba <tabba@google.com>
Link: https://patch.msgid.link/20260109082218.3236580-6-tabba@google.com
Signed-off-by: Marc Zyngier <maz@kernel.org>

Author: Fuad Tabba

tools/testing/selftests/kvm/include/kvm_util.h

@@ -939,7 +939,7 @@ void *vcpu_map_dirty_ring(struct kvm_vcpu *vcpu);
  * VM VCPU Args Set
  *
  * Input Args:
- *   vm - Virtual Machine
+ *   vcpu - vCPU
  *   num - number of arguments
  *   ... - arguments, each of type uint64_t
  *
@@ -1264,7 +1264,7 @@ static inline uint64_t vm_page_align(struct kvm_vm *vm, uint64_t v)
 }
 
 /*
- * Arch hook that is invoked via a constructor, i.e. before exeucting main(),
+ * Arch hook that is invoked via a constructor, i.e. before executing main(),
  * to allow for arch-specific setup that is common to all tests, e.g. computing
  * the default guest "mode".
  */

tools/testing/selftests/kvm/lib/kvm_util.c

@@ -1351,7 +1351,7 @@ struct kvm_vcpu *__vm_vcpu_add(struct kvm_vm *vm, uint32_t vcpu_id)
  * Output Args: None
  *
  * Return:
- *   Lowest virtual address at or below vaddr_min, with at least
+ *   Lowest virtual address at or above vaddr_min, with at least
  *   sz unused bytes.  TEST_ASSERT failure if no area of at least
  *   size sz is available.
  *