On Fri, Oct 25, 2024 at 04:49:43PM -0700, Nicolin Chen wrote:
> To support driver-allocated vIOMMU objects, it's suggested to call the
> allocator helper in IOMMU dirvers. However, there is no guarantee that
> drivers will all use it and allocate objects properly.
>
> Add a helper for iommufd core to verify if an unfinalized object is at
> least reserved in the ictx.
I don't think we need this..
iommufd_object_finalize() already does:
old = xa_store(&ictx->objects, obj->id, obj, GFP_KERNEL);
/* obj->id was returned from xa_alloc() so the xa_store() cannot fail */
WARN_ON(old);
So, we could enhance it to be more robust, like this patch is doing:
void iommufd_object_finalize(struct iommufd_ctx *ictx,
struct iommufd_object *obj)
{
void *old;
old = xa_cmpxchg(&ictx->objects, obj->id, XA_ZERO_ENTRY, obj,
GFP_KERNEL);
/* obj->id was returned from xa_alloc() so the xa_store() cannot fail */
WARN_ON(old != XA_ZERO_ENTRY);
It is always a driver bug to not initialize that object, so WARN_ON is
OK.
Jason
