Hi Jason,
On Thu, Mar 09, 2023 at 08:56:06PM -0400, Jason Gunthorpe wrote:
On Thu, Mar 09, 2023 at 12:08:59AM -0800, Yi Liu wrote:
diff --git a/include/linux/iommu.h b/include/linux/iommu.h index 3ef84ee359d2..a269bc62a31c 100644 --- a/include/linux/iommu.h +++ b/include/linux/iommu.h @@ -229,6 +229,7 @@ struct iommu_iotlb_gather {
after use. Return the data buffer if success, or ERR_PTR onfailure.- @domain_alloc: allocate iommu domain
- @domain_alloc_user: allocate user iommu domain
- @probe_device: Add device to iommu driver handling
- @release_device: Remove device from iommu driver handling
- @probe_finalize: Do final setup work after the device is added to an IOMMU
@@ -266,6 +267,9 @@ struct iommu_ops { /* Domain allocation and freeing by the iommu driver */ struct iommu_domain *(*domain_alloc)(unsigned iommu_domain_type);
- struct iommu_domain *(*domain_alloc_user)(struct device *dev,
struct iommu_domain *parent,const void *user_data);Since the kernel does the copy from user and manages the zero fill compat maybe this user_data have a union like Robin suggested.
But yes, this is the idea.
Reviewed-by: Jason Gunthorpe jgg@nvidia.com
We pass in a read-only data to this ->domain_alloc_user() while it also returns NULL on failure, matching ->domain_alloc(). So, there seems to be no error feedback pathway from the driver to user space.
Robin remarked in the SMMU series that an STE configuration can fail. So, a proper error feedback is required for this callback too.
To return a driver/HW specific error, I think we could define a "u8 out_error" in the user_data structure. So, we probably need a non-const pass-in here. What do you think?
Thanks Nic