Re: [PATCH v4 04/11] iommufd/viommu: Add IOMMU_VIOMMU_ALLOC ioctl

[Nicolin Chen <nicolinc@nvidia.com>]

On Fri, Oct 25, 2024 at 08:59:11AM +0000, Tian, Kevin wrote:
> > From: Nicolin Chen <nicolinc@nvidia.com>
> > Sent: Tuesday, October 22, 2024 8:19 AM
> >
> > Add a new ioctl for user space to do a vIOMMU allocation. It must be based
> > on a nesting parent HWPT, so take its refcount.
> >
> > If an IOMMU driver supports a driver-managed vIOMMU object, it must
> > define
> 
> why highlight 'driver-managed', implying a core-managed vIOMMU
> object some day?

Oh, core-managed vIOMMU is gone since this version. I should have
updated the commit message here too.

> > +/**
> > + * struct iommu_viommu_alloc - ioctl(IOMMU_VIOMMU_ALLOC)
> > + * @size: sizeof(struct iommu_viommu_alloc)
> > + * @flags: Must be 0
> > + * @type: Type of the virtual IOMMU. Must be defined in enum
> > iommu_viommu_type
> > + * @dev_id: The device's physical IOMMU will be used to back the virtual
> > IOMMU
> > + * @hwpt_id: ID of a nesting parent HWPT to associate to
> > + * @out_viommu_id: Output virtual IOMMU ID for the allocated object
> > + *
> > + * Allocate a virtual IOMMU object that represents the underlying physical
> > + * IOMMU's virtualization support. The vIOMMU object is a security-isolated
> > + * slice of the physical IOMMU HW that is unique to a specific VM.
> 
> the object itself is a software abstraction, while a 'slice' is a set of
> real hw resources.

Yea, let's do this:
 * Allocate a virtual IOMMU object, representing the underlying physical IOMMU's
 * virtualization support that is a security-isolated slice of the real IOMMU HW
 * that is unique to a specific VM.

Thanks
Nicolin