Re: [PATCH v2 02/19] iommufd/viommu: Add IOMMUFD_OBJ_VIOMMU and IOMMU_VIOMMU_ALLOC ioctl

Jason Gunthorpe
2024-09-05T17:41:04Z

On Thu, Sep 05, 2024 at 10:10:38AM -0700, Nicolin Chen wrote:
> On Thu, Sep 05, 2024 at 12:53:02PM -0300, Jason Gunthorpe wrote:
> > On Tue, Aug 27, 2024 at 09:59:39AM -0700, Nicolin Chen wrote:
> > > +/**
> > > + * 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 to allocate this virtual IOMMU for
> >
> > @dev_id: The device's physical IOMMU will be used to back t he vIOMMU
> >
> > > + * @hwpt_id: ID of a nesting parent HWPT to associate to
> >
> > A nesting parent HWPT that will provide translation for an vIOMMU DMA
> >
> > > + * @out_viommu_id: Output virtual IOMMU ID for the allocated object
> > > + *
> > > + * Allocate a virtual IOMMU object that holds a (shared) nesting parent HWPT
> >
> > 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. Operations global to the IOMMU are connected to the
> > vIOMMU, such as:
> > - Security namespace for guest owned ID, eg guest controlled cache tags
> > - Virtualization of various platforms IDs like RIDs and others
> > - direct assigned invalidation queues
> > - direct assigned interrupts
> > - non-affiliated event reporting
> > - Delivery of paravirtualized invalidation
>
> Ack.

Also write something about the HWPT..

> Looks like you prefer using "vIOMMU" v.s. "VIOMMU"? I would go
> through all the patches (QEMU including) to keep that aligned.

Yeah, VIOMMU just for all-caps constants

Jason