Re: [PATCH v2 06/19] iommufd/viommu: Add IOMMU_VIOMMU_SET/UNSET_VDEV_ID ioctl

Jason Gunthorpe
2025-05-09T22:07:21Z

On Fri, May 09, 2025 at 12:57:18PM +1000, Alexey Kardashevskiy wrote:
>
>
> On 7/5/25 22:24, Jason Gunthorpe wrote:
> > On Wed, May 07, 2025 at 09:18:29PM +1000, Alexey Kardashevskiy wrote:
> >
> > > > We should not destroy the vdevice for something like that. In a CC
> > > > case that would unplug it from the VM which is not right.
> > >
> > > vdevice is not directly seen by the guest, is not it? The guest will
> > > see, for example, an "AMD IOMMU" and assume there is device table
> > > for all 64K devices, and so on, it is QEMU which will be
> > > reallocating vdevice in the host's IOMMUFD. Did I miss something
> > > here? Thanks,
> >
> > I imagined the vdevice would trigger the CC call to create the vPCI
> > function in the guest attached to the secure iommu.
>
> What is this vPCI going to look like inside the guest? There still
> be AMD IOMMU PCI function and passed through to-be-trusted PCI
> function.

However the VMM tells it to look using the arguments to the create
vdevice ioctl?

I don't understand the question?

Jason