Re: [PATCH 1/3] VFIO: take reference to the KVM module

[Dan Williams <djbw@kernel.org>]

Sean Christopherson wrote:
> +Dan

+Yilun

[..]
> I added Dan because the PCI TSM stuff is picking up "struct kvm *kvm" references,
> and I want to head that off too, i.e. have it use the file approach instead of
> whatever it plans on doing (can't tell from the code, because there are no users).

The PCI TSM *reference* for 'struct kvm *' will be inherited from
vfio/iommufd. However, the TSM driver needs some context to manipulate
the VM. For example, TDX effectively needs:

    to_kvm_tdx(kvm)->td.tdr_page

...for operations like TDH.TDI.CREATE that sets up the context for the
privately assigned device.

It could follow the example of arch/x86/kvm/mmu/page_track.c and do:

    kvm_tdx_tdi_create(struct file *kvm, ...)

...and use file_to_kvm() for that limited helper that does not need to expose
'struct kvm_tdx' outside of arch/x86/.