Re: [PATCH 5/6] PCI/TSM: Add pci_tsm_guest_req() for managing TDIs

dan.j.williams
2025-11-06T00:13:48Z

Jonathan Cameron wrote:
> On Tue, 4 Nov 2025 20:00:54 -0800
> Dan Williams <dan.j.williams@intel.com> wrote:
>
> > A PCIe device function interface assigned to a TVM is a TEE Device
> > Interface (TDI). A TDI instantiated by pci_tsm_bind() needs additional
> > steps taken by the TVM to be accepted into the TVM's Trusted Compute
> > Boundary (TCB) and transitioned to the RUN state.
> >
> > pci_tsm_guest_req() is a channel for the guest to request TDISP collateral,
> > like Device Interface Reports, and effect TDISP state changes, like
> > LOCKED->RUN transititions. Similar to IDE establishment and pci_tsm_bind(),
> > these are long running operations involving SPDM message passing via the
> > DOE mailbox.
> >
> > The path for a TVM to invoke pci_tsm_guest_req() is:
> > * TSM triggers exit via guest-to-host-interface ABI (implementation specific)
> > * VMM invokes handler (KVM handle_exit() -> userspace io)
> > * handler issues request (userspace io handler -> ioctl() ->
> > pci_tsm_guest_req())
> > * handler supplies response
> > * VMM posts response, notifies/re-enters TVM
> >
> > This path is purely a transport for messages from TVM to platform TSM. By
> > design the host kernel does not and must not care about the content of
> > these messages. I.e. the host kernel is not in the TCB of the TVM.
> >
> > As this is an opaque passthrough interface, similar to fwctl, the kernel
> > requires that implementations stay within the bounds defined by 'enum
> > pci_tsm_req_scope'. Violation of those expectations likely has market and
> > regulatory consequences. Out of scope requests are blocked by default.
> >
> > Co-developed-by: Xu Yilun <yilun.xu@linux.intel.com>
> > Signed-off-by: Xu Yilun <yilun.xu@linux.intel.com>
> > Signed-off-by: Dan Williams <dan.j.williams@intel.com>
> More triviality inline.
>
>
> > diff --git a/drivers/pci/tsm.c b/drivers/pci/tsm.c
> > index f0e38d7fee38..4dd518b45eea 100644
> > --- a/drivers/pci/tsm.c
> > +++ b/drivers/pci/tsm.c
> > @@ -354,6 +354,69 @@ int pci_tsm_bind(struct pci_dev *pdev, struct kvm *kvm, u32 tdi_id)
> > }
> > EXPORT_SYMBOL_GPL(pci_tsm_bind);
>
> > +ssize_t pci_tsm_guest_req(struct pci_dev *pdev, enum pci_tsm_req_scope scope,
> > + sockptr_t req_in, size_t in_len, sockptr_t req_out,
> > + size_t out_len, u64 *tsm_code)
> > +{
> > + struct pci_tsm_pf0 *tsm_pf0;
> > + struct pci_tdi *tdi;
> > + int rc;
> > +
> > + /*
> > + * Forbid requests that are not directly related to TDISP
> > + * operations
> > + */
>
> /* Forbid requests that are not directly related to TDISP operations */
> Is just under 80 chars.

Indeed it is. Probably a case of rewording but then not reflowing with
clang-format.