Re: [PATCH 08/11] PCI/IDE: Add IDE establishment helpers

[Dan Williams <dan.j.williams@intel.com>]

Alexey Kardashevskiy wrote:
> 
> 
> On 19/12/24 18:25, Alexey Kardashevskiy wrote:
> > 
> > 
> > On 6/12/24 09:24, Dan Williams wrote:
> >> There are two components to establishing an encrypted link, provisioning
> >> the stream in config-space, and programming the keys into the link layer
> >> via the IDE_KM (key management) protocol. These helpers enable the
> >> former, and are in support of TSM coordinated IDE_KM. When / if native
> >> IDE establishment arrives it will share this same config-space
> >> provisioning flow, but for now IDE_KM, in any form, is saved for a
> >> follow-on change.
> >>
> >> With the TSM implementations of SEV-TIO and TDX Connect in mind this
> >> abstracts small differences in those implementations. For example, TDX
> >> Connect handles Root Port registers updates while SEV-TIO expects System
> >> Software to update the Root Port registers. This is the rationale for
> >> the PCI_IDE_SETUP_ROOT_PORT flag.
> >>
> >> The other design detail for TSM-coordinated IDE establishment is that
> >> the TSM manages allocation of stream-ids, this is why the stream_id is
> >> passed in to pci_ide_stream_setup().
> >>
> >> The flow is:
> >>
> >> pci_ide_stream_probe()
> >>    Gather stream settings (devid and address filters)
> >> pci_ide_stream_setup()
> >>    Program the stream settings into the endpoint, and optionally Root 
> >> Port)
> >> pci_ide_enable_stream()
> >>    Run the stream after IDE_KM
> >>
> >> In support of system administrators auditing where platform IDE stream
> >> resources are being spent, the allocated stream is reflected as a
> >> symlink from the host-bridge to the endpoint.
> >>
> >> Thanks to Wu Hao for a draft implementation of this infrastructure.
> >>
> >> Cc: Bjorn Helgaas <bhelgaas@google.com>
> >> Cc: Lukas Wunner <lukas@wunner.de>
> >> Cc: Samuel Ortiz <sameo@rivosinc.com>
> >> Co-developed-by: Alexey Kardashevskiy <aik@amd.com>
> >> Signed-off-by: Alexey Kardashevskiy <aik@amd.com>
> >> 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>
> >> ---
> >>   .../ABI/testing/sysfs-devices-pci-host-bridge      |   28 +++
> >>   drivers/pci/ide.c                                  |  192 
> >> ++++++++++++++++++++
> >>   drivers/pci/pci.h                                  |    4
> >>   drivers/pci/probe.c                                |    1
> >>   include/linux/pci-ide.h                            |   33 +++
> >>   include/linux/pci.h                                |    4
> >>   6 files changed, 262 insertions(+)
> >>   create mode 100644 
> >> Documentation/ABI/testing/sysfs-devices-pci-host-bridge
> >>   create mode 100644 include/linux/pci-ide.h
> >>
[..]
> >> +    __pci_ide_stream_setup(pdev, ide);
> >> +    if (flags & PCI_IDE_SETUP_ROOT_PORT)
> >> +        __pci_ide_stream_setup(rp, ide);
> 
> Oh, when we do this, the root port gets the same devid_start/end as the 
> device which is not correct, what should be there, the rootport bdfn? 
> Need to dig that but PCI_IDE_SETUP_ROOT_PORT should detect that it is a 
> root port. Thanks,

Why would the values be different? The Stream is associated with a set
of RIDs, I expect the PF and the Root Port to agree on that set?

Regardless, the PCI_IDE_SETUP_ROOT_PORT concept is dead so this could
support distinct settings per Root Port vs endpoint, but I am missing
where / why those would diverge.