From: Ira Weiny <ira.weiny@xxxxxxxxx> Changes from V8:[5] For this version I've punted a bit to get it out and drop the auxiliary bus functionality. I like where Jonathan is going with the port driver idea. I think eventually the irq/mailbox creation will need to be more generic in a PCI port driver. I've modeled this version on such an architecture but used the CXL port for the time being. From Dan Drop the auxiliary bus/device From Jonathan Cleanups From Bjorn Clean up commit messages move pci-doe.c to doe.c Clean up PCI spec references Ensure all messages use pci_*() Add offset to error messages to distinguish mailboxes use hex for DOE offsets Print 4 nibbles for Vendor ID and 2 for type. s/irq/IRQ in comments Fix long lines Fix typos Changes from V7:[4] Avoid code bloat by making pci-doe.c conditional on CONFIG_PCI_DOE which is auto selected by the CXL_PCI config option. Minor code clean ups Fix bug in pci_doe_supports_prot() Rebase to cxl-pending Changes from V6:[3] The big change is the removal of the auxiliary bus code from the PCI layer. The auxiliary bus usage is now in the CXL layer. The PCI layer provides helpers for subsystems to utilize DOE mailboxes by creating a pci_doe_mb object which controls a state machine for that mailbox capability. The CXL layer wraps this object in an auxiliary device and driver which can then be used to determine if the kernel is controlling the capability or it is available to be used by user space. Reads from user space via lspci are allowed. Writes are allowed but flagged via a tainting the kernel. Feedback from Bjorn, Jonathan, and Dan Details in each patch Changes from V5:[0] Rework the patch set to split PCI vs CXL changes Also make each change a bit more stand alone for easier review Add cxl_cdat structure Put CDAT related data structures in cdat.h Clarify some device lifetimes with comments Incorporate feedback from Jonathan, Bjorn and Dan The bigest change is placing the DOE scanning code into the pci_doe driver (part of the PCI codre). Validate the CDAT when it is read rather than before DSMAS parsing Do not report DSMAS failure as an error, report a warning and keep going. Retry reading the table 1 time. Update commit messages and this cover letter CXL drivers need various data which are provided through generic DOE mailboxes as defined in the PCIe 6.0 spec.[1] One such data is the Coherent Device Atribute Table (CDAT). CDAT data provides coherent information about the various devices in the system. It was developed because systems no longer have a priori knowledge of all coherent devices within a system. CDAT describes the coherent characteristics of the components on the CXL bus separate from system configurations. The OS can then, for example, use this information to form correct interleave sets. To begin reading the CDAT the OS must have support to access the DOE mailboxes provided by the CXL devices. Because DOE is not specific to DOE but is provided within the PCI spec, the series adds PCI DOE capability library functions. These functions allow for the iteration of the DOE capabilities on a device as well as creating pci_doe_mb structures which can control the operation of the DOE state machine. CXL iterates the DOE capabilities creates auxiliary bus devices. These devices are driven by a CXL DOE auxiliary driver which calls into the PCI DOE library functions as appropriate. The auxiliary bus architecture allows for root users to control which DOE mailboxes are controlled by the kernel and which should be allowed for unrestricted access by user space. One such use case is to allow for CXL Compliance Testing (CXL 2.0 14.16.4 Compliance Mode DOE). By default the kernel controls all mailboxes found. After the devices are created and the driver attaches, CDAT data is read from the device and DSMAS information parsed from that CDAT blob for use later. This work was tested using qemu with additional patches. [0] https://lore.kernel.org/linux-cxl/20211105235056.3711389-1-ira.weiny@xxxxxxxxx/ [1] https://pcisig.com/specifications [2] https://lore.kernel.org/qemu-devel/20210202005948.241655-1-ben.widawsky@xxxxxxxxx/ [3] https://lore.kernel.org/linux-cxl/20220201071952.900068-1-ira.weiny@xxxxxxxxx/ [4] https://lore.kernel.org/linux-cxl/20220330235920.2800929-1-ira.weiny@xxxxxxxxx/ [5] https://lore.kernel.org/linux-cxl/20220414203237.2198665-1-ira.weiny@xxxxxxxxx/ Ira Weiny (6): PCI: Replace magic constant for PCI Sig Vendor ID cxl/pci: Create PCI DOE mailbox's for memory devices cxl/port: Find a DOE mailbox which supports CDAT cxl/port: Introduce cxl_cdat_valid() cxl/port: Retry reading CDAT on failure cxl/port: Parse out DSMAS data from CDAT table Jonathan Cameron (3): PCI: Add vendor ID for the PCI SIG PCI: Create PCI library functions in support of DOE mailboxes. cxl/port: Read CDAT table drivers/cxl/Kconfig | 1 + drivers/cxl/cdat.h | 118 +++++++ drivers/cxl/core/pci.c | 267 ++++++++++++++ drivers/cxl/core/port.c | 45 +++ drivers/cxl/cxl.h | 7 + drivers/cxl/cxlmem.h | 10 + drivers/cxl/cxlpci.h | 3 + drivers/cxl/mem.c | 1 + drivers/cxl/pci.c | 111 ++++++ drivers/pci/Kconfig | 3 + drivers/pci/Makefile | 1 + drivers/pci/doe.c | 633 ++++++++++++++++++++++++++++++++++ drivers/pci/probe.c | 2 +- include/linux/pci-doe.h | 120 +++++++ include/linux/pci_ids.h | 1 + include/uapi/linux/pci_regs.h | 29 +- 16 files changed, 1350 insertions(+), 2 deletions(-) create mode 100644 drivers/cxl/cdat.h create mode 100644 drivers/pci/doe.c create mode 100644 include/linux/pci-doe.h -- 2.35.1
