On Mon, 24 May 2021 21:39:33 +0800 Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx> wrote: > Series first introduces generic support for DOE mailboxes as defined > in the ECN to the PCIe r5.0 specification available from the PCI SIG [0] > > A user is then introduced in the form of the table access protocol defined > in the CXL 2.0 specification [1] used to access the > Coherent Device Attribute Table (CDAT) defined in [2] > > Finally, in two patches that are not intended for merging, an example > of a generic IOCTL interface to perform synchronous exchanges from user > space in a kernel mediated fashion is introduced. The current consensus > seems in favour of not introducing such an interface, but instead > providing per protocol interfaces where appropriate. As this code was > developed in parallel with that discussion and may be of use to someone it > is included here. > Gentle, not particularly urgent, request for review on this set. I am currently missing ABI docs for the CDAT binary attribute, but that could be handled in a follow up patch. Thanks, Jonathan > Open questions. > * Do we need to prevent userspace access to the DOE when the kernel is > managing it (registered by driver)? Discussion in thread: > https://lore.kernel.org/linux-pci/20210419165451.2176200-1-Jonathan.Cameron@xxxxxxxxxx/ > * Does a generic userspace mediation interface make sense? > Currently it seems not, but as it was nearly ready, I've included > it in this patch set anyway. > * Move CXL cdat handling to a separate file, or wait until we can see > how it is going to be used? > > Changes since v3 > Thanks to Ira, Bjorn and Dan for feedback. > * Addition of a generic IOCTL interface and demo program for discussion. > * Fixed an issue with accidentally disabling interrupts. > * Ensure IRQ_HANDLED always returned as clearing of BUSY can result > in an interrupt, but there is no means of identifying this. > The best that can be done is to eat the interrupt. > * Edited comments to more directly tie them to the code the referred to. > * Lock scope documentation update. > * Dropped the CDAT dump to log patch as we are hopefully getting closer > to this being applied. > * Fixed the references to pcie_ missed when renaming to pci_ in v3. > > Set based on cxl/next > > All testing conducted against QEMU emulation of a CXL type 3 device > in conjunction with DOE mailbox patches v5 [3, 4] > > [0] https://pcisig.com/specifications > [1] https://www.computeexpresslink.org/download-the-specification > [2] https://uefi.org/node/4093 > [3] https://lore.kernel.org/qemu-devel/20210202005948.241655-1-ben.widawsky@xxxxxxxxx/ > [4] https://lore.kernel.org/qemu-devel/1619454964-10190-1-git-send-email-cbrowy@xxxxxxxxxxxxxxxx/ > > Jonathan Cameron (5): > PCI: Add vendor ID for the PCI SIG > PCI/DOE: Add Data Object Exchange support > cxl/mem: Add CDAT table reading from DOE > DONOTMERGE PCI/DOE Add per DOE chrdev for ioctl based access > DONOTMERGE: PCI/DOE: Add userspace example program to tools/pci > > drivers/cxl/Kconfig | 1 + > drivers/cxl/cxl.h | 21 + > drivers/cxl/mem.c | 174 ++++++++ > drivers/cxl/mem.h | 6 + > drivers/pci/Kconfig | 8 + > drivers/pci/Makefile | 1 + > drivers/pci/doe.c | 794 ++++++++++++++++++++++++++++++++++ > drivers/pci/pci-driver.c | 3 +- > include/linux/pci-doe.h | 100 +++++ > include/linux/pci.h | 3 + > include/linux/pci_ids.h | 1 + > include/uapi/linux/pci_doe.h | 32 ++ > include/uapi/linux/pci_regs.h | 29 +- > tools/pci/Build | 1 + > tools/pci/Makefile | 9 +- > tools/pci/doetest.c | 131 ++++++ > 16 files changed, 1311 insertions(+), 3 deletions(-) > create mode 100644 drivers/pci/doe.c > create mode 100644 include/linux/pci-doe.h > create mode 100644 include/uapi/linux/pci_doe.h > create mode 100644 tools/pci/doetest.c > > > base-commit: 35c32e3095d396c750f5cdfdaa94cba83d9b23c6
