On 2/11/2023 4:25 AM, Lukas Wunner wrote: > An upcoming user of DOE is CMA (Component Measurement and Authentication, > PCIe r6.0 sec 6.31). > > It builds on SPDM (Security Protocol and Data Model): > https://www.dmtf.org/dsp/DSP0274 > > SPDM message sizes are not always a multiple of dwords. To transport > them over DOE without using bounce buffers, allow sending requests and > receiving responses whose final dword is only partially populated. > > To be clear, PCIe r6.0 sec 6.30.1 specifies the Data Object Header 2 > "Length" in dwords and pci_doe_send_req() and pci_doe_recv_resp() > read/write dwords. So from a spec point of view, DOE is still specified > in dwords and allowing non-dword request/response buffers is merely for > the convenience of callers. > > Tested-by: Ira Weiny <ira.weiny@xxxxxxxxx> > Signed-off-by: Lukas Wunner <lukas@xxxxxxxxx> > Reviewed-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx> > --- > Changes v2 -> v3: > * Fix byte order of last dword on big endian arches (Ira) > * Explain in commit message and kerneldoc that arbitrary-sized > payloads are not stipulated by the spec, but merely for > convenience of the caller (Bjorn, Jonathan) > * Add code comment that "remainder" in pci_doe_recv_resp() signifies > the number of data bytes in the last payload dword (Ira) > > drivers/pci/doe.c | 74 +++++++++++++++++++++++++++++++---------------- > 1 file changed, 49 insertions(+), 25 deletions(-) > ...... > + > + if (payload_length) { > + /* Read all payload dwords except the last */ > + for (; i < payload_length - 1; i++) { > + pci_read_config_dword(pdev, offset + PCI_DOE_READ, > + &val); > + task->response_pl[i] = cpu_to_le32(val); > + pci_write_config_dword(pdev, offset + PCI_DOE_READ, 0); > + } > + > + /* Read last payload dword */ > pci_read_config_dword(pdev, offset + PCI_DOE_READ, &val); > - task->response_pl[i] = cpu_to_le32(val); > + cpu_to_le32s(&val); > + memcpy(&task->response_pl[i], &val, remainder); This "Read last payload dword" seems like making sense only when remainder != sizeof(u32). If remainder == sizeof(u32), it should be read in above reading loops. But this implementation also looks good to me. Reviewed-by: Ming Li <ming4.li@xxxxxxxxx> > /* Prior to the last ack, ensure Data Object Ready */ > - if (i == (payload_length - 1) && !pci_doe_data_obj_ready(doe_mb)) > + if (!pci_doe_data_obj_ready(doe_mb)) > return -EIO; > pci_write_config_dword(pdev, offset + PCI_DOE_READ, 0); > + i++; > } > > /* Flush excess length */
