Hi Lukas, On Mon, Jan 23, 2023 at 11:20:00AM +0100, 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. Can you add a note about this non-dwordness? The sec 6.30.1 Data Object Header 2 "Length" field is in DW and the code in pci_doe_send_req() and pci_doe_recv_resp() still reads/writes dwords. I don't see the 6.31 text that requires non-dword sizes. >From a spec point of view, AFAICS, DOE is still specified in dwords, but I guess you're leaving the actual PCI config-level DOE interface in dwords and just making it more convenient for callers by having pci_doe_*() hide the details of any partial dwords at the end by transferring the entire dword over PCI but only copying the requested bytes to/from the caller's buffer? > Tested-by: Ira Weiny <ira.weiny@xxxxxxxxx> > Signed-off-by: Lukas Wunner <lukas@xxxxxxxxx> > Cc: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx> > --- > drivers/pci/doe.c | 66 ++++++++++++++++++++++++++++------------------- > 1 file changed, 40 insertions(+), 26 deletions(-) > > diff --git a/drivers/pci/doe.c b/drivers/pci/doe.c > index 0263bcfdddd8..2113ec95379f 100644 > --- a/drivers/pci/doe.c > +++ b/drivers/pci/doe.c > @@ -76,13 +76,6 @@ struct pci_doe_protocol { > * @private: Private data for the consumer > * @work: Used internally by the mailbox > * @doe_mb: Used internally by the mailbox > - * > - * The payload sizes and rv are specified in bytes with the following > - * restrictions concerning the protocol. > - * > - * 1) The request_pl_sz must be a multiple of double words (4 bytes) > - * 2) The response_pl_sz must be >= a single double word (4 bytes) > - * 3) rv is returned as bytes but it will be a multiple of double words > */ > struct pci_doe_task { > struct pci_doe_protocol prot; > @@ -153,7 +146,7 @@ static int pci_doe_send_req(struct pci_doe_mb *doe_mb, > { > struct pci_dev *pdev = doe_mb->pdev; > int offset = doe_mb->cap_offset; > - size_t length; > + size_t length, remainder; > u32 val; > int i; > > @@ -171,7 +164,7 @@ static int pci_doe_send_req(struct pci_doe_mb *doe_mb, > return -EIO; > > /* Length is 2 DW of header + length of payload in DW */ > - length = 2 + task->request_pl_sz / sizeof(u32); > + length = 2 + DIV_ROUND_UP(task->request_pl_sz, sizeof(u32)); > if (length > PCI_DOE_MAX_LENGTH) > return -EIO; > if (length == PCI_DOE_MAX_LENGTH) > @@ -184,10 +177,20 @@ static int pci_doe_send_req(struct pci_doe_mb *doe_mb, > pci_write_config_dword(pdev, offset + PCI_DOE_WRITE, > FIELD_PREP(PCI_DOE_DATA_OBJECT_HEADER_2_LENGTH, > length)); > + > + /* Write payload */ > for (i = 0; i < task->request_pl_sz / sizeof(u32); i++) > pci_write_config_dword(pdev, offset + PCI_DOE_WRITE, > task->request_pl[i]); > > + /* Write last payload dword */ > + remainder = task->request_pl_sz % sizeof(u32); > + if (remainder) { > + val = 0; > + memcpy(&val, &task->request_pl[i], remainder); > + pci_write_config_dword(pdev, offset + PCI_DOE_WRITE, val); > + } > + > pci_doe_write_ctrl(doe_mb, PCI_DOE_CTRL_GO); > > return 0; > @@ -207,11 +210,11 @@ static bool pci_doe_data_obj_ready(struct pci_doe_mb *doe_mb) > > static int pci_doe_recv_resp(struct pci_doe_mb *doe_mb, struct pci_doe_task *task) > { > + size_t length, payload_length, remainder, received; > struct pci_dev *pdev = doe_mb->pdev; > int offset = doe_mb->cap_offset; > - size_t length, payload_length; > + int i = 0; > u32 val; > - int i; > > /* Read the first dword to get the protocol */ > pci_read_config_dword(pdev, offset + PCI_DOE_READ, &val); > @@ -238,15 +241,34 @@ static int pci_doe_recv_resp(struct pci_doe_mb *doe_mb, struct pci_doe_task *tas > > /* First 2 dwords have already been read */ > length -= 2; > - payload_length = min(length, task->response_pl_sz / sizeof(u32)); > - /* Read the rest of the response payload */ > - for (i = 0; i < payload_length; i++) { > - pci_read_config_dword(pdev, offset + PCI_DOE_READ, > - &task->response_pl[i]); > + received = task->response_pl_sz; > + payload_length = DIV_ROUND_UP(task->response_pl_sz, sizeof(u32)); > + remainder = task->response_pl_sz % sizeof(u32); > + if (!remainder) > + remainder = sizeof(u32); > + > + if (length < payload_length) { > + received = length * sizeof(u32); > + payload_length = length; > + remainder = sizeof(u32); > + } > + > + 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, > + &task->response_pl[i]); > + pci_write_config_dword(pdev, offset + PCI_DOE_READ, 0); > + } > + > + /* Read last payload dword */ > + pci_read_config_dword(pdev, offset + PCI_DOE_READ, &val); > + memcpy(&task->response_pl[i], &val, remainder); > /* 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 */ > @@ -260,7 +282,7 @@ static int pci_doe_recv_resp(struct pci_doe_mb *doe_mb, struct pci_doe_task *tas > if (FIELD_GET(PCI_DOE_STATUS_ERROR, val)) > return -EIO; > > - return min(length, task->response_pl_sz / sizeof(u32)) * sizeof(u32); > + return received; > } > > static void signal_task_complete(struct pci_doe_task *task, int rv) > @@ -560,14 +582,6 @@ static int pci_doe_submit_task(struct pci_doe_mb *doe_mb, > if (!pci_doe_supports_prot(doe_mb, task->prot.vid, task->prot.type)) > return -EINVAL; > > - /* > - * DOE requests must be a whole number of DW and the response needs to > - * be big enough for at least 1 DW > - */ > - if (task->request_pl_sz % sizeof(u32) || > - task->response_pl_sz < sizeof(u32)) > - return -EINVAL; > - > if (test_bit(PCI_DOE_FLAG_DEAD, &doe_mb->flags)) > return -EIO; > > -- > 2.39.1 >
