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charset="utf-8" On 17.11.23 21:09:18, Robert Richter wrote: > I will send an on-top patch for 6.8 that reworks that code area to > remove the pointer arithmetic. Here it is: From 13787f72c20b8c54754ae86015d982307eae0397 Mon Sep 17 00:00:00 2001 From: Robert Richter Subject: [PATCH] cxl/pci: Get rid of pointer arithmetic reading CDAT table Reading the CDAT table using DOE requires a Table Access Response Header in addition to the CDAT entry. In current implementation this has caused offsets with sizeof(__le32) to the actual buffers. This led to hardly readable code and even bugs (see fix of devm_kfree() in read_cdat_data()). Rework code to avoid calculations with sizeof(__le32). Introduce struct cdat_doe for this which contains the Table Access Response Header and a variable payload size for various data structures afterwards to access the CDAT table and its CDAT Data Structures without recalculating buffer offsets. Cc: Lukas Wunner Cc: Dave Jiang Cc: Fan Ni Signed-off-by: Robert Richter Reviewed-by: Dave Jiang --- drivers/cxl/core/pci.c | 80 ++++++++++++++++++++---------------------- drivers/cxl/cxlpci.h | 19 ++++++++++ 2 files changed, 57 insertions(+), 42 deletions(-) diff --git a/drivers/cxl/core/pci.c b/drivers/cxl/core/pci.c index 5aaa0b36c42a..f900740c6dea 100644 --- a/drivers/cxl/core/pci.c +++ b/drivers/cxl/core/pci.c @@ -517,14 +517,14 @@ EXPORT_SYMBOL_NS_GPL(cxl_hdm_decode_init, CXL); FIELD_PREP(CXL_DOE_TABLE_ACCESS_ENTRY_HANDLE, (entry_handle))) =20 static int cxl_cdat_get_length(struct device *dev, - struct pci_doe_mb *cdat_doe, + struct pci_doe_mb *doe_mb, size_t *length) { __le32 request =3D CDAT_DOE_REQ(0); __le32 response[2]; int rc; =20 - rc =3D pci_doe(cdat_doe, PCI_DVSEC_VENDOR_ID_CXL, + rc =3D pci_doe(doe_mb, PCI_DVSEC_VENDOR_ID_CXL, CXL_DOE_PROTOCOL_TABLE_ACCESS, &request, sizeof(request), &response, sizeof(response)); @@ -542,56 +542,54 @@ static int cxl_cdat_get_length(struct device *dev, } =20 static int cxl_cdat_read_table(struct device *dev, - struct pci_doe_mb *cdat_doe, - void *cdat_table, size_t *cdat_length) + struct pci_doe_mb *doe_mb, + struct cdat_doe *doe, size_t *length) { - size_t length =3D *cdat_length + sizeof(__le32); - __le32 *data =3D cdat_table; + size_t received, remaining =3D *length; int entry_handle =3D 0; __le32 saved_dw =3D 0; =20 do { __le32 request =3D CDAT_DOE_REQ(entry_handle); - struct cdat_entry_header *entry; - size_t entry_dw; int rc; =20 - rc =3D pci_doe(cdat_doe, PCI_DVSEC_VENDOR_ID_CXL, + rc =3D pci_doe(doe_mb, PCI_DVSEC_VENDOR_ID_CXL, CXL_DOE_PROTOCOL_TABLE_ACCESS, &request, sizeof(request), - data, length); + doe, sizeof(*doe) + remaining); if (rc < 0) { dev_err(dev, "DOE failed: %d", rc); return rc; } =20 - /* 1 DW Table Access Response Header + CDAT entry */ - entry =3D (struct cdat_entry_header *)(data + 1); + if (rc < sizeof(*doe)) + return -EIO; + + received =3D rc - sizeof(*doe); + if ((entry_handle =3D=3D 0 && - rc !=3D sizeof(__le32) + sizeof(struct cdat_header)) || + received !=3D sizeof(doe->header[0])) || (entry_handle > 0 && - (rc < sizeof(__le32) + sizeof(*entry) || - rc !=3D sizeof(__le32) + le16_to_cpu(entry->length)))) + (received < sizeof(doe->entry[0]) || + received !=3D le16_to_cpu(doe->entry->length)))) return -EIO; =20 /* Get the CXL table access header entry handle */ entry_handle =3D FIELD_GET(CXL_DOE_TABLE_ACCESS_ENTRY_HANDLE, - le32_to_cpu(data[0])); - entry_dw =3D rc / sizeof(__le32); - /* Skip Header */ - entry_dw -=3D 1; + le32_to_cpu(doe->doe_header)); + /* * Table Access Response Header overwrote the last DW of * previous entry, so restore that DW */ - *data =3D saved_dw; - length -=3D entry_dw * sizeof(__le32); - data +=3D entry_dw; - saved_dw =3D *data; + doe->doe_header =3D saved_dw; + remaining -=3D received; + doe =3D (void *)doe + received; + saved_dw =3D doe->doe_header; } while (entry_handle !=3D CXL_DOE_TABLE_ACCESS_LAST_ENTRY); =20 /* Length in CDAT header may exceed concatenation of CDAT entries */ - *cdat_length -=3D length - sizeof(__le32); + *length -=3D remaining; =20 return 0; } @@ -616,11 +614,11 @@ void read_cdat_data(struct cxl_port *port) { struct device *uport =3D port->uport_dev; struct device *dev =3D &port->dev; - struct pci_doe_mb *cdat_doe; + struct pci_doe_mb *doe_mb; struct pci_dev *pdev =3D NULL; struct cxl_memdev *cxlmd; - size_t cdat_length; - void *cdat_table, *cdat_buf; + struct cdat_doe *doe; + size_t length; int rc; =20 if (is_cxl_memdev(uport)) { @@ -637,40 +635,38 @@ void read_cdat_data(struct cxl_port *port) if (!pdev) return; =20 - cdat_doe =3D pci_find_doe_mailbox(pdev, PCI_DVSEC_VENDOR_ID_CXL, - CXL_DOE_PROTOCOL_TABLE_ACCESS); - if (!cdat_doe) { + doe_mb =3D pci_find_doe_mailbox(pdev, PCI_DVSEC_VENDOR_ID_CXL, + CXL_DOE_PROTOCOL_TABLE_ACCESS); + if (!doe_mb) { dev_dbg(dev, "No CDAT mailbox\n"); return; } =20 port->cdat_available =3D true; =20 - if (cxl_cdat_get_length(dev, cdat_doe, &cdat_length)) { + if (cxl_cdat_get_length(dev, doe_mb, &length)) { dev_dbg(dev, "No CDAT length\n"); return; } =20 - cdat_buf =3D devm_kzalloc(dev, cdat_length + sizeof(__le32), - GFP_KERNEL); - if (!cdat_buf) - return; + doe =3D devm_kzalloc(dev, sizeof(*doe) + length, GFP_KERNEL); + if (!doe) + goto err; =20 - rc =3D cxl_cdat_read_table(dev, cdat_doe, cdat_buf, &cdat_length); + rc =3D cxl_cdat_read_table(dev, doe_mb, doe, &length); if (rc) goto err; =20 - cdat_table =3D cdat_buf + sizeof(__le32); - if (cdat_checksum(cdat_table, cdat_length)) + if (cdat_checksum(doe->table, length)) goto err; =20 - port->cdat.table =3D cdat_table; - port->cdat.length =3D cdat_length; - return; + port->cdat.table =3D doe->table; + port->cdat.length =3D length; =20 + return; err: /* Don't leave table data allocated on error */ - devm_kfree(dev, cdat_buf); + devm_kfree(dev, doe); dev_err(dev, "Failed to read/validate CDAT.\n"); } EXPORT_SYMBOL_NS_GPL(read_cdat_data, CXL); diff --git a/drivers/cxl/cxlpci.h b/drivers/cxl/cxlpci.h index 0fa4799ea316..d12ed9d8dec1 100644 --- a/drivers/cxl/cxlpci.h +++ b/drivers/cxl/cxlpci.h @@ -85,6 +85,25 @@ struct cdat_entry_header { __le16 length; } __packed; =20 +/* + * Response contains the CDAT only response header of the DOE. The + * response payload is a CDAT structure (either CDAT header or entry), + * it may also mark the beginning of the CDAT table. + * + * Spec refs: + * + * CXL 3.1 Table 8-14: Read Entry Response + * CDAT Specification 1.03: 2 CDAT Data Structures + */ +struct cdat_doe { + __le32 doe_header; + union { + u8 table[0]; + struct cdat_header header[0]; + struct cdat_entry_header entry[0]; + }; +} __packed; + int devm_cxl_port_enumerate_dports(struct cxl_port *port); struct cxl_dev_state; int cxl_hdm_decode_init(struct cxl_dev_state *cxlds, struct cxl_hdm *cxlhd= m, --=20 2.39.2