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authorLukas Wunner <lukas@wunner.de>2023-03-11 17:40:01 +0300
committerDan Williams <dan.j.williams@intel.com>2023-03-21 22:27:08 +0300
commitfbaa38214cd9e150764ccaa82e04ecf42cc1140c (patch)
tree740bead46ae1b468da5ec7629794f658fa685f85 /include
parente8d018dd0257f744ca50a729e3d042cf2ec9da65 (diff)
downloadlinux-fbaa38214cd9e150764ccaa82e04ecf42cc1140c.tar.xz
cxl/pci: Fix CDAT retrieval on big endian
The CDAT exposed in sysfs differs between little endian and big endian arches: On big endian, every 4 bytes are byte-swapped. PCI Configuration Space is little endian (PCI r3.0 sec 6.1). Accessors such as pci_read_config_dword() implicitly swap bytes on big endian. That way, the macros in include/uapi/linux/pci_regs.h work regardless of the arch's endianness. For an example of implicit byte-swapping, see ppc4xx_pciex_read_config(), which calls in_le32(), which uses lwbrx (Load Word Byte-Reverse Indexed). DOE Read/Write Data Mailbox Registers are unlike other registers in Configuration Space in that they contain or receive a 4 byte portion of an opaque byte stream (a "Data Object" per PCIe r6.0 sec 7.9.24.5f). They need to be copied to or from the request/response buffer verbatim. So amend pci_doe_send_req() and pci_doe_recv_resp() to undo the implicit byte-swapping. The CXL_DOE_TABLE_ACCESS_* and PCI_DOE_DATA_OBJECT_DISC_* macros assume implicit byte-swapping. Byte-swap requests after constructing them with those macros and byte-swap responses before parsing them. Change the request and response type to __le32 to avoid sparse warnings. Per a request from Jonathan, replace sizeof(u32) with sizeof(__le32) for consistency. Fixes: c97006046c79 ("cxl/port: Read CDAT table") Tested-by: Ira Weiny <ira.weiny@intel.com> Signed-off-by: Lukas Wunner <lukas@wunner.de> Reviewed-by: Dan Williams <dan.j.williams@intel.com> Cc: stable@vger.kernel.org # v6.0+ Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> Link: https://lore.kernel.org/r/3051114102f41d19df3debbee123129118fc5e6d.1678543498.git.lukas@wunner.de Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Diffstat (limited to 'include')
-rw-r--r--include/linux/pci-doe.h8
1 files changed, 6 insertions, 2 deletions
diff --git a/include/linux/pci-doe.h b/include/linux/pci-doe.h
index ed9b4df792b8..43765eaf2342 100644
--- a/include/linux/pci-doe.h
+++ b/include/linux/pci-doe.h
@@ -34,6 +34,10 @@ struct pci_doe_mb;
* @work: Used internally by the mailbox
* @doe_mb: Used internally by the mailbox
*
+ * Payloads are treated as opaque byte streams which are transmitted verbatim,
+ * without byte-swapping. If payloads contain little-endian register values,
+ * the caller is responsible for conversion with cpu_to_le32() / le32_to_cpu().
+ *
* The payload sizes and rv are specified in bytes with the following
* restrictions concerning the protocol.
*
@@ -45,9 +49,9 @@ struct pci_doe_mb;
*/
struct pci_doe_task {
struct pci_doe_protocol prot;
- u32 *request_pl;
+ __le32 *request_pl;
size_t request_pl_sz;
- u32 *response_pl;
+ __le32 *response_pl;
size_t response_pl_sz;
int rv;
void (*complete)(struct pci_doe_task *task);