Re: [PATCH V6 07/10] cxl/mem: Read CDAT table

Jonathan Cameron
2022-02-04T13:47:03Z

On Mon, 31 Jan 2022 23:19:49 -0800
ira.weiny@intel.com wrote:

> From: Jonathan Cameron <Jonathan.Cameron@huawei.com>
>
> The OS will need CDAT data from the CXL devices to properly set up
> interleave sets.
>
> Search the DOE driver/devices attached to the CXL device for one which
> supports the CDAT protocol. If found, read the CDAT data from that
> mailbox.
>
> Currently this is only supported by a PCI CXL object through a DOE
> mailbox which supports CDAT. But any cxl_mem type object can provide
> this data later if need be. For example for testing.
>
> Cache this data for later parsing. Provide a sysfs binary attribute to
> allow dumping of the CDAT.
>
> Binary dumping is modeled on /sys/firmware/ACPI/tables/
>
> The ability to dump this table will be very useful for emulation of real
> devices once they become available as QEMU CXL type 3 device emulation will
> be able to load this file in.
>
> This does not support table updates at runtime. It will always provide
> whatever was there when first cached. Handling of table updates can be
> implemented later.
>
> Once there are more users, this code can move out to driver/cxl/cdat.c
> or similar.
>
> Finally create a complete list of DOE defines within cdat.h for anyone
> wishing to decode the CDAT table.
>
> Co-developed-by: Ira Weiny <ira.weiny@intel.com>
> Signed-off-by: Ira Weiny <ira.weiny@intel.com>
> Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
>
Changes look fine to me.

Thanks,

Jonathan

> ---
> Changes from V5:
> Add proper guards around cdat.h
> Split out finding the CDAT DOE mailbox
> Use cxl_cdat to group CDAT data together
> Adjust to use auxiliary_find_device() to find the DOE device
> which supplies the CDAT protocol.
> Rebased to latest
> Remove dev_dbg(length)
> Remove unneeded DOE Table access defines
> Move CXL_DOE_PROTOCOL_TABLE_ACCESS define into this patch where
> it is used
>
> Changes from V4:
> Split this into it's own patch
> Rearchitect this such that the memdev driver calls into the DOE
> driver via the cxl_mem state object. This allows CDAT data to
> come from any type of cxl_mem object not just PCI DOE.
> Rebase on new struct cxl_dev_state
> ---
> drivers/cxl/cdat.h | 97 +++++++++++++++++++++++++++++++++++++++
> drivers/cxl/core/memdev.c | 56 ++++++++++++++++++++++
> drivers/cxl/cxlmem.h | 25 ++++++++++
> drivers/cxl/pci.c | 87 +++++++++++++++++++++++++++++++++++
> 4 files changed, 265 insertions(+)
> create mode 100644 drivers/cxl/cdat.h
>
> diff --git a/drivers/cxl/cdat.h b/drivers/cxl/cdat.h
> new file mode 100644
> index 000000000000..4722b6bbbaf0
> --- /dev/null
> +++ b/drivers/cxl/cdat.h
> @@ -0,0 +1,97 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef __CXL_CDAT_H__
> +#define __CXL_CDAT_H__
> +
> +/*
> + * Coherent Device Attribute table (CDAT)
> + *
> + * Specification available from UEFI.org
> + *
> + * Whilst CDAT is defined as a single table, the access via DOE maiboxes is
> + * done one entry at a time, where the first entry is the header.
> + */
> +
> +#define CXL_DOE_TABLE_ACCESS_REQ_CODE 0x000000ff
> +#define CXL_DOE_TABLE_ACCESS_REQ_CODE_READ 0
> +#define CXL_DOE_TABLE_ACCESS_TABLE_TYPE 0x0000ff00
> +#define CXL_DOE_TABLE_ACCESS_TABLE_TYPE_CDATA 0
> +#define CXL_DOE_TABLE_ACCESS_ENTRY_HANDLE 0xffff0000
> +
> +/*
> + * CDAT entries are little endian and are read from PCI config space which
> + * is also little endian.
> + * As such, on a big endian system these will have been reversed.
> + * This prevents us from making easy use of packed structures.
> + * Style form pci_regs.h
> + */
> +
> +#define CDAT_HEADER_LENGTH_DW 4
> +#define CDAT_HEADER_LENGTH_BYTES (CDAT_HEADER_LENGTH_DW * sizeof(u32))
> +#define CDAT_HEADER_DW0_LENGTH 0xffffffff
> +#define CDAT_HEADER_DW1_REVISION 0x000000ff
> +#define CDAT_HEADER_DW1_CHECKSUM 0x0000ff00
> +/* CDAT_HEADER_DW2_RESERVED */
> +#define CDAT_HEADER_DW3_SEQUENCE 0xffffffff
> +
> +/* All structures have a common first DW */
> +#define CDAT_STRUCTURE_DW0_TYPE 0x000000ff
> +#define CDAT_STRUCTURE_DW0_TYPE_DSMAS 0
> +#define CDAT_STRUCTURE_DW0_TYPE_DSLBIS 1
> +#define CDAT_STRUCTURE_DW0_TYPE_DSMSCIS 2
> +#define CDAT_STRUCTURE_DW0_TYPE_DSIS 3
> +#define CDAT_STRUCTURE_DW0_TYPE_DSEMTS 4
> +#define CDAT_STRUCTURE_DW0_TYPE_SSLBIS 5
> +
> +#define CDAT_STRUCTURE_DW0_LENGTH 0xffff0000
> +
> +/* Device Scoped Memory Affinity Structure */
> +#define CDAT_DSMAS_DW1_DSMAD_HANDLE 0x000000ff
> +#define CDAT_DSMAS_DW1_FLAGS 0x0000ff00
> +#define CDAT_DSMAS_DPA_OFFSET(entry) ((u64)((entry)[3]) << 32 | (entry)[2])
> +#define CDAT_DSMAS_DPA_LEN(entry) ((u64)((entry)[5]) << 32 | (entry)[4])
> +#define CDAT_DSMAS_NON_VOLATILE(flags) ((flags & 0x04) >> 2)
> +
> +/* Device Scoped Latency and Bandwidth Information Structure */
> +#define CDAT_DSLBIS_DW1_HANDLE 0x000000ff
> +#define CDAT_DSLBIS_DW1_FLAGS 0x0000ff00
> +#define CDAT_DSLBIS_DW1_DATA_TYPE 0x00ff0000
> +#define CDAT_DSLBIS_BASE_UNIT(entry) ((u64)((entry)[3]) << 32 | (entry)[2])
> +#define CDAT_DSLBIS_DW4_ENTRY_0 0x0000ffff
> +#define CDAT_DSLBIS_DW4_ENTRY_1 0xffff0000
> +#define CDAT_DSLBIS_DW5_ENTRY_2 0x0000ffff
> +
> +/* Device Scoped Memory Side Cache Information Structure */
> +#define CDAT_DSMSCIS_DW1_HANDLE 0x000000ff
> +#define CDAT_DSMSCIS_MEMORY_SIDE_CACHE_SIZE(entry) \
> + ((u64)((entry)[3]) << 32 | (entry)[2])
> +#define CDAT_DSMSCIS_DW4_MEMORY_SIDE_CACHE_ATTRS 0xffffffff
> +
> +/* Device Scoped Initiator Structure */
> +#define CDAT_DSIS_DW1_FLAGS 0x000000ff
> +#define CDAT_DSIS_DW1_HANDLE 0x0000ff00
> +
> +/* Device Scoped EFI Memory Type Structure */
> +#define CDAT_DSEMTS_DW1_HANDLE 0x000000ff
> +#define CDAT_DSEMTS_DW1_EFI_MEMORY_TYPE_ATTR 0x0000ff00
> +#define CDAT_DSEMTS_DPA_OFFSET(entry) ((u64)((entry)[3]) << 32 | (entry)[2])
> +#define CDAT_DSEMTS_DPA_LENGTH(entry) ((u64)((entry)[5]) << 32 | (entry)[4])
> +
> +/* Switch Scoped Latency and Bandwidth Information Structure */
> +#define CDAT_SSLBIS_DW1_DATA_TYPE 0x000000ff
> +#define CDAT_SSLBIS_BASE_UNIT(entry) ((u64)((entry)[3]) << 32 | (entry)[2])
> +#define CDAT_SSLBIS_ENTRY_PORT_X(entry, i) ((entry)[4 + (i) * 2] & 0x0000ffff)
> +#define CDAT_SSLBIS_ENTRY_PORT_Y(entry, i) (((entry)[4 + (i) * 2] & 0xffff0000) >> 16)
> +#define CDAT_SSLBIS_ENTRY_LAT_OR_BW(entry, i) ((entry)[4 + (i) * 2 + 1] & 0x0000ffff)
> +
> +/**
> + * struct cxl_cdat - CXL CDAT data
> + *
> + * @table: cache of CDAT table
> + * @length: length of cached CDAT table
> + */
> +struct cxl_cdat {
> + void *table;
> + size_t length;
> +};
> +
> +#endif /* !__CXL_CDAT_H__ */
> diff --git a/drivers/cxl/core/memdev.c b/drivers/cxl/core/memdev.c
> index ee0156419d06..a01068e98333 100644
> --- a/drivers/cxl/core/memdev.c
> +++ b/drivers/cxl/core/memdev.c
> @@ -86,6 +86,35 @@ static ssize_t pmem_size_show(struct device *dev, struct device_attribute *attr,
> return sysfs_emit(buf, "%#llx\n", len);
> }
>
> +static ssize_t CDAT_read(struct file *filp, struct kobject *kobj,
> + struct bin_attribute *bin_attr, char *buf,
> + loff_t offset, size_t count)
> +{
> + struct device *dev = kobj_to_dev(kobj);
> + struct cxl_memdev *cxlmd = to_cxl_memdev(dev);
> +
> + if (!cxlmd->cdat.table)
> + return 0;
> +
> + return memory_read_from_buffer(buf, count, &offset,
> + cxlmd->cdat.table,
> + cxlmd->cdat.length);
> +}
> +
> +static BIN_ATTR_RO(CDAT, 0);
> +
> +static umode_t cxl_memdev_bin_attr_is_visible(struct kobject *kobj,
> + struct bin_attribute *attr, int i)
> +{
> + struct device *dev = kobj_to_dev(kobj);
> + struct cxl_memdev *cxlmd = to_cxl_memdev(dev);
> +
> + if ((attr == &bin_attr_CDAT) && cxlmd->cdat.table)
> + return 0400;
> +
> + return 0;
> +}
> +
> static struct device_attribute dev_attr_pmem_size =
> __ATTR(size, 0444, pmem_size_show, NULL);
>
> @@ -115,6 +144,11 @@ static struct attribute *cxl_memdev_attributes[] = {
> NULL,
> };
>
> +static struct bin_attribute *cxl_memdev_bin_attributes[] = {
> + &bin_attr_CDAT,
> + NULL,
> +};
> +
> static struct attribute *cxl_memdev_pmem_attributes[] = {
> &dev_attr_pmem_size.attr,
> NULL,
> @@ -136,6 +170,8 @@ static umode_t cxl_memdev_visible(struct kobject *kobj, struct attribute *a,
> static struct attribute_group cxl_memdev_attribute_group = {
> .attrs = cxl_memdev_attributes,
> .is_visible = cxl_memdev_visible,
> + .bin_attrs = cxl_memdev_bin_attributes,
> + .is_bin_visible = cxl_memdev_bin_attr_is_visible,
> };
>
> static struct attribute_group cxl_memdev_ram_attribute_group = {
> @@ -320,6 +356,21 @@ static const struct file_operations cxl_memdev_fops = {
> .llseek = noop_llseek,
> };
>
> +static int read_cdat_data(struct cxl_memdev *cxlmd, struct cxl_dev_state *cxlds)
> +{
> + struct device *dev = &cxlmd->dev;
> + size_t cdat_length;
> +
> + if (cxl_mem_cdat_get_length(cxlds, &cdat_length))
> + return 0;
> +
> + cxlmd->cdat.table = devm_kzalloc(dev, cdat_length, GFP_KERNEL);
> + if (!cxlmd->cdat.table)
> + return -ENOMEM;
> + cxlmd->cdat.length = cdat_length;
> + return cxl_mem_cdat_read_table(cxlds, &cxlmd->cdat);
> +}
> +
> struct cxl_memdev *devm_cxl_add_memdev(struct cxl_dev_state *cxlds)
> {
> struct cxl_memdev *cxlmd;
> @@ -336,6 +387,11 @@ struct cxl_memdev *devm_cxl_add_memdev(struct cxl_dev_state *cxlds)
> if (rc)
> goto err;
>
> + /* Cache the data early to ensure is_visible() works */
> + rc = read_cdat_data(cxlmd, cxlds);
> + if (rc)
> + goto err;
> +
> /*
> * Activate ioctl operations, no cxl_memdev_rwsem manipulation
> * needed as this is ordered with cdev_add() publishing the device.
> diff --git a/drivers/cxl/cxlmem.h b/drivers/cxl/cxlmem.h
> index 0fefe43951e3..15c653b20f37 100644
> --- a/drivers/cxl/cxlmem.h
> +++ b/drivers/cxl/cxlmem.h
> @@ -5,6 +5,7 @@
> #include <uapi/linux/cxl_mem.h>
> #include <linux/cdev.h>
> #include "cxl.h"
> +#include "cdat.h"
>
> /* CXL 2.0 8.2.8.5.1.1 Memory Device Status Register */
> #define CXLMDEV_STATUS_OFFSET 0x0
> @@ -41,6 +42,7 @@ struct cxl_memdev {
> struct device dev;
> struct cdev cdev;
> struct cxl_dev_state *cxlds;
> + struct cxl_cdat cdat;
> struct work_struct detach_work;
> int id;
> };
> @@ -143,6 +145,10 @@ struct cxl_endpoint_dvsec_info {
> * @serial: PCIe Device Serial Number
> * @mbox_send: @dev specific transport for transmitting mailbox commands
> * @wait_media_ready: @dev specific method to await media ready
> + * @cdat_get_length: @dev specific function for reading the CDAT table length
> + * returns -errno if CDAT not supported on this device
> + * @cdat_read_table: @dev specific function for reading the table
> + * returns -errno if CDAT not supported on this device
> *
> * See section 8.2.9.5.2 Capacity Configuration and Label Storage for
> * details on capacity parameters.
> @@ -179,6 +185,9 @@ struct cxl_dev_state {
>
> int (*mbox_send)(struct cxl_dev_state *cxlds, struct cxl_mbox_cmd *cmd);
> int (*wait_media_ready)(struct cxl_dev_state *cxlds);
> + int (*cdat_get_length)(struct cxl_dev_state *cxlds, size_t *length);
> + int (*cdat_read_table)(struct cxl_dev_state *cxlds,
> + struct cxl_cdat *cdat);
> };
>
> enum cxl_opcode {
> @@ -305,4 +314,20 @@ struct cxl_hdm {
> unsigned int interleave_mask;
> struct cxl_port *port;
> };
> +
> +static inline int cxl_mem_cdat_get_length(struct cxl_dev_state *cxlds, size_t *length)
> +{
> + if (cxlds->cdat_get_length)
> + return cxlds->cdat_get_length(cxlds, length);
> + return -EOPNOTSUPP;
> +}
> +
> +static inline int cxl_mem_cdat_read_table(struct cxl_dev_state *cxlds,
> + struct cxl_cdat *cdat)
> +{
> + if (cxlds->cdat_read_table)
> + return cxlds->cdat_read_table(cxlds, cdat);
> + return -EOPNOTSUPP;
> +}
> +
> #endif /* __CXL_MEM_H__ */
> diff --git a/drivers/cxl/pci.c b/drivers/cxl/pci.c
> index dcc55c4efd85..28b973a9e29e 100644
> --- a/drivers/cxl/pci.c
> +++ b/drivers/cxl/pci.c
> @@ -13,6 +13,7 @@
> #include "cxlmem.h"
> #include "cxlpci.h"
> #include "cxl.h"
> +#include "cdat.h"
>
> /**
> * DOC: cxl pci
> @@ -585,6 +586,90 @@ static int cxl_setup_doe_devices(struct cxl_dev_state *cxlds)
> return 0;
> }
>
> +#define CDAT_DOE_REQ(entry_handle) \
> + (FIELD_PREP(CXL_DOE_TABLE_ACCESS_REQ_CODE, \
> + CXL_DOE_TABLE_ACCESS_REQ_CODE_READ) | \
> + FIELD_PREP(CXL_DOE_TABLE_ACCESS_TABLE_TYPE, \
> + CXL_DOE_TABLE_ACCESS_TABLE_TYPE_CDATA) | \
> + FIELD_PREP(CXL_DOE_TABLE_ACCESS_ENTRY_HANDLE, (entry_handle)))
> +
> +static int cxl_cdat_get_length(struct cxl_dev_state *cxlds, size_t *length)
> +{
> + struct pci_doe_dev *doe_dev = cxlds->cdat_doe;
> + u32 cdat_request_pl = CDAT_DOE_REQ(0);
> + u32 cdat_response_pl[32];
> + struct pci_doe_exchange ex = {
> + .prot.vid = PCI_DVSEC_VENDOR_ID_CXL,
> + .prot.type = CXL_DOE_PROTOCOL_TABLE_ACCESS,
> + .request_pl = &cdat_request_pl,
> + .request_pl_sz = sizeof(cdat_request_pl),
> + .response_pl = cdat_response_pl,
> + .response_pl_sz = sizeof(cdat_response_pl),
> + };
> +
> + ssize_t rc;
> +
> + rc = pci_doe_exchange_sync(doe_dev, &ex);
> + if (rc < 0)
> + return rc;
> + if (rc < 1)
> + return -EIO;
> +
> + *length = cdat_response_pl[1];
> + return 0;
> +}
> +
> +static int cxl_cdat_read_table(struct cxl_dev_state *cxlds,
> + struct cxl_cdat *cdat)
> +{
> + struct pci_doe_dev *doe_dev = cxlds->cdat_doe;
> + size_t length = cdat->length;
> + u32 *data = cdat->table;
> + int entry_handle = 0;
> + int rc;
> +
> + do {
> + u32 cdat_request_pl = CDAT_DOE_REQ(entry_handle);
> + u32 cdat_response_pl[32];
> + struct pci_doe_exchange ex = {
> + .prot.vid = PCI_DVSEC_VENDOR_ID_CXL,
> + .prot.type = CXL_DOE_PROTOCOL_TABLE_ACCESS,
> + .request_pl = &cdat_request_pl,
> + .request_pl_sz = sizeof(cdat_request_pl),
> + .response_pl = cdat_response_pl,
> + .response_pl_sz = sizeof(cdat_response_pl),
> + };
> + size_t entry_dw;
> + u32 *entry;
> +
> + rc = pci_doe_exchange_sync(doe_dev, &ex);
> + if (rc < 0)
> + return rc;
> +
> + entry = cdat_response_pl + 1;
> + entry_dw = rc / sizeof(u32);
> + /* Skip Header */
> + entry_dw -= 1;
> + entry_dw = min(length / 4, entry_dw);
> + memcpy(data, entry, entry_dw * sizeof(u32));
> + length -= entry_dw * sizeof(u32);
> + data += entry_dw;
> + entry_handle = FIELD_GET(CXL_DOE_TABLE_ACCESS_ENTRY_HANDLE, cdat_response_pl[0]);
> +
> + } while (entry_handle != 0xFFFF);
> +
> + return 0;
> +}
> +
> +static void cxl_initialize_cdat_callbacks(struct cxl_dev_state *cxlds)
> +{
> + if (!cxlds->cdat_doe)
> + return;
> +
> + cxlds->cdat_get_length = cxl_cdat_get_length;
> + cxlds->cdat_read_table = cxl_cdat_read_table;
> +}
> +
> static int cxl_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
> {
> struct cxl_register_map map;
> @@ -657,6 +742,8 @@ static int cxl_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
> if (rc)
> return rc;
>
> + cxl_initialize_cdat_callbacks(cxlds);
> +
> rc = cxl_dvsec_ranges(cxlds);
> if (rc)
> dev_err(&pdev->dev,