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SubjectRe: [PATCH V10 6/9] cxl/port: Read CDAT table
On 22-06-04 17:50:46, ira.weiny@intel.com wrote:
> From: Jonathan Cameron <Jonathan.Cameron@huawei.com>
>
> The OS will need CDAT data from CXL devices to properly set up
> interleave sets. Currently this is supported through a DOE mailbox
> which supports CDAT.
>
> Cache the CDAT 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.
>
> Finally create a complete list of DOE defines within cdat.h for code
> wishing to decode the CDAT table.
>
> Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> Co-developed-by: Ira Weiny <ira.weiny@intel.com>
> Signed-off-by: Ira Weiny <ira.weiny@intel.com>
>
> ---
> Changes from V9:
> Add debugging output
> Jonathan Cameron
> Move read_cdat to port probe by using dev_groups for the
> sysfs attributes. This avoids issues with using devm
> before the driver is loaded while making sure the CDAT
> binary is available.
>
> Changes from V8:
> Fix length print format
> Incorporate feedback from Jonathan
> Move all this to cxl_port which can help support switches when
> the time comes.
>
> Changes from V6:
> Fix issue with devm use
> Move cached cdat data to cxl_dev_state
> Use new pci_doe_submit_task()
> Ensure the aux driver is locked while processing tasks
> Rebased on cxl-pending
>
> 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 | 99 ++++++++++++++++++++++++++++++
> drivers/cxl/core/pci.c | 136 ++++++++++++++++++++++++++++++++++++++++-
> drivers/cxl/cxl.h | 3 +
> drivers/cxl/cxlpci.h | 1 +
> drivers/cxl/port.c | 50 +++++++++++++++
> 5 files changed, 287 insertions(+), 2 deletions(-)
> 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..f5193a6a51fe
> --- /dev/null
> +++ b/drivers/cxl/cdat.h
> @@ -0,0 +1,99 @@
> +/* 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)
> +
> +#define CXL_DOE_PROTOCOL_TABLE_ACCESS 2
> +
> +/**
> + * 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/pci.c b/drivers/cxl/core/pci.c
> index d814d8317975..76fa8382b3c7 100644
> --- a/drivers/cxl/core/pci.c
> +++ b/drivers/cxl/core/pci.c
> @@ -9,8 +9,7 @@
> #include <cxlmem.h>
> #include <cxl.h>
> #include "core.h"
> -
> -#define CXL_DOE_PROTOCOL_TABLE_ACCESS 2
> +#include "cdat.h"
>
> /**
> * DOC: cxl core pci
> @@ -493,3 +492,136 @@ void cxl_cache_cdat_mb(struct cxl_port *port)
> }
> }
> EXPORT_SYMBOL_NS_GPL(cxl_cache_cdat_mb, CXL);
> +
> +#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 void cxl_doe_task_complete(struct pci_doe_task *task)
> +{
> + complete(task->private);
> +}
> +
> +static int cxl_cdat_get_length(struct cxl_port *port, size_t *length)
> +{
> + u32 cdat_request_pl = CDAT_DOE_REQ(0);
> + u32 cdat_response_pl[32];
> + DECLARE_COMPLETION_ONSTACK(c);
> + struct pci_doe_task task = {
> + .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),
> + .complete = cxl_doe_task_complete,
> + .private = &c,
> + };

This is looking like something that could be nicely populated with a macro.

> + int rc = 0;
> +
> + if (!port->cdat_mb) {
> + dev_err(&port->dev, "No CDAT mailbox\n");
> + return -EIO;
> + }

AIUI, !port->cdat_mb isn't actually an error. Does it make sense to simply
return 0 here?

> +
> + rc = pci_doe_submit_task(port->cdat_mb, &task);
> + if (rc < 0) {
> + dev_err(&port->dev, "DOE submit failed: %d", rc);
> + return rc;
> + }
> + wait_for_completion(&c);
> +
> + if (task.rv < 1)
> + return -EIO;
> +
> + *length = cdat_response_pl[1];
> + dev_dbg(&port->dev, "CDAT length %zu\n", *length);
> +
> + return rc;
> +}
> +
> +static int cxl_cdat_read_table(struct cxl_port *port,
> + struct cxl_cdat *cdat)
> +{
> + size_t length = cdat->length;
> + u32 *data = cdat->table;
> + int entry_handle = 0;
> + int rc = 0;
> +
> + if (!port->cdat_mb) {
> + dev_err(&port->dev, "No CDAT mailbox\n");
> + return -EIO;
> + }

Similar to above, maybe just return 0?

> +
> + do {
> + u32 cdat_request_pl = CDAT_DOE_REQ(entry_handle);
> + u32 cdat_response_pl[32];
> + DECLARE_COMPLETION_ONSTACK(c);
> + struct pci_doe_task task = {
> + .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),
> + .complete = cxl_doe_task_complete,
> + .private = &c,
> + };
> + size_t entry_dw;
> + u32 *entry;
> +
> + rc = pci_doe_submit_task(port->cdat_mb, &task);
> + if (rc < 0) {
> + dev_err(&port->dev, "DOE submit failed: %d", rc);
> + return rc;
> + }
> + wait_for_completion(&c);

I'd use the timeout variant, but if you don't want to, see below. I can't quite
tell if pci_doe_submit_task() is guaranteed to end with FLAG_DEAD at some
point...

> +
> + entry = cdat_response_pl + 1;
> + entry_dw = task.rv / 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]);

[0] looks suspicious...

> +
> + } while (entry_handle != 0xFFFF);
> +
> + return rc;
> +}
> +
> +void read_cdat_data(struct cxl_port *port)

I think you need kdoc here, specifically because you've opted not to do a
timed wait, which means its possible to wait forever.

> +{
> + struct device *dev = &port->dev;
> + size_t cdat_length;
> + int ret;
> +
> + if (cxl_cdat_get_length(port, &cdat_length))
> + return;
> +
> + port->cdat.table = devm_kzalloc(dev, cdat_length, GFP_KERNEL);
> + if (!port->cdat.table) {
> + ret = -ENOMEM;
> + goto error;
> + }
> +
> + port->cdat.length = cdat_length;
> + ret = cxl_cdat_read_table(port, &port->cdat);
> + if (ret) {
> + devm_kfree(dev, port->cdat.table);

Usually, when I see devm_kfree, it's a sign that it might not be a good
candidate for devm. You could consider plain kzalloc, and then putting the kfree
in the port destructor. I don't see anything incorrect though, so it's up to
you.

> + port->cdat.table = NULL;
> + port->cdat.length = 0;
> + ret = -EIO;
> + goto error;
> + }
> +
> + return;
> +error:
> + dev_err(dev, "CDAT data read error (%d)\n", ret);
> +}
> +EXPORT_SYMBOL_NS_GPL(read_cdat_data, CXL);
> diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
> index 0a86be589ffc..531b77d296c7 100644
> --- a/drivers/cxl/cxl.h
> +++ b/drivers/cxl/cxl.h
> @@ -8,6 +8,7 @@
> #include <linux/bitfield.h>
> #include <linux/bitops.h>
> #include <linux/io.h>
> +#include "cdat.h"
>
> /**
> * DOC: cxl objects
> @@ -268,6 +269,7 @@ struct cxl_nvdimm {
> * @dead: last ep has been removed, force port re-creation
> * @depth: How deep this port is relative to the root. depth 0 is the root.
> * @cdat_mb: Mailbox which supports the CDAT protocol
> + * @cdat: Cached CDAT data
> */
> struct cxl_port {
> struct device dev;
> @@ -280,6 +282,7 @@ struct cxl_port {
> bool dead;
> unsigned int depth;
> struct pci_doe_mb *cdat_mb;
> + struct cxl_cdat cdat;
> };
>
> /**
> diff --git a/drivers/cxl/cxlpci.h b/drivers/cxl/cxlpci.h
> index ddbb8b77752e..71009a167a92 100644
> --- a/drivers/cxl/cxlpci.h
> +++ b/drivers/cxl/cxlpci.h
> @@ -75,4 +75,5 @@ 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 *cxlhdm);
> void cxl_cache_cdat_mb(struct cxl_port *port);
> +void read_cdat_data(struct cxl_port *port);
> #endif /* __CXL_PCI_H__ */
> diff --git a/drivers/cxl/port.c b/drivers/cxl/port.c
> index 04f3d1fc6e07..fdff20cf79e6 100644
> --- a/drivers/cxl/port.c
> +++ b/drivers/cxl/port.c
> @@ -50,6 +50,8 @@ static int cxl_port_probe(struct device *dev)
> return PTR_ERR(cxlhdm);
>
> cxl_cache_cdat_mb(port);
> + /* Cache the data early to ensure is_visible() works */
> + read_cdat_data(port);
>
> if (is_cxl_endpoint(port)) {
> struct cxl_memdev *cxlmd = to_cxl_memdev(port->uport);
> @@ -80,10 +82,58 @@ static int cxl_port_probe(struct device *dev)
> return 0;
> }
>
> +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_port *port = to_cxl_port(dev);
> +
> + if (!port->cdat.table)
> + return 0;

With visibility setup below, do you need this?

> +
> + return memory_read_from_buffer(buf, count, &offset,
> + port->cdat.table,
> + port->cdat.length);
> +}
> +
> +static BIN_ATTR_RO(cdat, 0);
> +
> +static umode_t cxl_port_bin_attr_is_visible(struct kobject *kobj,
> + struct bin_attribute *attr, int i)
> +{
> + struct device *dev = kobj_to_dev(kobj);
> + struct cxl_port *port = to_cxl_port(dev);
> +
> + if ((attr == &bin_attr_cdat) && port->cdat.table)
> + return 0400;
> +
> + return 0;
> +}
> +
> +static struct bin_attribute *cxl_cdat_bin_attributes[] = {
> + &bin_attr_cdat,
> + NULL,
> +};
> +
> +static struct attribute_group cxl_cdat_attribute_group = {
> + .name = "CDAT",
> + .bin_attrs = cxl_cdat_bin_attributes,
> + .is_bin_visible = cxl_port_bin_attr_is_visible,
> +};
> +
> +static const struct attribute_group *cxl_port_attribute_groups[] = {
> + &cxl_cdat_attribute_group,
> + NULL,
> +};
> +
> static struct cxl_driver cxl_port_driver = {
> .name = "cxl_port",
> .probe = cxl_port_probe,
> .id = CXL_DEVICE_PORT,
> + .drv = {
> + .dev_groups = cxl_port_attribute_groups,
> + },
> };
>
> module_cxl_driver(cxl_port_driver);
> --
> 2.35.1
>

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