| Message ID | 165819557164.881384.15799533765517431824.stgit@dwillia2-xfh.jf.intel.com (mailing list archive) |
|---|---|
| State | Handled Elsewhere |
| Headers | show |
| Series | None | expand |
On Mon, 18 Jul 2022 18:55:01 -0700 Dan Williams <dan.j.williams@intel.com> wrote: > From: Ira Weiny <ira.weiny@intel.com> > > The per-device CDAT data provides performance data that is relevant for > mapping which CXL devices can participate in which CXL ranges by QTG > (QoS Throttling Group) (per ECN: CXL 2.0 CEDT CFMWS & QTG_DSM) [1]. The > QTG association specified in the ECN is advisory. Until the > cxl_acpi driver grows support for invoking the QTG _DSM method the CDAT > data is only of interest to userspace that may need it for debug > purposes. > > Search the DOE mailboxes available, query CDAT data, cache the data and > make it available via a sysfs binary attribute per endpoint at: > > /sys/bus/cxl/devices/endpointX/CDAT > > ...similar to other ACPI-structured table data in > /sys/firmware/ACPI/tables. The CDAT is relative to 'struct cxl_port' > objects since switches in addition to endpoints can host a CDAT > instance. Switch CDAT support is not implemented. > > This does not support table updates at runtime. It will always provide > whatever was there when first cached. It is also the case that table > updates are not expected outside of explicit DPA address map affecting > commands like Set Partition with the immediate flag set. Given that the > driver does not support Set Partition with the immediate flag set there > is no current need for update support. > > Link: https://www.computeexpresslink.org/spec-landing [1] > Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> > Co-developed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> > Signed-off-by: Ira Weiny <ira.weiny@intel.com> > [djbw: drop in-kernel parsing infra for now, and other minor fixups] > Signed-off-by: Dan Williams <dan.j.williams@intel.com> One comment inline that basically says the error message will do for now if we race with an autonomous update of CDAT by the device. (see response to earlier version on why that can happen). Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> > --- > diff --git a/drivers/cxl/core/pci.c b/drivers/cxl/core/pci.c > index 7672789c3225..9240df53ed87 100644 > --- a/drivers/cxl/core/pci.c > +++ b/drivers/cxl/core/pci.c > +/** > + * read_cdat_data - Read the CDAT data on this port > + * @port: Port to read data from > + * > + * This call will sleep waiting for responses from the DOE mailbox. > + */ > +void read_cdat_data(struct cxl_port *port) > +{ > + struct pci_doe_mb *cdat_doe; > + struct device *dev = &port->dev; > + struct device *uport = port->uport; > + size_t cdat_length; > + int rc; > + > + cdat_doe = find_cdat_doe(uport); > + if (!cdat_doe) { > + dev_dbg(dev, "No CDAT mailbox\n"); > + return; > + } > + > + port->cdat_available = true; > + > + if (cxl_cdat_get_length(dev, cdat_doe, &cdat_length)) { > + dev_dbg(dev, "No CDAT length\n"); > + return; > + } > + > + port->cdat.table = devm_kzalloc(dev, cdat_length, GFP_KERNEL); > + if (!port->cdat.table) > + return; > + > + port->cdat.length = cdat_length; > + rc = cxl_cdat_read_table(dev, cdat_doe, &port->cdat); > + if (rc) { > + /* Don't leave table data allocated on error */ > + devm_kfree(dev, port->cdat.table); > + port->cdat.table = NULL; > + port->cdat.length = 0; > + dev_err(dev, "CDAT data read error\n"); This will be sufficient for now for the race against autonomous CDAT update potential issue mentioned in earlier review. If it happens and someone really cares they can unbind and rebind the device. > + } > +} > +EXPORT_SYMBOL_NS_GPL(read_cdat_data, CXL); >
Jonathan Cameron wrote: > On Mon, 18 Jul 2022 18:55:01 -0700 > Dan Williams <dan.j.williams@intel.com> wrote: > > > From: Ira Weiny <ira.weiny@intel.com> > > > > The per-device CDAT data provides performance data that is relevant for > > mapping which CXL devices can participate in which CXL ranges by QTG > > (QoS Throttling Group) (per ECN: CXL 2.0 CEDT CFMWS & QTG_DSM) [1]. The > > QTG association specified in the ECN is advisory. Until the > > cxl_acpi driver grows support for invoking the QTG _DSM method the CDAT > > data is only of interest to userspace that may need it for debug > > purposes. > > > > Search the DOE mailboxes available, query CDAT data, cache the data and > > make it available via a sysfs binary attribute per endpoint at: > > > > /sys/bus/cxl/devices/endpointX/CDAT > > > > ...similar to other ACPI-structured table data in > > /sys/firmware/ACPI/tables. The CDAT is relative to 'struct cxl_port' > > objects since switches in addition to endpoints can host a CDAT > > instance. Switch CDAT support is not implemented. > > > > This does not support table updates at runtime. It will always provide > > whatever was there when first cached. It is also the case that table > > updates are not expected outside of explicit DPA address map affecting > > commands like Set Partition with the immediate flag set. Given that the > > driver does not support Set Partition with the immediate flag set there > > is no current need for update support. > > > > Link: https://www.computeexpresslink.org/spec-landing [1] > > Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> > > Co-developed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> > > Signed-off-by: Ira Weiny <ira.weiny@intel.com> > > [djbw: drop in-kernel parsing infra for now, and other minor fixups] > > Signed-off-by: Dan Williams <dan.j.williams@intel.com> > One comment inline that basically says the error message will do for now > if we race with an autonomous update of CDAT by the device. (see response > to earlier version on why that can happen). > > Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> > > --- > > diff --git a/drivers/cxl/core/pci.c b/drivers/cxl/core/pci.c > > index 7672789c3225..9240df53ed87 100644 > > --- a/drivers/cxl/core/pci.c > > +++ b/drivers/cxl/core/pci.c > > > > +/** > > + * read_cdat_data - Read the CDAT data on this port > > + * @port: Port to read data from > > + * > > + * This call will sleep waiting for responses from the DOE mailbox. > > + */ > > +void read_cdat_data(struct cxl_port *port) > > +{ > > + struct pci_doe_mb *cdat_doe; > > + struct device *dev = &port->dev; > > + struct device *uport = port->uport; > > + size_t cdat_length; > > + int rc; > > + > > + cdat_doe = find_cdat_doe(uport); > > + if (!cdat_doe) { > > + dev_dbg(dev, "No CDAT mailbox\n"); > > + return; > > + } > > + > > + port->cdat_available = true; > > + > > + if (cxl_cdat_get_length(dev, cdat_doe, &cdat_length)) { > > + dev_dbg(dev, "No CDAT length\n"); > > + return; > > + } > > + > > + port->cdat.table = devm_kzalloc(dev, cdat_length, GFP_KERNEL); > > + if (!port->cdat.table) > > + return; > > + > > + port->cdat.length = cdat_length; > > + rc = cxl_cdat_read_table(dev, cdat_doe, &port->cdat); > > + if (rc) { > > + /* Don't leave table data allocated on error */ > > + devm_kfree(dev, port->cdat.table); > > + port->cdat.table = NULL; > > + port->cdat.length = 0; > > + dev_err(dev, "CDAT data read error\n"); > > This will be sufficient for now for the race against autonomous CDAT > update potential issue mentioned in earlier review. If it happens > and someone really cares they can unbind and rebind the device. Even it is too late to change the spec, which I do not think it is, it is not too late to make a public statement that Linux has no interest in supporting such shenanigans outside of a documented set of explicit commands that have a CDAT-update side effect.
diff --git a/Documentation/ABI/testing/sysfs-bus-cxl b/Documentation/ABI/testing/sysfs-bus-cxl index 1fd5984b6158..e94c5aebc368 100644 --- a/Documentation/ABI/testing/sysfs-bus-cxl +++ b/Documentation/ABI/testing/sysfs-bus-cxl @@ -164,3 +164,13 @@ Description: expander memory (type-3). The 'target_type' attribute indicates the current setting which may dynamically change based on what memory regions are activated in this decode hierarchy. + +What: /sys/bus/cxl/devices/endpointX/CDAT +Date: July, 2022 +KernelVersion: v5.20 +Contact: linux-cxl@vger.kernel.org +Description: + (RO) If this sysfs entry is not present no DOE mailbox was + found to support CDAT data. If it is present and the length of + the data is 0 reading the CDAT data failed. Otherwise the CDAT + data is reported. diff --git a/drivers/cxl/core/pci.c b/drivers/cxl/core/pci.c index 7672789c3225..9240df53ed87 100644 --- a/drivers/cxl/core/pci.c +++ b/drivers/cxl/core/pci.c @@ -4,6 +4,7 @@ #include <linux/device.h> #include <linux/delay.h> #include <linux/pci.h> +#include <linux/pci-doe.h> #include <cxlpci.h> #include <cxlmem.h> #include <cxl.h> @@ -452,3 +453,175 @@ int cxl_hdm_decode_init(struct cxl_dev_state *cxlds, struct cxl_hdm *cxlhdm) return 0; } EXPORT_SYMBOL_NS_GPL(cxl_hdm_decode_init, CXL); + +#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 +#define CXL_DOE_TABLE_ACCESS_LAST_ENTRY 0xffff +#define CXL_DOE_PROTOCOL_TABLE_ACCESS 2 + +static struct pci_doe_mb *find_cdat_doe(struct device *uport) +{ + struct cxl_memdev *cxlmd; + struct cxl_dev_state *cxlds; + unsigned long index; + void *entry; + + cxlmd = to_cxl_memdev(uport); + cxlds = cxlmd->cxlds; + + xa_for_each(&cxlds->doe_mbs, index, entry) { + struct pci_doe_mb *cur = entry; + + if (pci_doe_supports_prot(cur, PCI_DVSEC_VENDOR_ID_CXL, + CXL_DOE_PROTOCOL_TABLE_ACCESS)) + return cur; + } + + return NULL; +} + +#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); +} + +struct cdat_doe_task { + u32 request_pl; + u32 response_pl[32]; + struct completion c; + struct pci_doe_task task; +}; + +#define DECLARE_CDAT_DOE_TASK(req, cdt) \ +struct cdat_doe_task cdt = { \ + .c = COMPLETION_INITIALIZER_ONSTACK(cdt.c), \ + .request_pl = req, \ + .task = { \ + .prot.vid = PCI_DVSEC_VENDOR_ID_CXL, \ + .prot.type = CXL_DOE_PROTOCOL_TABLE_ACCESS, \ + .request_pl = &cdt.request_pl, \ + .request_pl_sz = sizeof(cdt.request_pl), \ + .response_pl = cdt.response_pl, \ + .response_pl_sz = sizeof(cdt.response_pl), \ + .complete = cxl_doe_task_complete, \ + .private = &cdt.c, \ + } \ +} + +static int cxl_cdat_get_length(struct device *dev, + struct pci_doe_mb *cdat_doe, + size_t *length) +{ + DECLARE_CDAT_DOE_TASK(CDAT_DOE_REQ(0), t); + int rc; + + rc = pci_doe_submit_task(cdat_doe, &t.task); + if (rc < 0) { + dev_err(dev, "DOE submit failed: %d", rc); + return rc; + } + wait_for_completion(&t.c); + if (t.task.rv < sizeof(u32)) + return -EIO; + + *length = t.response_pl[1]; + dev_dbg(dev, "CDAT length %zu\n", *length); + + return 0; +} + +static int cxl_cdat_read_table(struct device *dev, + struct pci_doe_mb *cdat_doe, + struct cxl_cdat *cdat) +{ + size_t length = cdat->length; + u32 *data = cdat->table; + int entry_handle = 0; + + do { + DECLARE_CDAT_DOE_TASK(CDAT_DOE_REQ(entry_handle), t); + size_t entry_dw; + u32 *entry; + int rc; + + rc = pci_doe_submit_task(cdat_doe, &t.task); + if (rc < 0) { + dev_err(dev, "DOE submit failed: %d", rc); + return rc; + } + wait_for_completion(&t.c); + /* 1 DW header + 1 DW data min */ + if (t.task.rv < (2 * sizeof(u32))) + return -EIO; + + /* Get the CXL table access header entry handle */ + entry_handle = FIELD_GET(CXL_DOE_TABLE_ACCESS_ENTRY_HANDLE, + t.response_pl[0]); + entry = t.response_pl + 1; + entry_dw = t.task.rv / sizeof(u32); + /* Skip Header */ + entry_dw -= 1; + entry_dw = min(length / sizeof(u32), entry_dw); + /* Prevent length < 1 DW from causing a buffer overflow */ + if (entry_dw) { + memcpy(data, entry, entry_dw * sizeof(u32)); + length -= entry_dw * sizeof(u32); + data += entry_dw; + } + } while (entry_handle != CXL_DOE_TABLE_ACCESS_LAST_ENTRY); + + return 0; +} + +/** + * read_cdat_data - Read the CDAT data on this port + * @port: Port to read data from + * + * This call will sleep waiting for responses from the DOE mailbox. + */ +void read_cdat_data(struct cxl_port *port) +{ + struct pci_doe_mb *cdat_doe; + struct device *dev = &port->dev; + struct device *uport = port->uport; + size_t cdat_length; + int rc; + + cdat_doe = find_cdat_doe(uport); + if (!cdat_doe) { + dev_dbg(dev, "No CDAT mailbox\n"); + return; + } + + port->cdat_available = true; + + if (cxl_cdat_get_length(dev, cdat_doe, &cdat_length)) { + dev_dbg(dev, "No CDAT length\n"); + return; + } + + port->cdat.table = devm_kzalloc(dev, cdat_length, GFP_KERNEL); + if (!port->cdat.table) + return; + + port->cdat.length = cdat_length; + rc = cxl_cdat_read_table(dev, cdat_doe, &port->cdat); + if (rc) { + /* Don't leave table data allocated on error */ + devm_kfree(dev, port->cdat.table); + port->cdat.table = NULL; + port->cdat.length = 0; + dev_err(dev, "CDAT data read error\n"); + } +} +EXPORT_SYMBOL_NS_GPL(read_cdat_data, CXL); diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h index 570bd9f8141b..21a9d6fcc61e 100644 --- a/drivers/cxl/cxl.h +++ b/drivers/cxl/cxl.h @@ -289,6 +289,8 @@ struct cxl_nvdimm { * @component_reg_phys: component register capability base address (optional) * @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: Cached CDAT data + * @cdat_available: Should a CDAT attribute be available in sysfs */ struct cxl_port { struct device dev; @@ -301,6 +303,11 @@ struct cxl_port { resource_size_t component_reg_phys; bool dead; unsigned int depth; + struct cxl_cdat { + void *table; + size_t length; + } cdat; + bool cdat_available; }; /** diff --git a/drivers/cxl/cxlpci.h b/drivers/cxl/cxlpci.h index fce1c11729c2..eec597dbe763 100644 --- a/drivers/cxl/cxlpci.h +++ b/drivers/cxl/cxlpci.h @@ -74,4 +74,5 @@ static inline resource_size_t cxl_regmap_to_base(struct pci_dev *pdev, 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 read_cdat_data(struct cxl_port *port); #endif /* __CXL_PCI_H__ */ diff --git a/drivers/cxl/port.c b/drivers/cxl/port.c index 3cf308f114c4..5453771bf330 100644 --- a/drivers/cxl/port.c +++ b/drivers/cxl/port.c @@ -53,6 +53,9 @@ static int cxl_port_probe(struct device *dev) struct cxl_memdev *cxlmd = to_cxl_memdev(port->uport); struct cxl_dev_state *cxlds = cxlmd->cxlds; + /* Cache the data early to ensure is_visible() works */ + read_cdat_data(port); + get_device(&cxlmd->dev); rc = devm_add_action_or_reset(dev, schedule_detach, cxlmd); if (rc) @@ -78,10 +81,60 @@ 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_available) + return -ENXIO; + + if (!port->cdat.table) + return 0; + + return memory_read_from_buffer(buf, count, &offset, + port->cdat.table, + port->cdat.length); +} + +static BIN_ATTR_ADMIN_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_available) + return attr->attr.mode; + + return 0; +} + +static struct bin_attribute *cxl_cdat_bin_attributes[] = { + &bin_attr_CDAT, + NULL, +}; + +static struct attribute_group cxl_cdat_attribute_group = { + .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);