cxl fixes for v6.4-rc4

- Stop trusting capacity data before the "media ready" indication
 
 - Add missing HDM decoder capability enable for the cold-plug case
 
 - Fix a debug message induced crash
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Merge tag 'cxl-fixes-6.4-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/cxl/cxl

Pull compute express link fixes from Dan Williams:
 "The 'media ready' series prevents the driver from acting on bad
  capacity information, and it moves some checks earlier in the init
  sequence which impacts topics in the queue for 6.5.

  Additional hotplug testing uncovered a missing enable for memory
  decode. A debug crash fix is also included.

  Summary:

   - Stop trusting capacity data before the "media ready" indication

   - Add missing HDM decoder capability enable for the cold-plug case

   - Fix a debug message induced crash"

* tag 'cxl-fixes-6.4-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/cxl/cxl:
  cxl: Explicitly initialize resources when media is not ready
  cxl/port: Fix NULL pointer access in devm_cxl_add_port()
  cxl: Move cxl_await_media_ready() to before capacity info retrieval
  cxl: Wait Memory_Info_Valid before access memory related info
  cxl/port: Enable the HDM decoder capability for switch ports

drivers/cxl/core/mbox.c

@@ -1028,7 +1028,7 @@ static int cxl_mem_get_partition_info(struct cxl_dev_state *cxlds)
  * cxl_dev_state_identify() - Send the IDENTIFY command to the device.
  * @cxlds: The device data for the operation
  *
- * Return: 0 if identify was executed successfully.
+ * Return: 0 if identify was executed successfully or media not ready.
  *
  * This will dispatch the identify command to the device and on success populate
  * structures to be exported to sysfs.
@@ -1041,6 +1041,9 @@ int cxl_dev_state_identify(struct cxl_dev_state *cxlds)
 	u32 val;
 	int rc;
 
+	if (!cxlds->media_ready)
+		return 0;
+
 	mbox_cmd = (struct cxl_mbox_cmd) {
 		.opcode = CXL_MBOX_OP_IDENTIFY,
 		.size_out = sizeof(id),
@@ -1102,6 +1105,13 @@ int cxl_mem_create_range_info(struct cxl_dev_state *cxlds)
 	struct device *dev = cxlds->dev;
 	int rc;
 
+	if (!cxlds->media_ready) {
+		cxlds->dpa_res = DEFINE_RES_MEM(0, 0);
+		cxlds->ram_res = DEFINE_RES_MEM(0, 0);
+		cxlds->pmem_res = DEFINE_RES_MEM(0, 0);
+		return 0;
+	}
+
 	cxlds->dpa_res =
 		(struct resource)DEFINE_RES_MEM(0, cxlds->total_bytes);
 

drivers/cxl/core/pci.c

@@ -101,23 +101,57 @@ int devm_cxl_port_enumerate_dports(struct cxl_port *port)
 }
 EXPORT_SYMBOL_NS_GPL(devm_cxl_port_enumerate_dports, CXL);
 
-/*
- * Wait up to @media_ready_timeout for the device to report memory
- * active.
- */
-int cxl_await_media_ready(struct cxl_dev_state *cxlds)
+static int cxl_dvsec_mem_range_valid(struct cxl_dev_state *cxlds, int id)
+{
+	struct pci_dev *pdev = to_pci_dev(cxlds->dev);
+	int d = cxlds->cxl_dvsec;
+	bool valid = false;
+	int rc, i;
+	u32 temp;
+
+	if (id > CXL_DVSEC_RANGE_MAX)
+		return -EINVAL;
+
+	/* Check MEM INFO VALID bit first, give up after 1s */
+	i = 1;
+	do {
+		rc = pci_read_config_dword(pdev,
+					   d + CXL_DVSEC_RANGE_SIZE_LOW(id),
+					   &temp);
+		if (rc)
+			return rc;
+
+		valid = FIELD_GET(CXL_DVSEC_MEM_INFO_VALID, temp);
+		if (valid)
+			break;
+		msleep(1000);
+	} while (i--);
+
+	if (!valid) {
+		dev_err(&pdev->dev,
+			"Timeout awaiting memory range %d valid after 1s.\n",
+			id);
+		return -ETIMEDOUT;
+	}
+
+	return 0;
+}
+
+static int cxl_dvsec_mem_range_active(struct cxl_dev_state *cxlds, int id)
 {
 	struct pci_dev *pdev = to_pci_dev(cxlds->dev);
 	int d = cxlds->cxl_dvsec;
 	bool active = false;
-	u64 md_status;
 	int rc, i;
+	u32 temp;
 
+	if (id > CXL_DVSEC_RANGE_MAX)
+		return -EINVAL;
+
+	/* Check MEM ACTIVE bit, up to 60s timeout by default */
 	for (i = media_ready_timeout; i; i--) {
-		u32 temp;
-
 		rc = pci_read_config_dword(
-			pdev, d + CXL_DVSEC_RANGE_SIZE_LOW(0), &temp);
+			pdev, d + CXL_DVSEC_RANGE_SIZE_LOW(id), &temp);
 		if (rc)
 			return rc;
 
@@ -134,6 +168,39 @@ int cxl_await_media_ready(struct cxl_dev_state *cxlds)
 		return -ETIMEDOUT;
 	}
 
+	return 0;
+}
+
+/*
+ * Wait up to @media_ready_timeout for the device to report memory
+ * active.
+ */
+int cxl_await_media_ready(struct cxl_dev_state *cxlds)
+{
+	struct pci_dev *pdev = to_pci_dev(cxlds->dev);
+	int d = cxlds->cxl_dvsec;
+	int rc, i, hdm_count;
+	u64 md_status;
+	u16 cap;
+
+	rc = pci_read_config_word(pdev,
+				  d + CXL_DVSEC_CAP_OFFSET, &cap);
+	if (rc)
+		return rc;
+
+	hdm_count = FIELD_GET(CXL_DVSEC_HDM_COUNT_MASK, cap);
+	for (i = 0; i < hdm_count; i++) {
+		rc = cxl_dvsec_mem_range_valid(cxlds, i);
+		if (rc)
+			return rc;
+	}
+
+	for (i = 0; i < hdm_count; i++) {
+		rc = cxl_dvsec_mem_range_active(cxlds, i);
+		if (rc)
+			return rc;
+	}
+
 	md_status = readq(cxlds->regs.memdev + CXLMDEV_STATUS_OFFSET);
 	if (!CXLMDEV_READY(md_status))
 		return -EIO;
@@ -241,17 +308,36 @@ static void disable_hdm(void *_cxlhdm)
 	       hdm + CXL_HDM_DECODER_CTRL_OFFSET);
 }
 
-static int devm_cxl_enable_hdm(struct device *host, struct cxl_hdm *cxlhdm)
+int devm_cxl_enable_hdm(struct cxl_port *port, struct cxl_hdm *cxlhdm)
 {
-	void __iomem *hdm = cxlhdm->regs.hdm_decoder;
+	void __iomem *hdm;
 	u32 global_ctrl;
 
+	/*
+	 * If the hdm capability was not mapped there is nothing to enable and
+	 * the caller is responsible for what happens next.  For example,
+	 * emulate a passthrough decoder.
+	 */
+	if (IS_ERR(cxlhdm))
+		return 0;
+
+	hdm = cxlhdm->regs.hdm_decoder;
 	global_ctrl = readl(hdm + CXL_HDM_DECODER_CTRL_OFFSET);
+
+	/*
+	 * If the HDM decoder capability was enabled on entry, skip
+	 * registering disable_hdm() since this decode capability may be
+	 * owned by platform firmware.
+	 */
+	if (global_ctrl & CXL_HDM_DECODER_ENABLE)
+		return 0;
+
 	writel(global_ctrl | CXL_HDM_DECODER_ENABLE,
 	       hdm + CXL_HDM_DECODER_CTRL_OFFSET);
 
-	return devm_add_action_or_reset(host, disable_hdm, cxlhdm);
+	return devm_add_action_or_reset(&port->dev, disable_hdm, cxlhdm);
 }
+EXPORT_SYMBOL_NS_GPL(devm_cxl_enable_hdm, CXL);
 
 int cxl_dvsec_rr_decode(struct device *dev, int d,
 			struct cxl_endpoint_dvsec_info *info)
@@ -425,7 +511,7 @@ int cxl_hdm_decode_init(struct cxl_dev_state *cxlds, struct cxl_hdm *cxlhdm,
 	if (info->mem_enabled)
 		return 0;
 
-	rc = devm_cxl_enable_hdm(&port->dev, cxlhdm);
+	rc = devm_cxl_enable_hdm(port, cxlhdm);
 	if (rc)
 		return rc;
 

drivers/cxl/core/port.c

@@ -750,11 +750,10 @@ struct cxl_port *devm_cxl_add_port(struct device *host, struct device *uport,
 
 	parent_port = parent_dport ? parent_dport->port : NULL;
 	if (IS_ERR(port)) {
-		dev_dbg(uport, "Failed to add %s%s%s%s: %ld\n",
-			dev_name(&port->dev),
-			parent_port ? " to " : "",
+		dev_dbg(uport, "Failed to add%s%s%s: %ld\n",
+			parent_port ? " port to " : "",
 			parent_port ? dev_name(&parent_port->dev) : "",
-			parent_port ? "" : " (root port)",
+			parent_port ? "" : " root port",
 			PTR_ERR(port));
 	} else {
 		dev_dbg(uport, "%s added%s%s%s\n",

drivers/cxl/cxl.h

@@ -710,6 +710,7 @@ struct cxl_endpoint_dvsec_info {
 struct cxl_hdm;
 struct cxl_hdm *devm_cxl_setup_hdm(struct cxl_port *port,
 				   struct cxl_endpoint_dvsec_info *info);
+int devm_cxl_enable_hdm(struct cxl_port *port, struct cxl_hdm *cxlhdm);
 int devm_cxl_enumerate_decoders(struct cxl_hdm *cxlhdm,
 				struct cxl_endpoint_dvsec_info *info);
 int devm_cxl_add_passthrough_decoder(struct cxl_port *port);

drivers/cxl/cxlmem.h

@@ -266,6 +266,7 @@ struct cxl_poison_state {
  * @regs: Parsed register blocks
  * @cxl_dvsec: Offset to the PCIe device DVSEC
  * @rcd: operating in RCD mode (CXL 3.0 9.11.8 CXL Devices Attached to an RCH)
+ * @media_ready: Indicate whether the device media is usable
  * @payload_size: Size of space for payload
  *                (CXL 2.0 8.2.8.4.3 Mailbox Capabilities Register)
  * @lsa_size: Size of Label Storage Area
@@ -303,6 +304,7 @@ struct cxl_dev_state {
 	int cxl_dvsec;
 
 	bool rcd;
+	bool media_ready;
 	size_t payload_size;
 	size_t lsa_size;
 	struct mutex mbox_mutex; /* Protects device mailbox and firmware */

drivers/cxl/cxlpci.h

@@ -31,6 +31,8 @@
 #define   CXL_DVSEC_RANGE_BASE_LOW(i)	(0x24 + (i * 0x10))
 #define     CXL_DVSEC_MEM_BASE_LOW_MASK	GENMASK(31, 28)
 
+#define CXL_DVSEC_RANGE_MAX		2
+
 /* CXL 2.0 8.1.4: Non-CXL Function Map DVSEC */
 #define CXL_DVSEC_FUNCTION_MAP					2
 

drivers/cxl/mem.c

@@ -124,6 +124,9 @@ static int cxl_mem_probe(struct device *dev)
 	struct dentry *dentry;
 	int rc;
 
+	if (!cxlds->media_ready)
+		return -EBUSY;
+
 	/*
 	 * Someone is trying to reattach this device after it lost its port
 	 * connection (an endpoint port previously registered by this memdev was

drivers/cxl/pci.c

@@ -708,6 +708,12 @@ static int cxl_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 	if (rc)
 		dev_dbg(&pdev->dev, "Failed to map RAS capability.\n");
 
+	rc = cxl_await_media_ready(cxlds);
+	if (rc == 0)
+		cxlds->media_ready = true;
+	else
+		dev_warn(&pdev->dev, "Media not active (%d)\n", rc);
+
 	rc = cxl_pci_setup_mailbox(cxlds);
 	if (rc)
 		return rc;

drivers/cxl/port.c

@@ -60,13 +60,17 @@ static int discover_region(struct device *dev, void *root)
 static int cxl_switch_port_probe(struct cxl_port *port)
 {
 	struct cxl_hdm *cxlhdm;
-	int rc;
+	int rc, nr_dports;
 
-	rc = devm_cxl_port_enumerate_dports(port);
-	if (rc < 0)
-		return rc;
+	nr_dports = devm_cxl_port_enumerate_dports(port);
+	if (nr_dports < 0)
+		return nr_dports;
 
 	cxlhdm = devm_cxl_setup_hdm(port, NULL);
+	rc = devm_cxl_enable_hdm(port, cxlhdm);
+	if (rc)
+		return rc;
+
 	if (!IS_ERR(cxlhdm))
 		return devm_cxl_enumerate_decoders(cxlhdm, NULL);
 
@@ -75,7 +79,7 @@ static int cxl_switch_port_probe(struct cxl_port *port)
 		return PTR_ERR(cxlhdm);
 	}
 
-	if (rc == 1) {
+	if (nr_dports == 1) {
 		dev_dbg(&port->dev, "Fallback to passthrough decoder\n");
 		return devm_cxl_add_passthrough_decoder(port);
 	}
@@ -113,12 +117,6 @@ static int cxl_endpoint_port_probe(struct cxl_port *port)
 	if (rc)
 		return rc;
 
-	rc = cxl_await_media_ready(cxlds);
-	if (rc) {
-		dev_err(&port->dev, "Media not active (%d)\n", rc);
-		return rc;
-	}
-
 	rc = devm_cxl_enumerate_decoders(cxlhdm, &info);
 	if (rc)
 		return rc;

tools/testing/cxl/Kbuild

@@ -6,6 +6,7 @@ ldflags-y += --wrap=acpi_pci_find_root
 ldflags-y += --wrap=nvdimm_bus_register
 ldflags-y += --wrap=devm_cxl_port_enumerate_dports
 ldflags-y += --wrap=devm_cxl_setup_hdm
+ldflags-y += --wrap=devm_cxl_enable_hdm
 ldflags-y += --wrap=devm_cxl_add_passthrough_decoder
 ldflags-y += --wrap=devm_cxl_enumerate_decoders
 ldflags-y += --wrap=cxl_await_media_ready

tools/testing/cxl/test/mem.c

@@ -1256,6 +1256,7 @@ static int cxl_mock_mem_probe(struct platform_device *pdev)
 	if (rc)
 		return rc;
 
+	cxlds->media_ready = true;
 	rc = cxl_dev_state_identify(cxlds);
 	if (rc)
 		return rc;

tools/testing/cxl/test/mock.c

@@ -149,6 +149,21 @@ struct cxl_hdm *__wrap_devm_cxl_setup_hdm(struct cxl_port *port,
 }
 EXPORT_SYMBOL_NS_GPL(__wrap_devm_cxl_setup_hdm, CXL);
 
+int __wrap_devm_cxl_enable_hdm(struct cxl_port *port, struct cxl_hdm *cxlhdm)
+{
+	int index, rc;
+	struct cxl_mock_ops *ops = get_cxl_mock_ops(&index);
+
+	if (ops && ops->is_mock_port(port->uport))
+		rc = 0;
+	else
+		rc = devm_cxl_enable_hdm(port, cxlhdm);
+	put_cxl_mock_ops(index);
+
+	return rc;
+}
+EXPORT_SYMBOL_NS_GPL(__wrap_devm_cxl_enable_hdm, CXL);
+
 int __wrap_devm_cxl_add_passthrough_decoder(struct cxl_port *port)
 {
 	int rc, index;