1 files changed, 152 insertions, 15 deletions

diff --git a/drivers/cxl/core/pci.c b/drivers/cxl/core/pci.c
index 3305e9b750af..c4c99ff7b55e 100644
--- a/drivers/cxl/core/pci.c
+++ b/drivers/cxl/core/pci.c
@@ -175,16 +175,149 @@ static int wait_for_valid(struct cxl_dev_state *cxlds)
 	return -ETIMEDOUT;
 }
 
+static int cxl_set_mem_enable(struct cxl_dev_state *cxlds, u16 val)
+{
+	struct pci_dev *pdev = to_pci_dev(cxlds->dev);
+	int d = cxlds->cxl_dvsec;
+	u16 ctrl;
+	int rc;
+
+	rc = pci_read_config_word(pdev, d + CXL_DVSEC_CTRL_OFFSET, &ctrl);
+	if (rc < 0)
+		return rc;
+
+	if ((ctrl & CXL_DVSEC_MEM_ENABLE) == val)
+		return 1;
+	ctrl &= ~CXL_DVSEC_MEM_ENABLE;
+	ctrl |= val;
+
+	rc = pci_write_config_word(pdev, d + CXL_DVSEC_CTRL_OFFSET, ctrl);
+	if (rc < 0)
+		return rc;
+
+	return 0;
+}
+
+static void clear_mem_enable(void *cxlds)
+{
+	cxl_set_mem_enable(cxlds, 0);
+}
+
+static int devm_cxl_enable_mem(struct device *host, struct cxl_dev_state *cxlds)
+{
+	int rc;
+
+	rc = cxl_set_mem_enable(cxlds, CXL_DVSEC_MEM_ENABLE);
+	if (rc < 0)
+		return rc;
+	if (rc > 0)
+		return 0;
+	return devm_add_action_or_reset(host, clear_mem_enable, cxlds);
+}
+
+static bool range_contains(struct range *r1, struct range *r2)
+{
+	return r1->start <= r2->start && r1->end >= r2->end;
+}
+
+/* require dvsec ranges to be covered by a locked platform window */
+static int dvsec_range_allowed(struct device *dev, void *arg)
+{
+	struct range *dev_range = arg;
+	struct cxl_decoder *cxld;
+	struct range root_range;
+
+	if (!is_root_decoder(dev))
+		return 0;
+
+	cxld = to_cxl_decoder(dev);
+
+	if (!(cxld->flags & CXL_DECODER_F_LOCK))
+		return 0;
+	if (!(cxld->flags & CXL_DECODER_F_RAM))
+		return 0;
+
+	root_range = (struct range) {
+		.start = cxld->platform_res.start,
+		.end = cxld->platform_res.end,
+	};
+
+	return range_contains(&root_range, dev_range);
+}
+
+static void disable_hdm(void *_cxlhdm)
+{
+	u32 global_ctrl;
+	struct cxl_hdm *cxlhdm = _cxlhdm;
+	void __iomem *hdm = cxlhdm->regs.hdm_decoder;
+
+	global_ctrl = readl(hdm + CXL_HDM_DECODER_CTRL_OFFSET);
+	writel(global_ctrl & ~CXL_HDM_DECODER_ENABLE,
+	       hdm + CXL_HDM_DECODER_CTRL_OFFSET);
+}
+
+static int devm_cxl_enable_hdm(struct device *host, struct cxl_hdm *cxlhdm)
+{
+	void __iomem *hdm = cxlhdm->regs.hdm_decoder;
+	u32 global_ctrl;
+
+	global_ctrl = readl(hdm + CXL_HDM_DECODER_CTRL_OFFSET);
+	writel(global_ctrl | CXL_HDM_DECODER_ENABLE,
+	       hdm + CXL_HDM_DECODER_CTRL_OFFSET);
+
+	return devm_add_action_or_reset(host, disable_hdm, cxlhdm);
+}
+
 static bool __cxl_hdm_decode_init(struct cxl_dev_state *cxlds,
 				  struct cxl_hdm *cxlhdm,
 				  struct cxl_endpoint_dvsec_info *info)
 {
 	void __iomem *hdm = cxlhdm->regs.hdm_decoder;
-	bool global_enable;
+	struct cxl_port *port = cxlhdm->port;
+	struct device *dev = cxlds->dev;
+	struct cxl_port *root;
+	int i, rc, allowed;
 	u32 global_ctrl;
 
 	global_ctrl = readl(hdm + CXL_HDM_DECODER_CTRL_OFFSET);
-	global_enable = global_ctrl & CXL_HDM_DECODER_ENABLE;
+
+	/*
+	 * If the HDM Decoder Capability is already enabled then assume
+	 * that some other agent like platform firmware set it up.
+	 */
+	if (global_ctrl & CXL_HDM_DECODER_ENABLE) {
+		rc = devm_cxl_enable_mem(&port->dev, cxlds);
+		if (rc)
+			return false;
+		return true;
+	}
+
+	root = to_cxl_port(port->dev.parent);
+	while (!is_cxl_root(root) && is_cxl_port(root->dev.parent))
+		root = to_cxl_port(root->dev.parent);
+	if (!is_cxl_root(root)) {
+		dev_err(dev, "Failed to acquire root port for HDM enable\n");
+		return false;
+	}
+
+	for (i = 0, allowed = 0; info->mem_enabled && i < info->ranges; i++) {
+		struct device *cxld_dev;
+
+		cxld_dev = device_find_child(&root->dev, &info->dvsec_range[i],
+					     dvsec_range_allowed);
+		if (!cxld_dev) {
+			dev_dbg(dev, "DVSEC Range%d denied by platform\n", i);
+			continue;
+		}
+		dev_dbg(dev, "DVSEC Range%d allowed by platform\n", i);
+		put_device(cxld_dev);
+		allowed++;
+	}
+
+	if (!allowed) {
+		cxl_set_mem_enable(cxlds, 0);
+		info->mem_enabled = 0;
+	}
 
 	/*
 	 * Per CXL 2.0 Section 8.1.3.8.3 and 8.1.3.8.4 DVSEC CXL Range 1 Base
@@ -192,21 +325,19 @@ static bool __cxl_hdm_decode_init(struct cxl_dev_state *cxlds,
 	 * are ignored by the device, but the spec also recommends matching the
 	 * DVSEC Range 1,2 to HDM Decoder Range 0,1. So, non-zero info->ranges
 	 * are expected even though Linux does not require or maintain that
-	 * match.
+	 * match. If at least one DVSEC range is enabled and allowed, skip HDM
+	 * Decoder Capability Enable.
 	 */
-	if (!global_enable && info->mem_enabled && info->ranges)
+	if (info->mem_enabled)
 		return false;
 
-	/*
-	 * Permanently (for this boot at least) opt the device into HDM
-	 * operation. Individual HDM decoders still need to be enabled after
-	 * this point.
-	 */
-	if (!global_enable) {
-		dev_dbg(cxlds->dev, "Enabling HDM decode\n");
-		writel(global_ctrl | CXL_HDM_DECODER_ENABLE,
-		       hdm + CXL_HDM_DECODER_CTRL_OFFSET);
-	}
+	rc = devm_cxl_enable_hdm(&port->dev, cxlhdm);
+	if (rc)
+		return false;
+
+	rc = devm_cxl_enable_mem(&port->dev, cxlds);
+	if (rc)
+		return false;
 
 	return true;
 }
@@ -261,9 +392,14 @@ int cxl_hdm_decode_init(struct cxl_dev_state *cxlds, struct cxl_hdm *cxlhdm)
 		return rc;
 	}
 
+	/*
+	 * The current DVSEC values are moot if the memory capability is
+	 * disabled, and they will remain moot after the HDM Decoder
+	 * capability is enabled.
+	 */
 	info.mem_enabled = FIELD_GET(CXL_DVSEC_MEM_ENABLE, ctrl);
 	if (!info.mem_enabled)
-		return 0;
+		goto hdm_init;
 
 	for (i = 0; i < hdm_count; i++) {
 		u64 base, size;
@@ -312,6 +448,7 @@ int cxl_hdm_decode_init(struct cxl_dev_state *cxlds, struct cxl_hdm *cxlhdm)
 	 * If DVSEC ranges are being used instead of HDM decoder registers there
 	 * is no use in trying to manage those.
 	 */
+hdm_init:
 	if (!__cxl_hdm_decode_init(cxlds, cxlhdm, &info)) {
 		dev_err(dev,
 			"Legacy range registers configuration prevents HDM operation.\n");