commit 9ea191d15f4b279923a4c83a94b83436c79e3482
Author: Haren Myneni <haren@linux.ibm.com>
Date:   Tue Aug 13 14:40:23 2024 -0700

    drmgr/pci: Enable in-kernel functionality to update device tree
    
    drmgr updates the device tree by writing to /proc/ppc64/ofdt. Also
    invokes configure_connector RTAS call to retrieve new device nodes
    for IO ADD. But this functionality need /dev/mem access which is
    restricted under system lockdown.
    
    The kernel updates provided a sysfs file (/sys/kernel/dlpar) that
    will allow drmgr command invoke the following interfaces to update
    the device tree.
    
    dt add index <DRC index> ---> To add new device nodes to the device
    tree which is used for IO ADD.
    
    dt remove index <DRC index> ---> To remove device nodes for IO
    REMOVE
    
    This patch checks the kernel interface for the availability of
    device tree update feature and adds do_dt_kernel_dlpar() to invoke
    the above kernel interfaces.
    
    Signed-off-by: Haren Myneni <haren@linux.ibm.com>
    Signed-off-by: Tyrel Datwyler <tyreld@linux.ibm.com>

diff --git a/src/drmgr/common.c b/src/drmgr/common.c
index bfec0b9..70f4dfd 100644
--- a/src/drmgr/common.c
+++ b/src/drmgr/common.c
@@ -1504,6 +1504,12 @@ int kernel_dlpar_exists(void)
 			if (strstr(buf, "cpu"))
 				return 1;
 			break;
+		case DRC_TYPE_PCI:
+		case DRC_TYPE_PHB:
+		case DRC_TYPE_SLOT:
+			if (strstr(buf, "dt"))
+				return 1;
+			break;
 		default:
 			return 0;
 		}
diff --git a/src/drmgr/common_pci.c b/src/drmgr/common_pci.c
index 759589a..109e0d2 100644
--- a/src/drmgr/common_pci.c
+++ b/src/drmgr/common_pci.c
@@ -1619,3 +1619,32 @@ int disable_hp_children(char *drc_name)
 	}
 	return 0;
 }
+
+/*
+ * kernel interface to update device tree nodes.
+ * dlpar dt [add|remove] index <#drc index>
+ */
+int do_dt_kernel_dlpar(uint32_t index, int action)
+{
+	char cmdbuf[256];
+	int offset;
+
+	offset = sprintf(cmdbuf, "%s ", "dt");
+
+	switch (action) {
+	case ADD:
+		offset += sprintf(cmdbuf + offset, "add ");
+		break;
+	case REMOVE:
+		offset += sprintf(cmdbuf + offset, "remove ");
+		break;
+	default:
+		/* Should not happen */
+		say(ERROR, "Invalid action type specified\n");
+		return -EINVAL;
+	}
+
+	offset += sprintf(cmdbuf + offset, "index 0x%x", index);
+
+	return do_kernel_dlpar(cmdbuf, offset);
+}
diff --git a/src/drmgr/dr.h b/src/drmgr/dr.h
index 60c31c4..72ede55 100644
--- a/src/drmgr/dr.h
+++ b/src/drmgr/dr.h
@@ -188,4 +188,5 @@ static inline int do_kernel_dlpar(const char *cmd, int len)
 {
 	return do_kernel_dlpar_common(cmd, len, 0);
 }
+int do_dt_kernel_dlpar(uint32_t, int);
 #endif