[Powerpc-utils-devel] [PATCH v2] Kernel CPU DLPAR

[Nathan F. <nf...@au...>]

This patch is dependent on two additional patches that are queued
for inclusion in the kernel.

http://lists.ozlabs.org/pipermail/linuxppc-dev/2009-November/078181.html
http://lkml.org/lkml/2009/11/26/368

With this new kernel functionality CPU  DLPAR can be done completely
in the kernel.  Under this new scheme the drmgr command only has to write
the drc-index of a cpu to /sys/devices/system/cpu/probe to have the cpu
dlpar added and hotplug added to the system.  The DLPAR remove of a cpu
involves writing the path in the device tree for the the cpu to be
removed to he /sys/sdevices/system/cpu/release file.  This will hotplug
remove the cpu and dlpar remove it.

This updated patch corrects hotplugging of the cpu to only be done when
cpu kernel dlpar is not present.

Signed-off-by: Nathan Fontenot <nf...@au...>

---
 src/drmgr/common_cpu.c      |  127 +++++++++++++++++++++++++++++++++++---------
 src/drmgr/drcpu.h           |    5 +
 src/drmgr/drslot_chrp_cpu.c |   25 --------
 3 files changed, 108 insertions(+), 49 deletions(-)

Index: powerpc-utils/src/drmgr/common_cpu.c
===================================================================
--- powerpc-utils.orig/src/drmgr/common_cpu.c	2010-01-05 12:57:34.000000000 -0600
+++ powerpc-utils/src/drmgr/common_cpu.c	2010-01-15 12:48:18.000000000 -0600
@@ -604,7 +604,7 @@
  * @param drc_index
  * @returns pointer to cpu_info on success, NULL otherwise
  */
-int
+static int
 acquire_cpu(struct dr_node *cpu, struct dr_info *dr_info)
 {
 	struct of_node *of_nodes;
@@ -637,6 +637,57 @@
 	return 0;
 }
 
+int
+probe_cpu(struct dr_node *cpu, struct dr_info *dr_info)
+{
+	char drc_index[DR_STR_MAX];
+	int probe_file;
+	int write_len;
+	int rc = 0;
+
+	probe_file = open(CPU_PROBE_FILE, O_WRONLY);
+	if (probe_file <= 0) {
+		/* Attempt to add cpu from user-space, this may be an older
+		 * kernel without the infrastructure to handle dlpar.
+		 */
+		rc = acquire_cpu(cpu, dr_info);
+		if (rc)
+			return rc;
+
+		rc = online_cpu(cpu, dr_info);
+		if (rc) {
+			/* Roll back the operation.  Is this the correct
+			 * behavior?
+			 */
+			dbg("Unable to online %s\n", cpu->drc_name);
+			offline_cpu(cpu);
+			release_cpu(cpu, dr_info);
+			cpu->unusable = 1;
+		}
+
+	} else {
+		memset(drc_index, 0, DR_STR_MAX);
+		write_len = sprintf(drc_index, "0x%x", cpu->drc_index);
+
+		dbg("Probing cpu 0x%x\n", cpu->drc_index);
+		rc = write(probe_file, drc_index, write_len);
+		if (rc != write_len)
+			dbg("Probe failed! rc = %x\n", rc);
+		else
+			/* reset rc to success */
+			rc = 0;
+
+		close(probe_file);
+	}
+
+	if (!rc) {
+		update_cpu_node(cpu, NULL, dr_info);
+		refresh_cache_info(dr_info);
+	}
+
+	return rc;
+}
+
 /**
  * release_caches
  * Remove any unused cache info.  Failure to remove the cache, while not
@@ -688,39 +739,66 @@
 int
 release_cpu(struct dr_node *cpu, struct dr_info *dr_info)
 {
+	int release_file;
 	int rc;
 
-	/* Should we check to make sure all threads of the cpu are offline? */
+	release_file = open(CPU_RELEASE_FILE, O_WRONLY);
+	if (release_file > 0) {
+		/* DLPAR can be done in kernel */
+		char *path = cpu->ofdt_path + strlen(OFDT_BASE);
+		int write_len = strlen(path);
+
+		dbg("Releasing cpu \"%s\"\n", path);
+		rc = write(release_file, path, write_len);
+		if (rc != write_len)
+			dbg("Release failed! rc = %d\n", rc);
+		else
+			/* set rc to success */
+			rc = 0;
+
+		close(release_file);
+	} else {
+		/* Must do DLPAR from user-space */
+		rc = offline_cpu(cpu);
+		if (rc) {
+			err_msg("Could not offline cpu %s\n", cpu->drc_name);
+			return rc;
+		}
 
-	rc = release_drc(cpu->drc_index, CPU_DEV);
-	if (rc) {
-		dbg("Could not release drc resources for %s\n", cpu->name);
-		return rc;
-	}
+		rc = release_drc(cpu->drc_index, CPU_DEV);
+		if (rc) {
+			dbg("Could not release drc resources for %s\n",
+			    cpu->name);
+			return rc;
+		}
 
-	rc = remove_device_tree_nodes(cpu->ofdt_path);
-	if (rc) {
-		struct of_node *of_nodes;
+		rc = remove_device_tree_nodes(cpu->ofdt_path);
+		if (rc) {
+			struct of_node *of_nodes;
 
-		dbg("Could not remove device tree nodes %s\n", cpu->name);
+			dbg("Could not remove device tree nodes %s\n",
+			    cpu->name);
 		
-		of_nodes = configure_connector(cpu->drc_index);
-		if (of_nodes == NULL) {
-			err_msg("Call to configure_connector failed for %s. "
-				"The device tree\nmay contain invalid data "
-				"for this cpu and a re-activation of the "
-				"partition is needed to correct it.\n",
-				cpu->name);
-		} else {
-			rc = add_device_tree_nodes(CPU_OFDT_BASE, of_nodes);
-			free_of_node(of_nodes);
+			of_nodes = configure_connector(cpu->drc_index);
+			if (of_nodes == NULL) {
+				err_msg("Call to configure_connector failed "
+					"for %s. The device tree\nmay contain "
+					"invalid data for this cpu and a "
+					"re-activation of the partition is "
+					"needed to correct it.\n", cpu->name);
+			} else {
+				rc = add_device_tree_nodes(CPU_OFDT_BASE,
+							   of_nodes);
+				free_of_node(of_nodes);
+			}
+
+			acquire_drc(cpu->drc_index);
+			return rc;
 		}
 
-		acquire_drc(cpu->drc_index);
-		return rc;
+		release_caches(cpu, dr_info);
 	}
 
-	release_caches(cpu, dr_info);
 	return rc;
 }
 
Index: powerpc-utils/src/drmgr/drcpu.h
===================================================================
--- powerpc-utils.orig/src/drmgr/drcpu.h	2010-01-05 12:57:34.000000000 -0600
+++ powerpc-utils/src/drmgr/drcpu.h	2010-01-14 15:05:06.000000000 -0600
@@ -9,6 +9,9 @@
 
 #include "dr.h"
 
+#define CPU_PROBE_FILE		"/sys/devices/system/cpu/probe"
+#define CPU_RELEASE_FILE	"/sys/devices/system/cpu/release"
+
 struct cache_info {
 	char		name[DR_BUF_SZ];	/* node name */
 	char		path[DR_BUF_SZ];	/* node path */
@@ -45,7 +48,7 @@
 struct cache_info * cache_get_dependent_cache(struct cache_info *,
 					      struct dr_info *);
 int release_cpu(struct dr_node *, struct dr_info *);
-int acquire_cpu(struct dr_node *, struct dr_info *);
+int probe_cpu(struct dr_node *, struct dr_info *);
 struct dr_node *get_available_cpu(struct options *, struct dr_info *);
 
 #endif /* _H_DRCPU */
Index: powerpc-utils/src/drmgr/drslot_chrp_cpu.c
===================================================================
--- powerpc-utils.orig/src/drmgr/drslot_chrp_cpu.c	2010-01-05 12:57:34.000000000 -0600
+++ powerpc-utils/src/drmgr/drslot_chrp_cpu.c	2010-01-14 15:14:54.000000000 -0600
@@ -138,7 +138,7 @@
 		if (!cpu)
 			break;
 
-		rc = acquire_cpu(cpu, dr_info);
+		rc = probe_cpu(cpu, dr_info);
 		if (rc) {
 			dbg("Unable to acquire CPU with drc index %x\n",
 			    cpu->drc_index);
@@ -146,18 +146,6 @@
 			continue;
 		}
 
-		rc = online_cpu(cpu, dr_info);
-		if (rc) {
-			/* Roll back the operation.  Is this the correct
-			 * behavior?
-			 */
-			dbg("Unable to online %s\n", cpu->drc_name);
-			offline_cpu(cpu);
-			release_cpu(cpu, dr_info);
-			cpu->unusable = 1;
-			continue;
-		}
-
 		fprintf(stdout, "%s\n", cpu->drc_name);
 		count++;
 	}
@@ -201,15 +189,6 @@
 		if (!cpu)
 			break;
 
-		rc = offline_cpu(cpu);
-		if (rc) {
-			/* Need to online any threads we took offline */
-			online_cpu(cpu, dr_info);
-			err_msg("Could not offline cpu %s\n", cpu->drc_name);
-			cpu->unusable = 1;
-			continue;
-		}
-
 		/* cpu is invalid after release_cpu, so no recovery
 		 * steps seem feasible.  We could copy the cpu name
 		 * and look it up again if the operation fails.
@@ -217,8 +196,6 @@
 		rc = release_cpu(cpu, dr_info);
 		if (rc) {
 			online_cpu(cpu, dr_info);
-			err_msg("Offlined but could not release %s\n",
-				cpu->drc_name);
 			cpu->unusable = 1;
 			continue;
 		}