[PATCH v2 1/2] powerpc/pseries/dlpar: Remove device tree node for DLPAR IO remove

[PATCH v2 1/2] powerpc/pseries/dlpar: Remove device tree node for DLPAR IO remove

[Haren Myneni]

In the powerpc-pseries specific implementation, the IO hotplug
event is handled in the user space (drmgr tool). But update the
device tree and /dev/mem access to allocate buffers for some
RTAS calls are restricted when the kernel lockdown feature is
enabled. For the DLPAR IO REMOVE, the corresponding device tree
nodes and properties have to be removed from the device tree
after the device disable. The user space removes the device tree
nodes by updating /proc/ppc64/ofdt which is not allowed  under
system lockdown is enabled. This restriction can be resolved
by moving the complete IO hotplug handling in the kernel. But
the pseries implementation need user interaction to power off
and to remove device from the slot during hotplug event handling.

To overcome the /proc/ppc64/ofdt restriction, this patch extends
the /sys/kernel/dlpar interface and provides
‘dt remove index <drc_index>’ to the user space so that drmgr
tool can remove the corresponding device tree nodes based on DRC
index from the device tree.

Signed-off-by: Scott Cheloha <cheloha@linux.ibm.com>
Signed-off-by: Haren Myneni <haren@linux.ibm.com>

v2:
- Remove pr_info() and TODO comments
- Update more information in the commit logs
---
 arch/powerpc/include/asm/rtas.h        |  1 +
 arch/powerpc/platforms/pseries/dlpar.c | 85 +++++++++++++++++++++++++-
 2 files changed, 85 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/include/asm/rtas.h b/arch/powerpc/include/asm/rtas.h
index 065ffd1b2f8a..04406162fc5a 100644
--- a/arch/powerpc/include/asm/rtas.h
+++ b/arch/powerpc/include/asm/rtas.h
@@ -397,6 +397,7 @@ inline uint16_t pseries_errorlog_length(struct pseries_errorlog *sect)
 #define PSERIES_HP_ELOG_RESOURCE_SLOT	3
 #define PSERIES_HP_ELOG_RESOURCE_PHB	4
 #define PSERIES_HP_ELOG_RESOURCE_PMEM   6
+#define PSERIES_HP_ELOG_RESOURCE_DT	7
 
 #define PSERIES_HP_ELOG_ACTION_ADD	1
 #define PSERIES_HP_ELOG_ACTION_REMOVE	2
diff --git a/arch/powerpc/platforms/pseries/dlpar.c b/arch/powerpc/platforms/pseries/dlpar.c
index 47f8eabd1bee..59f2a8961946 100644
--- a/arch/powerpc/platforms/pseries/dlpar.c
+++ b/arch/powerpc/platforms/pseries/dlpar.c
@@ -330,6 +330,84 @@ int dlpar_unisolate_drc(u32 drc_index)
 	return 0;
 }
 
+static int changeset_detach_node_recursive(struct of_changeset *ocs,
+					struct device_node *node)
+{
+	struct device_node *child;
+	int rc;
+
+	for_each_child_of_node(node, child) {
+		rc = changeset_detach_node_recursive(ocs, child);
+		if (rc) {
+			of_node_put(child);
+			return rc;
+		}
+	}
+
+	return of_changeset_detach_node(ocs, node);
+}
+
+static int dlpar_hp_dt_remove(u32 drc_index)
+{
+	struct device_node *np;
+	struct of_changeset ocs;
+	u32 index;
+	int rc = 0;
+
+	/*
+	 * Prune all nodes with a matching index.
+	 */
+	of_changeset_init(&ocs);
+
+	for_each_node_with_property(np, "ibm,my-drc-index") {
+		rc = of_property_read_u32(np, "ibm,my-drc-index", &index);
+		if (rc) {
+			pr_err("%s: %pOF: of_property_read_u32 %s: %d\n",
+				__func__, np, "ibm,my-drc-index", rc);
+			of_node_put(np);
+			goto out;
+		}
+
+		if (index == drc_index) {
+			rc = changeset_detach_node_recursive(&ocs, np);
+			if (rc) {
+				of_node_put(np);
+				goto out;
+			}
+		}
+	}
+
+	rc = of_changeset_apply(&ocs);
+
+out:
+	of_changeset_destroy(&ocs);
+	return rc;
+}
+
+static int dlpar_hp_dt(struct pseries_hp_errorlog *phpe)
+{
+	int rc;
+
+	if (phpe->id_type != PSERIES_HP_ELOG_ID_DRC_INDEX)
+		return -EINVAL;
+
+	lock_device_hotplug();
+
+	switch (phpe->action) {
+	case PSERIES_HP_ELOG_ACTION_REMOVE:
+		rc = dlpar_hp_dt_remove(phpe->_drc_u.drc_index);
+		break;
+	default:
+		pr_err("Invalid action (%d) specified\n", phpe->action);
+		rc = -EINVAL;
+		break;
+	}
+
+	unlock_device_hotplug();
+
+	return rc;
+}
+
 int handle_dlpar_errorlog(struct pseries_hp_errorlog *hp_elog)
 {
 	int rc;
@@ -361,6 +439,9 @@ int handle_dlpar_errorlog(struct pseries_hp_errorlog *hp_elog)
 	case PSERIES_HP_ELOG_RESOURCE_PMEM:
 		rc = dlpar_hp_pmem(hp_elog);
 		break;
+	case PSERIES_HP_ELOG_RESOURCE_DT:
+		rc = dlpar_hp_dt(hp_elog);
+		break;
 
 	default:
 		pr_warn_ratelimited("Invalid resource (%d) specified\n",
@@ -413,6 +494,8 @@ static int dlpar_parse_resource(char **cmd, struct pseries_hp_errorlog *hp_elog)
 		hp_elog->resource = PSERIES_HP_ELOG_RESOURCE_MEM;
 	} else if (sysfs_streq(arg, "cpu")) {
 		hp_elog->resource = PSERIES_HP_ELOG_RESOURCE_CPU;
+	} else if (sysfs_streq(arg, "dt")) {
+		hp_elog->resource = PSERIES_HP_ELOG_RESOURCE_DT;
 	} else {
 		pr_err("Invalid resource specified.\n");
 		return -EINVAL;
@@ -554,7 +637,7 @@ static ssize_t dlpar_store(const struct class *class, const struct class_attribu
 static ssize_t dlpar_show(const struct class *class, const struct class_attribute *attr,
 			  char *buf)
 {
-	return sprintf(buf, "%s\n", "memory,cpu");
+	return sprintf(buf, "%s\n", "memory,cpu,dt");
 }
 
 static CLASS_ATTR_RW(dlpar);
-- 
2.43.5

[PATCH v2 2/2] powerpc/pseries/dlpar: Add device tree nodes for DLPAR IO add

[Haren Myneni]

In the powerpc-pseries specific implementation, the IO hotplug
event is handled in the user space (drmgr tool). For the DLPAR
IO ADD, the corresponding device tree nodes and properties will
be added to the device tree after the device enable. The user
space (drmgr tool) uses configure_connector RTAS call with the
DRC index to retrieve the device nodes and updates the device
tree by writing to /proc/ppc64/ofdt. Under system lockdown,
/dev/mem access to allocate buffers for configure_connector RTAS
call is restricted which means the user space can not issue this
RTAS call and also can not access to /proc/ppc64/ofdt. The
pseries implementation need user interaction to power-on and add
device to the slot during the ADD event handling. So adds
complexity if the complete hotplug ADD event handling moved to
the kernel.

To overcome /dev/mem access restriction, this patch extends the
/sys/kernel/dlpar interface and provides ‘dt add index <drc_index>’
to the user space. The drmgr tool uses this interface to update
the device tree whenever the device is added. This interface
retrieves device tree nodes for the corresponding DRC index using
the configure_connector RTAS call and adds new device nodes /
properties to the device tree.

Signed-off-by: Scott Cheloha <cheloha@linux.ibm.com>
Signed-off-by: Haren Myneni <haren@linux.ibm.com>
---
 arch/powerpc/platforms/pseries/dlpar.c | 130 +++++++++++++++++++++++++
 1 file changed, 130 insertions(+)

diff --git a/arch/powerpc/platforms/pseries/dlpar.c b/arch/powerpc/platforms/pseries/dlpar.c
index 59f2a8961946..2d960918cba8 100644
--- a/arch/powerpc/platforms/pseries/dlpar.c
+++ b/arch/powerpc/platforms/pseries/dlpar.c
@@ -23,6 +23,7 @@
 #include <linux/uaccess.h>
 #include <asm/rtas.h>
 #include <asm/rtas-work-area.h>
+#include <asm/prom.h>
 
 static struct workqueue_struct *pseries_hp_wq;
 
@@ -264,6 +265,20 @@ int dlpar_detach_node(struct device_node *dn)
 
 	return 0;
 }
+static int dlpar_changeset_attach_cc_nodes(struct of_changeset *ocs,
+					struct device_node *dn)
+{
+	int rc;
+
+	rc = of_changeset_attach_node(ocs, dn);
+
+	if (!rc && dn->child)
+		rc = dlpar_changeset_attach_cc_nodes(ocs, dn->child);
+	if (!rc && dn->sibling)
+		rc = dlpar_changeset_attach_cc_nodes(ocs, dn->sibling);
+
+	return rc;
+}
 
 #define DR_ENTITY_SENSE		9003
 #define DR_ENTITY_PRESENT	1
@@ -330,6 +345,118 @@ int dlpar_unisolate_drc(u32 drc_index)
 	return 0;
 }
 
+static struct device_node *
+get_device_node_with_drc_index(u32 index)
+{
+	struct device_node *np = NULL;
+	u32 node_index;
+	int rc;
+
+	for_each_node_with_property(np, "ibm,my-drc-index") {
+		rc = of_property_read_u32(np, "ibm,my-drc-index",
+					     &node_index);
+		if (rc) {
+			pr_err("%s: %pOF: of_property_read_u32 %s: %d\n",
+			       __func__, np, "ibm,my-drc-index", rc);
+			of_node_put(np);
+			return NULL;
+		}
+
+		if (index == node_index)
+			break;
+	}
+
+	return np;
+}
+
+static struct device_node *
+get_device_node_with_drc_info(u32 index)
+{
+	struct device_node *np = NULL;
+	struct of_drc_info drc;
+	struct property *info;
+	const __be32 *value;
+	u32 node_index;
+	int i, j, count;
+
+	for_each_node_with_property(np, "ibm,drc-info") {
+		info = of_find_property(np, "ibm,drc-info", NULL);
+		if (info == NULL) {
+			/* XXX can this happen? */
+			of_node_put(np);
+			return NULL;
+		}
+		value = of_prop_next_u32(info, NULL, &count);
+		if (value == NULL)
+			continue;
+		value++;
+		for (i = 0; i < count; i++) {
+			if (of_read_drc_info_cell(&info, &value, &drc))
+				break;
+			if (index > drc.last_drc_index)
+				continue;
+			node_index = drc.drc_index_start;
+			for (j = 0; j < drc.num_sequential_elems; j++) {
+				if (index == node_index)
+					return np;
+				node_index += drc.sequential_inc;
+			}
+		}
+	}
+
+	return NULL;
+}
+
+static int dlpar_hp_dt_add(u32 index)
+{
+	struct device_node *np, *nodes;
+	struct of_changeset ocs;
+	int rc;
+
+	/*
+	 * Do not add device node(s) if already exists in the
+	 * device tree.
+	 */
+	np = get_device_node_with_drc_index(index);
+	if (np) {
+		pr_err("%s: Adding device node for index (%d), but "
+				"already exists in the device tree\n",
+				__func__, index);
+		rc = -EINVAL;
+		goto out;
+	}
+
+	np = get_device_node_with_drc_info(index);
+
+	if (!np)
+		return -EIO;
+
+	/* Next, configure the connector. */
+	nodes = dlpar_configure_connector(cpu_to_be32(index), np);
+	if (!nodes) {
+		rc = -EIO;
+		goto out;
+	}
+
+	/*
+	 * Add the new nodes from dlpar_configure_connector() onto
+	 * the device-tree.
+	 */
+	of_changeset_init(&ocs);
+	rc = dlpar_changeset_attach_cc_nodes(&ocs, nodes);
+
+	if (!rc)
+		rc = of_changeset_apply(&ocs);
+	else
+		dlpar_free_cc_nodes(nodes);
+
+	of_changeset_destroy(&ocs);
+
+out:
+	of_node_put(np);
+	return rc;
+}
+
 static int changeset_detach_node_recursive(struct of_changeset *ocs,
 					struct device_node *node)
 {
@@ -394,6 +521,9 @@ static int dlpar_hp_dt(struct pseries_hp_errorlog *phpe)
 	lock_device_hotplug();
 
 	switch (phpe->action) {
+	case PSERIES_HP_ELOG_ACTION_ADD:
+		rc = dlpar_hp_dt_add(phpe->_drc_u.drc_index);
+		break;
 	case PSERIES_HP_ELOG_ACTION_REMOVE:
 		rc = dlpar_hp_dt_remove(phpe->_drc_u.drc_index);
 		break;
-- 
2.43.5

Re: [PATCH v2 1/2] powerpc/pseries/dlpar: Remove device tree node for DLPAR IO remove

[kernel test robot]

Hi Haren,

kernel test robot noticed the following build warnings:

[auto build test WARNING on powerpc/next]
[also build test WARNING on powerpc/fixes linus/master v6.11-rc3 next-20240816]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Haren-Myneni/powerpc-pseries-dlpar-Add-device-tree-nodes-for-DLPAR-IO-add/20240817-115833
base:   https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git next
patch link:    https://lore.kernel.org/r/20240817035401.125833-1-haren%40linux.ibm.com
patch subject: [PATCH v2 1/2] powerpc/pseries/dlpar: Remove device tree node for DLPAR IO remove
config: powerpc64-randconfig-r121-20240818 (https://download.01.org/0day-ci/archive/20240818/202408182142.wuIKqYae-lkp@intel.com/config)
compiler: clang version 20.0.0git (https://github.com/llvm/llvm-project 26670e7fa4f032a019d23d56c6a02926e854e8af)
reproduce: (https://download.01.org/0day-ci/archive/20240818/202408182142.wuIKqYae-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202408182142.wuIKqYae-lkp@intel.com/

sparse warnings: (new ones prefixed by >>)
>> arch/powerpc/platforms/pseries/dlpar.c:398:53: sparse: sparse: incorrect type in argument 1 (different base types) @@     expected unsigned int [usertype] drc_index @@     got restricted __be32 [usertype] drc_index @@
   arch/powerpc/platforms/pseries/dlpar.c:398:53: sparse:     expected unsigned int [usertype] drc_index
   arch/powerpc/platforms/pseries/dlpar.c:398:53: sparse:     got restricted __be32 [usertype] drc_index
   arch/powerpc/platforms/pseries/dlpar.c:418:43: sparse: sparse: incorrect type in assignment (different base types) @@     expected restricted __be32 [usertype] drc_count @@     got unsigned int [usertype] @@
   arch/powerpc/platforms/pseries/dlpar.c:418:43: sparse:     expected restricted __be32 [usertype] drc_count
   arch/powerpc/platforms/pseries/dlpar.c:418:43: sparse:     got unsigned int [usertype]
   arch/powerpc/platforms/pseries/dlpar.c:422:43: sparse: sparse: incorrect type in assignment (different base types) @@     expected restricted __be32 [usertype] drc_index @@     got unsigned int [usertype] @@
   arch/powerpc/platforms/pseries/dlpar.c:422:43: sparse:     expected restricted __be32 [usertype] drc_index
   arch/powerpc/platforms/pseries/dlpar.c:422:43: sparse:     got unsigned int [usertype]
   arch/powerpc/platforms/pseries/dlpar.c:426:42: sparse: sparse: incorrect type in assignment (different base types) @@     expected restricted __be32 [usertype] count @@     got unsigned int [usertype] @@
   arch/powerpc/platforms/pseries/dlpar.c:426:42: sparse:     expected restricted __be32 [usertype] count
   arch/powerpc/platforms/pseries/dlpar.c:426:42: sparse:     got unsigned int [usertype]
   arch/powerpc/platforms/pseries/dlpar.c:428:42: sparse: sparse: incorrect type in assignment (different base types) @@     expected restricted __be32 [usertype] index @@     got unsigned int [usertype] @@
   arch/powerpc/platforms/pseries/dlpar.c:428:42: sparse:     expected restricted __be32 [usertype] index
   arch/powerpc/platforms/pseries/dlpar.c:428:42: sparse:     got unsigned int [usertype]

vim +398 arch/powerpc/platforms/pseries/dlpar.c

   386	
   387	static int dlpar_hp_dt(struct pseries_hp_errorlog *phpe)
   388	{
   389		int rc;
   390	
   391		if (phpe->id_type != PSERIES_HP_ELOG_ID_DRC_INDEX)
   392			return -EINVAL;
   393	
   394		lock_device_hotplug();
   395	
   396		switch (phpe->action) {
   397		case PSERIES_HP_ELOG_ACTION_REMOVE:
 > 398			rc = dlpar_hp_dt_remove(phpe->_drc_u.drc_index);
   399			break;
   400		default:
   401			pr_err("Invalid action (%d) specified\n", phpe->action);
   402			rc = -EINVAL;
   403			break;
   404		}
   405	
   406		unlock_device_hotplug();
   407	
   408		return rc;
   409	}
   410	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

Re: [PATCH v2 2/2] powerpc/pseries/dlpar: Add device tree nodes for DLPAR IO add

[kernel test robot]

Hi Haren,

kernel test robot noticed the following build warnings:

[auto build test WARNING on powerpc/next]
[also build test WARNING on powerpc/fixes linus/master v6.11-rc3 next-20240816]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Haren-Myneni/powerpc-pseries-dlpar-Add-device-tree-nodes-for-DLPAR-IO-add/20240817-115833
base:   https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git next
patch link:    https://lore.kernel.org/r/20240817035401.125833-2-haren%40linux.ibm.com
patch subject: [PATCH v2 2/2] powerpc/pseries/dlpar: Add device tree nodes for DLPAR IO add
config: powerpc64-randconfig-r121-20240818 (https://download.01.org/0day-ci/archive/20240818/202408182302.o7QRO45S-lkp@intel.com/config)
compiler: clang version 20.0.0git (https://github.com/llvm/llvm-project 26670e7fa4f032a019d23d56c6a02926e854e8af)
reproduce: (https://download.01.org/0day-ci/archive/20240818/202408182302.o7QRO45S-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202408182302.o7QRO45S-lkp@intel.com/

sparse warnings: (new ones prefixed by >>)
>> arch/powerpc/platforms/pseries/dlpar.c:525:50: sparse: sparse: incorrect type in argument 1 (different base types) @@     expected unsigned int [usertype] index @@     got restricted __be32 [usertype] drc_index @@
   arch/powerpc/platforms/pseries/dlpar.c:525:50: sparse:     expected unsigned int [usertype] index
   arch/powerpc/platforms/pseries/dlpar.c:525:50: sparse:     got restricted __be32 [usertype] drc_index
   arch/powerpc/platforms/pseries/dlpar.c:528:53: sparse: sparse: incorrect type in argument 1 (different base types) @@     expected unsigned int [usertype] drc_index @@     got restricted __be32 [usertype] drc_index @@
   arch/powerpc/platforms/pseries/dlpar.c:528:53: sparse:     expected unsigned int [usertype] drc_index
   arch/powerpc/platforms/pseries/dlpar.c:528:53: sparse:     got restricted __be32 [usertype] drc_index
   arch/powerpc/platforms/pseries/dlpar.c:548:43: sparse: sparse: incorrect type in assignment (different base types) @@     expected restricted __be32 [usertype] drc_count @@     got unsigned int [usertype] @@
   arch/powerpc/platforms/pseries/dlpar.c:548:43: sparse:     expected restricted __be32 [usertype] drc_count
   arch/powerpc/platforms/pseries/dlpar.c:548:43: sparse:     got unsigned int [usertype]
   arch/powerpc/platforms/pseries/dlpar.c:552:43: sparse: sparse: incorrect type in assignment (different base types) @@     expected restricted __be32 [usertype] drc_index @@     got unsigned int [usertype] @@
   arch/powerpc/platforms/pseries/dlpar.c:552:43: sparse:     expected restricted __be32 [usertype] drc_index
   arch/powerpc/platforms/pseries/dlpar.c:552:43: sparse:     got unsigned int [usertype]
   arch/powerpc/platforms/pseries/dlpar.c:556:42: sparse: sparse: incorrect type in assignment (different base types) @@     expected restricted __be32 [usertype] count @@     got unsigned int [usertype] @@
   arch/powerpc/platforms/pseries/dlpar.c:556:42: sparse:     expected restricted __be32 [usertype] count
   arch/powerpc/platforms/pseries/dlpar.c:556:42: sparse:     got unsigned int [usertype]
   arch/powerpc/platforms/pseries/dlpar.c:558:42: sparse: sparse: incorrect type in assignment (different base types) @@     expected restricted __be32 [usertype] index @@     got unsigned int [usertype] @@
   arch/powerpc/platforms/pseries/dlpar.c:558:42: sparse:     expected restricted __be32 [usertype] index
   arch/powerpc/platforms/pseries/dlpar.c:558:42: sparse:     got unsigned int [usertype]

vim +525 arch/powerpc/platforms/pseries/dlpar.c

   513	
   514	static int dlpar_hp_dt(struct pseries_hp_errorlog *phpe)
   515	{
   516		int rc;
   517	
   518		if (phpe->id_type != PSERIES_HP_ELOG_ID_DRC_INDEX)
   519			return -EINVAL;
   520	
   521		lock_device_hotplug();
   522	
   523		switch (phpe->action) {
   524		case PSERIES_HP_ELOG_ACTION_ADD:
 > 525			rc = dlpar_hp_dt_add(phpe->_drc_u.drc_index);
   526			break;
   527		case PSERIES_HP_ELOG_ACTION_REMOVE:
   528			rc = dlpar_hp_dt_remove(phpe->_drc_u.drc_index);
   529			break;
   530		default:
   531			pr_err("Invalid action (%d) specified\n", phpe->action);
   532			rc = -EINVAL;
   533			break;
   534		}
   535	
   536		unlock_device_hotplug();
   537	
   538		return rc;
   539	}
   540	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki