[PATCH v2 1/2] powerpc/pseries: Implemented indexed-count hotplug memory add

[Sahil Mehta <smehta@linux.vnet.ibm.com>]

Indexed-count add for memory hotplug guarantees that a contiguous block
of <count> lmbs beginning at a specified <index> will be assigned (NOT
that <count> lmbs will be added). Because of Qemu's per-DIMM memory
management, the addition of a contiguous block of memory currently
requires a series of individual calls. Indexed-count add reduces
this series into a single call.

Signed-off-by: Sahil Mehta <smehta@linux.vnet.ibm.com>
---
v2:	-remove potential memory leak when parsing command
	-use u32s drc_index and count instead of u32 ic[]
	 in dlpar_memory

 arch/powerpc/include/asm/rtas.h                 |    2
 arch/powerpc/platforms/pseries/dlpar.c          |   34 +++++++-
 arch/powerpc/platforms/pseries/hotplug-memory.c |  100 +++++++++++++++++++++--
 3 files changed, 124 insertions(+), 12 deletions(-)

diff --git a/arch/powerpc/include/asm/rtas.h b/arch/powerpc/include/asm/rtas.h
index 51400ba..f46b271 100644
--- a/arch/powerpc/include/asm/rtas.h
+++ b/arch/powerpc/include/asm/rtas.h
@@ -307,6 +307,7 @@ struct pseries_hp_errorlog {
 	union {
 		__be32	drc_index;
 		__be32	drc_count;
+		__be32	indexed_count[2];
 		char	drc_name[1];
 	} _drc_u;
 };
@@ -322,6 +323,7 @@ struct pseries_hp_errorlog {
 #define PSERIES_HP_ELOG_ID_DRC_NAME	1
 #define PSERIES_HP_ELOG_ID_DRC_INDEX	2
 #define PSERIES_HP_ELOG_ID_DRC_COUNT	3
+#define PSERIES_HP_ELOG_ID_IC		4

 struct pseries_errorlog *get_pseries_errorlog(struct rtas_error_log *log,
 					      uint16_t section_id);
diff --git a/arch/powerpc/platforms/pseries/dlpar.c b/arch/powerpc/platforms/pseries/dlpar.c
index 2b93ae8..2a6dc9e 100644
--- a/arch/powerpc/platforms/pseries/dlpar.c
+++ b/arch/powerpc/platforms/pseries/dlpar.c
@@ -345,11 +345,17 @@ static int handle_dlpar_errorlog(struct pseries_hp_errorlog *hp_elog)
 	switch (hp_elog->id_type) {
 	case PSERIES_HP_ELOG_ID_DRC_COUNT:
 		hp_elog->_drc_u.drc_count =
-					be32_to_cpu(hp_elog->_drc_u.drc_count);
+				be32_to_cpu(hp_elog->_drc_u.drc_count);
 		break;
 	case PSERIES_HP_ELOG_ID_DRC_INDEX:
 		hp_elog->_drc_u.drc_index =
-					be32_to_cpu(hp_elog->_drc_u.drc_index);
+				be32_to_cpu(hp_elog->_drc_u.drc_index);
+		break;
+	case PSERIES_HP_ELOG_ID_IC:
+		hp_elog->_drc_u.indexed_count[0] =
+				be32_to_cpu(hp_elog->_drc_u.indexed_count[0]);
+		hp_elog->_drc_u.indexed_count[1] =
+				be32_to_cpu(hp_elog->_drc_u.indexed_count[1]);
 	}

 	switch (hp_elog->resource) {
@@ -409,7 +415,29 @@ static ssize_t dlpar_store(struct class *class, struct class_attribute *attr,
 		goto dlpar_store_out;
 	}

-	if (!strncmp(arg, "index", 5)) {
+	if (!strncmp(arg, "indexed-count", 13)) {
+		u32 index, count;
+		char *cstr, *istr;
+
+		hp_elog->id_type = PSERIES_HP_ELOG_ID_IC;
+		arg += strlen("indexed-count ");
+
+		cstr = kstrdup(arg, GFP_KERNEL);
+		istr = strchr(cstr, ' ');
+		*istr++ = '\0';
+
+		if (kstrtou32(cstr, 0, &count) || kstrtou32(istr, 0, &index)) {
+			rc = -EINVAL;
+			pr_err("Invalid index or count : \"%s\"\n", buf);
+			kfree(cstr);
+			goto dlpar_store_out;
+		}
+
+		kfree(cstr);
+
+		hp_elog->_drc_u.indexed_count[0] = cpu_to_be32(count);
+		hp_elog->_drc_u.indexed_count[1] = cpu_to_be32(index);
+	} else if (!strncmp(arg, "index", 5)) {
 		u32 index;

 		hp_elog->id_type = PSERIES_HP_ELOG_ID_DRC_INDEX;
diff --git a/arch/powerpc/platforms/pseries/hotplug-memory.c b/arch/powerpc/platforms/pseries/hotplug-memory.c
index 2ce1385..d7942ca 100644
--- a/arch/powerpc/platforms/pseries/hotplug-memory.c
+++ b/arch/powerpc/platforms/pseries/hotplug-memory.c
@@ -701,6 +701,83 @@ static int dlpar_memory_add_by_index(u32 drc_index, struct property *prop)
 	return rc;
 }

+static int dlpar_memory_add_by_ic(u32 lmbs_to_add, u32 drc_index,
+				  struct property *prop)
+{
+	struct of_drconf_cell *lmbs;
+	u32 num_lmbs, *p;
+	int i, rc;
+	int lmbs_available = 0, start_index = 0, end_index;
+
+	pr_info("Attempting to hot-add %u LMB(s) at index %x\n",
+		lmbs_to_add, drc_index);
+
+	if (lmbs_to_add == 0)
+		return -EINVAL;
+
+	p = prop->value;
+	num_lmbs = *p++;
+	lmbs = (struct of_drconf_cell *)p;
+
+	/* Navigate to drc_index */
+	while (start_index < num_lmbs) {
+		if (lmbs[start_index].drc_index == drc_index)
+			break;
+
+		start_index++;
+	}
+
+	end_index = start_index + lmbs_to_add;
+
+	/* Validate that there are enough LMBs to satisfy the request */
+	for (i = start_index; i < end_index; i++) {
+		if (lmbs[i].flags & DRCONF_MEM_RESERVED)
+			break;
+
+		lmbs_available++;
+	}
+
+	if (lmbs_available < lmbs_to_add)
+		return -EINVAL;
+
+	for (i = start_index; i < end_index; i++) {
+		if (lmbs[i].flags & DRCONF_MEM_ASSIGNED)
+			continue;
+
+		rc = dlpar_add_lmb(&lmbs[i]);
+		if (rc)
+			break;
+
+		lmbs[i].reserved = 1;
+	}
+
+	if (rc) {
+		pr_err("Memory indexed-count-add failed, removing any added LMBs\n");
+
+		for (i = start_index; i < end_index; i++) {
+			if (!lmbs[i].reserved)
+				continue;
+
+			rc = dlpar_remove_lmb(&lmbs[i]);
+			if (rc)
+				pr_err("Failed to remove LMB, drc index %x\n",
+				       be32_to_cpu(lmbs[i].drc_index));
+		}
+		rc = -EINVAL;
+	} else {
+		for (i = start_index; i < end_index; i++) {
+			if (!lmbs[i].reserved)
+				continue;
+
+			pr_info("Memory at %llx (drc index %x) was hot-added\n",
+				lmbs[i].base_addr, lmbs[i].drc_index);
+			lmbs[i].reserved = 0;
+		}
+	}
+
+	return rc;
+}
+
 int dlpar_memory(struct pseries_hp_errorlog *hp_elog)
 {
 	struct device_node *dn;
@@ -708,9 +785,6 @@ int dlpar_memory(struct pseries_hp_errorlog *hp_elog)
 	u32 count, drc_index;
 	int rc;

-	count = hp_elog->_drc_u.drc_count;
-	drc_index = hp_elog->_drc_u.drc_index;
-
 	lock_device_hotplug();

 	dn = of_find_node_by_path("/ibm,dynamic-reconfiguration-memory");
@@ -727,19 +801,27 @@ int dlpar_memory(struct pseries_hp_errorlog *hp_elog)

 	switch (hp_elog->action) {
 	case PSERIES_HP_ELOG_ACTION_ADD:
-		if (hp_elog->id_type == PSERIES_HP_ELOG_ID_DRC_COUNT)
+		if (hp_elog->id_type == PSERIES_HP_ELOG_ID_DRC_COUNT) {
+			count = hp_elog->_drc_u.drc_count;
 			rc = dlpar_memory_add_by_count(count, prop);
-		else if (hp_elog->id_type == PSERIES_HP_ELOG_ID_DRC_INDEX)
+		} else if (hp_elog->id_type == PSERIES_HP_ELOG_ID_DRC_INDEX) {
+			drc_index = hp_elog->_drc_u.drc_index;
 			rc = dlpar_memory_add_by_index(drc_index, prop);
-		else
+		} else if (hp_elog->id_type == PSERIES_HP_ELOG_ID_IC) {
+			count = hp_elog->_drc_u.indexed_count[0];
+			drc_index = hp_elog->_drc_u.indexed_count[1];
+			rc = dlpar_memory_add_by_ic(count, drc_index, prop);
+		} else
 			rc = -EINVAL;
 		break;
 	case PSERIES_HP_ELOG_ACTION_REMOVE:
-		if (hp_elog->id_type == PSERIES_HP_ELOG_ID_DRC_COUNT)
+		if (hp_elog->id_type == PSERIES_HP_ELOG_ID_DRC_COUNT) {
+			count = hp_elog->_drc_u.drc_count;
 			rc = dlpar_memory_remove_by_count(count, prop);
-		else if (hp_elog->id_type == PSERIES_HP_ELOG_ID_DRC_INDEX)
+		} else if (hp_elog->id_type == PSERIES_HP_ELOG_ID_DRC_INDEX) {
+			drc_index = hp_elog->_drc_u.drc_index;
 			rc = dlpar_memory_remove_by_index(drc_index, prop);
-		else
+		} else
 			rc = -EINVAL;
 		break;
 	default:

On 07/18/2016 10:04 AM, Sahil Mehta wrote:
> Indexed-count memory management allows addition and removal of contiguous
> lmb blocks with a single command. When compared to the series of calls
> previously required to manage contiguous blocks, indexed-count decreases
> command frequency and reduces risk of buffer overflow.
> 
> Changes in v2:
> --------------
> -[PATCH 1/2]:	-remove potential memory leak when parsing command
> 		-use u32s drc_index and count instead of u32 ic[]
> 		 in dlpar_memory
> -[PATCH 2/2]:	-use u32s drc_index and count instead of u32 ic[]
> 		 in dlpar_memory
> 
> -Sahil Mehta
> ---
>  include/asm/rtas.h                 |    2
>  platforms/pseries/dlpar.c          |   34 ++++++
>  platforms/pseries/hotplug-memory.c |  184 +++++++++++++++++++++++++++++++++++--
>  3 files changed, 208 insertions(+), 12 deletions(-)
> 
> _______________________________________________
> Linuxppc-dev mailing list
> Linuxppc-dev@lists.ozlabs.org
> https://lists.ozlabs.org/listinfo/linuxppc-dev
>