From e978a3ccaa714b5ff125857d2cbecbb6fdf6c094 Mon Sep 17 00:00:00 2001

From: Nathan Lynch <nathanl@linux.ibm.com>

Date: Fri, 12 Jun 2020 00:12:38 -0500

Subject: [PATCH] powerpc/pseries: remove obsolete memory hotplug DT notifier

 code

References: bsc#1181674 ltc#189159

Patch-mainline: v5.9-rc1

Git-commit: e978a3ccaa714b5ff125857d2cbecbb6fdf6c094

pseries_update_drconf_memory() runs from a DT notifier in response to

an update to the ibm,dynamic-memory property of the

/ibm,dynamic-reconfiguration-memory node. This property is an older

less compact format than the ibm,dynamic-memory-v2 property used in

most currently supported firmwares. There has never been an equivalent

function for the v2 property.

pseries_update_drconf_memory() compares the 'assigned' flag for each

LMB in the old vs new properties and adds or removes the block

accordingly. However it appears to be of no actual utility:

* Partition suspension and PRRNs are specified only to change LMBs'

  NUMA affinity information. This notifier should be a no-op for those

  scenarios since the assigned flags should not change.

* The memory hotplug/DLPAR path has a hack which short-circuits

  execution of the notifier:

     dlpar_memory()

        ...

        rtas_hp_event = true;

        drmem_update_dt()

           of_update_property()

              pseries_memory_notifier()

                 pseries_update_drconf_memory()

                    if (rtas_hp_event) return;

So this code only makes sense as a relic of the time when more of the

DLPAR workflow took place in user space. I don't see a purpose for it

now.

Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Link: https://lore.kernel.org/r/20200612051238.1007764-19-nathanl@linux.ibm.com

Acked-by: Michal Suchanek <msuchanek@suse.de>

---

 .../platforms/pseries/hotplug-memory.c        | 65 +------------------

 1 file changed, 1 insertion(+), 64 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/hotplug-memory.c b/arch/powerpc/platforms/pseries/hotplug-memory.c

index 67ece3ac9ac2..73a5dcd977e1 100644

--- a/arch/powerpc/platforms/pseries/hotplug-memory.c

+++ b/arch/powerpc/platforms/pseries/hotplug-memory.c

@@ -22,8 +22,6 @@

 #include <asm/drmem.h>

 #include "pseries.h"

-static bool rtas_hp_event;

-

 unsigned long pseries_memory_block_size(void)

 {

 	struct device_node *np;

@@ -871,11 +869,8 @@ int dlpar_memory(struct pseries_hp_errorlog *hp_elog)

 		break;

 	}

-	if (!rc) {

-		rtas_hp_event = true;

+	if (!rc)

 		rc = drmem_update_dt();

-		rtas_hp_event = false;

-	}

 	unlock_device_hotplug();

 	return rc;

@@ -911,60 +906,6 @@ static int pseries_add_mem_node(struct device_node *np)

 	return (ret < 0) ? -EINVAL : 0;

 }

-static int pseries_update_drconf_memory(struct of_reconfig_data *pr)

-{

-	struct of_drconf_cell_v1 *new_drmem, *old_drmem;

-	unsigned long memblock_size;

-	u32 entries;

-	__be32 *p;

-	int i, rc = -EINVAL;

-

-	if (rtas_hp_event)

-		return 0;

-

-	memblock_size = pseries_memory_block_size();

-	if (!memblock_size)

-		return -EINVAL;

-

-	if (!pr->old_prop)

-		return 0;

-

-	p = (__be32 *) pr->old_prop->value;

-	if (!p)

-		return -EINVAL;

-

-	/* The first int of the property is the number of lmb's described

-	 * by the property. This is followed by an array of of_drconf_cell

-	 * entries. Get the number of entries and skip to the array of

-	 * of_drconf_cell's.

-	 */

-	entries = be32_to_cpu(*p++);

-	old_drmem = (struct of_drconf_cell_v1 *)p;

-

-	p = (__be32 *)pr->prop->value;

-	p++;

-	new_drmem = (struct of_drconf_cell_v1 *)p;

-

-	for (i = 0; i < entries; i++) {

-		if ((be32_to_cpu(old_drmem[i].flags) & DRCONF_MEM_ASSIGNED) &&

-		    (!(be32_to_cpu(new_drmem[i].flags) & DRCONF_MEM_ASSIGNED))) {

-			rc = pseries_remove_memblock(

-				be64_to_cpu(old_drmem[i].base_addr),

-						     memblock_size);

-			break;

-		} else if ((!(be32_to_cpu(old_drmem[i].flags) &

-			    DRCONF_MEM_ASSIGNED)) &&

-			    (be32_to_cpu(new_drmem[i].flags) &

-			    DRCONF_MEM_ASSIGNED)) {

-			rc = memblock_add(be64_to_cpu(old_drmem[i].base_addr),

-					  memblock_size);

-			rc = (rc < 0) ? -EINVAL : 0;

-			break;

-		}

-	}

-	return rc;

-}

-

 static int pseries_memory_notifier(struct notifier_block *nb,

 				   unsigned long action, void *data)

 {

@@ -978,10 +919,6 @@ static int pseries_memory_notifier(struct notifier_block *nb,

 	case OF_RECONFIG_DETACH_NODE:

 		err = pseries_remove_mem_node(rd->dn);

 		break;

-	case OF_RECONFIG_UPDATE_PROPERTY:

-		if (!strcmp(rd->prop->name, "ibm,dynamic-memory"))

-			err = pseries_update_drconf_memory(rd);

-		break;

 	}

 	return notifier_from_errno(err);

 }

-- 

2.26.2