Patchwork [PATCH2/11] Add PRRN Event Handler

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Submitter Nathan Fontenot
Date March 9, 2013, 4 a.m.
Message ID <513AB3C9.6010302@linux.vnet.ibm.com>
Download mbox | patch
Permalink /patch/226299/
State Superseded, archived
Headers show

Comments

Nathan Fontenot - March 9, 2013, 4 a.m.
From: Jesse Larrew <jlarrew@linux.vnet.ibm.com>

A PRRN event is signaled via the RTAS event-scan mechanism, which
returns a Hot Plug Event message "fixed part" indicating "Platform
Resource Reassignment". In response to the Hot Plug Event message,
we must call ibm,update-nodes to determine which resources were
reassigned and then ibm,update-properties to obtain the new affinity
information about those resources.

The PRRN event-scan RTAS message contains only the "fixed part" with
the "Type" field set to the value 160 and no Extended Event Log. The
four-byte Extended Event Log Length field is repurposed (since no
Extended Event Log message is included) to pass the "scope" parameter
that causes the ibm,update-nodes to return the nodes affected by the
specific resource reassignment.

This patch adds a handler in rtasd for PRRN RTAS events. The function
pseries_devicetree_update() (from mobility.c) is used to make the
ibm,update-nodes/ibm,update-properties RTAS calls. Updating the NUMA maps
(handled by a subsequent patch) will require significant processing,
so pseries_devicetree_update() is called from an asynchronous workqueue
to allow rtasd to continue processing events.

Signed-off-by: Nathan Fontenot <nfont@linux.vnet.ibm.com>
---
 arch/powerpc/include/asm/rtas.h |    2 ++
 arch/powerpc/kernel/rtasd.c     |   35 ++++++++++++++++++++++++++++++++++-
 2 files changed, 36 insertions(+), 1 deletion(-)
Paul Mackerras - March 14, 2013, 8:51 a.m.
On Fri, Mar 08, 2013 at 10:00:09PM -0600, Nathan Fontenot wrote:
> From: Jesse Larrew <jlarrew@linux.vnet.ibm.com>
> 
> A PRRN event is signaled via the RTAS event-scan mechanism, which
> returns a Hot Plug Event message "fixed part" indicating "Platform
> Resource Reassignment". In response to the Hot Plug Event message,
> we must call ibm,update-nodes to determine which resources were
> reassigned and then ibm,update-properties to obtain the new affinity
> information about those resources.
> 
> The PRRN event-scan RTAS message contains only the "fixed part" with
> the "Type" field set to the value 160 and no Extended Event Log. The
> four-byte Extended Event Log Length field is repurposed (since no
> Extended Event Log message is included) to pass the "scope" parameter
> that causes the ibm,update-nodes to return the nodes affected by the
> specific resource reassignment.
> 
> This patch adds a handler in rtasd for PRRN RTAS events. The function
> pseries_devicetree_update() (from mobility.c) is used to make the
> ibm,update-nodes/ibm,update-properties RTAS calls. Updating the NUMA maps
> (handled by a subsequent patch) will require significant processing,
> so pseries_devicetree_update() is called from an asynchronous workqueue
> to allow rtasd to continue processing events.
> 
> Signed-off-by: Nathan Fontenot <nfont@linux.vnet.ibm.com>

[snip]

> +static s32 update_scope;

Do we have a guarantee that there can only be one of these events
outstanding at a time?  If so it would be nice to document that in a
comment next to this declaration, so we know in future that this is
why this is safe.

Paul.
Nathan Fontenot - March 19, 2013, 6:01 p.m.
On 03/14/2013 03:51 AM, Paul Mackerras wrote:
> On Fri, Mar 08, 2013 at 10:00:09PM -0600, Nathan Fontenot wrote:
>> From: Jesse Larrew <jlarrew@linux.vnet.ibm.com>
>>
>> A PRRN event is signaled via the RTAS event-scan mechanism, which
>> returns a Hot Plug Event message "fixed part" indicating "Platform
>> Resource Reassignment". In response to the Hot Plug Event message,
>> we must call ibm,update-nodes to determine which resources were
>> reassigned and then ibm,update-properties to obtain the new affinity
>> information about those resources.
>>
>> The PRRN event-scan RTAS message contains only the "fixed part" with
>> the "Type" field set to the value 160 and no Extended Event Log. The
>> four-byte Extended Event Log Length field is repurposed (since no
>> Extended Event Log message is included) to pass the "scope" parameter
>> that causes the ibm,update-nodes to return the nodes affected by the
>> specific resource reassignment.
>>
>> This patch adds a handler in rtasd for PRRN RTAS events. The function
>> pseries_devicetree_update() (from mobility.c) is used to make the
>> ibm,update-nodes/ibm,update-properties RTAS calls. Updating the NUMA maps
>> (handled by a subsequent patch) will require significant processing,
>> so pseries_devicetree_update() is called from an asynchronous workqueue
>> to allow rtasd to continue processing events.
>>
>> Signed-off-by: Nathan Fontenot <nfont@linux.vnet.ibm.com>
> 
> [snip]
> 
>> +static s32 update_scope;
> 
> Do we have a guarantee that there can only be one of these events
> outstanding at a time?  If so it would be nice to document that in a
> comment next to this declaration, so we know in future that this is
> why this is safe.
> 

We only allow for one event to be outstanding. When a PRRN Event is
received we flush any work currently queued up and add the new event
event to the workqueue (see prrn_schedule_work() from the patch).

As I understand flush_work(), this would wait for any work in flight
to complete, then remove all work before returning. I'll add a comment
and update the patch description.

-Nathan

Patch

Index: powerpc/arch/powerpc/include/asm/rtas.h
===================================================================
--- powerpc.orig/arch/powerpc/include/asm/rtas.h	2013-03-08 19:56:13.000000000 -0600
+++ powerpc/arch/powerpc/include/asm/rtas.h	2013-03-08 19:56:48.000000000 -0600
@@ -143,6 +143,8 @@ 
 #define RTAS_TYPE_PMGM_TIME_ALARM	0x6f
 #define RTAS_TYPE_PMGM_CONFIG_CHANGE	0x70
 #define RTAS_TYPE_PMGM_SERVICE_PROC	0x71
+/* Platform Resource Reassignment Notification */
+#define RTAS_TYPE_PRRN			0xA0
 
 /* RTAS check-exception vector offset */
 #define RTAS_VECTOR_EXTERNAL_INTERRUPT	0x500
Index: powerpc/arch/powerpc/kernel/rtasd.c
===================================================================
--- powerpc.orig/arch/powerpc/kernel/rtasd.c	2013-03-08 19:23:06.000000000 -0600
+++ powerpc/arch/powerpc/kernel/rtasd.c	2013-03-08 19:56:48.000000000 -0600
@@ -87,6 +87,8 @@ 
 			return "Resource Deallocation Event";
 		case RTAS_TYPE_DUMP:
 			return "Dump Notification Event";
+		case RTAS_TYPE_PRRN:
+			return "Platform Resource Reassignment Event";
 	}
 
 	return rtas_type[0];
@@ -265,7 +267,38 @@ 
 		spin_unlock_irqrestore(&rtasd_log_lock, s);
 		return;
 	}
+}
+
+static s32 update_scope;
+
+static void prrn_work_fn(struct work_struct *work)
+{
+	/*
+	 * For PRRN, we must pass the negative of the scope value in
+	 * the RTAS event.
+	 */
+	pseries_devicetree_update(-update_scope);
+}
+static DECLARE_WORK(prrn_work, prrn_work_fn);
+
+void prrn_schedule_update(u32 scope)
+{
+	flush_work(&prrn_work);
+	update_scope = scope;
+	schedule_work(&prrn_work);
+}
+
+static void pseries_handle_event(const struct rtas_error_log *log)
+{
+	pSeries_log_error((char *)log, ERR_TYPE_RTAS_LOG, 0);
+
+	if (log->type == RTAS_TYPE_PRRN)
+		/* For PRRN Events the extended log length is used to denote
+		 * the scope for calling rtas update-nodes.
+		 */
+		prrn_schedule_update(log->extended_log_length);
 
+	return;
 }
 
 static int rtas_log_open(struct inode * inode, struct file * file)
@@ -389,7 +422,7 @@ 
 		}
 
 		if (error == 0)
-			pSeries_log_error(logdata, ERR_TYPE_RTAS_LOG, 0);
+			pseries_handle_event((struct rtas_error_log *)logdata);
 
 	} while(error == 0);
 }