Re: [PATCH v3 2/3] powerpc/pseries: Introduce memory hotplug READD operation

[Nathan Fontenot]

On 01/06/2017 01:27 PM, John Allen wrote:
> Currently, memory must be hot removed and subsequently re-added in order
> to dynamically update the affinity of LMBs specified by a PRRN event.
> Earlier implementations of the PRRN event handler ran into issues in which
> the hot remove would occur successfully, but a hotplug event would be
> initiated from another source and grab the hotplug lock preventing the hot
> add from occurring. To prevent this situation, this patch introduces the
> notion of a hot "readd" action for memory which atomizes a hot remove and
> a hot add into a single, serialized operation on the hotplug queue.
> 
> Signed-off-by: John Allen 

Reviewed-by: Nathan Fontenot 

> ---
> diff --git a/arch/powerpc/include/asm/rtas.h b/arch/powerpc/include/asm/rtas.h
> index 9c23baa..076b892 100644
> --- a/arch/powerpc/include/asm/rtas.h
> +++ b/arch/powerpc/include/asm/rtas.h
> @@ -318,6 +318,7 @@ struct pseries_hp_errorlog {
> 
>  #define PSERIES_HP_ELOG_ACTION_ADD   1
>  #define PSERIES_HP_ELOG_ACTION_REMOVE2
> +#define PSERIES_HP_ELOG_ACTION_READD 3
> 
>  #define PSERIES_HP_ELOG_ID_DRC_NAME  1
>  #define PSERIES_HP_ELOG_ID_DRC_INDEX 2
> diff --git a/arch/powerpc/platforms/pseries/hotplug-memory.c 
> b/arch/powerpc/platforms/pseries/hotplug-memory.c
> index 0eb4b1d..06f10a8 100644
> --- a/arch/powerpc/platforms/pseries/hotplug-memory.c
> +++ b/arch/powerpc/platforms/pseries/hotplug-memory.c
> @@ -560,6 +560,44 @@ static int dlpar_memory_remove_by_index(u32 drc_index, 
> struct property *prop)
>   return rc;
>  }
> 
> +static int dlpar_memory_readd_by_index(u32 drc_index, struct property *prop)
> +{
> + struct of_drconf_cell *lmbs;
> + u32 num_lmbs, *p;
> + int lmb_found;
> + int i, rc;
> +
> + pr_info("Attempting to update LMB, drc index %x\n", drc_index);
> +
> + p = prop->value;
> + num_lmbs = *p++;
> + lmbs = (struct of_drconf_cell *)p;
> +
> + lmb_found = 0;
> + for (i = 0; i < num_lmbs; i++) {
> + if (lmbs[i].drc_index == drc_index) {
> + lmb_found = 1;
> + rc = dlpar_remove_lmb([i]);
> + if (!rc) {
> + rc = dlpar_add_lmb([i]);
> + if (rc)
> + dlpar_release_drc(lmbs[i].drc_index);
> + }
> + break;
> + }
> + }
> +
> + if (!lmb_found)
> + rc = -EINVAL;
> +
> + if (rc)
> + pr_info("Failed to update memory at %llx\n",
> + lmbs[i].base_addr);
> + else
> + pr_info("Memory at %llx was updated\n", lmbs[i].base_addr);
> +
> + return rc;
> +}
>  #else
>  static inline int pseries_remove_memblock(unsigned long base,
> unsigned int memblock_size)
> @@ -776,6 +814,9 @@ int dlpar_memory(struct pseries_hp_errorlog *hp_elog)
>   else
>   rc = -EINVAL;
>   break;
> + case PSERIES_HP_ELOG_ACTION_READD:
> + rc = dlpar_memory_readd_by_index(drc_index, prop);
> + break;
>   default:
>   pr_err("Invalid action (%d) specified\n", hp_elog->action);
>   rc = -EINVAL;
> 

[PATCH v3 2/3] powerpc/pseries: Introduce memory hotplug READD operation

[John Allen]

Currently, memory must be hot removed and subsequently re-added in order
to dynamically update the affinity of LMBs specified by a PRRN event.
Earlier implementations of the PRRN event handler ran into issues in which
the hot remove would occur successfully, but a hotplug event would be
initiated from another source and grab the hotplug lock preventing the hot
add from occurring. To prevent this situation, this patch introduces the
notion of a hot "readd" action for memory which atomizes a hot remove and
a hot add into a single, serialized operation on the hotplug queue.

Signed-off-by: John Allen 
---
diff --git a/arch/powerpc/include/asm/rtas.h b/arch/powerpc/include/asm/rtas.h
index 9c23baa..076b892 100644
--- a/arch/powerpc/include/asm/rtas.h
+++ b/arch/powerpc/include/asm/rtas.h
@@ -318,6 +318,7 @@ struct pseries_hp_errorlog {

 #define PSERIES_HP_ELOG_ACTION_ADD 1
 #define PSERIES_HP_ELOG_ACTION_REMOVE  2
+#define PSERIES_HP_ELOG_ACTION_READD   3

 #define PSERIES_HP_ELOG_ID_DRC_NAME1
 #define PSERIES_HP_ELOG_ID_DRC_INDEX   2
diff --git a/arch/powerpc/platforms/pseries/hotplug-memory.c 
b/arch/powerpc/platforms/pseries/hotplug-memory.c
index 0eb4b1d..06f10a8 100644
--- a/arch/powerpc/platforms/pseries/hotplug-memory.c
+++ b/arch/powerpc/platforms/pseries/hotplug-memory.c
@@ -560,6 +560,44 @@ static int dlpar_memory_remove_by_index(u32 drc_index, 
struct property *prop)
return rc;
 }

+static int dlpar_memory_readd_by_index(u32 drc_index, struct property *prop)
+{
+   struct of_drconf_cell *lmbs;
+   u32 num_lmbs, *p;
+   int lmb_found;
+   int i, rc;
+
+   pr_info("Attempting to update LMB, drc index %x\n", drc_index);
+
+   p = prop->value;
+   num_lmbs = *p++;
+   lmbs = (struct of_drconf_cell *)p;
+
+   lmb_found = 0;
+   for (i = 0; i < num_lmbs; i++) {
+   if (lmbs[i].drc_index == drc_index) {
+   lmb_found = 1;
+   rc = dlpar_remove_lmb([i]);
+   if (!rc) {
+   rc = dlpar_add_lmb([i]);
+   if (rc)
+   dlpar_release_drc(lmbs[i].drc_index);
+   }
+   break;
+   }
+   }
+
+   if (!lmb_found)
+   rc = -EINVAL;
+
+   if (rc)
+   pr_info("Failed to update memory at %llx\n",
+   lmbs[i].base_addr);
+   else
+   pr_info("Memory at %llx was updated\n", lmbs[i].base_addr);
+
+   return rc;
+}
 #else
 static inline int pseries_remove_memblock(unsigned long base,
  unsigned int memblock_size)
@@ -776,6 +814,9 @@ int dlpar_memory(struct pseries_hp_errorlog *hp_elog)
else
rc = -EINVAL;
break;
+   case PSERIES_HP_ELOG_ACTION_READD:
+   rc = dlpar_memory_readd_by_index(drc_index, prop);
+   break;
default:
pr_err("Invalid action (%d) specified\n", hp_elog->action);
rc = -EINVAL;