powerpc/pseries: Implement indexed-count hotplug memory remove

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

Signed-off-by: Sahil Mehta <sahilmehta17@gmail.com>
Signed-off-by: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

diff --git a/arch/powerpc/platforms/pseries/hotplug-memory.c b/arch/powerpc/platforms/pseries/hotplug-memory.c
index ad8b3a606a8e92e3ae707996b3a06937d4156f51..e28abfa013e523275a3213710ccb31cf8c7a721f 100644 (file)
--- a/arch/powerpc/platforms/pseries/hotplug-memory.c
+++ b/arch/powerpc/platforms/pseries/hotplug-memory.c
@@ -601,6 +601,94 @@ static int dlpar_memory_readd_by_index(u32 drc_index, struct property *prop)
 
        return rc;
 }
+
+static int dlpar_memory_remove_by_ic(u32 lmbs_to_remove, u32 drc_index,
+                                    struct property *prop)
+{
+       struct of_drconf_cell *lmbs;
+       u32 num_lmbs, *p;
+       int i, rc, start_lmb_found;
+       int lmbs_available = 0, start_index = 0, end_index;
+
+       pr_info("Attempting to hot-remove %u LMB(s) at %x\n",
+               lmbs_to_remove, drc_index);
+
+       if (lmbs_to_remove == 0)
+               return -EINVAL;
+
+       p = prop->value;
+       num_lmbs = *p++;
+       lmbs = (struct of_drconf_cell *)p;
+       start_lmb_found = 0;
+
+       /* Navigate to drc_index */
+       while (start_index < num_lmbs) {
+               if (lmbs[start_index].drc_index == drc_index) {
+                       start_lmb_found = 1;
+                       break;
+               }
+
+               start_index++;
+       }
+
+       if (!start_lmb_found)
+               return -EINVAL;
+
+       end_index = start_index + lmbs_to_remove;
+
+       /* 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_remove)
+               return -EINVAL;
+
+       for (i = start_index; i < end_index; i++) {
+               if (!(lmbs[i].flags & DRCONF_MEM_ASSIGNED))
+                       continue;
+
+               rc = dlpar_remove_lmb(&lmbs[i]);
+               if (rc)
+                       break;
+
+               lmbs[i].reserved = 1;
+       }
+
+       if (rc) {
+               pr_err("Memory indexed-count-remove failed, adding any removed LMBs\n");
+
+               for (i = start_index; i < end_index; i++) {
+                       if (!lmbs[i].reserved)
+                               continue;
+
+                       rc = dlpar_add_lmb(&lmbs[i]);
+                       if (rc)
+                               pr_err("Failed to add LMB, drc index %x\n",
+                                      be32_to_cpu(lmbs[i].drc_index));
+
+                       lmbs[i].reserved = 0;
+               }
+               rc = -EINVAL;
+       } else {
+               for (i = start_index; i < end_index; i++) {
+                       if (!lmbs[i].reserved)
+                               continue;
+
+                       dlpar_release_drc(lmbs[i].drc_index);
+                       pr_info("Memory at %llx (drc index %x) was hot-removed\n",
+                               lmbs[i].base_addr, lmbs[i].drc_index);
+
+                       lmbs[i].reserved = 0;
+               }
+       }
+
+       return rc;
+}
+
 #else
 static inline int pseries_remove_memblock(unsigned long base,
                                          unsigned int memblock_size)
@@ -632,6 +720,12 @@ static int dlpar_memory_readd_by_index(u32 drc_index, struct property *prop)
 {
        return -EOPNOTSUPP;
 }
+
+static int dlpar_memory_remove_by_ic(u32 lmbs_to_remove, u32 drc_index,
+                                    struct property *prop)
+{
+       return -EOPNOTSUPP;
+}
 #endif /* CONFIG_MEMORY_HOTREMOVE */
 
 static int dlpar_add_lmb(struct of_drconf_cell *lmb)
@@ -915,6 +1009,10 @@ int dlpar_memory(struct pseries_hp_errorlog *hp_elog)
                } 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 if (hp_elog->id_type == PSERIES_HP_ELOG_ID_DRC_IC) {
+                       count = hp_elog->_drc_u.ic.count;
+                       drc_index = hp_elog->_drc_u.ic.index;
+                       rc = dlpar_memory_remove_by_ic(count, drc_index, prop);
                } else {
                        rc = -EINVAL;
                }