On 04/24/2018 04:33 PM, Michael Bringmann wrote: > See comments below: > > On 04/24/2018 11:56 AM, Nathan Fontenot wrote: >> On 02/26/2018 02:52 PM, Michael Bringmann wrote: >>> hotplug/mobility: Recognize more changes to the associativity of >>> memory blocks described by the 'ibm,dynamic-memory' and 'cpu' >>> properties when processing the topology of LPARS in Post Migration >>> events. Previous efforts only recognized whether a memory block's >>> assignment had changed in the property. Changes here include: >>> >>> * Checking the aa_index values of the old/new properties and 'readd' >>> any block for which the setting has changed. >>> * Checking for changes in cpu associativity and making 'readd' calls >>> when differences are observed. >> >> As part of the post-migration updates do you need to hold a lock >> so that we don't attempt to process any of the cpu/memory changes >> while the device tree is being updated? >> >> You may be able to grab the device hotplug lock for this. > > The CPU Re-add process reuses the dlpar_cpu_remove / dlpar_cpu_add > code for POWERPC. These functions end up invoking device_online() / > device_offline() which in turn end up invoking the 'cpus_write_lock/unlock' > around every kernel change to the CPU structures. It was modeled > on the Memory Re-add process as we discussed a while back, which > also uses device_online and a corresponding write lock for each > LMB processed. > > Do you see a need for a coarser granularity of locking around > all or a group of the cpu/memory changes? The data structures > that the kernel outside of powerpc uses for CPUs and LMBs seem > to be quite well isolated from the device-tree properties.
My thinking was for memory and CPU updates, the idea being that all updates are queued up until after the post-LPM device tree updates happens. Grabbing the device_hotplug lock while updating the device tree would prevent any of the queued CPU/memory updates from happening. > >> >>> >>> Signed-off-by: Michael Bringmann <m...@linux.vnet.ibm.com> >>> --- >>> Changes in RFC: >>> -- Simplify code to update CPU nodes during mobility checks. >>> Remove functions to generate extra HP_ELOG messages in favor >>> of direct function calls to dlpar_cpu_readd_by_index. >>> -- Move check for "cpu" node type from pseries_update_cpu to >>> pseries_smp_notifier in 'hotplug-cpu.c' >>> -- Remove functions 'pseries_memory_readd_by_index' and >>> 'pseries_cpu_readd_by_index' as no longer needed outside of >>> 'mobility.c'. >>> --- >>> arch/powerpc/platforms/pseries/hotplug-cpu.c | 69 >>> +++++++++++++++++++++++ >>> arch/powerpc/platforms/pseries/hotplug-memory.c | 6 ++ >>> 2 files changed, 75 insertions(+) >>> >>> diff --git a/arch/powerpc/platforms/pseries/hotplug-cpu.c >>> b/arch/powerpc/platforms/pseries/hotplug-cpu.c >>> index a7d14aa7..91ef22a 100644 >>> --- a/arch/powerpc/platforms/pseries/hotplug-cpu.c >>> +++ b/arch/powerpc/platforms/pseries/hotplug-cpu.c >>> @@ -636,6 +636,27 @@ static int dlpar_cpu_remove_by_index(u32 drc_index) >>> return rc; >>> } >>> >>> +static int dlpar_cpu_readd_by_index(u32 drc_index) >>> +{ >>> + int rc = 0; >>> + >>> + pr_info("Attempting to update CPU, drc index %x\n", drc_index); >> >> Should make this say we are re-adding the CPU, it's a bit more specific as >> to what is really happening. > > Okay. I will update the notice from dlpar_memory_readd_by_index, as well. Looks like your current message mirrors what the memory readd routine has, let's just keep the message as is. -Nathan >> >>> + >>> + if (dlpar_cpu_remove_by_index(drc_index)) >>> + rc = -EINVAL; >>> + else if (dlpar_cpu_add(drc_index)) >>> + rc = -EINVAL; >>> + >>> + if (rc) >>> + pr_info("Failed to update cpu at drc_index %lx\n", >>> + (unsigned long int)drc_index); >>> + else >>> + pr_info("CPU at drc_index %lx was updated\n", >>> + (unsigned long int)drc_index); >>> + >>> + return rc; >>> +} >>> + >>> static int find_dlpar_cpus_to_remove(u32 *cpu_drcs, int cpus_to_remove) >>> { >>> struct device_node *dn; >>> @@ -826,6 +847,9 @@ int dlpar_cpu(struct pseries_hp_errorlog *hp_elog) >>> else >>> rc = -EINVAL; >>> break; >>> + case PSERIES_HP_ELOG_ACTION_READD: >>> + rc = dlpar_cpu_readd_by_index(drc_index); >>> + break; >>> default: >>> pr_err("Invalid action (%d) specified\n", hp_elog->action); >>> rc = -EINVAL; >>> @@ -876,12 +900,53 @@ static ssize_t dlpar_cpu_release(const char *buf, >>> size_t count) >>> >>> #endif /* CONFIG_ARCH_CPU_PROBE_RELEASE */ >>> >>> +static int pseries_update_cpu(struct of_reconfig_data *pr) >>> +{ >>> + u32 old_entries, new_entries; >>> + __be32 *p, *old_assoc, *new_assoc; >>> + int rc = 0; >>> + >>> + /* So far, we only handle the 'ibm,associativity' property, >>> + * here. >>> + * The first int of the property is the number of domains >>> + * described. This is followed by an array of level values. >>> + */ >>> + p = (__be32 *) pr->old_prop->value; >>> + if (!p) >>> + return -EINVAL; >>> + old_entries = be32_to_cpu(*p++); >>> + old_assoc = p; >>> + >>> + p = (__be32 *)pr->prop->value; >>> + if (!p) >>> + return -EINVAL; >>> + new_entries = be32_to_cpu(*p++); >>> + new_assoc = p; >>> + >>> + if (old_entries == new_entries) { >>> + int sz = old_entries * sizeof(int); >>> + >>> + if (!memcmp(old_assoc, new_assoc, sz)) >>> + rc = dlpar_cpu_readd_by_index( >>> + be32_to_cpu(pr->dn->phandle)); >>> + >>> + } else { >>> + rc = dlpar_cpu_readd_by_index( >>> + be32_to_cpu(pr->dn->phandle)); >>> + } >>> + >>> + return rc; >>> +} >> >> Do we need to do the full compare of the new vs. the old affinity property? >> >> I would think we would only get an updated property if the property changes. >> We don't care what changes in the property at this point, only that it >> changed. >> You could just call dlpar_cpu_readd_by_index() directly. > > Okay. > >> >> -Nathan > > Thanks. > Michael > >> >>> + >>> static int pseries_smp_notifier(struct notifier_block *nb, >>> unsigned long action, void *data) >>> { >>> struct of_reconfig_data *rd = data; >>> int err = 0; >>> >>> + if (strcmp(rd->dn->type, "cpu")) >>> + return notifier_from_errno(err); >>> + >>> switch (action) { >>> case OF_RECONFIG_ATTACH_NODE: >>> err = pseries_add_processor(rd->dn); >>> @@ -889,6 +954,10 @@ static int pseries_smp_notifier(struct notifier_block >>> *nb, >>> case OF_RECONFIG_DETACH_NODE: >>> pseries_remove_processor(rd->dn); >>> break; >>> + case OF_RECONFIG_UPDATE_PROPERTY: >>> + if (!strcmp(rd->prop->name, "ibm,associativity")) >>> + err = pseries_update_cpu(rd); >>> + break; >>> } >>> return notifier_from_errno(err); >>> } >>> diff --git a/arch/powerpc/platforms/pseries/hotplug-memory.c >>> b/arch/powerpc/platforms/pseries/hotplug-memory.c >>> index c1578f5..2341eae 100644 >>> --- a/arch/powerpc/platforms/pseries/hotplug-memory.c >>> +++ b/arch/powerpc/platforms/pseries/hotplug-memory.c >>> @@ -1040,6 +1040,12 @@ static int pseries_update_drconf_memory(struct >>> of_reconfig_data *pr) >>> memblock_size); >>> rc = (rc < 0) ? -EINVAL : 0; >>> break; >>> + } else if ((be32_to_cpu(old_drmem[i].aa_index) != >>> + be32_to_cpu(new_drmem[i].aa_index)) && >>> + (be32_to_cpu(new_drmem[i].flags) & >>> + DRCONF_MEM_ASSIGNED)) { >>> + rc = dlpar_memory_readd_by_index( >>> + be32_to_cpu(new_drmem[i].drc_index))> >>> } >>> } >>> return rc; >>> >> >