[PATCH v2 5/6] pseries: Implement memory hotplug add in the kernel
Nathan Fontenot
nfont at linux.vnet.ibm.com
Tue Nov 25 01:56:38 AEDT 2014
On 11/21/2014 01:49 AM, Cyril Bur wrote:
>
> On Mon, 2014-11-17 at 15:54 -0600, Nathan Fontenot wrote:
>> Move handling of memory hotplug add on pseries completely into the kernel.
>>
>> The current memory hotplug add path involves the drmgr command doing part
>> of this work in userspace and requesting the kernel to do additional pieces.
>> This patch allows us to handle the act completely in the kernel via rtas
>> hotplug events. This allows us to perform the operation faster and provide
>> a common memory hotplug add path for PowerVM and PowerKVM systems.
>>
>> The patch does introduce a static rtas_hp_event variable that is set to
>> true when updating the device tree during memory hotplug initiated from
>> a rtas hotplug event. This is needed because we do not need to do the
>> work in the of notifier, this work is already performed in handling the
>> hotplug request. At a later time we can remove this when we deprecate the
>> previous method of memory hotplug.
>>
>> Signed-off-by: Nathan Fontenot <nfont at linux.vnet.ibm.com>
>> ---
>> arch/powerpc/platforms/pseries/hotplug-memory.c | 244 +++++++++++++++++++++++
>> 1 file changed, 243 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/powerpc/platforms/pseries/hotplug-memory.c b/arch/powerpc/platforms/pseries/hotplug-memory.c
>> index 69d178b..b57d42b 100644
>> --- a/arch/powerpc/platforms/pseries/hotplug-memory.c
>> +++ b/arch/powerpc/platforms/pseries/hotplug-memory.c
>> @@ -16,6 +16,7 @@
>> #include <linux/memblock.h>
>> #include <linux/memory.h>
>> #include <linux/memory_hotplug.h>
>> +#include <linux/slab.h>
>>
>> #include <asm/firmware.h>
>> #include <asm/machdep.h>
>> @@ -23,6 +24,8 @@
>> #include <asm/sparsemem.h>
>> #include "pseries.h"
>>
>> +static bool rtas_hp_event;
>> +
>> unsigned long pseries_memory_block_size(void)
>> {
>> struct device_node *np;
>> @@ -66,6 +69,52 @@ unsigned long pseries_memory_block_size(void)
>> return memblock_size;
>> }
>>
>> +static void dlpar_free_drconf_property(struct property *prop)
>> +{
>> + kfree(prop->name);
>> + kfree(prop->value);
>> + kfree(prop);
>> +}
>> +
>> +static struct property *dlpar_clone_drconf_property(struct device_node *dn)
>> +{
>> + struct property *prop, *new_prop;
>> +
>> + prop = of_find_property(dn, "ibm,dynamic-memory", NULL);
>> + if (!prop)
>> + return NULL;
>> +
>> + new_prop = kzalloc(sizeof(*new_prop), GFP_KERNEL);
>> + if (!new_prop)
>> + return NULL;
>> +
>> + new_prop->name = kstrdup(prop->name, GFP_KERNEL);
>> + new_prop->value = kmalloc(prop->length, GFP_KERNEL);
>> + if (!new_prop->name || !new_prop->value) {
>> + dlpar_free_drconf_property(new_prop);
>> + return NULL;
>> + }
>> +
>> + memcpy(new_prop->value, prop->value, prop->length);
>> + new_prop->length = prop->length;
>> +
>> + return new_prop;
>> +}
>> +
>> +static struct memory_block *lmb_to_memblock(struct of_drconf_cell *lmb)
>> +{
>> + unsigned long section_nr;
>> + struct mem_section *mem_sect;
>> + struct memory_block *mem_block;
>> + u64 phys_addr = be64_to_cpu(lmb->base_addr);
>> +
>> + section_nr = pfn_to_section_nr(PFN_DOWN(phys_addr));
>> + mem_sect = __nr_to_section(section_nr);
>> +
>> + mem_block = find_memory_block(mem_sect);
>> + return mem_block;
>> +}
>> +
>> #ifdef CONFIG_MEMORY_HOTREMOVE
>> static int pseries_remove_memblock(unsigned long base, unsigned int memblock_size)
>> {
>> @@ -136,19 +185,209 @@ static inline int pseries_remove_mem_node(struct device_node *np)
>> }
>> #endif /* CONFIG_MEMORY_HOTREMOVE */
>>
>> +static int dlpar_add_lmb(struct of_drconf_cell *lmb)
>> +{
>> + struct memory_block *mem_block;
>> + u64 phys_addr;
>> + uint32_t drc_index;
> I started commenting this and it turns out you've used uint32_t almost
> everywhere for values you've pulled from the device tree or the elog.
> These should be u32.
ok, that should be an easy fix.
>> + unsigned long pages_per_block;
>> + unsigned long block_sz;
>> + int nid, sections_per_block;
>> + int rc;
>> +
>> + if (be32_to_cpu(lmb->flags) & DRCONF_MEM_ASSIGNED)
>> + return -EINVAL;
>> +
>> + phys_addr = be64_to_cpu(lmb->base_addr);
>> + drc_index = be32_to_cpu(lmb->drc_index);
>> + block_sz = memory_block_size_bytes();
>> + sections_per_block = block_sz / MIN_MEMORY_BLOCK_SIZE;
>> + pages_per_block = PAGES_PER_SECTION * sections_per_block;
>> +
> Perhaps I'm being a bit slow here but it isn't exactly clear what you're
> getting with all those variables and could you explain what that
> statement below is checking for?
>
>> + if (phys_addr & ((pages_per_block << PAGE_SHIFT) - 1))
>> + return -EINVAL;
We could probably get rid of this check, The values were are validating
come from the device tree and if it's wrong we have more serious problems
than a failure in mem hotplug.
This would also remove the need for the pages_per_block and sections_per_block
variables.
>> +
>> + rc = dlpar_acquire_drc(drc_index);
>> + if (rc)
>> + return rc;
>> +
>> + /* Find the node id for this address */
>> + nid = memory_add_physaddr_to_nid(phys_addr);
>> +
>> + /* Add the memory */
>> + rc = add_memory(nid, phys_addr, block_sz);
>> + if (rc) {
>> + dlpar_release_drc(drc_index);
>> + return rc;
>> + }
>> +
>> + /* Register this block of memory */
>> + rc = memblock_add(phys_addr, block_sz);
>> + if (rc) {
>> + remove_memory(nid, phys_addr, block_sz);
>> + dlpar_release_drc(drc_index);
>> + return rc;
>> + }
>> +
>> + mem_block = lmb_to_memblock(lmb);
>> + if (!mem_block) {
>> + remove_memory(nid, phys_addr, block_sz);
>> + dlpar_release_drc(drc_index);
>> + return -EINVAL;
>> + }
>> +
>> + rc = device_online(&mem_block->dev);
>> + put_device(&mem_block->dev);
>> + if (rc) {
>> + remove_memory(nid, phys_addr, block_sz);
>> + dlpar_release_drc(drc_index);
>> + return rc;
>> + }
>> +
>> + lmb->flags |= cpu_to_be32(DRCONF_MEM_ASSIGNED);
>> + return 0;
>> +}
>> +
>> +static int dlpar_memory_add_by_count(struct pseries_hp_errorlog *hp_elog,
>> + struct property *prop)
>> +{
>> + struct of_drconf_cell *lmbs;
>> + uint32_t num_lmbs;
>> + __be32 *p;
>> + int i, lmbs_to_add;
>> + int lmbs_available = 0;
>> + int lmbs_added = 0;
>> + int rc;
>> +
>> + lmbs_to_add = be32_to_cpu(hp_elog->_drc_u.drc_count);
> Didn't you already do the endian conversion back in
> handle_dlpar_errorlog?
Yep, already fixed in the next patchset.
>> + pr_info("Attempting to hot-add %d LMB(s)\n", lmbs_to_add);
>> +
>> + if (lmbs_to_add == 0)
>> + return -EINVAL;
>> +
>> + p = prop->value;
>> + num_lmbs = be32_to_cpu(*p++);
>> + lmbs = (struct of_drconf_cell *)p;
>> +
>> + /* Validate that there are enough LMBs to satisfy the request */
>> + for (i = 0; i < num_lmbs; i++) {
>> + if (!(be32_to_cpu(lmbs[i].flags) & DRCONF_MEM_ASSIGNED))
>> + lmbs_available++;
>> + }
>> +
>> + if (lmbs_available < lmbs_to_add)
>> + return -EINVAL;
>> +
> I'm wondering why the next 3 lines when the if could be incorporated
> into the for condition
> for (i = 0; i < num_lmbs && lmbs_to_add != lmbs_added; i++) {
> (or lmbs_to_add < lmbs_added)...
It could. I tend to put less in the for() statement. Just my preference on
readability.
>> + for (i = 0; i < num_lmbs; i++) {
>> + if (lmbs_to_add == lmbs_added)
>> + break;
>> +
>> + rc = dlpar_add_lmb(&lmbs[i]);
>> + if (rc)
>> + continue;
>> +
>> + lmbs_added++;
>> + pr_info("Memory at %llx (drc index %x) has been hot-added\n",
>> + be64_to_cpu(lmbs[i].base_addr),
>> + be32_to_cpu(lmbs[i].drc_index));
> This message feels a tad premature, you're going to roll back if the
> requested amount couldn't be added which is good but then there's going
> to be a confusing mix of 'hot-added' followed by 'hot-removed'. Could
> this message be moved to when you clear the reserved fields?
Ahh... good point. I will do that.
>> +
>> + /* Mark this lmb so we can remove it later if all of the
>> + * requested LMBs cannot be added.
>> + */
>> + lmbs[i].reserved = 1;
> Writing 1 like that into a __be variable will upset sparse.
>
> As a more general comment that it might be worth not passing around __be
> structures and convert them all into CPU endian in one place so that all
> these functions can do away with the endian conversion calls.
This may be possible. I will have to look at how the struct is passed around
what is used in it. It would be nice to have fewer conversion calls.
>> + }
>> +
>> + if (lmbs_added != lmbs_to_add) {
>> + /* TODO: remove added lmbs */
>> + rc = -EINVAL;
>> + }
>> +
>> + /* Clear the reserved fields */
>> + for (i = 0; i < num_lmbs; i++)
>> + lmbs[i].reserved = 0;
>> +
>> + return rc;
>> +}
>> +
>> +static int dlpar_memory_add_by_index(struct pseries_hp_errorlog *hp_elog,
>> + struct property *prop)
>> +{
>> + struct of_drconf_cell *lmbs;
>> + uint32_t num_lmbs, drc_index;
>> + __be32 *p;
>> + int i, lmb_found;
>> + int rc;
>> +
>> + drc_index = be32_to_cpu(hp_elog->_drc_u.drc_index);
> Didn't you already do the endian conversion back in
> handle_dlpar_errorlog?
>> + pr_info("Attempting to hot-add LMB, drc index %x\n", drc_index);
>> +
>> + p = prop->value;
>> + num_lmbs = be32_to_cpu(*p++);
>> + lmbs = (struct of_drconf_cell *)p;
>> +
>> + lmb_found = 0;
>> + for (i = 0; i < num_lmbs; i++) {
>> + if (lmbs[i].drc_index == hp_elog->_drc_u.drc_index) {
> Probably wanted to use your local variable drc_index here also
> lmbs[i].drc_index is __be and I don't think you've converted it but the
> other side of the condition has been...
Yep.
-Nathan
>> + lmb_found = 1;
>> + rc = dlpar_add_lmb(&lmbs[i]);
>> + break;
>> + }
>> + }
>> +
>> + if (!lmb_found)
>> + rc = -EINVAL;
>> +
>> + if (rc)
>> + pr_info("Failed to hot-add memory, drc index %x\n", drc_index);
>> + else
>> + pr_info("Memory at %llx (drc index %x) has been hot-added\n",
>> + be64_to_cpu(lmbs[i].base_addr), drc_index);
>> +
>> + return rc;
>> +}
>> +
>> int dlpar_memory(struct pseries_hp_errorlog *hp_elog)
>> {
>> - int rc = 0;
>> + struct device_node *dn;
>> + struct property *prop;
>> + int rc;
>>
>> lock_device_hotplug();
>>
>> + dn = of_find_node_by_path("/ibm,dynamic-reconfiguration-memory");
>> + if (!dn)
>> + return -EINVAL;
>> +
>> + prop = dlpar_clone_drconf_property(dn);
>> + if (!prop) {
>> + of_node_put(dn);
>> + return -EINVAL;
>> + }
>> +
>> switch (hp_elog->action) {
>> + case PSERIES_HP_ELOG_ACTION_ADD:
>> + if (hp_elog->id_type == PSERIES_HP_ELOG_ID_DRC_COUNT)
>> + rc = dlpar_memory_add_by_count(hp_elog, prop);
>> + else if (hp_elog->id_type == PSERIES_HP_ELOG_ID_DRC_INDEX)
>> + rc = dlpar_memory_add_by_index(hp_elog, prop);
>> + else
>> + rc = -EINVAL;
>> + break;
>> default:
>> pr_err("Invalid action (%d) specified\n", hp_elog->action);
>> rc = -EINVAL;
>> break;
>> }
>>
>> + if (rc)
>> + dlpar_free_drconf_property(prop);
>> + else {
>> + rtas_hp_event = true;
>> + of_update_property(dn, prop);
>> + rtas_hp_event = false;
>> + }
>> +
>> + of_node_put(dn);
>> unlock_device_hotplug();
>> return rc;
>> }
>> @@ -193,6 +432,9 @@ static int pseries_update_drconf_memory(struct of_prop_reconfig *pr)
>> __be32 *p;
>> int i, rc = -EINVAL;
>>
>> + if (rtas_hp_event)
>> + return 0;
>> +
>> memblock_size = pseries_memory_block_size();
>> if (!memblock_size)
>> return -EINVAL;
>>
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>> Linuxppc-dev at lists.ozlabs.org
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>
>
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