On Mon, 2014-09-15 at 15:32 -0500, Nathan Fontenot wrote:
> This patch adds the ability to do memory hotplug adding in the kernel.
>
> Currently the hotplug add/remove of memory is handled by the drmgr
> command. The drmgr command performs the add/remove by performing
> some work in user-space and making requests to the kernel to handle
> other pieces. By moving all of the work to the kernel we can do the
> add and remove faster, and provide a common place to do memory hotplug
> for both the PowerVM and PowerKVM environments.
>
> Signed-off-by: Nathan Fontenot <nf...@linux.vnet.ibm.com>
> ---
> arch/powerpc/platforms/pseries/hotplug-memory.c | 170
> +++++++++++++++++++++++
> 1 file changed, 170 insertions(+)
>
> diff --git a/arch/powerpc/platforms/pseries/hotplug-memory.c
> b/arch/powerpc/platforms/pseries/hotplug-memory.c
> index 0e60e15..b254773 100644
> --- a/arch/powerpc/platforms/pseries/hotplug-memory.c
> +++ b/arch/powerpc/platforms/pseries/hotplug-memory.c
> @@ -17,6 +17,7 @@
> #include <linux/vmalloc.h>
> #include <linux/memory.h>
> #include <linux/memory_hotplug.h>
> +#include <linux/slab.h>
>
> #include <asm/firmware.h>
> #include <asm/machdep.h>
> @@ -24,6 +25,8 @@
> #include <asm/sparsemem.h>
> #include <asm/rtas.h>
>
> +#include "pseries.h"
> +
> DEFINE_MUTEX(dlpar_mem_mutex);
>
> unsigned long pseries_memory_block_size(void)
> @@ -69,6 +72,53 @@ 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 + 1, 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;
> + *(((char *)new_prop->value) + new_prop->length) = 0;
It's not a string, is it?
> + 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_memory(u64 start, u64 size)
> {
> @@ -155,13 +205,133 @@ static inline int pseries_remove_mem_node(struct
> device_node *np)
> }
> #endif /* CONFIG_MEMORY_HOTREMOVE */
>
> +static int dlpar_add_one_lmb(struct of_drconf_cell *lmb)
> +{
> + struct memory_block *mem_block;
> + u64 phys_addr;
> + unsigned long pages_per_block;
> + unsigned long block_sz;
> + int nid, sections_per_block;
> + int rc;
> +
> + phys_addr = be64_to_cpu(lmb->base_addr);
of_drconf_cell needs endian annotations.
> + block_sz = memory_block_size_bytes();
> + sections_per_block = block_sz / MIN_MEMORY_BLOCK_SIZE;
> + pages_per_block = PAGES_PER_SECTION * sections_per_block;
> +
> + if (phys_addr & ((pages_per_block << PAGE_SHIFT) - 1))
> + return -EINVAL;
> +
> + nid = memory_add_physaddr_to_nid(phys_addr);
> + rc = add_memory(nid, phys_addr, block_sz);
> + if (rc)
> + return rc;
> +
> + rc = memblock_add(phys_addr, block_sz);
> + if (rc) {
> + remove_memory(nid, phys_addr, block_sz);
> + return rc;
> + }
> +
> + mem_block = lmb_to_memblock(lmb);
> + if (!mem_block) {
> + remove_memory(nid, phys_addr, block_sz);
> + return -EINVAL;
> + }
That could all use a lot of comments. ie. why do we have to add it twice?
> + rc = device_online(&mem_block->dev);
> + put_device(&mem_block->dev);
> + if (rc)
> + remove_memory(nid, phys_addr, block_sz);
> +
> + return rc;
> +}
> +
> +static int dlpar_memory_add(struct pseries_hp_errorlog *hp_elog)
> +{
> + struct of_drconf_cell *lmb;
> + struct device_node *dn;
> + struct property *prop;
> + uint32_t entries, *p;
*p should be __be32.
> + int i, lmbs_to_add;
> + int lmbs_added = 0;
> + int rc = -EINVAL;
Don't pre-initialise your rc variables.
> + if (hp_elog->id_type == PSERIES_HP_ELOG_ID_DRC_COUNT) {
> + lmbs_to_add = be32_to_cpu(hp_elog->_drc_u.drc_count);
> + pr_info("Attempting to hot-add %d LMB(s)\n", lmbs_to_add);
> + } else {
> + lmbs_to_add = 1;
> + pr_info("Attempting to hot-add LMB, drc index %x\n",
> + be32_to_cpu(hp_elog->_drc_u.drc_index));
> + }
> +
> + 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;
> + }
> +
> + p = prop->value;
> + entries = be32_to_cpu(*p++);
> + lmb = (struct of_drconf_cell *)p;
So if I'm reading this right the hp_elog either contains an index or a count of
LMBs to add. But it doesn't contain anything about which address ranges to add
or any of those details. That is all in the ibm,dynamic-memory property - but
how did it get in there?
> +
> + for (i = 0; i < entries; i++, lmb++) {
> + u32 drc_index = be32_to_cpu(lmb->drc_index);
> +
> + if (lmbs_to_add == lmbs_added)
> + break;
> +
> + if (be32_to_cpu(lmb->flags) & DRCONF_MEM_ASSIGNED)
> + continue;
> +
> + if (hp_elog->id_type == PSERIES_HP_ELOG_ID_DRC_INDEX
> + && lmb->drc_index != hp_elog->_drc_u.drc_index)
> + continue;
> +
> + rc = dlpar_acquire_drc(drc_index);
> + if (rc)
> + continue;
> +
> + rc = dlpar_add_one_lmb(lmb);
> + if (rc) {
> + dlpar_release_drc(drc_index);
> + continue;
> + }
In both the above error cases you just move along. That means we potentially
hotplugged some memory but not everything that we were asked to. That seems
like a bad idea, we should either do everything or nothing.
> +
> + lmb->flags |= cpu_to_be32(DRCONF_MEM_ASSIGNED);
> + lmbs_added++;
> + pr_info("Memory at %llx (drc index %x) has been hot-added\n",
> + be64_to_cpu(lmb->base_addr), drc_index);
> + }
> +
> + if (lmbs_added)
> + rc = of_update_property(dn, prop);
> + else
> + dlpar_free_drconf_property(prop);
The value of rc here is not clear. It could be EINVAL or it could be the result
of the last dlpar_add_one_lmb(lmb). gcc would have told you that if you hadn't
initialised it.
> +
> + of_node_put(dn);
> + return rc ? rc : lmbs_added;
This looks wrong.
Doesn't the rc eventually go back to dlpar_write(), which expects 0 for success?
That should show up as the write failing in userspace.
> int dlpar_memory(struct pseries_hp_errorlog *hp_elog)
> {
> int rc = 0;
Don't initialise to zero, that way gcc can tell you if there's a path where you
forget to initialise it. It also means you can't accidentally return success.
> + if (hp_elog->id_type != PSERIES_HP_ELOG_ID_DRC_COUNT
> + && hp_elog->id_type != PSERIES_HP_ELOG_ID_DRC_INDEX)
> + return -EINVAL;
This would look nicer as a switch I think.
> mutex_lock(&dlpar_mem_mutex);
>
> switch (hp_elog->action) {
> + case PSERIES_HP_ELOG_ACTION_ADD:
> + rc = dlpar_memory_add(hp_elog);
> + break;
> default:
> pr_err("Invalid action (%d) specified\n", hp_elog->action);
> rc = -EINVAL;
>
cheers
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