memory_hotplug_max() uses hot_add_drconf_memory_max() to get maxmimum
addressable memory by referring to ibm,dyanamic-memory property. There
are three problems with the current approach:
1 hot_add_drconf_memory_max() assumes that ibm,dynamic-memory includes
all the LMBs of the guest, but that is not true for PowerKVM which
populates only DR LMBs (LMBs that can be hotplugged/removed) in that
property.
2 hot_add_drconf_memory_max() multiplies lmb-size with lmb-count to arrive
at the max possible address. Since ibm,dynamic-memory doesn't include
RMA LMBs, the address thus obtained will be less than the actual max
address. For example, if max possible memory size is 32G, with lmb-size
of 256MB there can be 127 LMBs in ibm,dynamic-memory (1 LMB for RMA
which won't be present here). hot_add_drconf_memory_max() would then
return the max addressable memory as 127 * 256MB = 31.75GB, the max
address should have been 32G which is what ibm,lrdr-capacity shows.
3 In PowerKVM, there can be a gap between the end of boot time RAM and
beginning of hotplug RAM area. So just multiplying lmb-count with
lmb-size will not provide the correct max possible address for PowerKVM.
This patch fixes 1 by using ibm,lrdr-capacity property to return the max
addressable memory whenever the property is present. Then it fixes 2 & 3
by fetching the address of the last LMB in ibm,dynamic-memory property.
NOTE: There are some unnecessary changes in the patch because of converting
spaces to tabs w/o which checkpatch.pl complains.
Signed-off-by: Bharata B Rao <bhar...@linux.vnet.ibm.com>
---
Changes in v1
-------------
- Return 0 from hot_add_drconf_memory_max() when
ibm,dynamic-reconfiguration-memory node isn't available. This restores
the existing behaviour.
- Rebase against next branch of
git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git
arch/powerpc/mm/numa.c | 34 +++++++++++++++++++++++++---------
1 file changed, 25 insertions(+), 9 deletions(-)
diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
index 669a15e..6a26ce8 100644
--- a/arch/powerpc/mm/numa.c
+++ b/arch/powerpc/mm/numa.c
@@ -1164,17 +1164,33 @@ int hot_add_scn_to_nid(unsigned long scn_addr)
static u64 hot_add_drconf_memory_max(void)
{
struct device_node *memory = NULL;
- unsigned int drconf_cell_cnt = 0;
- u64 lmb_size = 0;
+ struct device_node *dn = NULL;
+ unsigned int drconf_cell_cnt = 0;
+ u64 lmb_size = 0;
const __be32 *dm = NULL;
+ const __be64 *lrdr = NULL;
+ struct of_drconf_cell drmem;
+
+ dn = of_find_node_by_path("/rtas");
+ if (dn) {
+ lrdr = of_get_property(dn, "ibm,lrdr-capacity", NULL);
+ of_node_put(dn);
+ if (lrdr)
+ return be64_to_cpup(lrdr);
+ }
+
+ memory = of_find_node_by_path("/ibm,dynamic-reconfiguration-memory");
+ if (memory) {
+ drconf_cell_cnt = of_get_drconf_memory(memory, &dm);
+ lmb_size = of_get_lmb_size(memory);
- memory = of_find_node_by_path("/ibm,dynamic-reconfiguration-memory");
- if (memory) {
- drconf_cell_cnt = of_get_drconf_memory(memory, &dm);
- lmb_size = of_get_lmb_size(memory);
- of_node_put(memory);
- }
- return lmb_size * drconf_cell_cnt;
+ /* Advance to the last cell, each cell has 6 32 bit integers */
+ dm += (drconf_cell_cnt - 1) * 6;
+ read_drconf_cell(&drmem, &dm);
+ of_node_put(memory);
+ return drmem.base_addr + lmb_size;
+ }
+ return 0;
}
/*
--
2.1.0
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