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spapr: Ensure all LMBs are represented in ibm,dynamic-memory

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Memory hotplug can fail for some combinations of RAM and maxmem when
DDW is enabled in the presence of devices like nec-usb-xhci. DDW depends
on maximum addressable memory returned by guest and this value is currently
being calculated wrongly by the guest kernel routine memory_hotplug_max().
While there is an attempt to fix the guest kernel, this patch works
around the problem within QEMU itself.

memory_hotplug_max() routine in the guest kernel arrives at max
addressable memory by multiplying lmb-size with the lmb-count obtained
from ibm,dynamic-memory property. There are two assumptions here:

- All LMBs are part of ibm,dynamic memory: This is not true for PowerKVM
  where only hot-pluggable LMBs are present in this property.
- The memory area comprising of RAM and hotplug region is contiguous: This
  needn't be true always for PowerKVM as there can be gap between
  boot time RAM and hotplug region.

To work around this guest kernel bug, ensure that ibm,dynamic-memory
has information about all the LMBs (RMA, boot-time LMBs, future
hotpluggable LMBs, and dummy LMBs to cover the gap between RAM and
hotpluggable region).

RMA is represented separately by memory@0 node. Hence mark RMA LMBs
and also the LMBs for the gap b/n RAM and hotpluggable region as
reserved and as having no valid DRC so that these LMBs are not considered
by the guest.

Signed-off-by: Bharata B Rao <bharata@linux.vnet.ibm.com>
Reviewed-by: Michael Roth <mdroth@linux.vnet.ibm.com>
Reviewed-by: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
This commit is contained in:
Bharata B Rao 2016-06-10 10:44:48 +05:30 committed by David Gibson
parent bc9ca5958d
commit d0e5a8f293
2 changed files with 40 additions and 21 deletions
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37
hw/ppc/spapr.c
View File

@ -762,14 +762,17 @@ static int spapr_populate_drconf_memory(sPAPRMachineState *spapr, void *fdt)
int ret, i, offset;
uint64_t lmb_size = SPAPR_MEMORY_BLOCK_SIZE;
uint32_t prop_lmb_size[] = {0, cpu_to_be32(lmb_size)};
uint32_t nr_lmbs = (machine->maxram_size - machine->ram_size)/lmb_size;
uint32_t hotplug_lmb_start = spapr->hotplug_memory.base / lmb_size;
uint32_t nr_lmbs = (spapr->hotplug_memory.base +
memory_region_size(&spapr->hotplug_memory.mr)) /
lmb_size;
uint32_t *int_buf, *cur_index, buf_len;
int nr_nodes = nb_numa_nodes ? nb_numa_nodes : 1;
/*
* Don't create the node if there are no DR LMBs.
* Don't create the node if there is no hotpluggable memory
*/
if (!nr_lmbs) {
if (machine->ram_size == machine->maxram_size) {
return 0;
}
@ -803,13 +806,14 @@ static int spapr_populate_drconf_memory(sPAPRMachineState *spapr, void *fdt)
int_buf[0] = cpu_to_be32(nr_lmbs);
cur_index++;
for (i = 0; i < nr_lmbs; i++) {
sPAPRDRConnector *drc;
sPAPRDRConnectorClass *drck;
uint64_t addr = i * lmb_size + spapr->hotplug_memory.base;;
uint64_t addr = i * lmb_size;
uint32_t *dynamic_memory = cur_index;
drc = spapr_dr_connector_by_id(SPAPR_DR_CONNECTOR_TYPE_LMB,
addr/lmb_size);
if (i >= hotplug_lmb_start) {
sPAPRDRConnector *drc;
sPAPRDRConnectorClass *drck;
drc = spapr_dr_connector_by_id(SPAPR_DR_CONNECTOR_TYPE_LMB, i);
g_assert(drc);
drck = SPAPR_DR_CONNECTOR_GET_CLASS(drc);
@ -818,12 +822,25 @@ static int spapr_populate_drconf_memory(sPAPRMachineState *spapr, void *fdt)
dynamic_memory[2] = cpu_to_be32(drck->get_index(drc));
dynamic_memory[3] = cpu_to_be32(0); /* reserved */
dynamic_memory[4] = cpu_to_be32(numa_get_node(addr, NULL));
if (addr < machine->ram_size ||
memory_region_present(get_system_memory(), addr)) {
if (memory_region_present(get_system_memory(), addr)) {
dynamic_memory[5] = cpu_to_be32(SPAPR_LMB_FLAGS_ASSIGNED);
} else {
dynamic_memory[5] = cpu_to_be32(0);
}
} else {
/*
* LMB information for RMA, boot time RAM and gap b/n RAM and
* hotplug memory region -- all these are marked as reserved
* and as having no valid DRC.
*/
dynamic_memory[0] = cpu_to_be32(addr >> 32);
dynamic_memory[1] = cpu_to_be32(addr & 0xffffffff);
dynamic_memory[2] = cpu_to_be32(0);
dynamic_memory[3] = cpu_to_be32(0); /* reserved */
dynamic_memory[4] = cpu_to_be32(-1);
dynamic_memory[5] = cpu_to_be32(SPAPR_LMB_FLAGS_RESERVED |
SPAPR_LMB_FLAGS_DRC_INVALID);
}
cur_index += SPAPR_DR_LMB_LIST_ENTRY_SIZE;
}

6
include/hw/ppc/spapr.h
View File

@ -620,9 +620,11 @@ int spapr_rng_populate_dt(void *fdt);
#define SPAPR_DR_LMB_LIST_ENTRY_SIZE 6
/*
* This flag value defines the LMB as assigned in ibm,dynamic-memory
* property under ibm,dynamic-reconfiguration-memory node.
* Defines for flag value in ibm,dynamic-memory property under
* ibm,dynamic-reconfiguration-memory node.
*/
#define SPAPR_LMB_FLAGS_ASSIGNED 0x00000008
#define SPAPR_LMB_FLAGS_DRC_INVALID 0x00000020
#define SPAPR_LMB_FLAGS_RESERVED 0x00000080
#endif /* !defined (__HW_SPAPR_H__) */