On Fri, Jun 10, 2016 at 10:44:48AM +0530, Bharata B Rao wrote: > 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 <bhar...@linux.vnet.ibm.com>
Applied to ppc-for-2.7, thanks. > --- > Changes in v4: > > - Included address information for all LMBs in ibm,dynamic-memory. > - Use both RESERVED and DRC_INVALID flag bits for non-hotpluggable LMBs. > > v3: https://lists.gnu.org/archive/html/qemu-ppc/2016-06/msg00187.html > > hw/ppc/spapr.c | 57 > ++++++++++++++++++++++++++++++++------------------ > include/hw/ppc/spapr.h | 6 ++++-- > 2 files changed, 41 insertions(+), 22 deletions(-) > > diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c > index 0636642..9a4a803 100644 > --- a/hw/ppc/spapr.c > +++ b/hw/ppc/spapr.c > @@ -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; > } > > @@ -803,26 +806,40 @@ 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); > - g_assert(drc); > - drck = SPAPR_DR_CONNECTOR_GET_CLASS(drc); > - > - dynamic_memory[0] = cpu_to_be32(addr >> 32); > - dynamic_memory[1] = cpu_to_be32(addr & 0xffffffff); > - 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)) { > - dynamic_memory[5] = cpu_to_be32(SPAPR_LMB_FLAGS_ASSIGNED); > + 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); > + > + dynamic_memory[0] = cpu_to_be32(addr >> 32); > + dynamic_memory[1] = cpu_to_be32(addr & 0xffffffff); > + 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 (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 { > - dynamic_memory[5] = cpu_to_be32(0); > + /* > + * 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; > diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h > index 971df3d..3ac85c0 100644 > --- a/include/hw/ppc/spapr.h > +++ b/include/hw/ppc/spapr.h > @@ -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__) */ -- David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson
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