Re: [Qemu-devel] [RFC PATCH v4 2/5] spapr: Add LMB DR connectors

[Bharata B Rao <bharata@linux.vnet.ibm.com>]

On Tue, Jun 23, 2015 at 11:32:34AM +1000, David Gibson wrote:
> On Fri, Jun 19, 2015 at 03:47:54PM +0530, Bharata B Rao wrote:
> > Enable memory hotplug for pseries 2.4 and add LMB DR connectors.
> > With memory hotplug, enforce NUMA node memory size and maxmem to be
> > a multiple of SPAPR_MEMORY_BLOCK_SIZE (256M) since that's the granularity
> > in which LMBs are represented and hot-added.
> > 
> > LMB DR connectors will be used by the memory hotplug code.
> > 
> > Signed-off-by: Bharata B Rao <bharata@linux.vnet.ibm.com>
> > Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
> >                [spapr_drc_reset implementation]
> > ---
> >  hw/ppc/spapr.c         | 78 ++++++++++++++++++++++++++++++++++++++++++++++++++
> >  include/hw/ppc/spapr.h |  2 ++
> >  2 files changed, 80 insertions(+)
> > 
> > diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> > index 87a29dc..f9af89b 100644
> > --- a/hw/ppc/spapr.c
> > +++ b/hw/ppc/spapr.c
> > @@ -59,6 +59,7 @@
> >  #include "hw/nmi.h"
> >  
> >  #include "hw/compat.h"
> > +#include "qemu-common.h"
> >  
> >  #include <libfdt.h>
> >  
> > @@ -1436,10 +1437,76 @@ static void spapr_cpu_init(sPAPRMachineState *spapr, PowerPCCPU *cpu)
> >      qemu_register_reset(spapr_cpu_reset, cpu);
> >  }
> >  
> > +static void spapr_drc_reset(void *opaque)
> 
> This function needs a different name, since it's only called for LMB
> drcs, not all drcs.
> 
> > +{
> > +    sPAPRDRConnector *drc = opaque;
> > +    DeviceState *d = DEVICE(drc);
> > +
> > +    if (d) {
> > +        device_reset(d);
> > +    }
> > +}
> > +
> > +static void spapr_create_lmb_dr_connectors(sPAPRMachineState *spapr)
> > +{
> > +    MachineState *machine = MACHINE(qdev_get_machine());
> > +    uint64_t lmb_size = SPAPR_MEMORY_BLOCK_SIZE;
> > +    uint32_t nr_rma_lmbs = spapr->rma_size/lmb_size;
> > +    uint32_t nr_lmbs = machine->maxram_size/lmb_size - nr_rma_lmbs;
> > +    uint32_t nr_assigned_lmbs = machine->ram_size/lmb_size - nr_rma_lmbs;
> > +    int i;
> > +
> > +    for (i = 0; i < nr_lmbs; i++) {
> > +        sPAPRDRConnector *drc;
> > +        uint64_t addr;
> > +
> > +        if (i < nr_assigned_lmbs) {
> > +            addr = (i + nr_rma_lmbs) * lmb_size;
> > +        } else {
> > +            addr = (i - nr_assigned_lmbs) * lmb_size +
> > +                SPAPR_MACHINE(qdev_get_machine())->hotplug_memory.base;
> > +        }
> > +
> > +        drc = spapr_dr_connector_new(qdev_get_machine(),
> > +                SPAPR_DR_CONNECTOR_TYPE_LMB, addr/lmb_size);
> > +        qemu_register_reset(spapr_drc_reset, drc);
> 
> Actually.. I'm not sure what spapr_drc_reset is needed for at all.
> Won't the device reset hook get called through the normal qdev path
> anyway?  The PCI hotplug code doesn't have an explicit register_reset,
> so why does the memory hotplug code need it?

I followed what Michael did for PHB hotplug. I don't see any ill-effects
of not having this special reset routine.

> 
> > +    }
> > +}
> > +
> > +/*
> > + * If LMB DR is enabled node memory size and max memory size should
> > + * be a multiple of SPAPR_MEMORY_BLOCK_SIZE (256M).
> > + */
> > +static void spapr_validate_node_memory(sPAPRMachineState *spapr)
> > +{
> > +    int i;
> > +    MachineState *machine = MACHINE(qdev_get_machine());
> > +
> > +    if (!spapr->dr_lmb_enabled) {
> > +        return;
> > +    }
> > +
> > +    if (machine->maxram_size % SPAPR_MEMORY_BLOCK_SIZE) {
> > +        error_report("maxmem should be a multiple of %lld MB",
> > +                      SPAPR_MEMORY_BLOCK_SIZE/M_BYTE);
> > +        exit(EXIT_FAILURE);
> > +    }
> > +
> > +    for (i = 0; i < nb_numa_nodes; i++) {
> > +        if (numa_info[i].node_mem &&
> > +            numa_info[i].node_mem % SPAPR_MEMORY_BLOCK_SIZE) {
> > +            error_report("Memory size on node %d should be a multiple "
> > +                         "of %lld MB", i, SPAPR_MEMORY_BLOCK_SIZE/M_BYTE);
> > +            exit(EXIT_FAILURE);
> > +        }
> > +    }
> > +}
> > +
> >  /* pSeries LPAR / sPAPR hardware init */
> >  static void ppc_spapr_init(MachineState *machine)
> >  {
> >      sPAPRMachineState *spapr = SPAPR_MACHINE(machine);
> > +    sPAPRMachineClass *smc = SPAPR_MACHINE_GET_CLASS(machine);
> >      const char *kernel_filename = machine->kernel_filename;
> >      const char *kernel_cmdline = machine->kernel_cmdline;
> >      const char *initrd_filename = machine->initrd_filename;
> > @@ -1518,6 +1585,9 @@ static void ppc_spapr_init(MachineState *machine)
> >                                                 smp_threads),
> >                                    XICS_IRQS);
> >  
> > +    spapr->dr_lmb_enabled = smc->dr_lmb_enabled;
> 
> I don't see any point to copying this value into the MachineState -
> I'm guessing this is a leftover from sPAPREnvironment.  Anywhere you
> have the MachineState you can get to the MachineClass and use the
> value directly from there.

Correct. Will fix this in next version.

Regards,
Bharata.