Re: [Qemu-ppc] [RFC PATCH v3 21/24] spapr: Initialize hotplug memory address space

[Igor Mammedov]

On Fri, 24 Apr 2015 12:17:43 +0530
Bharata B Rao <address@hidden> wrote:

> Initialize a hotplug memory region under which all the hotplugged
> memory is accommodated. Also enable memory hotplug by setting
> CONFIG_MEM_HOTPLUG.
> 
> Modelled on i386 memory hotplug.
> 
> Signed-off-by: Bharata B Rao <address@hidden>
> ---
>  default-configs/ppc64-softmmu.mak |  1 +
>  hw/ppc/spapr.c                    | 38 ++++++++++++++++++++++++++++++++++++++
>  include/hw/ppc/spapr.h            | 12 ++++++++++++
>  3 files changed, 51 insertions(+)
> 
> diff --git a/default-configs/ppc64-softmmu.mak 
> b/default-configs/ppc64-softmmu.mak
> index 22ef132..16b3011 100644
> --- a/default-configs/ppc64-softmmu.mak
> +++ b/default-configs/ppc64-softmmu.mak
> @@ -51,3 +51,4 @@ CONFIG_XICS_KVM=$(and $(CONFIG_PSERIES),$(CONFIG_KVM))
>  # For PReP
>  CONFIG_MC146818RTC=y
>  CONFIG_ISA_TESTDEV=y
> +CONFIG_MEM_HOTPLUG=y
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index 910a50f..9dc4c36 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -125,6 +125,9 @@ struct sPAPRMachineState {
>  
>      /*< public >*/
>      char *kvm_type;
> +    ram_addr_t hotplug_memory_base;
> +    MemoryRegion hotplug_memory;
> +    bool enforce_aligned_dimm;
>  };
>  
>  sPAPREnvironment *spapr;
> @@ -1514,6 +1517,7 @@ static void ppc_spapr_init(MachineState *machine)
>      QemuOpts *opts = qemu_opts_find(qemu_find_opts("smp-opts"), NULL);
>      int sockets = opts ? qemu_opt_get_number(opts, "sockets", 0) : 0;
>      int cores = (smp_cpus/smp_threads) ? smp_cpus/smp_threads : 1;
> +    sPAPRMachineState *ms = SPAPR_MACHINE(machine);
>  
>      sockets = sockets ? sockets : cores;
>      msi_supported = true;
> @@ -1613,6 +1617,36 @@ static void ppc_spapr_init(MachineState *machine)
>          memory_region_add_subregion(sysmem, 0, rma_region);
>      }
>  
> +    /* initialize hotplug memory address space */
> +    if (machine->ram_size < machine->maxram_size) {
> +        ram_addr_t hotplug_mem_size =
> +            machine->maxram_size - machine->ram_size;
> +
> +        if (machine->ram_slots > SPAPR_MAX_RAM_SLOTS) {
> +            error_report("unsupported amount of memory slots: %"PRIu64,
> +                         machine->ram_slots);
> +            exit(EXIT_FAILURE);
> +        }
> +
> +        ms->hotplug_memory_base = ROUND_UP(machine->ram_size,
> +                                    SPAPR_HOTPLUG_MEM_ALIGN);
> +
> +        if (ms->enforce_aligned_dimm) {
> +            hotplug_mem_size += SPAPR_HOTPLUG_MEM_ALIGN * machine->ram_slots;
> +        }
> +
> +        if ((ms->hotplug_memory_base + hotplug_mem_size) < hotplug_mem_size) 
> {
> +            error_report("unsupported amount of maximum memory: " 
> RAM_ADDR_FMT,
> +                         machine->maxram_size);
> +            exit(EXIT_FAILURE);
> +        }
> +
> +        memory_region_init(&ms->hotplug_memory, OBJECT(ms),
> +                           "hotplug-memory", hotplug_mem_size);
> +        memory_region_add_subregion(sysmem, ms->hotplug_memory_base,
> +                                    &ms->hotplug_memory);
> +    }
> +
>      filename = qemu_find_file(QEMU_FILE_TYPE_BIOS, "spapr-rtas.bin");
>      spapr->rtas_size = get_image_size(filename);
>      spapr->rtas_blob = g_malloc(spapr->rtas_size);
> @@ -1844,11 +1878,15 @@ static void spapr_set_kvm_type(Object *obj, const 
> char *value, Error **errp)
>  
>  static void spapr_machine_initfn(Object *obj)
>  {
> +    sPAPRMachineState *ms = SPAPR_MACHINE(obj);
> +
>      object_property_add_str(obj, "kvm-type",
>                              spapr_get_kvm_type, spapr_set_kvm_type, NULL);
>      object_property_set_description(obj, "kvm-type",
>                                      "Specifies the KVM virtualization mode 
> (HV, PR)",
>                                      NULL);
> +
> +    ms->enforce_aligned_dimm = true;
>  }
>  
>  static void ppc_cpu_do_nmi_on_cpu(void *arg)
> diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
> index ecac6e3..53560e9 100644
> --- a/include/hw/ppc/spapr.h
> +++ b/include/hw/ppc/spapr.h
> @@ -542,6 +542,18 @@ struct sPAPREventLogEntry {
>  
>  #define SPAPR_MEMORY_BLOCK_SIZE (1 << 28) /* 256MB */
>  
> +/*
> + * This defines the maximum number of DIMM slots we can have for sPAPR
> + * guest. This is not defined by sPAPR but we are defining it to 4096 slots
> + * here. With the worst case addition of SPAPR_MEMORY_BLOCK_SIZE
> + * (256MB) memory per slot, we should be able to support 1TB of guest
> + * hotpluggable memory.
> + */
> +#define SPAPR_MAX_RAM_SLOTS     (1ULL << 12)
why not write 4096 instead of (1ULL << 12), much easier to read.

BTW:
KVM supports upto 509 memory slots including slots consumed by
initial memory.

> +
> +/* 1GB alignment for hotplug memory region */
> +#define SPAPR_HOTPLUG_MEM_ALIGN (1ULL << 30)
> +
>  void spapr_events_init(sPAPREnvironment *spapr);
>  void spapr_events_fdt_skel(void *fdt, uint32_t epow_irq);
>  int spapr_h_cas_compose_response(target_ulong addr, target_ulong size);