Re: [Qemu-devel] [RFC PATCH v4 1/5] spapr: Initialize hotplug memory address space

[David Gibson <david@gibson.dropbear.id.au>]

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On Fri, Jun 19, 2015 at 03:47:53PM +0530, Bharata B Rao 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 <bharata@linux.vnet.ibm.com>
> ---
>  default-configs/ppc64-softmmu.mak |  1 +
>  hw/ppc/spapr.c                    | 28 ++++++++++++++++++++++++++++
>  include/hw/ppc/spapr.h            | 12 ++++++++++++
>  3 files changed, 41 insertions(+)
> 
> diff --git a/default-configs/ppc64-softmmu.mak b/default-configs/ppc64-softmmu.mak
> index ab62cc7..e77cb1a 100644
> --- a/default-configs/ppc64-softmmu.mak
> +++ b/default-configs/ppc64-softmmu.mak
> @@ -52,3 +52,4 @@ 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 5ca817c..87a29dc 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -1549,6 +1549,34 @@ 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);
> +        }
> +
> +        spapr->hotplug_memory.base = ROUND_UP(machine->ram_size,
> +                                              SPAPR_HOTPLUG_MEM_ALIGN);
> +
> +        hotplug_mem_size += SPAPR_HOTPLUG_MEM_ALIGN * machine->ram_slots;

I'm not sure what this adjustment is about.  Are you putting a gap of
size SPAPR_HOTPLUG_MEM_ALIGN between each memory slot?  That doesn't
see to match the DRC initialization code in the next patch which
assigns all the LMBs in the hotplug area contiguous addresses.

> +        if ((spapr->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(&spapr->hotplug_memory.mr, OBJECT(spapr),
> +                           "hotplug-memory", hotplug_mem_size);
> +        memory_region_add_subregion(sysmem, spapr->hotplug_memory.base,
> +                                    &spapr->hotplug_memory.mr);
> +    }
> +
>      filename = qemu_find_file(QEMU_FILE_TYPE_BIOS, "spapr-rtas.bin");
>      if (!filename) {
>          error_report("Could not find LPAR rtas '%s'", "spapr-rtas.bin");
> diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
> index 91a61ab..8a1929b 100644
> --- a/include/hw/ppc/spapr.h
> +++ b/include/hw/ppc/spapr.h
> @@ -5,6 +5,7 @@
>  #include "hw/boards.h"
>  #include "hw/ppc/xics.h"
>  #include "hw/ppc/spapr_drc.h"
> +#include "hw/mem/pc-dimm.h"
>  
>  struct VIOsPAPRBus;
>  struct sPAPRPHBState;
> @@ -76,6 +77,7 @@ struct sPAPRMachineState {
>  
>      /*< public >*/
>      char *kvm_type;
> +    MemoryHotplugState hotplug_memory;
>  };
>  
>  #define H_SUCCESS         0
> @@ -609,4 +611,14 @@ int spapr_rtc_import_offset(DeviceState *dev, int64_t legacy_offset);
>  
>  #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 32 slots
> + * based on default number of slots provided by PowerPC kernel.
> + */
> +#define SPAPR_MAX_RAM_SLOTS     32
> +
> +/* 1GB alignment for hotplug memory region */
> +#define SPAPR_HOTPLUG_MEM_ALIGN (1ULL << 30)
> +
>  #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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