On 07/10/2014 08:29 PM, Alexander Graf wrote:
>
> On 09.07.14 15:59, Alexey Kardashevskiy wrote:
>> On 07/09/2014 05:46 PM, Paolo Bonzini wrote:> Il 09/07/2014 07:57, Alexey
>> Kardashevskiy ha scritto:
>>>> 0b183fc87 "memory: move mem_path handling to
>>>> memory_region_allocate_system_memory" disabled -mempath use for all
>>>> machines that do not use memory_region_allocate_system_memory() to
>>>> register RAM. Since SPAPR uses memory_region_init_ram(), the huge pages
>>>> support was disabled for it.
>>>>
>>>> This replaces memory_region_init_ram()+vmstate_register_ram_global() with
>>>> memory_region_allocate_system_memory() to get huge pages back.
>>>>
>>>> Cc: Paolo Bonzini <pbonz...@redhat.com>
>>>> Cc: Hu Tao <hu...@cn.fujitsu.com>
>>>> Signed-off-by: Alexey Kardashevskiy <a...@ozlabs.ru>
>>>> ---
>>>> hw/ppc/spapr.c | 4 ++--
>>>> 1 file changed, 2 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
>>>> index a23c0f0..8fa9f7e 100644
>>>> --- a/hw/ppc/spapr.c
>>>> +++ b/hw/ppc/spapr.c
>>>> @@ -1337,8 +1337,8 @@ static void ppc_spapr_init(MachineState *machine)
>>>> ram_addr_t nonrma_base = rma_alloc_size;
>>>> ram_addr_t nonrma_size = spapr->ram_limit - rma_alloc_size;
>>>>
>>>> - memory_region_init_ram(ram, NULL, "ppc_spapr.ram", nonrma_size);
>>>> - vmstate_register_ram_global(ram);
>>>> + memory_region_allocate_system_memory(ram, NULL, "ppc_spapr.ram",
>>>> + nonrma_size);
>>> The reason why I didn't do this in the simple way is that depending on the
>>> value of nonrma_base you may get smaller hugepages than you wanted.
>>>
>>> For example, if the hugepage size is 1G but nonrma_base is 32M, you will
>>> not be able to get a page size larger than 32M.
>>>
>>> Depending on the value of nonrma_base, it may be better to allocate the
>>> whole spapr->ram_limit to ppc_spapr.ram, and just ignore the first part
>>> of it.
>>>
>>> I see in target-ppc/kvm.c that rma_alloc_size is capped to 256M, and in
>>> practice it is 128M (arch/powerpc/kvm/book3s_hv_builtin.c. Considering
>>> that Linux overcommits so the memory isn't lost in the non-hugepage case, I
>>> think it's better to just waste the 128M of address space.
>>>
>>> Paolo
>>>
>>>> memory_region_add_subregion(sysmem, nonrma_base, ram);
>>>> }
>> Did you mean something like below? If so, I have to change MR tree and
>> place RMA under RAM, I guess.
>> I'll try to give it a try tomorrow on bare PPC970.
>>
>>
>>
>>
>> ---
>> hw/ppc/spapr.c | 19 ++++++++++++-------
>> target-ppc/kvm.c | 9 +--------
>> target-ppc/kvm_ppc.h | 2 +-
>> 3 files changed, 14 insertions(+), 16 deletions(-)
>>
>> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
>> index a23c0f0..47ae6c1 100644
>> --- a/hw/ppc/spapr.c
>> +++ b/hw/ppc/spapr.c
>> @@ -1223,6 +1223,7 @@ static void ppc_spapr_init(MachineState *machine)
>> int i;
>> MemoryRegion *sysmem = get_system_memory();
>> MemoryRegion *ram = g_new(MemoryRegion, 1);
>> + MemoryRegion *rma_region;
>> hwaddr rma_alloc_size;
>> hwaddr node0_size = (nb_numa_nodes > 1) ? numa_info[0].node_mem :
>> ram_size;
>> uint32_t initrd_base = 0;
>> @@ -1230,6 +1231,7 @@ static void ppc_spapr_init(MachineState *machine)
>> long load_limit, rtas_limit, fw_size;
>> bool kernel_le = false;
>> char *filename;
>> + void *rma = NULL;
>> msi_supported = true;
>> @@ -1239,7 +1241,7 @@ static void ppc_spapr_init(MachineState *machine)
>> cpu_ppc_hypercall = emulate_spapr_hypercall;
>> /* Allocate RMA if necessary */
>> - rma_alloc_size = kvmppc_alloc_rma("ppc_spapr.rma", sysmem);
>> + rma_alloc_size = kvmppc_alloc_rma(&rma);
>> if (rma_alloc_size == -1) {
>> hw_error("qemu: Unable to create RMA\n");
>> @@ -1333,13 +1335,16 @@ static void ppc_spapr_init(MachineState *machine)
>> /* allocate RAM */
>> spapr->ram_limit = ram_size;
>> - if (spapr->ram_limit > rma_alloc_size) {
>> - ram_addr_t nonrma_base = rma_alloc_size;
>> - ram_addr_t nonrma_size = spapr->ram_limit - rma_alloc_size;
>> + memory_region_allocate_system_memory(ram, NULL, "ppc_spapr.ram",
>> + spapr->ram_limit);
>> + memory_region_add_subregion(sysmem, 0, ram);
>> - memory_region_init_ram(ram, NULL, "ppc_spapr.ram", nonrma_size);
>> - vmstate_register_ram_global(ram);
>> - memory_region_add_subregion(sysmem, nonrma_base, ram);
>> + if (rma_alloc_size && rma) {
>> + rma_region = g_new(MemoryRegion, 1);
>> + memory_region_init_ram_ptr(rma_region, NULL, "ppc_spapr.rma",
>> + rma_alloc_size, rma);
>> + vmstate_register_ram_global(rma_region);
>> + memory_region_add_subregion(sysmem, 0, rma_region);
>> }
>> filename = qemu_find_file(QEMU_FILE_TYPE_BIOS, "spapr-rtas.bin");
>> diff --git a/target-ppc/kvm.c b/target-ppc/kvm.c
>> index 995706a..9ca14d2 100644
>> --- a/target-ppc/kvm.c
>> +++ b/target-ppc/kvm.c
>> @@ -1582,13 +1582,11 @@ int kvmppc_smt_threads(void)
>> }
>> #ifdef TARGET_PPC64
>> -off_t kvmppc_alloc_rma(const char *name, MemoryRegion *sysmem)
>> +off_t kvmppc_alloc_rma(void **rma)
>> {
>> - void *rma;
>> off_t size;
>> int fd;
>> struct kvm_allocate_rma ret;
>> - MemoryRegion *rma_region;
>> /* If cap_ppc_rma == 0, contiguous RMA allocation is not supported
>> * if cap_ppc_rma == 1, contiguous RMA allocation is supported, but
>> @@ -1617,11 +1615,6 @@ off_t kvmppc_alloc_rma(const char *name,
>> MemoryRegion *sysmem)
>> return -1;
>> };
>> - rma_region = g_new(MemoryRegion, 1);
>> - memory_region_init_ram_ptr(rma_region, NULL, name, size, rma);
>> - vmstate_register_ram_global(rma_region);
>> - memory_region_add_subregion(sysmem, 0, rma_region);
>> -
>
> I don't see where you set *rma here.
That patch was an RFC, this is why :)
>
> Apart from that while I think that with hugetlbfs we might actually waste a
> few MB of RAM, I don't think it's a real problem for systems that require
> an RMA. So semantically the change works well for me. Please verify it
> works though :).
I managed to verify that it still works on PPC970 and will report the
patch(es) soon.
--
Alexey
