Re: [Qemu-devel] [PATCH v3] spapr: make sure RMA is in first mode of first memory node

[Alexander Graf <agraf@suse.de>]

On 07.11.2013, at 09:33, Thomas Huth <thuth@linux.vnet.ibm.com> wrote:

> On Thu,  7 Nov 2013 14:50:00 +1100
> Alexey Kardashevskiy <aik@ozlabs.ru> wrote:
> 
>> The SPAPR specification says that the RMA starts at the LPAR's logical
>> address 0 and is the first logical memory block reported in
>> the LPAR’s device tree.
>> 
>> So SLOF only maps the first block and that block needs to span
>> the full RMA.
>> 
>> This makes sure that the RMA area is where SLOF expects it.
>> 
>> Cc: Thomas Huth <thuth@linux.vnet.ibm.com>
>> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
>> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
>> ---
>> Changes:
>> v3:
>> * removed unnecessary RMA fixup from spapr_populate_memory()
>> 
>> v2:
>> * changed as recommended by Alex Graf
>> ---
>> hw/ppc/spapr.c | 12 ++++++++----
>> 1 file changed, 8 insertions(+), 4 deletions(-)
>> 
>> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
>> index 7e53a5f..1f320f6 100644
>> --- a/hw/ppc/spapr.c
>> +++ b/hw/ppc/spapr.c
>> @@ -532,9 +532,6 @@ static int spapr_populate_memory(sPAPREnvironment *spapr, void *fdt)
>> 
>>     /* memory node(s) */
>>     node0_size = (nb_numa_nodes > 1) ? node_mem[0] : ram_size;
>> -    if (spapr->rma_size > node0_size) {
>> -        spapr->rma_size = node0_size;
>> -    }
>> 
>>     /* RMA */
>>     mem_reg_property[0] = 0;
>> @@ -1113,6 +1110,7 @@ static void ppc_spapr_init(QEMUMachineInitArgs *args)
>>     MemoryRegion *sysmem = get_system_memory();
>>     MemoryRegion *ram = g_new(MemoryRegion, 1);
>>     hwaddr rma_alloc_size;
>> +    hwaddr node0_size = (nb_numa_nodes > 1) ? node_mem[0] : ram_size;
>>     uint32_t initrd_base = 0;
>>     long kernel_size = 0, initrd_size = 0;
>>     long load_limit, rtas_limit, fw_size;
>> @@ -1137,7 +1135,7 @@ static void ppc_spapr_init(QEMUMachineInitArgs *args)
>>     if (rma_alloc_size && (rma_alloc_size < ram_size)) {
> 
> Uh, sorry for not seeing this earlier, ... but should that be
> "rma_alloc_size < node0_size" instead of "rma_alloc_size < ram_size"?
> For example, if rma_alloc_size = 256 MB, ram_size = 512 MB but
> node0_size = 128 MB, this will set rma_size to 256 MB ...
> 
>>         spapr->rma_size = rma_alloc_size;
>>     } else {
>> -        spapr->rma_size = ram_size;
>> +        spapr->rma_size = node0_size;
>> 
>>         /* With KVM, we don't actually know whether KVM supports an
>>          * unbounded RMA (PR KVM) or is limited by the hash table size
>> @@ -1154,6 +1152,12 @@ static void ppc_spapr_init(QEMUMachineInitArgs *args)
>>         }
>>     }
>> 
>> +    if (spapr->rma_size > node0_size) {
>> +        fprintf(stderr, "Error: Numa node 0 has to span the RMA (%#08"HWADDR_PRIx")\n",
>> +                spapr->rma_size);
>> +        exit(1);
>> +    }
> 
> ... so in the above example you would get the error + exit here.
> Or did I miss something?

No, nice catch :). I'm really eagerly awaiting wide public availability of HV capable POWER hardware so that we can finally get rid of all the 970 code...


Alex