Re: [Qemu-devel] [PATCH 1/5] target-ppc: Extend rtas-blob

[Aravinda Prasad <aravinda@linux.vnet.ibm.com>]

On Tuesday 02 September 2014 11:19 AM, Alexey Kardashevskiy wrote:
> On 09/02/2014 03:25 PM, Aravinda Prasad wrote:
>>
>>
>> On Tuesday 02 September 2014 09:39 AM, Alexey Kardashevskiy wrote:
>>> On 09/01/2014 09:23 PM, Aravinda Prasad wrote:
>>>>
>>>>
>>>> On Monday 01 September 2014 01:16 PM, Alexey Kardashevskiy wrote:
>>>>> On 08/25/2014 11:45 PM, Aravinda Prasad wrote:
>>>>>> Extend rtas-blob to accommodate error log. Error log
>>>>>> structure is saved in rtas space upon a machine check
>>>>>> exception.
>>>>>>
>>>>>> Signed-off-by: Aravinda Prasad <aravinda@linux.vnet.ibm.com>
>>>>>> ---
>>>>>>  hw/ppc/spapr.c                  |   13 ++++++++++---
>>>>>>  hw/ppc/spapr_rtas.c             |    4 ++--
>>>>>>  include/hw/ppc/spapr.h          |    2 +-
>>>>>>  pc-bios/spapr-rtas/spapr-rtas.S |   12 ++++++++++++
>>>>>>  4 files changed, 25 insertions(+), 6 deletions(-)
>>>>>>
>>>>>> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
>>>>>> index d01978f..1120988 100644
>>>>>> --- a/hw/ppc/spapr.c
>>>>>> +++ b/hw/ppc/spapr.c
>>>>>> @@ -85,6 +85,12 @@
>>>>>>  
>>>>>>  #define HTAB_SIZE(spapr)        (1ULL << ((spapr)->htab_shift))
>>>>>>  
>>>>>> +/*
>>>>>> + * The rtas-entry-offset should match the value specified in
>>>>>> + * spapr-rtas.S
>>>>>> + */
>>>>>> +#define RTAS_ENTRY_OFFSET       0x1000
>>>>>> +
>>>>>>  typedef struct sPAPRMachineState sPAPRMachineState;
>>>>>>  
>>>>>>  #define TYPE_SPAPR_MACHINE      "spapr-machine"
>>>>>> @@ -670,7 +676,8 @@ static int spapr_populate_memory(sPAPREnvironment *spapr, void *fdt)
>>>>>>  static void spapr_finalize_fdt(sPAPREnvironment *spapr,
>>>>>>                                 hwaddr fdt_addr,
>>>>>>                                 hwaddr rtas_addr,
>>>>>> -                               hwaddr rtas_size)
>>>>>> +                               hwaddr rtas_size,
>>>>>> +                               hwaddr rtas_entry)
>>>>>>  {
>>>>>>      int ret, i;
>>>>>>      size_t cb = 0;
>>>>>> @@ -705,7 +712,7 @@ static void spapr_finalize_fdt(sPAPREnvironment *spapr,
>>>>>>      }
>>>>>>  
>>>>>>      /* RTAS */
>>>>>> -    ret = spapr_rtas_device_tree_setup(fdt, rtas_addr, rtas_size);
>>>>>> +    ret = spapr_rtas_device_tree_setup(fdt, rtas_addr, rtas_size, rtas_entry);
>>>>>>      if (ret < 0) {
>>>>>>          fprintf(stderr, "Couldn't set up RTAS device tree properties\n");
>>>>>>      }
>>>>>> @@ -808,7 +815,7 @@ static void ppc_spapr_reset(void)
>>>>>>  
>>>>>>      /* Load the fdt */
>>>>>>      spapr_finalize_fdt(spapr, spapr->fdt_addr, spapr->rtas_addr,
>>>>>> -                       spapr->rtas_size);
>>>>>> +                       spapr->rtas_size, spapr->rtas_addr + RTAS_ENTRY_OFFSET);
>>>>>>  
>>>>>>      /* Set up the entry state */
>>>>>>      first_ppc_cpu = POWERPC_CPU(first_cpu);
>>>>>> diff --git a/hw/ppc/spapr_rtas.c b/hw/ppc/spapr_rtas.c
>>>>>> index 9ba1ba6..02ddbf9 100644
>>>>>> --- a/hw/ppc/spapr_rtas.c
>>>>>> +++ b/hw/ppc/spapr_rtas.c
>>>>>> @@ -328,7 +328,7 @@ void spapr_rtas_register(int token, const char *name, spapr_rtas_fn fn)
>>>>>>  }
>>>>>>  
>>>>>>  int spapr_rtas_device_tree_setup(void *fdt, hwaddr rtas_addr,
>>>>>> -                                 hwaddr rtas_size)
>>>>>> +                                 hwaddr rtas_size, hwaddr rtas_entry)
>>>>>>  {
>>>>>>      int ret;
>>>>>>      int i;
>>>>>> @@ -349,7 +349,7 @@ int spapr_rtas_device_tree_setup(void *fdt, hwaddr rtas_addr,
>>>>>>      }
>>>>>>  
>>>>>>      ret = qemu_fdt_setprop_cell(fdt, "/rtas", "linux,rtas-entry",
>>>>>> -                                rtas_addr);
>>>>>> +                                rtas_entry);
>>>>>>      if (ret < 0) {
>>>>>>          fprintf(stderr, "Couldn't add linux,rtas-entry property: %s\n",
>>>>>>                  fdt_strerror(ret));
>>>>>> diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
>>>>>> index bbba51a..dedfa67 100644
>>>>>> --- a/include/hw/ppc/spapr.h
>>>>>> +++ b/include/hw/ppc/spapr.h
>>>>>> @@ -436,7 +436,7 @@ target_ulong spapr_rtas_call(PowerPCCPU *cpu, sPAPREnvironment *spapr,
>>>>>>                               uint32_t token, uint32_t nargs, target_ulong args,
>>>>>>                               uint32_t nret, target_ulong rets);
>>>>>>  int spapr_rtas_device_tree_setup(void *fdt, hwaddr rtas_addr,
>>>>>> -                                 hwaddr rtas_size);
>>>>>> +                                 hwaddr rtas_size, hwaddr rtas_entry);
>>>>>>  
>>>>>>  #define SPAPR_TCE_PAGE_SHIFT   12
>>>>>>  #define SPAPR_TCE_PAGE_SIZE    (1ULL << SPAPR_TCE_PAGE_SHIFT)
>>>>>> diff --git a/pc-bios/spapr-rtas/spapr-rtas.S b/pc-bios/spapr-rtas/spapr-rtas.S
>>>>>> index 903bec2..8c9b17e 100644
>>>>>> --- a/pc-bios/spapr-rtas/spapr-rtas.S
>>>>>> +++ b/pc-bios/spapr-rtas/spapr-rtas.S
>>>>>> @@ -30,6 +30,18 @@
>>>>>>  
>>>>>>  .globl	_start
>>>>>>  _start:
>>>>>> +	/*
>>>>>> +	 * Reserve space for error log in RTAS blob.
>>>>>> +	 *
>>>>>> +	 * Either we can reserve initial bytes for error log followed by
>>>>>> +	 * rtas-entry or space can be reserved after rtas-entry. I prefer
>>>>>> +	 * former, as we already have rtas-base and rtas-entry (currently
>>>>>> +	 * both pointing to rtas-base) defined in qemu and we can update
>>>>>> +	 * rtas-entry to point to an offset from rtas-base. This avoids
>>>>>> +	 * unnecessary definition of rtas-error-offset while keeping
>>>>>> +	 * rtas-entry redundant.
>>>>>> +	 */
>>>>>> +	. = 0x1000
>>>>>
>>>>>
>>>>> Why not this (and not changing spapr-rtas.S)?
>>>>>
>>>>> --- a/hw/ppc/spapr.c
>>>>> +++ b/hw/ppc/spapr.c
>>>>> @@ -875,7 +875,8 @@ static void ppc_spapr_reset(void)
>>>>>                         spapr->rtas_size);
>>>>>
>>>>>      /* Copy RTAS over */
>>>>> -    cpu_physical_memory_write(spapr->rtas_addr, spapr->rtas_blob,
>>>>> +    cpu_physical_memory_write(spapr->rtas_addr + RTAS_ENTRY_OFFSET,
>>>>> +                              spapr->rtas_blob,
>>>>>                                spapr->rtas_size);
>>>>
>>>> This is possible, however requires suitable adjustment to make sure
>>>> spapr->rtas_addr has enough space allocated.
>>>
>>>
>>> How is adding RTAS_ENTRY_OFFSET not enough to make sure that is has enough
>>> space? QEMU copies RTAS to guest memory, QEMU makes up rtas_addr/entry
>>> properties.
>>
>> QEMU adds spapr-rtas.bin as a rom, with rom->addr set to
>> spapr->rtas_addr, rom->datasize set to 20 bytes (the size of current
>> spapr-rtas.bin) and contents of spapr-rtas.bin read into rom->data
>> (malloc-ed region).
>>
>> I think, access to spapr->rtas_addr is mapped to this rom. Hence it is
>> necessary to have rtas_addr and rtas_size consistent with the Rom
>> struct. If we use spapr->rtas_addr + RTAS_ENTRY_OFFSET then we are
>> trying to access an invalid offset in rom region.
> 
> 
> What is that "rom" struct you are referring to? In upstream QEMU, I can
> only see:
> 
> ppc_spapr_init():
> [...]
> filename = qemu_find_file(QEMU_FILE_TYPE_BIOS, "spapr-rtas.bin")

In ppc_spapr_init() just after qemu_find_file() we have:

spapr->rtas_size = load_image_targphys(filename, spapr->rtas_addr, ...);

load_image_targphys() -> rom_add_file_fixed() -> rom_add_file(), where
Rom is initialized.

> spapr->rtas_size = get_image_size(filename);
> spapr->rtas_blob = g_malloc(spapr->rtas_size);
> if (load_image_size(filename, spapr->rtas_blob, spapr->rtas_size) < 0) {
> [...]
> 
> and then
> 
> ppc_spapr_reset():
> [...]
> spapr->rtas_addr = rtas_limit - RTAS_MAX_SIZE
> [...]
> cpu_physical_memory_write(spapr->rtas_addr, spapr->rtas_blob,
>                           spapr->rtas_size);
> [...]
> 
> 
> 
>>
>>
>>>
>>>
>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>>  	mr	4,3
>>>>>>  	lis	3,KVMPPC_H_RTAS@h
>>>>>>  	ori	3,3,KVMPPC_H_RTAS@l
>>>>>>
>>>>>
>>>>>
>>>>
>>>
>>>
>>
> 
> 

-- 
Regards,
Aravinda