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

[Alexey Kardashevskiy <aik@au1.ibm.com>]

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")
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
>>>>>
>>>>
>>>>
>>>
>>
>>
> 


-- 
Alexey Kardashevskiy
IBM OzLabs, LTC Team

e-mail: aik@au1.ibm.com
notes: Alexey Kardashevskiy/Australia/IBM