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

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

On Tuesday 02 September 2014 12:04 PM, Alexey Kardashevskiy wrote:
> On 09/02/2014 03:56 PM, Aravinda Prasad wrote:
>>
>>
>> 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, ...);
> 
> 
> What tree has this? Mine does not.
> 
> ka1:~/p/qemu$ grep load_image_targphys hw/ppc/spapr.c
>             initrd_size = load_image_targphys(initrd_filename, initrd_base,
>     fw_size = load_image_targphys(filename, 0, FW_MAX_SIZE);
> ka1:~/p/qemu$
> 

I am using git://git.qemu.org/qemu.git, master branch.

I have 88e89a57f9 as the latest commit and I see:

$ grep load_image_targphys hw/ppc/spapr.c
    spapr->rtas_size = load_image_targphys(filename, spapr->rtas_addr,
         initrd_size = load_image_targphys(initrd_filename, initrd_base,
    fw_size = load_image_targphys(filename, 0, FW_MAX_SIZE);


This was introduced in commit a3467baa.

Regards,
Aravinda

> 
> 
>>
>> 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