Re: [Qemu-devel] [PATCH] fw_cfg: fix the life cycle and the name of "qemu_extra_params_fw"

[Laszlo Ersek]

On 01/31/19 16:06, Michael S. Tsirkin wrote:
> On Thu, Jan 31, 2019 at 03:27:01PM +0100, Laszlo Ersek wrote:
>> On 01/18/19 23:31, Laszlo Ersek wrote:
>>> Commit 19bcc4bc3213 ("fw_cfg: Make qemu_extra_params_fw locally",
>>> 2019-01-04) changed the storage duration of the "qemu_extra_params_fw"
>>> array from static to automatic. This broke the interface contract on the
>>> fw_cfg_add_file() function, which is documented as follows, in
>>> "include/hw/nvram/fw_cfg.h":
>>>
>>>> [...] The data referenced by the starting pointer is only linked, NOT
>>>> copied, into the data structure of the fw_cfg device. [...]
>>>
>>> As a result, when guest firmware fetches the "etc/boot-menu-wait" fw_cfg
>>> file, it now sees garbage. Fix the regression by changing the storage
>>> duration to allocated. (The call is reached at most once, on the realize
>>> path of the board-specific fw_cfg sysbus device.)
>>>
>>> While at it, clean up the name and the assignment of the object as well.
>>>
>>> Cc: Gerd Hoffmann <address@hidden>
>>> Cc: Markus Armbruster <address@hidden>
>>> Cc: Philippe Mathieu-Daudé <address@hidden>
>>> Fixes: 19bcc4bc3213e78c303ad480a7a578f62258252d
>>> Signed-off-by: Laszlo Ersek <address@hidden>
>>> ---
>>>  hw/nvram/fw_cfg.c | 9 +++++----
>>>  1 file changed, 5 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/hw/nvram/fw_cfg.c b/hw/nvram/fw_cfg.c
>>> index 53e8e010a8b7..7fdf04adc97f 100644
>>> --- a/hw/nvram/fw_cfg.c
>>> +++ b/hw/nvram/fw_cfg.c
>>> @@ -118,7 +118,6 @@ static void fw_cfg_bootsplash(FWCfgState *s)
>>>  {
>>>      const char *boot_splash_filename = NULL;
>>>      const char *boot_splash_time = NULL;
>>> -    uint8_t qemu_extra_params_fw[2];
>>>      char *filename, *file_data;
>>>      gsize file_size;
>>>      int file_type;
>>> @@ -132,6 +131,8 @@ static void fw_cfg_bootsplash(FWCfgState *s)
>>>      /* insert splash time if user configurated */
>>>      if (boot_splash_time) {
>>>          int64_t bst_val = qemu_opt_get_number(opts, "splash-time", -1);
>>> +        uint16_t bst_le16;
>>> +
>>>          /* validate the input */
>>>          if (bst_val < 0 || bst_val > 0xffff) {
>>>              error_report("splash-time is invalid,"
>>> @@ -139,9 +140,9 @@ static void fw_cfg_bootsplash(FWCfgState *s)
>>>              exit(1);
>>>          }
>>>          /* use little endian format */
>>> -        qemu_extra_params_fw[0] = (uint8_t)(bst_val & 0xff);
>>> -        qemu_extra_params_fw[1] = (uint8_t)((bst_val >> 8) & 0xff);
>>> -        fw_cfg_add_file(s, "etc/boot-menu-wait", qemu_extra_params_fw, 2);
>>> +        bst_le16 = cpu_to_le16(bst_val);
>>> +        fw_cfg_add_file(s, "etc/boot-menu-wait",
>>> +                        g_memdup(&bst_le16, sizeof bst_le16), sizeof 
>>> bst_le16);
>>>      }
>>>  
>>>      /* insert splash file if user configurated */
>>>
>>
>> I hope a polite ping can't hurt; can we get this merged please?
>>
>> Thanks
>> LAszlo
> 
> Sure it does not hurt. I have it tagged  for the next pull.
> 

Thanks!
Laszlo