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

[Michael S. Tsirkin]

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.