Re: [Qemu-ppc] [PATCH] spapr: add missing break in h_get_cpu_characteristics()

[Greg Kurz]

On Fri, 2 Feb 2018 07:11:08 -0200
Daniel Henrique Barboza <address@hidden> wrote:

> On 02/01/2018 05:47 PM, Greg Kurz wrote:
> > Detected by Coverity (CID 1385702). This fixes the recently added hypercall
> > to let guests properly apply Spectre and Meltdown workarounds.  
> 
> Paolo Bonzini reported this error in a reply to the pull request that
> added the patch:
> 
> "Re: [Qemu-ppc] [Qemu-devel] [PULL 12/12] target/ppc/spapr: Add H-Call 
> H_GET_CPU_CHARACTERISTICS
> 
> On 28/01/2018 22:28, David Gibson wrote:
> 
> > +    switch (safe_indirect_branch) {
> > +    case SPAPR_CAP_FIXED:
> > +        characteristics |= H_CPU_CHAR_BCCTRL_SERIALISED;  
> 
> Missing "break;" here.
> 
> Paolo
> 
> "
> 
> I think it is nice to mention in the commit msg that Paolo also detected 
> this same error,
> specially given that his email was sent before this patch.
> 

Heh, Paolo's mail landed in the pull req thread in my mail client and I saw
it after sending the patch :P ... also I'm pretty sure Paolo was made aware
of this issue by Coverity, just as I was :)

From: address@hidden
To: address@hidden
Subject: New Defects reported by Coverity Scan for QEMU
Date: Thu, 01 Feb 2018 18:11:33 +0000 (UTC)

Hi,

Please find the latest report on new defect(s) introduced to QEMU found with
Coverity Scan.

...

*** CID 1385702:  Control flow issues  (MISSING_BREAK)
/hw/ppc/spapr_hcall.c: 1700 in h_get_cpu_characteristics()
1694             break;
1695         }
1696     
1697         switch (safe_indirect_branch) {
1698         case SPAPR_CAP_FIXED:
1699             characteristics |= H_CPU_CHAR_BCCTRL_SERIALISED;
>>>     CID 1385702:  Control flow issues  (MISSING_BREAK)
>>>     The above case falls through to this one.  
1700         default: /* broken */
1701             assert(safe_indirect_branch == SPAPR_CAP_BROKEN);
1702             break;
1703         }
1704     
1705         args[0] = characteristics;


No big deal I guess :)

> 
> Thanks,
> 
> 
> Daniel
> 
> 
> >
> > Fixes: c59704b25473 "target/ppc/spapr: Add H-Call H_GET_CPU_CHARACTERISTICS"
> > Signed-off-by: Greg Kurz <address@hidden>
> > ---
> >   hw/ppc/spapr_hcall.c |    1 +
> >   1 file changed, 1 insertion(+)
> >
> > diff --git a/hw/ppc/spapr_hcall.c b/hw/ppc/spapr_hcall.c
> > index 4d0e6eb0cf1d..596f58378a40 100644
> > --- a/hw/ppc/spapr_hcall.c
> > +++ b/hw/ppc/spapr_hcall.c
> > @@ -1697,6 +1697,7 @@ static target_ulong 
> > h_get_cpu_characteristics(PowerPCCPU *cpu,
> >       switch (safe_indirect_branch) {
> >       case SPAPR_CAP_FIXED:
> >           characteristics |= H_CPU_CHAR_BCCTRL_SERIALISED;
> > +        break;
> >       default: /* broken */
> >           assert(safe_indirect_branch == SPAPR_CAP_BROKEN);
> >           break;
> >
> >  
>