Re: [Qemu-ppc] [GIT PULL for qemu-pseries REPOST] pseries: Update SLOF firmware image

[Alexey Kardashevskiy]

On 14/08/2019 14:33, Aravinda Prasad wrote:
> On Tuesday 13 August 2019 07:47 PM, David Gibson wrote:
> > On Tue, Aug 13, 2019 at 01:00:24PM +0530, Aravinda Prasad wrote:
> > > On Monday 12 August 2019 03:38 PM, David Gibson wrote:
> > > > On Mon, Aug 05, 2019 at 02:14:39PM +0530, Aravinda Prasad wrote:
> > > > > Alexey/David,
> > > > >
> > > > > With the SLOF changes, QEMU cannot resize the RTAS blob. Resizing is
> > > > > required for FWNMI support which extends the RTAS blob to include an
> > > > > error log upon a machine check.
> > > > >
> > > > > The check to valid RTAS buffer fails in the guest because the rtas-size
> > > > > updated in QEMU is not reflecting in the guest.
> > > > >
> > > > > Any workaround for this?
> > > >
> > > > Well, we should still be able to do it, it just means fwnmi would need
> > > > a SLOF change.  It's an inconvenience, but not really a big deal.
> > >
> > > Yes. Alexey and I were discussing about the following changes to SLOf:
> > >
> > > diff --git a/lib/libhvcall/hvcall.S b/lib/libhvcall/hvcall.S
> > > index b19f6dbeff2c..880d29a29122 100644
> > > --- a/lib/libhvcall/hvcall.S
> > > +++ b/lib/libhvcall/hvcall.S
> > > @@ -134,6 +134,7 @@ ENTRY(hv_rtas)
> > >          ori     r3,r3,KVMPPC_H_RTAS@l
> > >          HVCALL
> > >          blr
> > > +    .space 2048
> > >          .globl hv_rtas_size
> > >   hv_rtas_size:
> > >          .long . - hv_rtas;
> > >
> > >
> > > But this will statically reserve space for RTAS even when
> > > SPAPR_CAP_FWNMI_MCE is OFF.
> >
> > Sure.  We could flag that in the DT somehow, and have SLOF reserve the
> > space conditionally.
> >
> > Or we could just ignore it. 2 kiB is miniscule compared to our minimum
> > guest size, and our current RTAS is microscopic compared to PowerVM.
>
> I also think so, 2kiB is miniscule so we can allocate it statically.
>
> Alexey,
>
> Can you please include the above one line fix to SLOF?


I am thinking of:
===
@@ -132,20 +132,22 @@ ENTRY(hv_rtas)
        mr      r4,r3
        lis     r3,KVMPPC_H_RTAS@h
        ori     r3,r3,KVMPPC_H_RTAS@l
        HVCALL
        blr
+       .space 2048 - (. - hv_rtas)
        .globl hv_rtas_size
 hv_rtas_size:
        .long . - hv_rtas;

 ENTRY(hv_rtas_broken_sc1)
        mr      r4,r3
        lis     r3,KVMPPC_H_RTAS@h
        ori     r3,r3,KVMPPC_H_RTAS@l
        .long   0x7c000268
        blr
+       .space 2048 - (. - hv_rtas_broken_sc1)
        .globl hv_rtas_broken_sc1_size
 hv_rtas_broken_sc1_size:
        .long . - hv_rtas_broken_sc1;
===

to align the rtas blob to 2k precisely. But QEMU hardcoded 
RTAS_ERROR_LOG_OFFSET bothers me a bit, I should probably put some sort 
of a magic marker at which RTAS log can start.

David, any thoughts? The marker could be as simple as a zero, for example.


--
Alexey