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Re: [Qemu-ppc] [GIT PULL for qemu-pseries REPOST] pseries: Update SLOF f
From: |
David Gibson |
Subject: |
Re: [Qemu-ppc] [GIT PULL for qemu-pseries REPOST] pseries: Update SLOF firmware image |
Date: |
Sun, 25 Aug 2019 11:03:10 +1000 |
User-agent: |
Mutt/1.12.1 (2019-06-15) |
On Fri, Aug 23, 2019 at 02:09:44PM +1000, Alexey Kardashevskiy wrote:
>
>
> 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.
Eh, TBH I don't think an agreed upon magic marker has all that much
advantage on an agreed upon offset. Let's keep it simple and retain
the fixed offset for now. If that's ever a problem we'll need a
synchronized qemu & SLOF update, but that's ok - that's an
inconvenience, not a disaster.
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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