Re: [PATCH] ppc/pnv: Fix NMI system reset SRR1 value

[Greg Kurz <groug@kaod.org>]

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On Thu, 7 May 2020 23:51:54 +1000
David Gibson <david@gibson.dropbear.id.au> wrote:

> On Thu, May 07, 2020 at 09:48:24PM +1000, Nicholas Piggin wrote:
> > Commit a77fed5bd926 ("ppc/pnv: Add support for NMI interface") got the

Please note that the culprit patch was merged with a different SHA1:

https://git.qemu.org/?p=qemu.git;a=commit;h=01b552b05b0f21f8ff57a508f7ad26f7abbcd123

> > SRR1 setting wrong for sresets that hit outside of power-save states.
> > 
> > Fix this, better documenting the source for the bit definitions.
> > 
> > Fixes: a77fed5bd926 ("ppc/pnv: Add support for NMI interface") got the

Fixes: 01b552b05b0f ("ppc/pnv: Add support for NMI interface")

> > Cc: Cédric Le Goater <clg@kaod.org>
> > Cc: David Gibson <david@gibson.dropbear.id.au>
> > Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
> 
> Applied to ppc-for-5.1, thanks.
> > ---
> > 
> > Thanks to Cedric for pointing out concerns with a previous MCE patch
> > that unearthed this as well. Linux does not actually care what these
> > SRR1[42:45] bits look like for non-powersave sresets, but we should
> > follow documented behaviour as far as possible.
> > 
> >  hw/ppc/pnv.c | 26 ++++++++++++++++++++------
> >  1 file changed, 20 insertions(+), 6 deletions(-)
> > 
> > diff --git a/hw/ppc/pnv.c b/hw/ppc/pnv.c
> > index a3b7a8d0ff..1b4748ce6d 100644
> > --- a/hw/ppc/pnv.c
> > +++ b/hw/ppc/pnv.c
> > @@ -1986,12 +1986,26 @@ static void pnv_cpu_do_nmi_on_cpu(CPUState *cs, run_on_cpu_data arg)
> >  
> >      cpu_synchronize_state(cs);
> >      ppc_cpu_do_system_reset(cs);
> > -    /*
> > -     * SRR1[42:45] is set to 0100 which the ISA defines as implementation
> > -     * dependent. POWER processors use this for xscom triggered interrupts,
> > -     * which come from the BMC or NMI IPIs.
> > -     */
> > -    env->spr[SPR_SRR1] |= PPC_BIT(43);
> > +    if (env->spr[SPR_SRR1] & PPC_BITMASK(46, 47)) {
> > +        /*
> > +	 * Power-save wakeups, as indicated by non-zero SRR1[46:47] put the
> > +	 * wakeup reason in SRR1[42:45], system reset is indicated with 0b0100
> > +	 * (PPC_BIT(43)).
> > +	 */
> > +        if (!(env->spr[SPR_SRR1] & PPC_BIT(43))) {
> > +            warn_report("ppc_cpu_do_system_reset does not set system reset wakeup reason");
> > +            env->spr[SPR_SRR1] |= PPC_BIT(43);
> > +        }
> > +    } else {
> > +        /*
> > +	 * For non-powersave system resets, SRR1[42:45] are defined to be
> > +	 * implementation-dependent. The POWER9 User Manual specifies that
> > +	 * an external (SCOM driven, which may come from a BMC nmi command or
> > +	 * another CPU requesting a NMI IPI) system reset exception should be
> > +	 * 0b0010 (PPC_BIT(44)).
> > +         */
> > +        env->spr[SPR_SRR1] |= PPC_BIT(44);
> > +    }
> >  }
> >  
> >  static void pnv_nmi(NMIState *n, int cpu_index, Error **errp)
> 


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