[PATCH 3/3] pseries/scm: buffer pmem's bound addr in dt for kexec kernel

[Pingfan Liu]

On Fri, Feb 28, 2020 at 2:52 PM Christophe Leroy
<christophe.leroy at c-s.fr> wrote:
>
>
>
> Le 28/02/2020 à 06:53, Pingfan Liu a écrit :
> > At present, plpar_hcall(H_SCM_BIND_MEM, ...) takes a very long time, so
> > if dumping to fsdax, it will take a very long time.
> >
> > Take a closer look, during the papr_scm initialization, the only
> > configuration is through drc_pmem_bind()-> plpar_hcall(H_SCM_BIND_MEM,
> > ...), which helps to set up the bound address.
> >
> > On pseries, for kexec -l/-p kernel, there is no reset of hardware, and this
> > step can be stepped around to save times.  So the pmem bound address can be
> > passed to the 2nd kernel through a dynamic added property "bound-addr" in
> > dt node 'ibm,pmemory'.
> >
> > Signed-off-by: Pingfan Liu <kernelfans at gmail.com>
> > To: linuxppc-dev at lists.ozlabs.org
> > Cc: Benjamin Herrenschmidt <benh at kernel.crashing.org>
> > Cc: Paul Mackerras <paulus at samba.org>
> > Cc: Michael Ellerman <mpe at ellerman.id.au>
> > Cc: Hari Bathini <hbathini at linux.ibm.com>
> > Cc: Aneesh Kumar K.V <aneesh.kumar at linux.ibm.com>
> > Cc: Oliver O'Halloran <oohall at gmail.com>
> > Cc: Dan Williams <dan.j.williams at intel.com>
> > Cc: kexec at lists.infradead.org
> > ---
> > note: I can not find such a pseries machine, and not finish it yet.
> > ---
> >   arch/powerpc/platforms/pseries/papr_scm.c | 32 +++++++++++++++++++++----------
> >   1 file changed, 22 insertions(+), 10 deletions(-)
> >
> > diff --git a/arch/powerpc/platforms/pseries/papr_scm.c b/arch/powerpc/platforms/pseries/papr_scm.c
> > index c2ef320..555e746 100644
> > --- a/arch/powerpc/platforms/pseries/papr_scm.c
> > +++ b/arch/powerpc/platforms/pseries/papr_scm.c
> > @@ -382,7 +382,7 @@ static int papr_scm_probe(struct platform_device *pdev)
> >   {
> >       struct device_node *dn = pdev->dev.of_node;
> >       u32 drc_index, metadata_size;
> > -     u64 blocks, block_size;
> > +     u64 blocks, block_size, bound_addr = 0;
> >       struct papr_scm_priv *p;
> >       const char *uuid_str;
> >       u64 uuid[2];
> > @@ -439,17 +439,29 @@ static int papr_scm_probe(struct platform_device *pdev)
> >       p->metadata_size = metadata_size;
> >       p->pdev = pdev;
> >
> > -     /* request the hypervisor to bind this region to somewhere in memory */
> > -     rc = drc_pmem_bind(p);
> > +     of_property_read_u64(dn, "bound-addr", &bound_addr);
> > +     if (bound_addr)
> > +             p->bound_addr = bound_addr;
> > +     else {
>
> All legs of an if/else must have { } when one leg need them, see codying
> style.
OK,
>
> > +             struct property *property;
> > +             u64 big;
> >
> > -     /* If phyp says drc memory still bound then force unbound and retry */
> > -     if (rc == H_OVERLAP)
> > -             rc = drc_pmem_query_n_bind(p);
> > +             /* request the hypervisor to bind this region to somewhere in memory */
> > +             rc = drc_pmem_bind(p);
> >
> > -     if (rc != H_SUCCESS) {
> > -             dev_err(&p->pdev->dev, "bind err: %d\n", rc);
> > -             rc = -ENXIO;
> > -             goto err;
> > +             /* If phyp says drc memory still bound then force unbound and retry */
> > +             if (rc == H_OVERLAP)
> > +                     rc = drc_pmem_query_n_bind(p);
> > +
> > +             if (rc != H_SUCCESS) {
> > +                     dev_err(&p->pdev->dev, "bind err: %d\n", rc);
> > +                     rc = -ENXIO;
> > +                     goto err;
> > +             }
> > +             big = cpu_to_be64(p->bound_addr);
> > +             property = new_property("bound-addr", sizeof(u64), &big,
> > +                     NULL);
>
> Why plitting this line in two parts ? You have lines far longer above.
> In powerpc we allow lines 90 chars long.
OK, good to know it.

Thanks,
Pingfan