[PATCH] lib: sbi: Fix PMP CSR detection

[Anup Patel]

> -----Original Message-----
> From: opensbi <opensbi-bounces at lists.infradead.org> On Behalf Of Atish
> Patra
> Sent: 25 September 2020 01:09
> To: Pragnesh Patel <pragnesh.patel at sifive.com>
> Cc: Yash Shah <yash.shah at sifive.com>; Bin Meng <bmeng.cn at gmail.com>;
> Sagar Shrikant Kadam <sagar.kadam at sifive.com>; OpenSBI
> <opensbi at lists.infradead.org>
> Subject: Re: [PATCH] lib: sbi: Fix PMP CSR detection
> 
> On Wed, Sep 23, 2020 at 12:36 AM Pragnesh Patel
> <pragnesh.patel at sifive.com> wrote:
> >
> > HiFive unleashed currently implements fewer than 56 bits of physical
> > address so existing PMP CSR detection is broken.
> >
> > PMP address register encodes bits 55-2 of a 56-bit physical address,
> > Not all physical address bits may be implemented, So just check
> > minimum 1 bit.
> >
> It's good to add .
> As per the privilege spec,
> 
> Are there any other usecase for PMP_ADDR_MASK in future? If not, we can
> remove that as well.

Based on this fix, (as a separate test) it will be good if we can detect number
of physical address bits implemented by RISC-V platform when atleast one
PMPADDRx CSR is available. This will require PMP_ADDR_MASK define.

> 
> > Fixes: 74d1db706293 ("lib: sbi: Improve PMP CSR detection and
> > progamming")
> >
> > Signed-off-by: Pragnesh Patel <pragnesh.patel at sifive.com>
> > ---
> >  lib/sbi/sbi_hart.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/lib/sbi/sbi_hart.c b/lib/sbi/sbi_hart.c index
> > 4cbe8ce..6413194 100644
> > --- a/lib/sbi/sbi_hart.c
> > +++ b/lib/sbi/sbi_hart.c
> > @@ -403,7 +403,7 @@ static void hart_detect_features(struct sbi_scratch
> *scratch)
> >         __check_csr_32(__csr + 32, __rdonly, __wrval, __field, __skip)
> >
> >         /* Detect number of PMP regions */
> > -       __check_csr_64(CSR_PMPADDR0, 0, PMP_ADDR_MASK, pmp_count,
> __pmp_skip);
> > +       __check_csr_64(CSR_PMPADDR0, 0, 1UL, pmp_count, __pmp_skip);
> >  __pmp_skip:
> >
> >         /* Detect number of MHPM counters */
> > --
> > 2.17.1
> >
> >
> > --
> > opensbi mailing list
> > opensbi at lists.infradead.org
> > http://lists.infradead.org/mailman/listinfo/opensbi
> 
> Otherwise,
> 
> Reviewed-by: Atish Patra <atish.patra at wdc.com>

Looks good to me.

Reviewed-by: Anup Patel <anup.patel at wdc.com>

Regards,
Anup