[PATCH v3 6/6] RISC-V: Do not use cpumask data structure for hartid bitmap

[Geert Uytterhoeven]

Hi Atish,

On Wed, Jan 26, 2022 at 9:28 AM Geert Uytterhoeven <geert at linux-m68k.org> wrote:
> On Wed, Jan 26, 2022 at 3:21 AM Atish Patra <atishp at atishpatra.org> wrote:
> > On Tue, Jan 25, 2022 at 2:26 PM Jessica Clarke <jrtc27 at jrtc27.com> wrote:
> > > On 20 Jan 2022, at 09:09, Atish Patra <atishp at rivosinc.com> wrote:
> > > > Currently, SBI APIs accept a hartmask that is generated from struct
> > > > cpumask. Cpumask data structure can hold upto NR_CPUs value. Thus, it
> > > > is not the correct data structure for hartids as it can be higher
> > > > than NR_CPUs for platforms with sparse or discontguous hartids.
> > > >
> > > > Remove all association between hartid mask and struct cpumask.
> > > >
> > > > Reviewed-by: Anup Patel <anup at brainfault.org> (For Linux RISC-V changes)
> > > > Acked-by: Anup Patel <anup at brainfault.org> (For KVM RISC-V changes)
> > > > Signed-off-by: Atish Patra <atishp at rivosinc.com>
>
> > I am yet to reproduce it on my end.
> > @Geert Uytterhoeven: can you please try the below diff on your end.
>
> Unfortunately it doesn't fix the issue for me.
>
> /me debugging...

Found it: after this commit, the SBI_EXT_RFENCE_REMOTE_FENCE_I and
SBI_EXT_RFENCE_REMOTE_SFENCE_VMA ecalls are now called with
hmask = 0x8000000000000001 and hbase = 1 instead of hmask = 3 and
hbase = 0.

cpuid 1 maps to  hartid 0
cpuid 0 maps to hartid 1

    __sbi_rfence_v02:364: cpuid 1 hartid 0
    __sbi_rfence_v02:377: hartid 0 hbase 1
    hmask |= 1UL << (hartid - hbase);

oops

    __sbi_rfence_v02_call:303: SBI_EXT_RFENCE_REMOTE_FENCE_I hmask
8000000000000001 hbase 1

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert at linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds