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    SubjectRe: [PATCH v3 6/6] RISC-V: Do not use cpumask data structure for hartid bitmap
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    On Jan 27 2022, Geert Uytterhoeven wrote:

    > Hi Atish,
    >
    > On Thu, Jan 27, 2022 at 9:48 AM Geert Uytterhoeven <geert@linux-m68k.org> wrote:
    >> On Thu, Jan 27, 2022 at 2:02 AM Atish Patra <atishp@atishpatra.org> wrote:
    > > Ahh yes. hmask will be incorrect if the bootcpu(cpu 0) is a higher
    >> > hartid and it is trying to do a remote tlb flush/IPI
    >> > to lower the hartid. We should generate the hartid array before the loop.
    >> >
    >> > Can you try this diff ? It seems to work for me during multiple boot
    >> > cycle on the unleashed.
    >> >
    >> > You can find the patch here as well
    >> > https://github.com/atishp04/linux/commits/v5.17-rc1
    >>
    >> Thanks, that fixes the issue for me.
    >>
    >> > --- a/arch/riscv/kernel/sbi.c
    >> > +++ b/arch/riscv/kernel/sbi.c
    >
    >> > @@ -345,13 +368,21 @@ static int __sbi_rfence_v02(int fid, const
    >> > struct cpumask *cpu_mask,
    >> > unsigned long arg4, unsigned long arg5)
    >> > {
    >> > unsigned long hartid, cpuid, hmask = 0, hbase = 0;
    >> > - int result;
    >> > + int result, index = 0, max_index = 0;
    >> > + unsigned long hartid_arr[NR_CPUS] = {0};
    >>
    >> That's up to 256 bytes on the stack. And more if the maximum
    >> number of cores is increased.
    >
    > I.e. 4 KiB with the proposed increase to 256 CPUs, as mentioned in

    And those 4K need to be cleared each time the function is called, even
    if there is only a small number of cpus.

    --
    Andreas Schwab, schwab@linux-m68k.org
    GPG Key fingerprint = 7578 EB47 D4E5 4D69 2510 2552 DF73 E780 A9DA AEC1
    "And now for something completely different."

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