Re: [PATCH v11 0/9] riscv: add SBI Supervisor Software Events support

[Anup Patel]

On Thu, Oct 29, 2026 at 8:36 AM Zhanpeng Zhang
<zhangzhanpeng.jasper@xxxxxxxxxxxxx> wrote:
>
> Hi Anup, Paul, Himanshu,
>
> On 10/29/26 12:55 AM, Anup Patel wrote:
>
> > [...]
> >
> > Changes in v11
> > ==============
> >
> > Rebased on latest for-next branch of linux-riscv tree (commit a5ae1bf65cee).
> > Also, tested PMU driver with both PMU irqs and PMU SSE events.
> >
>
> Thanks for rebasing and testing the series. I was a little surprised
> to see v11 posted, as I am still working through Himanshu's v10 review
> and validating the fixes on hardware. It would have been helpful to
> coordinate before reposting so that those changes could be included.
>
> I guess this follows Paul's request to rebase onto riscv/for-next.
> However, there is one change beyond the rebase that I would like to
> clarify: why does patch 4 remove the scoped_guard(preempt) sections
> from the CPU hotplug paths? These were present in v10 RESEND, and
> the local helpers still retain their preemption-disabled assertions.
> Is there a reason this protection is no longer needed?

Yes, this is based on discussion with Paul yesterday.

This series is blocking the whole RAS ACPI support.

>
> The changes discussed on the v10 threads are still outstanding in
> this posting:
>
> - Preserve TASK_TI_A0/A1/A2 across nested exceptions.
> - Replace the temporary GUP-based perf user-stack copy with nofault
>    uaccess, following the x86 approach.
> - Address the per-CPU initialization/preemption concern.
> - Split the MAINTAINERS updates into a separate patch.

There is always going to be new updates since it will take
time to harden the SSE implementation. All these changes
can be done as separate follow-on patches.

>
> Additional fixes from Sashiko review, the kernel test robot report,
> and our follow-up debugging are also being consolidated:
>
> - NMI-safe entry and lockdep irqflags tracking.
> - The unused-function warning reported by the kernel test robot.
> - RV32 vmalloc synchronization before nofault fixup.
> - Faulting-PC validation in the kprobe single-step fault path.
> - Per-counter STOP handling in SSE error paths.
> - Ordinary IRQ CPU-PM notifier ordering and IRQ cleanup tracking.

Same comment as above, please do this as separate series.
No point in holding all other dependent work endlessly.

>
> In particular, Himanshu identified the missing preservation of
> TASK_TI_A0/A1/A2 across nested exceptions [1]. Following his review,
> I validated the fix with hardware A/B testing: removing it reproduced
> corruption, while the fixed kernel completed the same test sequence.
> This also gives us a solid basis for replacing the temporary GUP
> workaround with nofault uaccess.
>
> Paul, please hold off on taking this version into for-next until
> these fixes are included. The rebase and PMU testing are useful, but
> there are still outstanding correctness issues.
>
> I will consolidate the changes and post v12 against riscv/for-next,
> with an updated changelog and validation results. Let's coordinate
> the next posting to keep everything together.
>
> Thanks,
> Zhanpeng
>
> [1] https://lore.kernel.org/r/as79MHtNYd-VbUug@xxxxxxxxxxxxxxxxxxxxxxxxxxx/

Regards,
Anup