[PATCH v3 2/2] riscv: Fix text patching when IPI are used

[Conor Dooley]

On Tue, Mar 05, 2024 at 08:33:30AM +0530, Anup Patel wrote:
> On Tue, Mar 5, 2024 at 1:54 AM Björn Töpel <bjorn at kernel.org> wrote:
> >
> > Conor Dooley <conor at kernel.org> writes:
> >
> > > On Thu, Feb 29, 2024 at 01:10:56PM +0100, Alexandre Ghiti wrote:
> > >> For now, we use stop_machine() to patch the text and when we use IPIs for
> > >> remote icache flushes (which is emitted in patch_text_nosync()), the system
> > >> hangs.
> > >>
> > >> So instead, make sure every CPU executes the stop_machine() patching
> > >> function and emit a local icache flush there.
> > >>
> > >> Co-developed-by: Björn Töpel <bjorn at rivosinc.com>
> > >> Signed-off-by: Björn Töpel <bjorn at rivosinc.com>
> > >> Signed-off-by: Alexandre Ghiti <alexghiti at rivosinc.com>
> > >> Reviewed-by: Andrea Parri <parri.andrea at gmail.com>
> > >
> > > What commit does this fix?
> >
> > Hmm. The bug is exposed when the AIA IPI are introduced, and used
> > (instead of the firmware-based).
> >
> > I'm not sure this is something we'd like backported, but rather a
> > prerequisite to AIA.
> >
> > @Anup @Alex WDYT?
> >
> 
> The current text patching never considered IPIs being injected
> directly in S-mode from hart to another so we are seeing this
> issue now with AIA IPIs.
> 
> We certainly don't need to backport this fix since it's more
> of a preparatory fix for AIA IPIs.

Whether or not this is backportable, if it fixes a bug, it should get
a Fixes: tag for the commit that it fixes. Fixes: isn't "the backport"
tag, cc: stable is.
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