linux-kernel - Re: [PATCH] powerpc/32: Restore disabling of interrupts at interrupt/syscall exit

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Message-ID: <176680916371.22434.11687040747709449917.b4-ty@linux.ibm.com>
Date: Sat, 27 Dec 2025 09:53:50 +0530
From: Madhavan Srinivasan <maddy@...ux.ibm.com>
To: Michael Ellerman <mpe@...erman.id.au>, Nicholas Piggin <npiggin@...il.com>,
        "Christophe Leroy (CS GROUP)" <chleroy@...nel.org>
Cc: linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        Christian Zigotzky <chzigotzky@...osoft.de>,
        Guenter Roeck <linux@...ck-us.net>
Subject: Re: [PATCH] powerpc/32: Restore disabling of interrupts at interrupt/syscall exit

On Fri, 19 Dec 2025 13:23:52 +0100, Christophe Leroy (CS GROUP) wrote:
> Commit 2997876c4a1a ("powerpc/32: Restore clearing of MSR[RI] at
> interrupt/syscall exit") delayed clearing of MSR[RI], but missed that
> both MSR[RI] and MSR[EE] are cleared at the same time, so the commit
> also delayed the disabling of interrupts, leading to unexpected
> behaviour.
> 
> To fix that, mostly revert the blamed commit and restore the clearing
> of MSR[RI] in interrupt_exit_kernel_prepare() instead. For 8xx it
> implies adding a synchronising instruction after the mtspr in order to
> make sure no instruction counter interrupt (used for perf events) will
> fire just after clearing MSR[RI].
> 
> [...]

Applied to powerpc/fixes.

[1/1] powerpc/32: Restore disabling of interrupts at interrupt/syscall exit
      https://git.kernel.org/powerpc/c/608328ba5b0619cbc28b409296b5e3840bcb97b6

cheers