CVE-2023-52740

In the Linux kernel, the following vulnerability has been resolved:
powerpc/64s/interrupt: Fix interrupt exit race with security mitigation
switch The RFI and STF security mitigation options can flip the
interrupt_exit_not_reentrant static branch condition concurrently with the
interrupt exit code which tests that branch. Interrupt exit tests this
condition to set MSR[EE|RI] for exit, then again in the case a soft-masked
interrupt is found pending, to recover the MSR so the interrupt can be
replayed before attempting to exit again. If the condition changes between
these two tests, the MSR and irq soft-mask state will become corrupted,
leading to warnings and possible crashes. For example, if the branch is
initially true then false, MSR[EE] will be 0 but PACA_IRQ_HARD_DIS clear
and EE may not get enabled, leading to warnings in irq_64.c.