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Commit 9524f227 authored by Nicholas Piggin's avatar Nicholas Piggin Committed by Michael Ellerman
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powerpc/64s: Fix irq state management in runlatch functions



When irqs are soft-disabled, MSR[EE] is volatile and can change from
1 to 0 asynchronously (if a PACA_IRQ_MUST_HARD_MASK interrupt hits).
So it can not be used to check hard IRQ enabled status, except to
confirm it is disabled.

ppc64_runlatch_on/off functions use MSR this way to decide whether to
re-enable MSR[EE] after disabling it, which leads to MSR[EE] being
enabled when it shouldn't be (when a PACA_IRQ_MUST_HARD_MASK had
disabled it between reading the MSR and clearing EE).

This has been tolerated in the kernel previously, and it doesn't seem
to cause a problem, but it is unexpected and may trip warnings or cause
other problems as we tighten up this state management. Fix this by only
re-enabling if PACA_IRQ_HARD_DIS is clear.

Signed-off-by: default avatarNicholas Piggin <npiggin@gmail.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220926054305.2671436-5-npiggin@gmail.com
parent e485f6c7
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