x86/hyperv: check cpu mask after interrupt has been disabled
commit ad0a6bad44
upstream.
We've observed crashes due to an empty cpu mask in
hyperv_flush_tlb_others. Obviously the cpu mask in question is changed
between the cpumask_empty call at the beginning of the function and when
it is actually used later.
One theory is that an interrupt comes in between and a code path ends up
changing the mask. Move the check after interrupt has been disabled to
see if it fixes the issue.
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Cc: stable@kernel.org
Link: https://lore.kernel.org/r/20210105175043.28325-1-wei.liu@kernel.org
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
5.4-rM2-2.2.x-imx-squashed
parent
1a202b9b9d
commit
984f57e425
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@ -66,11 +66,17 @@ static void hyperv_flush_tlb_others(const struct cpumask *cpus,
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if (!hv_hypercall_pg)
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goto do_native;
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if (cpumask_empty(cpus))
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return;
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local_irq_save(flags);
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/*
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* Only check the mask _after_ interrupt has been disabled to avoid the
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* mask changing under our feet.
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*/
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if (cpumask_empty(cpus)) {
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local_irq_restore(flags);
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return;
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}
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flush_pcpu = (struct hv_tlb_flush **)
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this_cpu_ptr(hyperv_pcpu_input_arg);
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