diff options
| author | Wei Liu | 2021-01-05 17:50:43 +0000 |
|---|---|---|
| committer | Wei Liu | 2021-01-06 11:03:16 +0000 |
| commit | ad0a6bad44758afa3b440c254a24999a0c7e35d5 (patch) | |
| tree | a8e21b9bb6c20536d3313279b249b99964d5d77b | |
| parent | dfe94d4086e40e92b1926bddcefa629b791e9b28 (diff) | |
x86/hyperv: check cpu mask after interrupt has been disabled
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>
| -rw-r--r-- | arch/x86/hyperv/mmu.c | 12 |
1 files changed, 9 insertions, 3 deletions
diff --git a/arch/x86/hyperv/mmu.c b/arch/x86/hyperv/mmu.c index 5208ba49c89a..2c87350c1fb0 100644 --- a/arch/x86/hyperv/mmu.c +++ b/arch/x86/hyperv/mmu.c @@ -66,11 +66,17 @@ static void hyperv_flush_tlb_others(const struct cpumask *cpus, if (!hv_hypercall_pg) goto do_native; - if (cpumask_empty(cpus)) - return; - local_irq_save(flags); + /* + * Only check the mask _after_ interrupt has been disabled to avoid the + * mask changing under our feet. + */ + if (cpumask_empty(cpus)) { + local_irq_restore(flags); + return; + } + flush_pcpu = (struct hv_tlb_flush **) this_cpu_ptr(hyperv_pcpu_input_arg); |