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authorWei Liu <wei.liu@kernel.org>2021-01-05 20:50:43 +0300
committerWei Liu <wei.liu@kernel.org>2021-01-06 14:03:16 +0300
commitad0a6bad44758afa3b440c254a24999a0c7e35d5 (patch)
treea8e21b9bb6c20536d3313279b249b99964d5d77b /arch/x86/hyperv/mmu.c
parentdfe94d4086e40e92b1926bddcefa629b791e9b28 (diff)
downloadlinux-ad0a6bad44758afa3b440c254a24999a0c7e35d5.tar.xz
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>
Diffstat (limited to 'arch/x86/hyperv/mmu.c')
-rw-r--r--arch/x86/hyperv/mmu.c12
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);