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Diffstat (limited to 'arch/x86/kernel/cpu/mshyperv.c')
-rw-r--r--arch/x86/kernel/cpu/mshyperv.c24
1 files changed, 24 insertions, 0 deletions
diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
index 6c044543545e..f37e02e41a77 100644
--- a/arch/x86/kernel/cpu/mshyperv.c
+++ b/arch/x86/kernel/cpu/mshyperv.c
@@ -30,6 +30,7 @@
#include <asm/apic.h>
#include <asm/timer.h>
#include <asm/reboot.h>
+#include <asm/nmi.h>
struct ms_hyperv_info ms_hyperv;
EXPORT_SYMBOL_GPL(ms_hyperv);
@@ -157,6 +158,26 @@ static unsigned char hv_get_nmi_reason(void)
return 0;
}
+#ifdef CONFIG_X86_LOCAL_APIC
+/*
+ * Prior to WS2016 Debug-VM sends NMIs to all CPUs which makes
+ * it dificult to process CHANNELMSG_UNLOAD in case of crash. Handle
+ * unknown NMI on the first CPU which gets it.
+ */
+static int hv_nmi_unknown(unsigned int val, struct pt_regs *regs)
+{
+ static atomic_t nmi_cpu = ATOMIC_INIT(-1);
+
+ if (!unknown_nmi_panic)
+ return NMI_DONE;
+
+ if (atomic_cmpxchg(&nmi_cpu, -1, raw_smp_processor_id()) != -1)
+ return NMI_HANDLED;
+
+ return NMI_DONE;
+}
+#endif
+
static void __init ms_hyperv_init_platform(void)
{
/*
@@ -182,6 +203,9 @@ static void __init ms_hyperv_init_platform(void)
pr_info("HyperV: LAPIC Timer Frequency: %#x\n",
lapic_timer_frequency);
}
+
+ register_nmi_handler(NMI_UNKNOWN, hv_nmi_unknown, NMI_FLAG_FIRST,
+ "hv_nmi_unknown");
#endif
if (ms_hyperv.features & HV_X64_MSR_TIME_REF_COUNT_AVAILABLE)