diff --git a/xen/arch/x86/traps.c b/xen/arch/x86/traps.c
index 9679bfdb08..f7992ff230 100644
--- a/xen/arch/x86/traps.c
+++ b/xen/arch/x86/traps.c
@@ -2348,6 +2348,19 @@ void asm_domain_crash_synchronous(unsigned long addr)
         do_softirq();
 }
 
+#ifdef CONFIG_DEBUG
+void check_ist_exit(const struct cpu_user_regs *regs, bool ist_exit)
+{
+    const unsigned int ist_mask =
+        (1U << X86_EXC_NMI) | (1U << X86_EXC_DB) |
+        (1U << X86_EXC_DF)  | (1U << X86_EXC_MC);
+    uint8_t ev = regs->entry_vector;
+    bool is_ist = (ev < TRAP_nr) && ((1U << ev) & ist_mask);
+
+    ASSERT(is_ist == ist_exit);
+}
+#endif
+
 /*
  * Local variables:
  * mode: C
diff --git a/xen/arch/x86/x86_64/entry.S b/xen/arch/x86/x86_64/entry.S
index 266c0a0990..671e3b3fd5 100644
--- a/xen/arch/x86/x86_64/entry.S
+++ b/xen/arch/x86/x86_64/entry.S
@@ -650,8 +650,15 @@ ret_from_intr:
         .section .text.entry, "ax", @progbits
 
         ALIGN
-/* No special register assumptions. */
+/* %r12=ist_exit */
 restore_all_xen:
+
+#ifdef CONFIG_DEBUG
+        mov   %rsp, %rdi
+        mov   %r12, %rsi
+        call  check_ist_exit
+#endif
+
         /*
          * Check whether we need to switch to the per-CPU page tables, in
          * case we return to late PV exit code (from an NMI or #MC).
@@ -1032,6 +1039,10 @@ handle_ist_exception:
         INDIRECT_CALL %rdx
         mov   %r15, STACK_CPUINFO_FIELD(xen_cr3)(%r14)
         mov   %bl, STACK_CPUINFO_FIELD(use_pv_cr3)(%r14)
+
+        /* This is an IST exit */
+        mov   $1, %r12d
+
         cmpb  $TRAP_nmi,UREGS_entry_vector(%rsp)
         jne   ret_from_intr