diff --git a/arch/x86/include/asm/x86_init.h b/arch/x86/include/asm/x86_init.h
index 28ac3cb9b987..b0f313278967 100644
--- a/arch/x86/include/asm/x86_init.h
+++ b/arch/x86/include/asm/x86_init.h
@@ -149,12 +149,24 @@ struct x86_init_acpi {
  * @enc_status_change_finish	Notify HV after the encryption status of a range is changed
  * @enc_tlb_flush_required	Returns true if a TLB flush is needed before changing page encryption status
  * @enc_cache_flush_required	Returns true if a cache flush is needed before changing page encryption status
+ * @enc_kexec_begin		Begin the two-step process of converting shared memory back
+ *				to private. It stops the new conversions from being started
+ *				and waits in-flight conversions to finish, if possible.
+ *				The @crash parameter denotes whether the function is being
+ *				called in the crash shutdown path.
+ * @enc_kexec_finish		Finish the two-step process of converting shared memory to
+ *				private. All memory is private after the call when
+ *				the function returns.
+ *				It is called on only one CPU while the others are shut down
+ *				and with interrupts disabled.
  */
 struct x86_guest {
 	int (*enc_status_change_prepare)(unsigned long vaddr, int npages, bool enc);
 	int (*enc_status_change_finish)(unsigned long vaddr, int npages, bool enc);
 	bool (*enc_tlb_flush_required)(bool enc);
 	bool (*enc_cache_flush_required)(void);
+	void (*enc_kexec_begin)(bool crash);
+	void (*enc_kexec_finish)(void);
 };
 
 /**
diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c
index f06501445cd9..fc52ea80cdc8 100644
--- a/arch/x86/kernel/crash.c
+++ b/arch/x86/kernel/crash.c
@@ -128,6 +128,18 @@ void native_machine_crash_shutdown(struct pt_regs *regs)
 #ifdef CONFIG_HPET_TIMER
 	hpet_disable();
 #endif
+
+	/*
+	 * Non-crash kexec calls enc_kexec_begin() while scheduling is still
+	 * active. This allows the callback to wait until all in-flight
+	 * shared<->private conversions are complete. In a crash scenario,
+	 * enc_kexec_begin() gets called after all but one CPU have been shut
+	 * down and interrupts have been disabled. This allows the callback to
+	 * detect a race with the conversion and report it.
+	 */
+	x86_platform.guest.enc_kexec_begin(true);
+	x86_platform.guest.enc_kexec_finish();
+
 	crash_save_cpu(regs, safe_smp_processor_id());
 }
 
diff --git a/arch/x86/kernel/reboot.c b/arch/x86/kernel/reboot.c
index f3130f762784..097313147ad3 100644
--- a/arch/x86/kernel/reboot.c
+++ b/arch/x86/kernel/reboot.c
@@ -12,6 +12,7 @@
 #include <linux/delay.h>
 #include <linux/objtool.h>
 #include <linux/pgtable.h>
+#include <linux/kexec.h>
 #include <acpi/reboot.h>
 #include <asm/io.h>
 #include <asm/apic.h>
@@ -716,6 +717,14 @@ static void native_machine_emergency_restart(void)
 
 void native_machine_shutdown(void)
 {
+	/*
+	 * Call enc_kexec_begin() while all CPUs are still active and
+	 * interrupts are enabled. This will allow all in-flight memory
+	 * conversions to finish cleanly.
+	 */
+	if (kexec_in_progress)
+		x86_platform.guest.enc_kexec_begin(false);
+
 	/* Stop the cpus and apics */
 #ifdef CONFIG_X86_IO_APIC
 	/*
@@ -752,6 +761,9 @@ void native_machine_shutdown(void)
 #ifdef CONFIG_X86_64
 	x86_platform.iommu_shutdown();
 #endif
+
+	if (kexec_in_progress)
+		x86_platform.guest.enc_kexec_finish();
 }
 
 static void __machine_emergency_restart(int emergency)
diff --git a/arch/x86/kernel/x86_init.c b/arch/x86/kernel/x86_init.c
index a7143bb7dd93..8a79fb505303 100644
--- a/arch/x86/kernel/x86_init.c
+++ b/arch/x86/kernel/x86_init.c
@@ -138,6 +138,8 @@ static int enc_status_change_prepare_noop(unsigned long vaddr, int npages, bool
 static int enc_status_change_finish_noop(unsigned long vaddr, int npages, bool enc) { return 0; }
 static bool enc_tlb_flush_required_noop(bool enc) { return false; }
 static bool enc_cache_flush_required_noop(void) { return false; }
+static void enc_kexec_begin_noop(bool crash) {}
+static void enc_kexec_finish_noop(void) {}
 static bool is_private_mmio_noop(u64 addr) {return false; }
 
 struct x86_platform_ops x86_platform __ro_after_init = {
@@ -161,6 +163,8 @@ struct x86_platform_ops x86_platform __ro_after_init = {
 		.enc_status_change_finish  = enc_status_change_finish_noop,
 		.enc_tlb_flush_required	   = enc_tlb_flush_required_noop,
 		.enc_cache_flush_required  = enc_cache_flush_required_noop,
+		.enc_kexec_begin	   = enc_kexec_begin_noop,
+		.enc_kexec_finish	   = enc_kexec_finish_noop,
 	},
 };
 
