x86: vmclear vmcss on all cpus when doing kdump if necessary

index 317ff17..43e0db3 100644
@@ -163,6 +163,8 @@ struct kimage_arch {
 };
 #endif
 
+extern struct atomic_notifier_head vmclear_notifier_list;
+
 #endif /* __ASSEMBLY__ */
 
 #endif /* _ASM_X86_KEXEC_H */

index 13ad899..c953d50 100644
@@ -16,6 +16,8 @@
 #include <linux/delay.h>
 #include <linux/elf.h>
 #include <linux/elfcore.h>
+#include <linux/module.h>
+#include <linux/notifier.h>
 
 #include <asm/processor.h>
 #include <asm/hardirq.h>

@@ -30,6 +32,19 @@
 
 int in_crash_kexec;
 
+/*
+ * The list is used to VMCLEAR vmcss loaded on all
+ * cpus. And when loading kvm_intel module, the
+ * vmclear function will be registered in the list.
+ */
+ATOMIC_NOTIFIER_HEAD(vmclear_notifier_list);
+EXPORT_SYMBOL_GPL(vmclear_notifier_list);
+
+static inline void cpu_emergency_vmclear_loaded_vmcss(void)
+{
+	atomic_notifier_call_chain(&vmclear_notifier_list, 0, NULL);
+}
+
 #if defined(CONFIG_SMP) && defined(CONFIG_X86_LOCAL_APIC)
 
 static void kdump_nmi_callback(int cpu, struct pt_regs *regs)

@@ -46,6 +61,11 @@ static void kdump_nmi_callback(int cpu, struct pt_regs *regs)
 #endif
 	crash_save_cpu(regs, cpu);
 
+	/*
+	 * VMCLEAR vmcss loaded on all cpus if needed.
+	 */
+	cpu_emergency_vmclear_loaded_vmcss();
+
 	/* Disable VMX or SVM if needed.
 	 *
 	 * We need to disable virtualization on all CPUs.

@@ -88,6 +108,11 @@ void native_machine_crash_shutdown(struct pt_regs *regs)
 
 	kdump_nmi_shootdown_cpus();
 
+	/*
+	 * VMCLEAR vmcss loaded on this cpu if needed.
+	 */
+	cpu_emergency_vmclear_loaded_vmcss();
+
 	/* Booting kdump kernel with VMX or SVM enabled won't work,
 	 * because (among other limitations) we can't disable paging
 	 * with the virt flags.

index 4ff0ab9..2fbb128 100644
@@ -41,6 +41,7 @@
 #include <asm/i387.h>
 #include <asm/xcr.h>
 #include <asm/perf_event.h>
+#include <asm/kexec.h>
 
 #include "trace.h"
 

@@ -963,6 +964,49 @@ static void vmcs_load(struct vmcs *vmcs)
 		       vmcs, phys_addr);
 }
 
+#ifdef CONFIG_KEXEC
+/*
+ * This bitmap is used to indicate whether the vmclear
+ * operation is enabled on all cpus. All disabled by
+ * default.
+ */
+static cpumask_t crash_vmclear_enabled_bitmap = CPU_MASK_NONE;
+
+static inline void crash_enable_local_vmclear(int cpu)
+{
+	cpumask_set_cpu(cpu, &crash_vmclear_enabled_bitmap);
+}
+
+static inline void crash_disable_local_vmclear(int cpu)
+{
+	cpumask_clear_cpu(cpu, &crash_vmclear_enabled_bitmap);
+}
+
+static inline int crash_local_vmclear_enabled(int cpu)
+{
+	return cpumask_test_cpu(cpu, &crash_vmclear_enabled_bitmap);
+}
+
+static void vmclear_local_loaded_vmcss(void);
+static int crash_vmclear_local_loaded_vmcss(struct notifier_block *this,
+					    unsigned long val, void *ptr)
+{
+	int cpu = raw_smp_processor_id();
+
+	if (crash_local_vmclear_enabled(cpu))
+		vmclear_local_loaded_vmcss();
+
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block crash_vmclear_notifier = {
+	.notifier_call = crash_vmclear_local_loaded_vmcss,
+};
+#else
+static inline void crash_enable_local_vmclear(int cpu) { }
+static inline void crash_disable_local_vmclear(int cpu) { }
+#endif /* CONFIG_KEXEC */
+
 static void __loaded_vmcs_clear(void *arg)
 {
 	struct loaded_vmcs *loaded_vmcs = arg;

@@ -972,8 +1016,10 @@ static void __loaded_vmcs_clear(void *arg)
 		return; /* vcpu migration can race with cpu offline */
 	if (per_cpu(current_vmcs, cpu) == loaded_vmcs->vmcs)
 		per_cpu(current_vmcs, cpu) = NULL;
+	crash_disable_local_vmclear(cpu);
 	list_del(&loaded_vmcs->loaded_vmcss_on_cpu_link);
 	loaded_vmcs_init(loaded_vmcs);
+	crash_enable_local_vmclear(cpu);
 }
 
 static void loaded_vmcs_clear(struct loaded_vmcs *loaded_vmcs)

@@ -1491,8 +1537,10 @@ static void vmx_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
 
 		kvm_make_request(KVM_REQ_TLB_FLUSH, vcpu);
 		local_irq_disable();
+		crash_disable_local_vmclear(cpu);
 		list_add(&vmx->loaded_vmcs->loaded_vmcss_on_cpu_link,
 			 &per_cpu(loaded_vmcss_on_cpu, cpu));
+		crash_enable_local_vmclear(cpu);
 		local_irq_enable();
 
 		/*

@@ -2302,6 +2350,18 @@ static int hardware_enable(void *garbage)
 		return -EBUSY;
 
 	INIT_LIST_HEAD(&per_cpu(loaded_vmcss_on_cpu, cpu));
+
+	/*
+	 * Now we can enable the vmclear operation in kdump
+	 * since the loaded_vmcss_on_cpu list on this cpu
+	 * has been initialized.
+	 *
+	 * Though the cpu is not in VMX operation now, there
+	 * is no problem to enable the vmclear operation
+	 * for the loaded_vmcss_on_cpu list is empty!
+	 */
+	crash_enable_local_vmclear(cpu);
+
 	rdmsrl(MSR_IA32_FEATURE_CONTROL, old);
 
 	test_bits = FEATURE_CONTROL_LOCKED;

@@ -7230,6 +7290,11 @@ static int __init vmx_init(void)
 	if (r)
 		goto out3;
 
+#ifdef CONFIG_KEXEC
+	atomic_notifier_chain_register(&vmclear_notifier_list,
+				       &crash_vmclear_notifier);
+#endif
+
 	vmx_disable_intercept_for_msr(MSR_FS_BASE, false);
 	vmx_disable_intercept_for_msr(MSR_GS_BASE, false);
 	vmx_disable_intercept_for_msr(MSR_KERNEL_GS_BASE, true);

@@ -7265,6 +7330,11 @@ static void __exit vmx_exit(void)
 	free_page((unsigned long)vmx_io_bitmap_b);
 	free_page((unsigned long)vmx_io_bitmap_a);
 
+#ifdef CONFIG_KEXEC
+	atomic_notifier_chain_unregister(&vmclear_notifier_list,
+					 &crash_vmclear_notifier);
+#endif
+
 	kvm_exit();
 }