Per popular request..

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
 arch/x86/include/asm/tlbflush.h |   18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

--- a/arch/x86/include/asm/tlbflush.h
+++ b/arch/x86/include/asm/tlbflush.h
@@ -376,6 +376,9 @@ static inline void invalidate_user_asid(
 		  (unsigned long *)this_cpu_ptr(&cpu_tlbstate.user_pcid_flush_mask));
 }
 
+/*
+ * flush the entire current user mapping
+ */
 static inline void __native_flush_tlb(void)
 {
 	invalidate_user_asid(this_cpu_read(cpu_tlbstate.loaded_mm_asid));
@@ -389,6 +392,9 @@ static inline void __native_flush_tlb(vo
 	preempt_enable();
 }
 
+/*
+ * flush everything
+ */
 static inline void __native_flush_tlb_global(void)
 {
 	unsigned long cr4, flags;
@@ -420,6 +426,9 @@ static inline void __native_flush_tlb_gl
 	raw_local_irq_restore(flags);
 }
 
+/*
+ * flush one page in the user mapping
+ */
 static inline void __native_flush_tlb_single(unsigned long addr)
 {
 	u32 loaded_mm_asid = this_cpu_read(cpu_tlbstate.loaded_mm_asid);
@@ -439,15 +448,24 @@ static inline void __native_flush_tlb_si
 		invpcid_flush_one(user_pcid(loaded_mm_asid), addr);
 }
 
+/*
+ * flush everything
+ */
 static inline void __flush_tlb_all(void)
 {
 	if (boot_cpu_has(X86_FEATURE_PGE)) {
 		__flush_tlb_global();
 	} else {
+		/*
+		 * !PGE -> !PCID (setup_pcid()), thus every flush is total.
+		 */
 		__flush_tlb();
 	}
 }
 
+/*
+ * flush one page in the kernel mapping
+ */
 static inline void __flush_tlb_one(unsigned long addr)
 {
 	count_vm_tlb_event(NR_TLB_LOCAL_FLUSH_ONE);