[patch V149 14/50] x86/mm: Clarify which functions are supposed to flush what

[Thomas Gleixner]

From: Peter Zijlstra <pet...@infradead.org>

Per popular request..

Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org>
Signed-off-by: Ingo Molnar <mi...@kernel.org>
Signed-off-by: Thomas Gleixner <t...@linutronix.de>
Cc: Andy Lutomirski <l...@kernel.org>
Cc: Boris Ostrovsky <boris.ostrov...@oracle.com>
Cc: Borislav Petkov <b...@alien8.de>
Cc: Brian Gerst <brge...@gmail.com>
Cc: Dave Hansen <dave.han...@linux.intel.com>
Cc: David Laight <david.lai...@aculab.com>
Cc: Denys Vlasenko <dvlas...@redhat.com>
Cc: Eduardo Valentin <edu...@amazon.com>
Cc: Greg KH <gre...@linuxfoundation.org>
Cc: H. Peter Anvin <h...@zytor.com>
Cc: Josh Poimboeuf <jpoim...@redhat.com>
Cc: Juergen Gross <jgr...@suse.com>
Cc: Linus Torvalds <torva...@linux-foundation.org>
Cc: Will Deacon <will.dea...@arm.com>
Cc: aligu...@amazon.com
Cc: daniel.gr...@iaik.tugraz.at
Cc: hu...@google.com
Cc: keesc...@google.com
Cc: linux...@kvack.org
---
 arch/x86/include/asm/tlbflush.h |   23 +++++++++++++++++++++--
 1 file changed, 21 insertions(+), 2 deletions(-)

--- a/arch/x86/include/asm/tlbflush.h
+++ b/arch/x86/include/asm/tlbflush.h
@@ -231,6 +231,9 @@ static inline void cr4_set_bits_and_upda
 
 extern void initialize_tlbstate_and_flush(void);
 
+/*
+ * flush the entire current user mapping
+ */
 static inline void __native_flush_tlb(void)
 {
        /*
@@ -243,6 +246,9 @@ static inline void __native_flush_tlb(vo
        preempt_enable();
 }
 
+/*
+ * flush everything
+ */
 static inline void __native_flush_tlb_global(void)
 {
        unsigned long cr4, flags;
@@ -272,17 +278,27 @@ 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)
 {
        asm volatile("invlpg (%0)" ::"r" (addr) : "memory");
 }
 
+/*
+ * flush everything
+ */
 static inline void __flush_tlb_all(void)
 {
-       if (boot_cpu_has(X86_FEATURE_PGE))
+       if (boot_cpu_has(X86_FEATURE_PGE)) {
                __flush_tlb_global();
-       else
+       } else {
+               /*
+                * !PGE -> !PCID (setup_pcid()), thus every flush is total.
+                */
                __flush_tlb();
+       }
 
        /*
         * Note: if we somehow had PCID but not PGE, then this wouldn't work --
@@ -293,6 +309,9 @@ static inline void __flush_tlb_all(void)
         */
 }
 
+/*
+ * 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);