Patch "x86/mm: Add comments to clarify which TLB-flush functions are supposed to flush what" has been added to the 4.14-stable tree

This is a note to let you know that I've just added the patch titled

x86/mm: Add comments to clarify which TLB-flush functions are supposed to flush what

to the 4.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
x86-mm-add-comments-to-clarify-which-tlb-flush-functions-are-supposed-to-flush-what.patch
and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Peter Zijlstra <[email protected]>
Date: Tue, 5 Dec 2017 13:34:52 +0100
Subject: x86/mm: Add comments to clarify which TLB-flush functions are supposed to flush what

From: Peter Zijlstra <[email protected]>

commit 3f67af51e56f291d7417d77c4f67cd774633c5e1 upstream.

Per popular request..

---
 arch/x86/include/asm/tlbflush.h |   23 +++++++++++++++++++++--
 1 file changed, 21 insertions(+), 2 deletions(-)

@@ -228,6 +228,9 @@ 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)
 {
 	/*

@@ -240,6 +243,9 @@ static inline void __native_flush_tlb(vo
 	preempt_enable();
 }
 
+/*
+ * flush everything
+ */
 static inline void __native_flush_tlb_global(void)
 {
 	unsigned long cr4, flags;

@@ -269,17 +275,27 @@ 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 --

@@ -290,6 +306,9 @@ 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);

Patches currently in stable-queue which might be from [email protected] are

queue-4.14/x86-entry-rename-sysenter_stack-to-cpu_entry_area_entry_stack.patch queue-4.14/x86-mm-put-mmu-to-hardware-asid-translation-in-one-place.patch queue-4.14/x86-vsyscall-64-explicitly-set-_page_user-in-the-pagetable-hierarchy.patch queue-4.14/x86-uv-use-the-right-tlb-flush-api.patch queue-4.14/x86-decoder-fix-and-update-the-opcodes-map.patch queue-4.14/x86-mm-dump_pagetables-check-page_present-for-real.patch queue-4.14/x86-ldt-prevent-ldt-inheritance-on-exec.patch queue-4.14/x86-microcode-dont-abuse-the-tlb-flush-interface.patch queue-4.14/x86-doc-remove-obvious-weirdnesses-from-the-x86-mm-layout-documentation.patch queue-4.14/init-invoke-init_espfix_bsp-from-mm_init.patch queue-4.14/x86-cpu_entry_area-move-it-to-a-separate-unit.patch queue-4.14/x86-vsyscall-64-warn-and-fail-vsyscall-emulation-in-native-mode.patch queue-4.14/x86-mm-create-asm-invpcid.h.patch queue-4.14/x86-mm-remove-superfluous-barriers.patch queue-4.14/x86-ldt-rework-locking.patch queue-4.14/arch-mm-allow-arch_dup_mmap-to-fail.patch queue-4.14/x86-cpu_entry_area-move-it-out-of-the-fixmap.patch queue-4.14/tools-headers-sync-objtool-uapi-header.patch queue-4.14/x86-mm-remove-hard-coded-asid-limit-checks.patch queue-4.14/x86-kconfig-limit-nr_cpus-on-32-bit-to-a-sane-amount.patch queue-4.14/objtool-fix-64-bit-build-on-32-bit-host.patch queue-4.14/x86-mm-add-comments-to-clarify-which-tlb-flush-functions-are-supposed-to-flush-what.patch queue-4.14/x86-mm-move-the-cr3-construction-functions-to-tlbflush.h.patch queue-4.14/x86-mm-dump_pagetables-make-the-address-hints-correct-and-readable.patch queue-4.14/x86-insn-eval-add-utility-functions-to-get-segment-selector.patch queue-4.14/objtool-move-synced-files-to-their-original-relative-locations.patch queue-4.14/x86-mm-use-__flush_tlb_one-for-kernel-memory.patch queue-4.14/objtool-move-kernel-headers-code-sync-check-to-a-script.patch queue-4.14/x86-mm-64-improve-the-memory-map-documentation.patch queue-4.14/objtool-fix-cross-build.patch