Patch "kaiser: asm/tlbflush.h handle noPGE at lower level" has been added to the 4.4-stable tree

[<gregkh@linuxfoundation.org>]

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

    kaiser: asm/tlbflush.h handle noPGE at lower level

to the 4.4-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:
     kaiser-asm-tlbflush.h-handle-nopge-at-lower-level.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From foo@baz Wed Jan  3 18:58:12 CET 2018
From: Hugh Dickins <hughd@google.com>
Date: Sat, 4 Nov 2017 18:23:24 -0700
Subject: kaiser: asm/tlbflush.h handle noPGE at lower level

From: Hugh Dickins <hughd@google.com>


I found asm/tlbflush.h too twisty, and think it safer not to avoid
__native_flush_tlb_global_irq_disabled() in the kaiser_enabled case,
but instead let it handle kaiser_enabled along with cr3: it can just
use __native_flush_tlb() for that, no harm in re-disabling preemption.

(This is not the same change as Kirill and Dave have suggested for
upstream, flipping PGE in cr4: that's neat, but needs a cpu_has_pge
check; cr3 is enough for kaiser, and thought to be cheaper than cr4.)

Also delete the X86_FEATURE_INVPCID invpcid_flush_all_nonglobals()
preference from __native_flush_tlb(): unlike the invpcid_flush_all()
preference in __native_flush_tlb_global(), it's not seen in upstream
4.14, and was recently reported to be surprisingly slow.

Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 arch/x86/include/asm/tlbflush.h |   27 +++------------------------
 1 file changed, 3 insertions(+), 24 deletions(-)

--- a/arch/x86/include/asm/tlbflush.h
+++ b/arch/x86/include/asm/tlbflush.h
@@ -151,14 +151,6 @@ static inline void kaiser_flush_tlb_on_r
 
 static inline void __native_flush_tlb(void)
 {
-	if (this_cpu_has(X86_FEATURE_INVPCID)) {
-		/*
-		 * Note, this works with CR4.PCIDE=0 or 1.
-		 */
-		invpcid_flush_all_nonglobals();
-		return;
-	}
-
 	/*
 	 * If current->mm == NULL then we borrow a mm which may change during a
 	 * task switch and therefore we must not be preempted while we write CR3
@@ -182,11 +174,8 @@ static inline void __native_flush_tlb_gl
 		/* restore PGE as it was before */
 		native_write_cr4(cr4);
 	} else {
-		/*
-		 * x86_64 microcode update comes this way when CR4.PGE is not
-		 * enabled, and it's safer for all callers to allow this case.
-		 */
-		native_write_cr3(native_read_cr3());
+		/* do it with cr3, letting kaiser flush user PCID */
+		__native_flush_tlb();
 	}
 }
 
@@ -194,12 +183,6 @@ static inline void __native_flush_tlb_gl
 {
 	unsigned long flags;
 
-	if (kaiser_enabled) {
-		/* Globals are not used at all */
-		__native_flush_tlb();
-		return;
-	}
-
 	if (this_cpu_has(X86_FEATURE_INVPCID)) {
 		/*
 		 * Using INVPCID is considerably faster than a pair of writes
@@ -255,11 +238,7 @@ static inline void __native_flush_tlb_si
 
 static inline void __flush_tlb_all(void)
 {
-	if (cpu_has_pge)
-		__flush_tlb_global();
-	else
-		__flush_tlb();
-
+	__flush_tlb_global();
 	/*
 	 * Note: if we somehow had PCID but not PGE, then this wouldn't work --
 	 * we'd end up flushing kernel translations for the current ASID but


Patches currently in stable-queue which might be from hughd@google.com are

queue-4.4/kaiser-vmstat-show-nr_kaisertable-as-nr_overhead.patch
queue-4.4/kaiser-add-nokaiser-boot-option-using-alternative.patch
queue-4.4/kaiser-fix-unlikely-error-in-alloc_ldt_struct.patch
queue-4.4/kaiser-_pgd_alloc-without-__gfp_repeat-to-avoid-stalls.patch
queue-4.4/kaiser-kaiser_flush_tlb_on_return_to_user-check-pcid.patch
queue-4.4/x86-paravirt-dont-patch-flush_tlb_single.patch
queue-4.4/kaiser-merged-update.patch
queue-4.4/kaiser-delete-kaiser_real_switch-option.patch
queue-4.4/kaiser-kaiser_remove_mapping-move-along-the-pgd.patch
queue-4.4/kaiser-fix-perf-crashes.patch
queue-4.4/kaiser-drop-is_atomic-arg-to-kaiser_pagetable_walk.patch
queue-4.4/kaiser-load_new_mm_cr3-let-switch_user_cr3-flush-user.patch
queue-4.4/kaiser-enhanced-by-kernel-and-user-pcids.patch
queue-4.4/kaiser-x86_cr3_pcid_noflush-and-x86_cr3_pcid_user.patch
queue-4.4/kaiser-use-alternative-instead-of-x86_cr3_pcid_noflush.patch
queue-4.4/kaiser-stack-map-page_size-at-thread_size-page_size.patch
queue-4.4/kaiser-name-that-0x1000-kaiser_shadow_pgd_offset.patch
queue-4.4/kaiser-fix-regs-to-do_nmi-ifndef-config_kaiser.patch
queue-4.4/kaiser-do-not-set-_page_nx-on-pgd_none.patch
queue-4.4/kaiser-tidied-up-asm-kaiser.h-somewhat.patch
queue-4.4/kaiser-cleanups-while-trying-for-gold-link.patch
queue-4.4/kaiser-tidied-up-kaiser_add-remove_mapping-slightly.patch
queue-4.4/kaiser-fix-build-and-fixme-in-alloc_ldt_struct.patch
queue-4.4/kaiser-kernel-address-isolation.patch
queue-4.4/kaiser-enomem-if-kaiser_pagetable_walk-null.patch
queue-4.4/kaiser-asm-tlbflush.h-handle-nopge-at-lower-level.patch
queue-4.4/kaiser-paranoid_entry-pass-cr3-need-to-paranoid_exit.patch
queue-4.4/kaiser-kaiser-depends-on-smp.patch
queue-4.4/kaiser-pcid-0-for-kernel-and-128-for-user.patch