x86/mm/tlb: Revert the recent lazy TLB patches

Revert commits:

  95b0e6357d3e x86/mm/tlb: Always use lazy TLB mode
  64482aafe55f x86/mm/tlb: Only send page table free TLB flush to lazy TLB CPUs
  ac0315896970 x86/mm/tlb: Make lazy TLB mode lazier
  61d0beb5796a x86/mm/tlb: Restructure switch_mm_irqs_off()
  2ff6ddf19c0e x86/mm/tlb: Leave lazy TLB mode at page table free time

In order to simplify the TLB invalidate fixes for x86 and unify the
parts that need backporting.  We'll try again later.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Rik van Riel <riel@surriel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 16 insertions, 5 deletions

diff --git a/arch/x86/include/asm/tlbflush.h b/arch/x86/include/asm/tlbflush.h
index 511bf5fae8b8..6690cd3fc8b1 100644
--- a/arch/x86/include/asm/tlbflush.h
+++ b/arch/x86/include/asm/tlbflush.h
@@ -148,6 +148,22 @@ static inline unsigned long build_cr3_noflush(pgd_t *pgd, u16 asid)
 #define __flush_tlb_one_user(addr) __native_flush_tlb_one_user(addr)
 #endif
 
+static inline bool tlb_defer_switch_to_init_mm(void)
+{
+	/*
+	 * If we have PCID, then switching to init_mm is reasonably
+	 * fast.  If we don't have PCID, then switching to init_mm is
+	 * quite slow, so we try to defer it in the hopes that we can
+	 * avoid it entirely.  The latter approach runs the risk of
+	 * receiving otherwise unnecessary IPIs.
+	 *
+	 * This choice is just a heuristic.  The tlb code can handle this
+	 * function returning true or false regardless of whether we have
+	 * PCID.
+	 */
+	return !static_cpu_has(X86_FEATURE_PCID);
+}
+
 struct tlb_context {
 	u64 ctx_id;
 	u64 tlb_gen;
@@ -538,9 +554,4 @@ extern void arch_tlbbatch_flush(struct arch_tlbflush_unmap_batch *batch);
 	native_flush_tlb_others(mask, info)
 #endif
 
-extern void tlb_flush_remove_tables(struct mm_struct *mm);
-extern void tlb_flush_remove_tables_local(void *arg);
-
-#define HAVE_TLB_FLUSH_REMOVE_TABLES
-
 #endif /* _ASM_X86_TLBFLUSH_H */