powerpc/mm/book3s64/radix: Flush the full mm even when need_flush_all is set

With the previous patch, we should now not be using need_flush_all for
powerpc. But then make sure we force a PID tlbie flush with RIC=2 if
we ever find need_flush_all set. Also don't reset it after a mmu
gather flush.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20191024075801.22434-3-aneesh.kumar@linux.ibm.com

arch/powerpc/mm/book3s64/radix_tlb.c

@@ -995,7 +995,7 @@ void radix__tlb_flush(struct mmu_gather *tlb)
 	 * that flushes the process table entry cache upon process teardown.
 	 * See the comment for radix in arch_exit_mmap().
 	 */
-	if (tlb->fullmm) {
+	if (tlb->fullmm || tlb->need_flush_all) {
 		__flush_all_mm(mm, true);
 	} else if ( (psize = radix_get_mmu_psize(page_size)) == -1) {
 		if (!tlb->freed_tables)
@@ -1008,7 +1008,6 @@ void radix__tlb_flush(struct mmu_gather *tlb)
 		else
 			radix__flush_tlb_pwc_range_psize(mm, start, end, psize);
 	}
-	tlb->need_flush_all = 0;
 }
 
 static __always_inline void __radix__flush_tlb_range_psize(struct mm_struct *mm,

include/asm-generic/tlb.h

@@ -428,7 +428,7 @@ static inline void tlb_change_page_size(struct mmu_gather *tlb,
 {
 #ifdef CONFIG_HAVE_MMU_GATHER_PAGE_SIZE
 	if (tlb->page_size && tlb->page_size != page_size) {
-		if (!tlb->fullmm)
+		if (!tlb->fullmm && !tlb->need_flush_all)
 			tlb_flush_mmu(tlb);
 	}