target/ppc: 4xx optimise tlbwe_lo TLB flushing

Rather than tlbwe_lo always flushing all TCG TLBs, have it flush just
those corresponding to the old software TLB, and only if it was valid.

Tested-by: BALATON Zoltan <balaton@eik.bme.hu>
Acked-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>

target/ppc/mmu_helper.c

@@ -813,12 +813,20 @@ void helper_4xx_tlbwe_hi(CPUPPCState *env, target_ulong entry,
 void helper_4xx_tlbwe_lo(CPUPPCState *env, target_ulong entry,
                          target_ulong val)
 {
+    CPUState *cs = env_cpu(env);
     ppcemb_tlb_t *tlb;
 
     qemu_log_mask(CPU_LOG_MMU, "%s entry %i val " TARGET_FMT_lx "\n",
                   __func__, (int)entry, val);
     entry &= PPC4XX_TLB_ENTRY_MASK;
     tlb = &env->tlb.tlbe[entry];
+    /* Invalidate previous TLB (if it's valid) */
+    if (tlb->prot & PAGE_VALID) {
+        qemu_log_mask(CPU_LOG_MMU, "%s: invalidate old TLB %d start "
+                      TARGET_FMT_lx " end " TARGET_FMT_lx "\n", __func__,
+                      (int)entry, tlb->EPN, tlb->EPN + tlb->size);
+        ppcemb_tlb_flush(cs, tlb);
+    }
     tlb->attr = val & PPC4XX_TLBLO_ATTR_MASK;
     tlb->RPN = val & PPC4XX_TLBLO_RPN_MASK;
     tlb->prot = PAGE_READ;
@@ -836,8 +844,6 @@ void helper_4xx_tlbwe_lo(CPUPPCState *env, target_ulong entry,
                   tlb->prot & PAGE_WRITE ? 'w' : '-',
                   tlb->prot & PAGE_EXEC ? 'x' : '-',
                   tlb->prot & PAGE_VALID ? 'v' : '-', (int)tlb->PID);
-
-    env->tlb_need_flush |= TLB_NEED_LOCAL_FLUSH;
 }
 
 target_ulong helper_4xx_tlbsx(CPUPPCState *env, target_ulong address)