From 479f36ef8e9763781ba53fca780b4e09c001fe0e Mon Sep 17 00:00:00 2001
From: Paolo Bonzini <pbonzini@redhat.com>
Date: Sat, 17 Feb 2018 17:20:41 -0500
Subject: [PATCH] exec: avoid unnecessary cacheline bounce on
 ram_list.mru_block

Whenever the MRU cache hits for the list of RAM blocks, qemu_get_ram_block
does an unnecessary write that causes a processor cache line to bounce
from one core to another. This causes a performance hit.

Backports commit 68851b98e5bf6d397498b74f1776801274ab8d48 from qemu
---
 qemu/exec.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/qemu/exec.c b/qemu/exec.c
index 9e5af124..5df6a3a8 100644
--- a/qemu/exec.c
+++ b/qemu/exec.c
@@ -683,7 +683,7 @@ static RAMBlock *qemu_get_ram_block(struct uc_struct *uc, ram_addr_t addr)
     /* The list is protected by the iothread lock here.  */
     block = uc->ram_list.mru_block;
     if (block && addr - block->offset < block->max_length) {
-        goto found;
+        return block;
     }
     QTAILQ_FOREACH(block, &uc->ram_list.blocks, next) {
         if (addr - block->offset < block->max_length) {