From 2f3881255e6a50d9821f390972b07c1e9d9de626 Mon Sep 17 00:00:00 2001
From: Paolo Bonzini <pbonzini@redhat.com>
Date: Thu, 8 Mar 2018 15:58:15 +0100
Subject: [PATCH 02/17] address_space_write: address_space_to_flatview needs
 RCU lock

RH-Author: Paolo Bonzini <pbonzini@redhat.com>
Message-id: <20180308155819.20598-3-pbonzini@redhat.com>
Patchwork-id: 79191
O-Subject: [RHEL7.5 qemu-kvm-rhev PATCH 2/6] address_space_write: address_space_to_flatview needs RCU lock
Bugzilla: 1554930
RH-Acked-by: Cornelia Huck <cohuck@redhat.com>
RH-Acked-by: Thomas Huth <thuth@redhat.com>
RH-Acked-by: Laurent Vivier <lvivier@redhat.com>

address_space_write is calling address_space_to_flatview but it can
be called outside the RCU lock.  To fix it, push the rcu_read_lock/unlock
pair up from flatview_write to address_space_write.

Reviewed-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
(cherry pick from commit 4c6ebbb364aa6f42c5d8e83e932e967eb83f0e44)

Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
---
 exec.c | 37 ++++++++++++++++++++++---------------
 1 file changed, 22 insertions(+), 15 deletions(-)

diff --git a/exec.c b/exec.c
index 5a12e55..8b50133 100644
--- a/exec.c
+++ b/exec.c
@@ -2942,6 +2942,7 @@ static MemTxResult flatview_write_continue(FlatView *fv, hwaddr addr,
     return result;
 }
 
+/* Called from RCU critical section.  */
 static MemTxResult flatview_write(FlatView *fv, hwaddr addr, MemTxAttrs attrs,
                                   const uint8_t *buf, int len)
 {
@@ -2950,25 +2951,14 @@ static MemTxResult flatview_write(FlatView *fv, hwaddr addr, MemTxAttrs attrs,
     MemoryRegion *mr;
     MemTxResult result = MEMTX_OK;
 
-    if (len > 0) {
-        rcu_read_lock();
-        l = len;
-        mr = flatview_translate(fv, addr, &addr1, &l, true);
-        result = flatview_write_continue(fv, addr, attrs, buf, len,
-                                         addr1, l, mr);
-        rcu_read_unlock();
-    }
+    l = len;
+    mr = flatview_translate(fv, addr, &addr1, &l, true);
+    result = flatview_write_continue(fv, addr, attrs, buf, len,
+                                     addr1, l, mr);
 
     return result;
 }
 
-MemTxResult address_space_write(AddressSpace *as, hwaddr addr,
-                                              MemTxAttrs attrs,
-                                              const uint8_t *buf, int len)
-{
-    return flatview_write(address_space_to_flatview(as), addr, attrs, buf, len);
-}
-
 /* Called within RCU critical section.  */
 MemTxResult flatview_read_continue(FlatView *fv, hwaddr addr,
                                    MemTxAttrs attrs, uint8_t *buf,
@@ -3077,6 +3067,23 @@ MemTxResult address_space_rw(AddressSpace *as, hwaddr addr,
                        addr, attrs, buf, len, is_write);
 }
 
+MemTxResult address_space_write(AddressSpace *as, hwaddr addr,
+                                MemTxAttrs attrs,
+                                const uint8_t *buf, int len)
+{
+    MemTxResult result = MEMTX_OK;
+    FlatView *fv;
+
+    if (len > 0) {
+        rcu_read_lock();
+        fv = address_space_to_flatview(as);
+        result = flatview_write(fv, addr, attrs, buf, len);
+        rcu_read_unlock();
+    }
+
+    return result;
+}
+
 void cpu_physical_memory_rw(hwaddr addr, uint8_t *buf,
                             int len, int is_write)
 {
-- 
1.8.3.1