From 026e3aa58780db72c38618e576f4c6029e3b029a Mon Sep 17 00:00:00 2001
From: Paolo Bonzini <pbonzini@redhat.com>
Date: Thu, 8 Mar 2018 15:58:17 +0100
Subject: [PATCH 04/17] address_space_access_valid: address_space_to_flatview
 needs RCU lock

RH-Author: Paolo Bonzini <pbonzini@redhat.com>
Message-id: <20180308155819.20598-5-pbonzini@redhat.com>
Patchwork-id: 79195
O-Subject: [RHEL7.5 qemu-kvm-rhev PATCH 4/6] address_space_access_valid: 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_access_valid 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_access_valid to address_space_access_valid.

Reviewed-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
(cherry pick from commit 11e732a5ed46903f997985bed4c3767ca28a7eb6)

[squashed fix for rcu_read_unlock() that should have been removed,
 for which I'll send a pull request upstream tomorrow]

Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
---
 exec.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/exec.c b/exec.c
index 43c66da..431b85b 100644
--- a/exec.c
+++ b/exec.c
@@ -3259,14 +3259,12 @@ static bool flatview_access_valid(FlatView *fv, hwaddr addr, int len,
     MemoryRegion *mr;
     hwaddr l, xlat;
 
-    rcu_read_lock();
     while (len > 0) {
         l = len;
         mr = flatview_translate(fv, addr, &xlat, &l, is_write);
         if (!memory_access_is_direct(mr, is_write)) {
             l = memory_access_size(mr, l, addr);
             if (!memory_region_access_valid(mr, xlat, l, is_write)) {
-                rcu_read_unlock();
                 return false;
             }
         }
@@ -3274,15 +3272,20 @@ static bool flatview_access_valid(FlatView *fv, hwaddr addr, int len,
         len -= l;
         addr += l;
     }
-    rcu_read_unlock();
     return true;
 }
 
 bool address_space_access_valid(AddressSpace *as, hwaddr addr,
                                 int len, bool is_write)
 {
-    return flatview_access_valid(address_space_to_flatview(as),
-                                 addr, len, is_write);
+    FlatView *fv;
+    bool result;
+
+    rcu_read_lock();
+    fv = address_space_to_flatview(as);
+    result = flatview_access_valid(fv, addr, len, is_write);
+    rcu_read_unlock();
+    return result;
 }
 
 static hwaddr
-- 
1.8.3.1