ShuriZma
/
xemu
mirror of https://github.com/xemu-project/xemu.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

tcg: add memory barriers in page_find_alloc accesses 

page_find is reading the radix tree outside all locks, so it has to
use the RCU primitives.  It does not need RCU critical sections
because the PageDescs are never removed, so there is never a need
to wait for the end of code sections that use a PageDesc.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Paolo Bonzini 2015-08-12 09:41:40 +02:00
parent 2496ff1311
commit 6940fab84b
1 changed files with 4 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
translate-all.c
View File

@ -431,26 +431,26 @@ static PageDesc *page_find_alloc(tb_page_addr_t index, int alloc)
/* Level 2..N-1. */
for (i = V_L1_SHIFT / V_L2_BITS - 1; i > 0; i--) {
void **p = *lp;
void **p = atomic_rcu_read(lp);
if (p == NULL) {
if (!alloc) {
return NULL;
}
p = g_new0(void *, V_L2_SIZE);
*lp = p;
atomic_rcu_set(lp, p);
}
lp = p + ((index >> (i * V_L2_BITS)) & (V_L2_SIZE - 1));
}
pd = *lp;
pd = atomic_rcu_read(lp);
if (pd == NULL) {
if (!alloc) {
return NULL;
}
pd = g_new0(PageDesc, V_L2_SIZE);
*lp = pd;
atomic_rcu_set(lp, pd);
}
return pd + (index & (V_L2_SIZE - 1));