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[v3,2/6] cputlb: handle first atomic write to the page

Message ID 20170427051824.30194-3-nikunj@linux.vnet.ibm.com (mailing list archive)
State New, archived
Headers show

Commit Message

Nikunj A. Dadhania April 27, 2017, 5:18 a.m. UTC 
In case where the conditional write is the first write to the page,
TLB_NOTDIRTY will be set and stop_the_world is triggered. Handle this as
a special case and set the dirty bit. After that fall through to the
actual atomic instruction below.

Signed-off-by: Nikunj A Dadhania <nikunj@linux.vnet.ibm.com>
Reviewed-by: Richard Henderson <rth@twiddle.net>
---
 cputlb.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)
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Patch

diff --git a/cputlb.c b/cputlb.c
index f5d056c..743776a 100644
--- a/cputlb.c
+++ b/cputlb.c
@@ -930,7 +930,13 @@  static void *atomic_mmu_lookup(CPUArchState *env, target_ulong addr,
         tlb_addr = tlbe->addr_write;
     }
 
-    /* Notice an IO access, or a notdirty page.  */
+    /* Check notdirty */
+    if (unlikely(tlb_addr & TLB_NOTDIRTY)) {
+        tlb_set_dirty(ENV_GET_CPU(env), addr);
+        tlb_addr = tlb_addr & ~TLB_NOTDIRTY;
+    }
+
+    /* Notice an IO access  */
     if (unlikely(tlb_addr & ~TARGET_PAGE_MASK)) {
         /* There's really nothing that can be done to
            support this apart from stop-the-world.  */