diff mbox series

[PULL,1/3] tcg: update comments for save_iotlb_data in cputlb

Message ID 20200725160548.750749-2-richard.henderson@linaro.org
State Accepted
Commit 570ef3093b5ed327249397ad0295cf01c67d9db4
Headers show
Series misc tcg-related patches | expand

Commit Message

Richard Henderson July 25, 2020, 4:05 p.m. UTC 
From: Alex Bennée <alex.bennee@linaro.org>


I missed Emilio's review comments:

  Message-ID: <20200718205107.GA994221@sff>

and the patch got merged. Correcting the comments now.

Reviewed-by: Emilio G. Cota <cota@braap.org>

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>

Message-Id: <20200720122358.26881-1-alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

---
 accel/tcg/cputlb.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

-- 
2.25.1
diff mbox series

Patch

diff --git a/accel/tcg/cputlb.c b/accel/tcg/cputlb.c
index d370aedb47..5698292749 100644
--- a/accel/tcg/cputlb.c
+++ b/accel/tcg/cputlb.c
@@ -1075,10 +1075,8 @@  static uint64_t io_readx(CPUArchState *env, CPUIOTLBEntry *iotlbentry,
 
 /*
  * Save a potentially trashed IOTLB entry for later lookup by plugin.
- *
- * We also need to track the thread storage address because the RCU
- * cleanup that runs when we leave the critical region (the current
- * execution) is actually in a different thread.
+ * This is read by tlb_plugin_lookup if the iotlb entry doesn't match
+ * because of the side effect of io_writex changing memory layout.
  */
 static void save_iotlb_data(CPUState *cs, hwaddr addr,
                             MemoryRegionSection *section, hwaddr mr_offset)
@@ -1408,8 +1406,9 @@  void *tlb_vaddr_to_host(CPUArchState *env, abi_ptr addr,
  * This almost never fails as the memory access being instrumented
  * should have just filled the TLB. The one corner case is io_writex
  * which can cause TLB flushes and potential resizing of the TLBs
- * loosing the information we need. In those cases we need to recover
- * data from a copy of the io_tlb entry.
+ * losing the information we need. In those cases we need to recover
+ * data from a copy of the iotlbentry. As long as this always occurs
+ * from the same thread (which a mem callback will be) this is safe.
  */
 
 bool tlb_plugin_lookup(CPUState *cpu, target_ulong addr, int mmu_idx,