From: Alex Bennée <alex.bennee@linaro.org>
Date: Thu, 21 Sep 2017 11:06:25 +0000 (+0100)
Subject: accel/tcg/cputlb: avoid recursive BQL (fixes #1706296)
X-Git-Tag: v2.10.1~7
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=4d824886c84cd88dd2f3ce9061835689152c25f8;p=thirdparty%2Fqemu.git

accel/tcg/cputlb: avoid recursive BQL (fixes #1706296)

The mmio path (see exec.c:prepare_mmio_access) already protects itself
against recursive locking and it makes sense to do the same for
io_readx/writex. Otherwise any helper running in the BQL context will
assert when it attempts to write to device memory as in the case of
the bug report.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
CC: Richard Jones <rjones@redhat.com>
CC: Paolo Bonzini <bonzini@gnu.org>
CC: qemu-stable@nongnu.org
Message-Id: <20170921110625.9500-1-alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
(cherry picked from commit 8b81253332b5a3f3c67b6462f39caef47a00dd29)
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
---

diff --git a/accel/tcg/cputlb.c b/accel/tcg/cputlb.c
index 85635ae8ad6..140d73a308a 100644
--- a/accel/tcg/cputlb.c
+++ b/accel/tcg/cputlb.c
@@ -763,7 +763,7 @@ static uint64_t io_readx(CPUArchState *env, CPUIOTLBEntry *iotlbentry,
 
     cpu->mem_io_vaddr = addr;
 
-    if (mr->global_locking) {
+    if (mr->global_locking && !qemu_mutex_iothread_locked()) {
         qemu_mutex_lock_iothread();
         locked = true;
     }
@@ -791,7 +791,7 @@ static void io_writex(CPUArchState *env, CPUIOTLBEntry *iotlbentry,
     cpu->mem_io_vaddr = addr;
     cpu->mem_io_pc = retaddr;
 
-    if (mr->global_locking) {
+    if (mr->global_locking && !qemu_mutex_iothread_locked()) {
         qemu_mutex_lock_iothread();
         locked = true;
     }