system/cpus: rename qemu_mutex_lock_iothread() to bql_lock()

The Big QEMU Lock (BQL) has many names and they are confusing. The
actual QemuMutex variable is called qemu_global_mutex but it's commonly
referred to as the BQL in discussions and some code comments. The
locking APIs, however, are called qemu_mutex_lock_iothread() and
qemu_mutex_unlock_iothread().

The "iothread" name is historic and comes from when the main thread was
split into into KVM vcpu threads and the "iothread" (now called the main
loop thread). I have contributed to the confusion myself by introducing
a separate --object iothread, a separate concept unrelated to the BQL.

The "iothread" name is no longer appropriate for the BQL. Rename the
locking APIs to:
- void bql_lock(void)
- void bql_unlock(void)
- bool bql_locked(void)

There are more APIs with "iothread" in their names. Subsequent patches
will rename them. There are also comments and documentation that will be
updated in later patches.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Paul Durrant <paul@xen.org>
Acked-by: Fabiano Rosas <farosas@suse.de>
Acked-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Acked-by: Peter Xu <peterx@redhat.com>
Acked-by: Eric Farman <farman@linux.ibm.com>
Reviewed-by: Harsh Prateek Bora <harshpb@linux.ibm.com>
Acked-by: Hyman Huang <yong.huang@smartx.com>
Reviewed-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Message-id: 20240102153529.486531-2-stefanha@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

1 files changed, 3 insertions, 3 deletions

diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
index ed5677c0ae..1a07faddb4 100644
--- a/hw/i386/intel_iommu.c
+++ b/hw/i386/intel_iommu.c
@@ -1665,7 +1665,7 @@ static bool vtd_switch_address_space(VTDAddressSpace *as)
 {
     bool use_iommu, pt;
     /* Whether we need to take the BQL on our own */
-    bool take_bql = !qemu_mutex_iothread_locked();
+    bool take_bql = !bql_locked();
 
     assert(as);
 
@@ -1683,7 +1683,7 @@ static bool vtd_switch_address_space(VTDAddressSpace *as)
      * it. We'd better make sure we have had it already, or, take it.
      */
     if (take_bql) {
-        qemu_mutex_lock_iothread();
+        bql_lock();
     }
 
     /* Turn off first then on the other */
@@ -1738,7 +1738,7 @@ static bool vtd_switch_address_space(VTDAddressSpace *as)
     }
 
     if (take_bql) {
-        qemu_mutex_unlock_iothread();
+        bql_unlock();
     }
 
     return use_iommu;