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From: Peter Xu <peterx@redhat.com>
To: qemu-devel@nongnu.org
Cc: Paolo Bonzini <pbonzini@redhat.com>,
	"Dr . David Alan Gilbert" <dgilbert@redhat.com>,
	peterx@redhat.com
Subject: [PATCH RFC v3 04/11] KVM: Use a big lock to replace per-kml slots_lock
Date: Sat, 23 May 2020 19:20:28 -0400
Message-ID: <20200523232035.1029349-5-peterx@redhat.com> (raw)
In-Reply-To: <20200523232035.1029349-1-peterx@redhat.com>

Per-kml slots_lock will bring some trouble if we want to take all slots_lock of
all the KMLs, especially when we're in a context that we could have taken some
of the KML slots_lock, then we even need to figure out what we've taken and
what we need to take.

Make this simple by merging all KML slots_lock into a single slots lock.

Per-kml slots_lock isn't anything that helpful anyway - so far only x86 has two
address spaces (so, two slots_locks).  All the rest archs will be having one
address space always, which means there's actually one slots_lock so it will be
the same as before.

Signed-off-by: Peter Xu <peterx@redhat.com>
---
 accel/kvm/kvm-all.c      | 32 +++++++++++++++++---------------
 include/sysemu/kvm_int.h |  2 --
 2 files changed, 17 insertions(+), 17 deletions(-)

diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
index 6e015aa2d4..6bdb7909cc 100644
--- a/accel/kvm/kvm-all.c
+++ b/accel/kvm/kvm-all.c
@@ -160,8 +160,10 @@ static const KVMCapabilityInfo kvm_required_capabilites[] = {
 static NotifierList kvm_irqchip_change_notifiers =
     NOTIFIER_LIST_INITIALIZER(kvm_irqchip_change_notifiers);
 
-#define kvm_slots_lock(kml)      qemu_mutex_lock(&(kml)->slots_lock)
-#define kvm_slots_unlock(kml)    qemu_mutex_unlock(&(kml)->slots_lock)
+static QemuMutex kml_slots_lock;
+
+#define kvm_slots_lock()  qemu_mutex_lock(&kml_slots_lock)
+#define kvm_slots_unlock()  qemu_mutex_unlock(&kml_slots_lock)
 
 int kvm_get_max_memslots(void)
 {
@@ -211,9 +213,9 @@ bool kvm_has_free_slot(MachineState *ms)
     bool result;
     KVMMemoryListener *kml = &s->memory_listener;
 
-    kvm_slots_lock(kml);
+    kvm_slots_lock();
     result = !!kvm_get_free_slot(kml);
-    kvm_slots_unlock(kml);
+    kvm_slots_unlock();
 
     return result;
 }
@@ -279,7 +281,7 @@ int kvm_physical_memory_addr_from_host(KVMState *s, void *ram,
     KVMMemoryListener *kml = &s->memory_listener;
     int i, ret = 0;
 
-    kvm_slots_lock(kml);
+    kvm_slots_lock();
     for (i = 0; i < s->nr_slots; i++) {
         KVMSlot *mem = &kml->slots[i];
 
@@ -289,7 +291,7 @@ int kvm_physical_memory_addr_from_host(KVMState *s, void *ram,
             break;
         }
     }
-    kvm_slots_unlock(kml);
+    kvm_slots_unlock();
 
     return ret;
 }
@@ -468,7 +470,7 @@ static int kvm_section_update_flags(KVMMemoryListener *kml,
         return 0;
     }
 
-    kvm_slots_lock(kml);
+    kvm_slots_lock();
 
     while (size && !ret) {
         slot_size = MIN(kvm_max_slot_size, size);
@@ -484,7 +486,7 @@ static int kvm_section_update_flags(KVMMemoryListener *kml,
     }
 
 out:
-    kvm_slots_unlock(kml);
+    kvm_slots_unlock();
     return ret;
 }
 
@@ -754,7 +756,7 @@ static int kvm_physical_log_clear(KVMMemoryListener *kml,
         return ret;
     }
 
-    kvm_slots_lock(kml);
+    kvm_slots_lock();
 
     for (i = 0; i < s->nr_slots; i++) {
         mem = &kml->slots[i];
@@ -780,7 +782,7 @@ static int kvm_physical_log_clear(KVMMemoryListener *kml,
         }
     }
 
-    kvm_slots_unlock(kml);
+    kvm_slots_unlock();
 
     return ret;
 }
@@ -1085,7 +1087,7 @@ static void kvm_set_phys_mem(KVMMemoryListener *kml,
     ram = memory_region_get_ram_ptr(mr) + section->offset_within_region +
           (start_addr - section->offset_within_address_space);
 
-    kvm_slots_lock(kml);
+    kvm_slots_lock();
 
     if (!add) {
         do {
@@ -1143,7 +1145,7 @@ static void kvm_set_phys_mem(KVMMemoryListener *kml,
     } while (size);
 
 out:
-    kvm_slots_unlock(kml);
+    kvm_slots_unlock();
 }
 
 static void kvm_region_add(MemoryListener *listener,
@@ -1170,9 +1172,9 @@ static void kvm_log_sync(MemoryListener *listener,
     KVMMemoryListener *kml = container_of(listener, KVMMemoryListener, listener);
     int r;
 
-    kvm_slots_lock(kml);
+    kvm_slots_lock();
     r = kvm_physical_sync_dirty_bitmap(kml, section);
-    kvm_slots_unlock(kml);
+    kvm_slots_unlock();
     if (r < 0) {
         abort();
     }
@@ -1272,7 +1274,7 @@ void kvm_memory_listener_register(KVMState *s, KVMMemoryListener *kml,
 {
     int i;
 
-    qemu_mutex_init(&kml->slots_lock);
+    qemu_mutex_init(&kml_slots_lock);
     kml->slots = g_malloc0(s->nr_slots * sizeof(KVMSlot));
     kml->as_id = as_id;
 
diff --git a/include/sysemu/kvm_int.h b/include/sysemu/kvm_int.h
index c660a70c51..f143b28671 100644
--- a/include/sysemu/kvm_int.h
+++ b/include/sysemu/kvm_int.h
@@ -27,8 +27,6 @@ typedef struct KVMSlot
 
 typedef struct KVMMemoryListener {
     MemoryListener listener;
-    /* Protects the slots and all inside them */
-    QemuMutex slots_lock;
     KVMSlot *slots;
     int as_id;
 } KVMMemoryListener;
-- 
2.26.2



  parent reply index

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-23 23:20 [PATCH RFC v3 00/11] KVM: Dirty ring support (QEMU part) Peter Xu
2020-05-23 23:20 ` [PATCH RFC v3 01/11] linux-headers: Update Peter Xu
2020-05-24 13:27   ` Peter Maydell
2020-05-24 14:06     ` Peter Xu
2020-05-24 17:50       ` Peter Maydell
2020-05-25 14:29         ` Peter Xu
2020-05-23 23:20 ` [PATCH RFC v3 02/11] memory: Introduce log_sync_global() to memory listener Peter Xu
2020-05-23 23:20 ` [PATCH RFC v3 03/11] KVM: Fixup kvm_log_clear_one_slot() ioctl return check Peter Xu
2020-05-24 16:39   ` Philippe Mathieu-Daudé
2020-05-23 23:20 ` Peter Xu [this message]
2020-05-23 23:20 ` [PATCH RFC v3 05/11] KVM: Create the KVMSlot dirty bitmap on flag changes Peter Xu
2020-05-23 23:20 ` [PATCH RFC v3 06/11] KVM: Provide helper to get kvm dirty log Peter Xu
2020-05-23 23:20 ` [PATCH RFC v3 07/11] KVM: Provide helper to sync dirty bitmap from slot to ramblock Peter Xu
2020-05-23 23:20 ` [PATCH RFC v3 08/11] KVM: Simplify dirty log sync in kvm_set_phys_mem Peter Xu
2020-05-23 23:20 ` [PATCH RFC v3 09/11] KVM: Cache kvm slot dirty bitmap size Peter Xu
2020-05-23 23:20 ` [PATCH RFC v3 10/11] KVM: Add dirty-gfn-count property Peter Xu
2020-05-23 23:20 ` [PATCH RFC v3 11/11] KVM: Dirty ring support Peter Xu
2020-05-24 13:06 ` [PATCH RFC v3 00/11] KVM: Dirty ring support (QEMU part) Peter Xu
2020-05-26 14:17 ` Peter Xu

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