Add a parameter for size of dirty ring. If zero, dirty ring is
disabled. Otherwise dirty ring will be enabled with the per-vcpu size
as specified. If dirty ring cannot be enabled due to unsupported
kernel, it'll fallback to dirty logging. By default, dirty ring is
not enabled (dirty-ring-size==0).
Signed-off-by: Peter Xu <pet...@redhat.com>
---
accel/kvm/kvm-all.c | 64 +++++++++++++++++++++++++++++++++++++++++++++
qemu-options.hx | 3 +++
2 files changed, 67 insertions(+)
diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
index ea7b8f7ca5..6d145a8b98 100644
--- a/accel/kvm/kvm-all.c
+++ b/accel/kvm/kvm-all.c
@@ -127,6 +127,8 @@ struct KVMState
KVMMemoryListener *ml;
AddressSpace *as;
} *as;
+ int kvm_dirty_ring_size;
+ int kvm_dirty_gfn_count; /* If nonzero, then kvm dirty ring enabled */
};
KVMState *kvm_state;
@@ -2077,6 +2079,33 @@ static int kvm_init(MachineState *ms)
s->memory_listener.listener.coalesced_io_add = kvm_coalesce_mmio_region;
s->memory_listener.listener.coalesced_io_del = kvm_uncoalesce_mmio_region;
+ /*
+ * Enable KVM dirty ring if supported, otherwise fall back to
+ * dirty logging mode
+ */
+ if (s->kvm_dirty_ring_size > 0) {
+ /* Read the max supported pages */
+ ret = kvm_vm_check_extension(kvm_state, KVM_CAP_DIRTY_LOG_RING);
+ if (ret > 0) {
+ if (s->kvm_dirty_ring_size > ret) {
+ error_report("KVM dirty ring size %d too big (maximum is %d). "
+ "Please use a smaller value.",
+ s->kvm_dirty_ring_size, ret);
+ goto err;
+ }
+
+ ret = kvm_vm_enable_cap(s, KVM_CAP_DIRTY_LOG_RING, 0,
+ s->kvm_dirty_ring_size);
+ if (ret) {
+ error_report("Enabling of KVM dirty ring failed: %d", ret);
+ goto err;
+ }
+
+ s->kvm_dirty_gfn_count =
+ s->kvm_dirty_ring_size / sizeof(struct kvm_dirty_gfn);
+ }
+ }
+
kvm_memory_listener_register(s, &s->memory_listener,
&address_space_memory, 0);
memory_listener_register(&kvm_io_listener,
@@ -3037,6 +3066,33 @@ bool kvm_kernel_irqchip_split(void)
return kvm_state->kernel_irqchip_split == ON_OFF_AUTO_ON;
}
+static void kvm_get_dirty_ring_size(Object *obj, Visitor *v,
+ const char *name, void *opaque,
+ Error **errp)
+{
+ KVMState *s = KVM_STATE(obj);
+ int64_t value = s->kvm_dirty_ring_size;
+
+ visit_type_int(v, name, &value, errp);
+}
+
+static void kvm_set_dirty_ring_size(Object *obj, Visitor *v,
+ const char *name, void *opaque,
+ Error **errp)
+{
+ KVMState *s = KVM_STATE(obj);
+ Error *error = NULL;
+ int64_t value;
+
+ visit_type_int(v, name, &value, &error);
+ if (error) {
+ error_propagate(errp, error);
+ return;
+ }
+
+ s->kvm_dirty_ring_size = value;
+}
+
static void kvm_accel_instance_init(Object *obj)
{
KVMState *s = KVM_STATE(obj);
@@ -3044,6 +3100,8 @@ static void kvm_accel_instance_init(Object *obj)
s->kvm_shadow_mem = -1;
s->kernel_irqchip_allowed = true;
s->kernel_irqchip_split = ON_OFF_AUTO_AUTO;
+ /* By default off */
+ s->kvm_dirty_ring_size = 0;
}
static void kvm_accel_class_init(ObjectClass *oc, void *data)
@@ -3065,6 +3123,12 @@ static void kvm_accel_class_init(ObjectClass *oc, void
*data)
NULL, NULL, &error_abort);
object_class_property_set_description(oc, "kvm-shadow-mem",
"KVM shadow MMU size", &error_abort);
+
+ object_class_property_add(oc, "dirty-ring-size", "int",
+ kvm_get_dirty_ring_size, kvm_set_dirty_ring_size,
+ NULL, NULL, &error_abort);
+ object_class_property_set_description(oc, "dirty-ring-size",
+ "KVM dirty ring size (<=0 to disable)", &error_abort);
}
static const TypeInfo kvm_accel_type = {
diff --git a/qemu-options.hx b/qemu-options.hx
index 224a8e8712..140bd38726 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -119,6 +119,7 @@ DEF("accel", HAS_ARG, QEMU_OPTION_accel,
" kernel-irqchip=on|off|split controls accelerated irqchip
support (default=on)\n"
" kvm-shadow-mem=size of KVM shadow MMU in bytes\n"
" tb-size=n (TCG translation block cache size)\n"
+ " dirty-ring-size=n (KVM dirty ring size in Bytes)\n"
" thread=single|multi (enable multi-threaded TCG)\n",
QEMU_ARCH_ALL)
STEXI
@item -accel @var{name}[,prop=@var{value}[,...]]
@@ -140,6 +141,8 @@ irqchip completely is not recommended except for debugging
purposes.
Defines the size of the KVM shadow MMU.
@item tb-size=@var{n}
Controls the size (in MiB) of the TCG translation block cache.
+@item dirty-ring-size=@val{n}
+Controls the size (in Bytes) of KVM dirty ring (<=0 to disable).
@item thread=single|multi
Controls number of TCG threads. When the TCG is multi-threaded there will be
one
thread per vCPU therefor taking advantage of additional host cores. The default
--
2.24.1
