* Peter Xu (pet...@redhat.com) wrote: > 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);
What happens if I was to pass dirty-ring-size=1 ? Then the count would be 0 and things would get upset somewhere? Do you need to check for a minimum postive value? > + } > + } > + > 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); I don't think someone passing in a non-number should cause an abort; it should exit, but I don't think it should abort/core. > + 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). I don't see the point in allowing < 0 ; I'd ban it. Dave > @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 > > -- Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK