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[PULL 16/28] KVM: Add dirty-ring-size property
From: |
Paolo Bonzini |
Subject: |
[PULL 16/28] KVM: Add dirty-ring-size property |
Date: |
Mon, 24 May 2021 18:41:19 +0200 |
From: Peter Xu <peterx@redhat.com>
Add a parameter for dirty gfn count for dirty rings. If zero, dirty ring is
disabled. Otherwise dirty ring will be enabled with the per-vcpu gfn count as
specified. If dirty ring cannot be enabled due to unsupported kernel or
illegal parameter, it'll fallback to dirty logging.
By default, dirty ring is not enabled (dirty-gfn-count default to 0).
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20210506160549.130416-9-peterx@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
accel/kvm/kvm-all.c | 46 +++++++++++++++++++++++++++++++++++++++++++++
qemu-options.hx | 12 ++++++++++++
2 files changed, 58 insertions(+)
diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
index df9fbf59a6..5afe15ae66 100644
--- a/accel/kvm/kvm-all.c
+++ b/accel/kvm/kvm-all.c
@@ -126,6 +126,8 @@ struct KVMState
KVMMemoryListener *ml;
AddressSpace *as;
} *as;
+ uint64_t kvm_dirty_ring_bytes; /* Size of the per-vcpu dirty ring */
+ uint32_t kvm_dirty_ring_size; /* Number of dirty GFNs per ring */
};
KVMState *kvm_state;
@@ -3182,6 +3184,42 @@ 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);
+ uint32_t value = s->kvm_dirty_ring_size;
+
+ visit_type_uint32(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;
+ uint32_t value;
+
+ if (s->fd != -1) {
+ error_setg(errp, "Cannot set properties after the accelerator has been
initialized");
+ return;
+ }
+
+ visit_type_uint32(v, name, &value, &error);
+ if (error) {
+ error_propagate(errp, error);
+ return;
+ }
+ if (value & (value - 1)) {
+ error_setg(errp, "dirty-ring-size must be a power of two.");
+ return;
+ }
+
+ s->kvm_dirty_ring_size = value;
+}
+
static void kvm_accel_instance_init(Object *obj)
{
KVMState *s = KVM_STATE(obj);
@@ -3191,6 +3229,8 @@ 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;
+ /* KVM dirty ring is by default off */
+ s->kvm_dirty_ring_size = 0;
}
static void kvm_accel_class_init(ObjectClass *oc, void *data)
@@ -3212,6 +3252,12 @@ static void kvm_accel_class_init(ObjectClass *oc, void
*data)
NULL, NULL);
object_class_property_set_description(oc, "kvm-shadow-mem",
"KVM shadow MMU size");
+
+ object_class_property_add(oc, "dirty-ring-size", "uint32",
+ kvm_get_dirty_ring_size, kvm_set_dirty_ring_size,
+ NULL, NULL);
+ object_class_property_set_description(oc, "dirty-ring-size",
+ "Size of KVM dirty page ring buffer (default: 0, i.e. use bitmap)");
}
static const TypeInfo kvm_accel_type = {
diff --git a/qemu-options.hx b/qemu-options.hx
index e22fb94d99..ecdb064409 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -141,6 +141,7 @@ DEF("accel", HAS_ARG, QEMU_OPTION_accel,
" kvm-shadow-mem=size of KVM shadow MMU in bytes\n"
" split-wx=on|off (enable TCG split w^x mapping)\n"
" tb-size=n (TCG translation block cache size)\n"
+ " dirty-ring-size=n (KVM dirty ring GFN count, default 0)\n"
" thread=single|multi (enable multi-threaded TCG)\n",
QEMU_ARCH_ALL)
SRST
``-accel name[,prop=value[,...]]``
@@ -181,6 +182,17 @@ SRST
where both the back-end and front-ends support it and no
incompatible TCG features have been enabled (e.g.
icount/replay).
+
+ ``dirty-ring-size=n``
+ When the KVM accelerator is used, it controls the size of the per-vCPU
+ dirty page ring buffer (number of entries for each vCPU). It should
+ be a value that is power of two, and it should be 1024 or bigger (but
+ still less than the maximum value that the kernel supports). 4096
+ could be a good initial value if you have no idea which is the best.
+ Set this value to 0 to disable the feature. By default, this feature
+ is disabled (dirty-ring-size=0). When enabled, KVM will instead
+ record dirty pages in a bitmap.
+
ERST
DEF("smp", HAS_ARG, QEMU_OPTION_smp,
--
2.31.1
- [PULL 25/28] doc: Add notes about -mon option mode=control argument., (continued)
- [PULL 25/28] doc: Add notes about -mon option mode=control argument., Paolo Bonzini, 2021/05/24
- [PULL 07/28] qtest: add a QOM object for qtest, Paolo Bonzini, 2021/05/24
- [PULL 27/28] hw/scsi: Fix sector translation bug in scsi_unmap_complete_noio, Paolo Bonzini, 2021/05/24
- [PULL 26/28] configure: Avoid error messages about missing *-config-*.h files, Paolo Bonzini, 2021/05/24
- [PULL 28/28] gitlab-ci: use --meson=git for CFI jobs, Paolo Bonzini, 2021/05/24
- [PULL 17/28] KVM: Disable manual dirty log when dirty ring enabled, Paolo Bonzini, 2021/05/24
- [PULL 05/28] i386/cpu: Expose AVX_VNNI instruction to guest, Paolo Bonzini, 2021/05/24
- [PULL 14/28] KVM: Simplify dirty log sync in kvm_set_phys_mem, Paolo Bonzini, 2021/05/24
- [PULL 15/28] KVM: Cache kvm slot dirty bitmap size, Paolo Bonzini, 2021/05/24
- [PULL 24/28] qemu-config: load modules when instantiating option groups, Paolo Bonzini, 2021/05/24
- [PULL 16/28] KVM: Add dirty-ring-size property,
Paolo Bonzini <=
- [PULL 23/28] vl: allow not specifying size in -m when using -M memory-backend, Paolo Bonzini, 2021/05/24
- [PULL 12/28] KVM: Provide helper to get kvm dirty log, Paolo Bonzini, 2021/05/24
- Re: [PULL 00/28] Misc patches for 2021-05-24, no-reply, 2021/05/24
- Re: [PULL 00/28] Misc patches for 2021-05-24, Peter Maydell, 2021/05/24