[PATCH] kvm: mirror "-machine dirty_gfn_count" to the accelerator property

[huangy81@chinatelecom.cn]

QEMU enable the dirty ring feature by specifing the "-accel" sub-parameter.
https://lore.kernel.org/qemu-devel/20210108165050.406906-10-peterx@redhat.com/
Libvirt use "-machine accel=kvm" option to specify the accelerator by default,
which is incompatible with above option.

This patch introduce the "dirty_gfn_count" sub-parameter of the "-machine"
in the way that the commit "23b089" has done. So that Libvirt can enable this
feature by adding "-machine dirty_gfn_count=xxx" to the QEMU command line.

Signed-off-by: Hyman <huangy81@chinatelecom.cn>
---
 softmmu/vl.c       | 3 ++-
 util/qemu-config.c | 4 ++++
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/softmmu/vl.c b/softmmu/vl.c
index 7ddf405..d8e3dec 100644
--- a/softmmu/vl.c
+++ b/softmmu/vl.c
@@ -1666,7 +1666,8 @@ static int machine_set_property(void *opaque,
         object_register_sugar_prop(ACCEL_CLASS_NAME("xen"), qom_name, value);
         return 0;
     }
-    if (g_str_equal(qom_name, "kvm-shadow-mem")) {
+    if (g_str_equal(qom_name, "kvm-shadow-mem") ||
+        g_str_equal(qom_name, "dirty-gfn-count")) {
         object_register_sugar_prop(ACCEL_CLASS_NAME("kvm"), qom_name, value);
         return 0;
     }
diff --git a/util/qemu-config.c b/util/qemu-config.c
index e2a700b..70f1b50 100644
--- a/util/qemu-config.c
+++ b/util/qemu-config.c
@@ -234,6 +234,10 @@ static QemuOptsList machine_opts = {
             .help = "Up to 8 chars in set of [A-Za-z0-9. ](lower case chars"
                     " converted to upper case) to pass to machine"
                     " loader, boot manager, and guest kernel",
+        },{
+            .name = "dirty_gfn_count",
+            .type = QEMU_OPT_NUMBER,
+            .help = "KVM dirty ring GFN count",
         },
         { /* End of list */ }
     }
-- 
1.8.3.1