[Qemu-devel] Nested SVM only enabled (by default) in pc-i440fx-2.1?

[Mark Kanda]

Hi all,

I noticed nested SVM is enabled only in pc-i440fx-2.1 (default is 
disabled); this was added when 2.1 was the latest:

        75d373ef97 ("target-i386: Disable SVM by default in KVM mode")

However, this change was not carried forward to newer machine types. Is 
this an oversight? Is there a reason we (still) need SVM disabled by 
default?

Default setting - target/i386/cpu.c:

        static PropValue kvm_default_props[] = {
            { "kvmclock", "on" },
            ...
            { "monitor", "off" },
            { "svm", "off" },
            { NULL, NULL },
        };

2.1 override - hw/i386/pc_piix.c:

        static void pc_compat_2_1_fn(MachineState *machine)
        {
            pc_compat_2_2_fn(machine);
            x86_cpu_change_kvm_default("svm", NULL);
        }

Thanks and best regards,
-Mark