Re: [PATCH v18 1/6] hw/arm/virt: Introduce RAS platform version and RAS machine option

From: Peter Maydell <peter.maydell@linaro.org>
To: Xiang Zheng <zhengxiang9@huawei.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	Igor Mammedov <imammedo@redhat.com>,
	Shannon Zhao <shannon.zhaosl@gmail.com>,
	Laszlo Ersek <lersek@redhat.com>,
	James Morse <james.morse@arm.com>,
	gengdongjiu <gengdongjiu@huawei.com>,
	Marcelo Tosatti <mtosatti@redhat.com>,
	Richard Henderson <rth@twiddle.net>,
	Eduardo Habkost <ehabkost@redhat.com>,
	Jonathan Cameron <jonathan.cameron@huawei.com>,
	"xuwei (O)" <xuwei5@huawei.com>, kvm-devel <kvm@vger.kernel.org>,
	QEMU Developers <qemu-devel@nongnu.org>,
	qemu-arm <qemu-arm@nongnu.org>, Linuxarm <linuxarm@huawei.com>,
	wanghaibin.wang@huawei.com
Subject: Re: [PATCH v18 1/6] hw/arm/virt: Introduce RAS platform version and RAS machine option
Date: Fri, 27 Sep 2019 15:02:02 +0100	[thread overview]
Message-ID: <CAFEAcA9cQwAJfPBC9fRcxLZVzZqag0Si62nTBNwDPyQiPVwPcg@mail.gmail.com> (raw)
In-Reply-To: <20190906083152.25716-2-zhengxiang9@huawei.com>

On Fri, 6 Sep 2019 at 09:33, Xiang Zheng <zhengxiang9@huawei.com> wrote:
>
> From: Dongjiu Geng <gengdongjiu@huawei.com>
>
> Support RAS Virtualization feature since version 4.2, disable it by
> default in the old versions. Also add a machine option which allows user
> to enable it explicitly.
>
> Signed-off-by: Dongjiu Geng <gengdongjiu@huawei.com>
> Signed-off-by: Xiang Zheng <zhengxiang9@huawei.com>
> ---
>  hw/arm/virt.c         | 33 +++++++++++++++++++++++++++++++++
>  include/hw/arm/virt.h |  2 ++
>  2 files changed, 35 insertions(+)
>
> diff --git a/hw/arm/virt.c b/hw/arm/virt.c
> index d74538b021..e0451433c8 100644
> --- a/hw/arm/virt.c
> +++ b/hw/arm/virt.c
> @@ -1783,6 +1783,20 @@ static void virt_set_its(Object *obj, bool value, Error **errp)
>      vms->its = value;
>  }
>
> +static bool virt_get_ras(Object *obj, Error **errp)
> +{
> +    VirtMachineState *vms = VIRT_MACHINE(obj);
> +
> +    return vms->ras;
> +}
> +
> +static void virt_set_ras(Object *obj, bool value, Error **errp)
> +{
> +    VirtMachineState *vms = VIRT_MACHINE(obj);
> +
> +    vms->ras = value;
> +}
> +
>  static char *virt_get_gic_version(Object *obj, Error **errp)
>  {
>      VirtMachineState *vms = VIRT_MACHINE(obj);
> @@ -2026,6 +2040,19 @@ static void virt_instance_init(Object *obj)
>                                      "Valid values are none and smmuv3",
>                                      NULL);
>
> +    if (vmc->no_ras) {
> +        vms->ras = false;
> +    } else {
> +        /* Default disallows RAS instantiation */
> +        vms->ras = false;
> +        object_property_add_bool(obj, "ras", virt_get_ras,
> +                                 virt_set_ras, NULL);
> +        object_property_set_description(obj, "ras",
> +                                        "Set on/off to enable/disable "
> +                                        "RAS instantiation",
> +                                        NULL);
> +    }

For a property which is disabled by default, you don't need
to have a separate flag in the VirtMachineClass struct.
Those are only needed for properties where we need the old machine
types to have the property be 'off' but new machine types
need to default to it be 'on'. Since vms->ras is false
by default anyway, you can just have this part:

> +        /* Default disallows RAS instantiation */
> +        vms->ras = false;
> +        object_property_add_bool(obj, "ras", virt_get_ras,
> +                                 virt_set_ras, NULL);
> +        object_property_set_description(obj, "ras",
> +                                        "Set on/off to enable/disable "
> +                                        "RAS instantiation",
> +                                        NULL);

Compare the 'vms->secure' flag and associated property
for an example of this.

>      vms->irqmap = a15irqmap;
>
>      virt_flash_create(vms);
> @@ -2058,8 +2085,14 @@ DEFINE_VIRT_MACHINE_AS_LATEST(4, 2)
>
>  static void virt_machine_4_1_options(MachineClass *mc)
>  {
> +    VirtMachineClass *vmc = VIRT_MACHINE_CLASS(OBJECT_CLASS(mc));
> +
>      virt_machine_4_2_options(mc);
>      compat_props_add(mc->compat_props, hw_compat_4_1, hw_compat_4_1_len);
> +    /* Disable memory recovery feature for 4.1 as RAS support was
> +     * introduced with 4.2.
> +     */
> +    vmc->no_ras = true;
>  }
>  DEFINE_VIRT_MACHINE(4, 1)

thanks
-- PMM