Re: [PATCH v2 15/18] xen: convert "-machine igd-passthru" to an accelerator property

[Philippe Mathieu-Daudé]

On 12/9/19 4:01 PM, Paolo Bonzini wrote:
> The first machine property to fall is Xen's Intel integrated graphics
> passthrough.  The "-machine igd-passthru" option does not set anymore
> a property on the machine object, but desugars to a GlobalProperty on
> accelerator objects.
>
> The setter is very simple, since the value ends up in a
> global variable, so this patch also provides an example before the more
> complicated cases that follow it.
>
> Signed-off-by: Paolo Bonzini <address@hidden>
> ---
>   hw/core/machine.c   | 20 --------------------
>   hw/xen/xen-common.c | 16 ++++++++++++++++
>   include/hw/boards.h |  1 -
>   qemu-options.hx     |  7 ++++---
>   vl.c                | 14 ++++----------
>   5 files changed, 24 insertions(+), 34 deletions(-)
>
> diff --git a/hw/core/machine.c b/hw/core/machine.c
> index 45ddfb6..d7a0356 100644
> --- a/hw/core/machine.c
> +++ b/hw/core/machine.c
> @@ -412,20 +412,6 @@ static void machine_set_graphics(Object *obj, bool value, 
> Error **errp)
>       ms->enable_graphics = value;
>   }
>   
> -static bool machine_get_igd_gfx_passthru(Object *obj, Error **errp)
> -{
> -    MachineState *ms = MACHINE(obj);
> -
> -    return ms->igd_gfx_passthru;
> -}
> -
> -static void machine_set_igd_gfx_passthru(Object *obj, bool value, Error **errp)
> -{
> -    MachineState *ms = MACHINE(obj);
> -
> -    ms->igd_gfx_passthru = value;
> -}
> -
>   static char *machine_get_firmware(Object *obj, Error **errp)
>   {
>       MachineState *ms = MACHINE(obj);
> @@ -862,12 +848,6 @@ static void machine_class_init(ObjectClass *oc, void *data)
>       object_class_property_set_description(oc, "graphics",
>           "Set on/off to enable/disable graphics emulation", &error_abort);
>   
> -    object_class_property_add_bool(oc, "igd-passthru",
> -        machine_get_igd_gfx_passthru, machine_set_igd_gfx_passthru,
> -        &error_abort);
> -    object_class_property_set_description(oc, "igd-passthru",
> -        "Set on/off to enable/disable igd passthrou", &error_abort);

So before this option was available in builds/targets ...

> -
>       object_class_property_add_str(oc, "firmware",
>           machine_get_firmware, machine_set_firmware,
>           &error_abort);
> diff --git a/hw/xen/xen-common.c b/hw/xen/xen-common.c
> index 5284b0d..6cba30c 100644
> --- a/hw/xen/xen-common.c
> +++ b/hw/xen/xen-common.c
> @@ -124,6 +124,16 @@ static void xen_change_state_handler(void *opaque, int 
> running,
>       }
>   }
>   
> +static bool xen_get_igd_gfx_passthru(Object *obj, Error **errp)
> +{
> +    return has_igd_gfx_passthru;
> +}
> +
> +static void xen_set_igd_gfx_passthru(Object *obj, bool value, Error **errp)
> +{
> +    has_igd_gfx_passthru = value;
> +}
> +
>   static void xen_setup_post(MachineState *ms, AccelState *accel)
>   {
>       int rc;
> @@ -177,6 +187,12 @@ static void xen_accel_class_init(ObjectClass *oc, void 
> *data)
>       ac->compat_props = g_ptr_array_new();
>   
>       compat_props_add(ac->compat_props, compat, G_N_ELEMENTS(compat));
> +
> +    object_class_property_add_bool(oc, "igd-passthru",
> +        xen_get_igd_gfx_passthru, xen_set_igd_gfx_passthru,
> +        &error_abort);
> +    object_class_property_set_description(oc, "igd-passthru",
> +        "Set on/off to enable/disable igd passthrou", &error_abort);

... and now it is only available when building with --enable-xen.

This is a good cleanup.

I wonder if ppl uses 'igd-passthru=off' without Xen, won't it break 
their command line?

>   }
>   
>   #define TYPE_XEN_ACCEL ACCEL_CLASS_NAME("xen")
> diff --git a/include/hw/boards.h b/include/hw/boards.h
> index 36fcbda..cdcf481 100644
> --- a/include/hw/boards.h
> +++ b/include/hw/boards.h
> @@ -287,7 +287,6 @@ struct MachineState {
>       bool mem_merge;
>       bool usb;
>       bool usb_disabled;
> -    bool igd_gfx_passthru;
>       char *firmware;
>       bool iommu;
>       bool suppress_vmdesc;
> diff --git a/qemu-options.hx b/qemu-options.hx
> index 9775258..6f12b31 100644
> --- a/qemu-options.hx
> +++ b/qemu-options.hx
> @@ -37,7 +37,6 @@ DEF("machine", HAS_ARG, QEMU_OPTION_machine, \
>       "                kvm_shadow_mem=size of KVM shadow MMU in bytes\n"
>       "                dump-guest-core=on|off include guest memory in a core dump 
> (default=on)\n"
>       "                mem-merge=on|off controls memory merge support (default: 
> on)\n"
> -    "                igd-passthru=on|off controls IGD GFX passthrough support 
> (default=off)\n"
>       "                aes-key-wrap=on|off controls support for AES key wrapping 
> (default=on)\n"
>       "                dea-key-wrap=on|off controls support for DEA key wrapping 
> (default=on)\n"
>       "                suppress-vmdesc=on|off disables self-describing migration 
> (default=off)\n"
> @@ -71,8 +70,6 @@ more than one accelerator specified, the next one is used if 
> the previous one
>   fails to initialize.
>   @item kernel_irqchip=on|off
>   Controls in-kernel irqchip support for the chosen accelerator when available.
> -@item gfx_passthru=on|off
> -Enables IGD GFX passthrough support for the chosen machine when available.
>   @item vmport=on|off|auto
>   Enables emulation of VMWare IO port, for vmmouse etc. auto says to select the
>   value based on accel. For accel=xen the default is off otherwise the default
> @@ -120,6 +117,7 @@ ETEXI
>   DEF("accel", HAS_ARG, QEMU_OPTION_accel,
>       "-accel [accel=]accelerator[,prop[=value][,...]]\n"
>       "                select accelerator (kvm, xen, hax, hvf, whpx or tcg; use 
> 'help' for a list)\n"

Here we could use:

#ifdef CONFIG_XEN_BACKEND

(not sure we want such #ifdefry although)

> +    "                igd-passthru=on|off (enable Xen integrated Intel graphics 
> passthrough, default=off)\n"

#endif

>       "                tb-size=n (TCG translation block cache size)\n"
>       "                thread=single|multi (enable multi-threaded TCG)\n", 
> QEMU_ARCH_ALL)
>   STEXI
> @@ -130,6 +128,9 @@ kvm, xen, hax, hvf, whpx or tcg can be available. By 
> default, tcg is used. If th
>   more than one accelerator specified, the next one is used if the previous one
>   fails to initialize.
>   @table @option
> +@item igd-passthru=on|off
> +When Xen is in use, this option controls whether Intel integrated graphics
> +devices can be passed through to the guest (default=off)
>   @item tb-size=@var{n}
>   Controls the size (in MiB) of the TCG translation block cache.
>   @item thread=single|multi
> diff --git a/vl.c b/vl.c
> index e6ff56b..ee872f2 100644
> --- a/vl.c
> +++ b/vl.c
> @@ -1257,13 +1257,6 @@ static void configure_msg(QemuOpts *opts)
>   }
>   
>   
> -/* Now we still need this for compatibility with XEN. */
> -bool has_igd_gfx_passthru;
> -static void igd_gfx_passthru(void)
> -{
> -    has_igd_gfx_passthru = current_machine->igd_gfx_passthru;
> -}
> -
>   /***********************************************************/
>   /* USB devices */
>   
> @@ -2642,6 +2635,10 @@ static int machine_set_property(void *opaque,
>       if (g_str_equal(qom_name, "accel")) {
>           return 0;
>       }

Similarly:

#ifdef CONFIG_XEN_BACKEND

> +    if (g_str_equal(qom_name, "igd-passthru")) {
> +        object_register_sugar_prop(ACCEL_CLASS_NAME("xen"), qom_name, value);
> +        return 0;
> +    }

#endif

>   
>       return object_parse_property_opt(opaque, name, value, "type", errp);
>   }
> @@ -4456,9 +4453,6 @@ int main(int argc, char **argv, char **envp)
>               exit(1);
>       }
>   
> -    /* Check if IGD GFX passthrough. */
> -    igd_gfx_passthru();
> -
>       /* init generic devices */
>       rom_set_order_override(FW_CFG_ORDER_OVERRIDE_DEVICE);
>       qemu_opts_foreach(qemu_find_opts("device"),