Re: [Qemu-arm] [PATCH RESEND v2 02/21] sysbus: Set user_creatable=false by default on TYPE_SYS_BUS_DEVICE

[Cornelia Huck]

On Wed,  3 May 2017 17:35:45 -0300
Eduardo Habkost <address@hidden> wrote:

> commit 33cd52b5d7b9adfd009e95f07e6c64dd88ae2a31 unset
> cannot_instantiate_with_device_add_yet in TYPE_SYSBUS, making all
> sysbus devices appear on "-device help" and lack the "no-user"
> flag in "info qdm".
> 
> To fix this, we can set user_creatable=false by default on
> TYPE_SYS_BUS_DEVICE, but this requires setting
> user_creatable=true explicitly on the sysbus devices that
> actually work with -device.
> 
> Fortunately today we have just a few has_dynamic_sysbus=1
> machines: virt, pc-q35-*, ppce500, and spapr.
> 
> virt, ppce500, and spapr have extra checks to ensure just a few
> device types can be instantiated:
> 
> * virt supports only TYPE_VFIO_CALXEDA_XGMAC, TYPE_VFIO_AMD_XGBE.
> * ppce500 supports only TYPE_ETSEC_COMMON.
> * spapr supports only TYPE_SPAPR_PCI_HOST_BRIDGE.
> 
> This patch sets user_creatable=true explicitly on those 4 device
> classes.
> 
> Now, the more complex cases:
> 
> pc-q35-*: q35 has no sysbus device whitelist yet (which is a
> separate bug). We are in the process of fixing it and building a
> sysbus whitelist on q35, but in the meantime we can fix the
> "-device help" and "info qdm" bugs mentioned above. Also, despite
> not being strictly necessary for fixing the q35 bug, reducing the
> list of user_creatable=true devices will help us be more
> confident when building the q35 whitelist.
> 
> xen: We also have a hack at xen_set_dynamic_sysbus(), that sets
> has_dynamic_sysbus=true at runtime when using the Xen
> accelerator. This hack is only used to allow xen-backend devices
> to be dynamically plugged/unplugged.
> 
> This means today we can use -device with the following 22 device
> types, that are the ones compiled into the qemu-system-x86_64 and
> qemu-system-i386 binaries:
> 
> * allwinner-ahci
> * amd-iommu
> * cfi.pflash01
> * esp
> * fw_cfg_io
> * fw_cfg_mem
> * generic-sdhci
> * hpet
> * intel-iommu
> * ioapic
> * isabus-bridge
> * kvmclock
> * kvm-ioapic
> * kvmvapic
> * SUNW,fdtwo
> * sysbus-ahci
> * sysbus-fdc
> * sysbus-ohci
> * unimplemented-device
> * virtio-mmio
> * xen-backend
> * xen-sysdev
> 
> This patch adds user_creatable=true explicitly to those devices,
> temporarily, just to keep 100% compatibility with existing
> behavior of q35. Subsequent patches will remove
> user_creatable=true from the devices that are really not meant to
> user-creatable on any machine, and remove the FIXME comment from
> the ones that are really supposed to be user-creatable. This is
> being done in separate patches because we still don't have an
> obvious list of devices that will be whitelisted by q35, and I
> would like to get each device reviewed individually.
> 
> Cc: Alexander Graf <address@hidden>
> Cc: Alex Williamson <address@hidden>
> Cc: Alistair Francis <address@hidden>
> Cc: Beniamino Galvani <address@hidden>
> Cc: Christian Borntraeger <address@hidden>
> Cc: Cornelia Huck <address@hidden>
> Cc: David Gibson <address@hidden>
> Cc: "Edgar E. Iglesias" <address@hidden>
> Cc: Eduardo Habkost <address@hidden>
> Cc: Frank Blaschka <address@hidden>
> Cc: Gabriel L. Somlo <address@hidden>
> Cc: Gerd Hoffmann <address@hidden>
> Cc: Igor Mammedov <address@hidden>
> Cc: Jason Wang <address@hidden>
> Cc: John Snow <address@hidden>
> Cc: Juergen Gross <address@hidden>
> Cc: Kevin Wolf <address@hidden>
> Cc: Laszlo Ersek <address@hidden>
> Cc: Marcel Apfelbaum <address@hidden>
> Cc: Markus Armbruster <address@hidden>
> Cc: Max Reitz <address@hidden>
> Cc: "Michael S. Tsirkin" <address@hidden>
> Cc: Paolo Bonzini <address@hidden>
> Cc: Peter Maydell <address@hidden>
> Cc: Pierre Morel <address@hidden>
> Cc: Prasad J Pandit <address@hidden>
> Cc: address@hidden
> Cc: address@hidden
> Cc: address@hidden
> Cc: Richard Henderson <address@hidden>
> Cc: Rob Herring <address@hidden>
> Cc: Shannon Zhao <address@hidden>
> Cc: address@hidden
> Cc: Thomas Huth <address@hidden>
> Cc: Yi Min Zhao <address@hidden>
> Acked-by: John Snow <address@hidden>
> Acked-by: Juergen Gross <address@hidden>
> Acked-by: Marcel Apfelbaum <address@hidden>
> Signed-off-by: Eduardo Habkost <address@hidden>
> ---
> Changes v1 -> v2:
> * Rewrite commit message: don't pretend we are actually fixing
>   the q35 issue. We're just fixing "info qdm" and "-device help".
>   Making it easier to fix q35 is just a nice side-effect.
> * Rewrite FIXME comments to make it clear that we just have
>   user_creatable=true because we don't know yet if the device
>   should be in the q35 whitelist
> ---
>  hw/block/fdc.c           | 10 ++++++++++
>  hw/block/pflash_cfi01.c  |  5 +++++
>  hw/core/sysbus.c         | 11 +++++++++++
>  hw/i386/amd_iommu.c      |  5 +++++
>  hw/i386/intel_iommu.c    |  5 +++++
>  hw/i386/kvm/clock.c      |  5 +++++
>  hw/i386/kvm/ioapic.c     |  5 +++++
>  hw/i386/kvmvapic.c       |  5 +++++
>  hw/ide/ahci.c            | 10 ++++++++++
>  hw/intc/ioapic.c         |  5 +++++
>  hw/isa/isa-bus.c         |  5 +++++
>  hw/misc/unimp.c          |  5 +++++
>  hw/net/fsl_etsec/etsec.c |  2 ++
>  hw/nvram/fw_cfg.c        | 10 ++++++++++
>  hw/ppc/spapr_pci.c       |  2 ++
>  hw/scsi/esp.c            |  5 +++++
>  hw/sd/sdhci.c            |  5 +++++
>  hw/timer/hpet.c          |  5 +++++
>  hw/usb/hcd-ohci.c        |  5 +++++
>  hw/vfio/amd-xgbe.c       |  2 ++
>  hw/vfio/calxeda-xgmac.c  |  2 ++
>  hw/virtio/virtio-mmio.c  |  5 +++++
>  hw/xen/xen_backend.c     | 10 ++++++++++
>  23 files changed, 129 insertions(+)
> 

> diff --git a/hw/core/sysbus.c b/hw/core/sysbus.c
> index c0f560b289..6a2eec8dd0 100644
> --- a/hw/core/sysbus.c
> +++ b/hw/core/sysbus.c
> @@ -326,6 +326,17 @@ static void sysbus_device_class_init(ObjectClass *klass, 
> void *data)
>      DeviceClass *k = DEVICE_CLASS(klass);
>      k->init = sysbus_device_init;
>      k->bus_type = TYPE_SYSTEM_BUS;
> +    /*
> +     * device_add plugs devices into suitable bus.  For "real" buses,

s/suitable/a suitable/

> +     * that actually connects the device.  For sysbus, the connections
> +     * need to be made separately, and device_add can't do that.  The
> +     * device would be left unconnected, and will probably not work
> +     *
> +     * However, a few machines and a few devices can handle a few sysbus
> +     * devices. In this case, the device subclass needs to override

Should that rather be "a few machines can handle a few specific sysbus
devices"?

> +     * it and set user_creatable=true.
> +     */
> +    k->user_creatable = false;
>  }
> 
>  static const TypeInfo sysbus_device_type_info = {