On Fri, Feb 07, 2020 at 11:51:55AM +0100, Auger Eric wrote:
> Hi,
>
> On 2/7/20 11:23 AM, Michael S. Tsirkin wrote:
> > On Fri, Feb 07, 2020 at 10:32:00AM +0100, Eric Auger wrote:
> >> At the moment, the kernel only supports device tree
> >> integration of the virtio-iommu. DT bindings between the
> >> PCI root complex and the IOMMU must be created by the machine
> >> in conformance to:
> >>
> >> Documentation/devicetree/bindings/virtio/iommu.txt.
> >>
> >> To make sure the end-user is aware of this, force him to use the
> >> temporary device option "x-dt-binding" and also double check the
> >> machine has a hotplug handler for the virtio-iommu-pci device.
> >> This hotplug handler is in charge of creating those DT bindings.
> >>
> >> Signed-off-by: Eric Auger <eric.au...@redhat.com>
> >> Suggested-by: Michael S. Tsirkin <m...@redhat.com>
> >
> > how about setting it by default from machine class?
> Do you mean in ARM virt machine class? But this wouldn't prevent a user
> from launching an ACPI booted guest. I thought you wanted the end-user
> to know what he does.
>
> I don't figure out a way to know if the guest is booted in dt or acpi
> mode. I can get access to those info:
> - whether acpi is enabled
> - whether a FW is loaded
>
> But a FW can be loaded, acpi enabled and eventually the guest is DT
> booted with acpi=off in kernel opts.
So let's say this configuration does not support the virtio-iommu
at the moment. Is that a big deal?
> Maybe at this point I could only support the case where no FW is loaded.
> In machvirt I would not register the virtio-iommu-pci hotplug handler in
> case a FW is loaded. Then I could get rid of the new x-dt-binding prop.
>
> Thoughts?
>
> Eric
Also an option.
> > See
> > [PATCH 1/2] spapr: Disable legacy virtio devices for pseries-5.0 and later
> > [PATCH 2/2] spapr: Enable virtio iommu_platform=on by default
> > which does it for spapr.
>
> >
> >> ---
> >>
> >> May be squashed with previous patch
> >> ---
> >> hw/virtio/virtio-iommu-pci.c | 18 ++++++++++++++++++
> >> 1 file changed, 18 insertions(+)
> >>
> >> diff --git a/hw/virtio/virtio-iommu-pci.c b/hw/virtio/virtio-iommu-pci.c
> >> index d539fcce75..3d06e14000 100644
> >> --- a/hw/virtio/virtio-iommu-pci.c
> >> +++ b/hw/virtio/virtio-iommu-pci.c
> >> @@ -14,6 +14,7 @@
> >> #include "virtio-pci.h"
> >> #include "hw/virtio/virtio-iommu.h"
> >> #include "hw/qdev-properties.h"
> >> +#include "qapi/error.h"
> >>
> >> typedef struct VirtIOIOMMUPCI VirtIOIOMMUPCI;
> >>
> >> @@ -27,10 +28,12 @@ typedef struct VirtIOIOMMUPCI VirtIOIOMMUPCI;
> >> struct VirtIOIOMMUPCI {
> >> VirtIOPCIProxy parent_obj;
> >> VirtIOIOMMU vdev;
> >> + bool dt_binding;
> >> };
> >>
> >> static Property virtio_iommu_pci_properties[] = {
> >> DEFINE_PROP_UINT32("class", VirtIOPCIProxy, class_code, 0),
> >> + DEFINE_PROP_BOOL("x-dt-binding", VirtIOIOMMUPCI, dt_binding, false),
> >> DEFINE_PROP_END_OF_LIST(),
> >> };
> >>
> >> @@ -39,6 +42,21 @@ static void virtio_iommu_pci_realize(VirtIOPCIProxy
> >> *vpci_dev, Error **errp)
> >> VirtIOIOMMUPCI *dev = VIRTIO_IOMMU_PCI(vpci_dev);
> >> DeviceState *vdev = DEVICE(&dev->vdev);
> >>
> >> + if (!dev->dt_binding) {
> >> + error_setg(errp,
> >> + "Instantiation currently only is possible if the
> >> machine "
> >> + "creates device tree iommu-map bindings, ie. ACPI is
> >> not "
> >> + "yet supported");
> >> + error_append_hint(errp, "use -virtio-iommu-pci,x-dt-binding\n");
> >> + return;
> >> + }
> >> +
> >> + if (!qdev_get_machine_hotplug_handler(DEVICE(vpci_dev))) {
> >> + error_setg(errp,
> >> + "The machine does not implement a virtio-iommu-pci
> >> hotplug "
> >> + " handler that creates the device tree iommu-map
> >> bindings");
> >> + return;
> >> + }
> >> qdev_set_parent_bus(vdev, BUS(&vpci_dev->bus));
> >> object_property_set_link(OBJECT(dev),
> >> OBJECT(pci_get_bus(&vpci_dev->pci_dev)),
> >> --
> >> 2.20.1
> >
