Re: [PATCH v5 03/12] hw/i386/pc: Move IOMMU singleton into PCMachineState

[Igor Mammedov <imammedo@redhat.com>]

On Wed, 20 Oct 2021 18:27:37 +0100
Jean-Philippe Brucker <jean-philippe@linaro.org> wrote:

> We're about to support a third vIOMMU for x86, virtio-iommu which
> doesn't inherit X86IOMMUState. Move the IOMMU singleton into
> PCMachineState, so it can be shared between all three vIOMMUs.
> 
> The x86_iommu_get_default() helper is still needed by KVM and IOAPIC to
> fetch the default IRQ-remapping IOMMU. Since virtio-iommu doesn't
> support IRQ remapping, this interface doesn't need to change for the
> moment. We could later replace X86IOMMUState with an "IRQ remapping
> IOMMU" interface if necessary.
> 
> Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>

Reviewed-by: Igor Mammedov <imammedo@redhat.com>

> ---
>  include/hw/i386/pc.h |  1 +
>  hw/i386/pc.c         | 12 +++++++++++-
>  hw/i386/x86-iommu.c  | 26 ++++++++------------------
>  3 files changed, 20 insertions(+), 19 deletions(-)
> 
> diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
> index 11426e26dc..b72e5bf9d1 100644
> --- a/include/hw/i386/pc.h
> +++ b/include/hw/i386/pc.h
> @@ -35,6 +35,7 @@ typedef struct PCMachineState {
>      I2CBus *smbus;
>      PFlashCFI01 *flash[2];
>      ISADevice *pcspk;
> +    DeviceState *iommu;
>  
>      /* Configuration options: */
>      uint64_t max_ram_below_4g;
> diff --git a/hw/i386/pc.c b/hw/i386/pc.c
> index 54e4c00dce..fcbf328e8d 100644
> --- a/hw/i386/pc.c
> +++ b/hw/i386/pc.c
> @@ -1330,6 +1330,15 @@ static void pc_machine_device_pre_plug_cb(HotplugHandler *hotplug_dev,
>      } else if (object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_PMEM_PCI) ||
>                 object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_MEM_PCI)) {
>          pc_virtio_md_pci_pre_plug(hotplug_dev, dev, errp);
> +    } else if (object_dynamic_cast(OBJECT(dev), TYPE_X86_IOMMU_DEVICE)) {
> +        PCMachineState *pcms = PC_MACHINE(hotplug_dev);
> +
> +        if (pcms->iommu) {
> +            error_setg(errp, "QEMU does not support multiple vIOMMUs "
> +                       "for x86 yet.");
> +            return;
> +        }
> +        pcms->iommu = dev;
>      }
>  }
>  
> @@ -1384,7 +1393,8 @@ static HotplugHandler *pc_get_hotplug_handler(MachineState *machine,
>      if (object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM) ||
>          object_dynamic_cast(OBJECT(dev), TYPE_CPU) ||
>          object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_PMEM_PCI) ||
> -        object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_MEM_PCI)) {
> +        object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_MEM_PCI) ||
> +        object_dynamic_cast(OBJECT(dev), TYPE_X86_IOMMU_DEVICE)) {
>          return HOTPLUG_HANDLER(machine);
>      }
>  
> diff --git a/hw/i386/x86-iommu.c b/hw/i386/x86-iommu.c
> index dc968c7a53..01d11325a6 100644
> --- a/hw/i386/x86-iommu.c
> +++ b/hw/i386/x86-iommu.c
> @@ -77,25 +77,17 @@ void x86_iommu_irq_to_msi_message(X86IOMMUIrq *irq, MSIMessage *msg_out)
>      msg_out->data = msg.msi_data;
>  }
>  
> -/* Default X86 IOMMU device */
> -static X86IOMMUState *x86_iommu_default = NULL;
> -
> -static void x86_iommu_set_default(X86IOMMUState *x86_iommu)
> +X86IOMMUState *x86_iommu_get_default(void)
>  {
> -    assert(x86_iommu);
> +    MachineState *ms = MACHINE(qdev_get_machine());
> +    PCMachineState *pcms =
> +        PC_MACHINE(object_dynamic_cast(OBJECT(ms), TYPE_PC_MACHINE));
>  
> -    if (x86_iommu_default) {
> -        error_report("QEMU does not support multiple vIOMMUs "
> -                     "for x86 yet.");
> -        exit(1);
> +    if (pcms &&
> +        object_dynamic_cast(OBJECT(pcms->iommu), TYPE_X86_IOMMU_DEVICE)) {
> +        return X86_IOMMU_DEVICE(pcms->iommu);
>      }
> -
> -    x86_iommu_default = x86_iommu;
> -}
> -
> -X86IOMMUState *x86_iommu_get_default(void)
> -{
> -    return x86_iommu_default;
> +    return NULL;
>  }
>  
>  static void x86_iommu_realize(DeviceState *dev, Error **errp)
> @@ -131,8 +123,6 @@ static void x86_iommu_realize(DeviceState *dev, Error **errp)
>      if (x86_class->realize) {
>          x86_class->realize(dev, errp);
>      }
> -
> -    x86_iommu_set_default(X86_IOMMU_DEVICE(dev));
>  }
>  
>  static Property x86_iommu_properties[] = {