Re: [PATCH v2 03/19] intel_iommu: Implement get_viommu_cap() callback

[Eric Auger <eric.auger@redhat.com>]

Hi Zhenzhong,

On 6/20/25 9:17 AM, Zhenzhong Duan wrote:
> Implement get_viommu_cap() callback and expose stage-1 capability for now.
>
> VFIO uses it to create nested parent domain which is further used to create
> nested domain in vIOMMU. All these will be implemented in following patches.
>
> Suggested-by: Yi Liu <yi.l.liu@intel.com>
> Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
> ---
>  MAINTAINERS           |  1 +
>  include/hw/iommu.h    | 14 ++++++++++++++
>  hw/i386/intel_iommu.c | 12 ++++++++++++
>  3 files changed, 27 insertions(+)
>  create mode 100644 include/hw/iommu.h
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 94c4076127..27817974a6 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -2277,6 +2277,7 @@ F: include/system/iommufd.h
>  F: backends/host_iommu_device.c
>  F: include/system/host_iommu_device.h
>  F: include/qemu/chardev_open.h
> +F: include/hw/iommu.h
>  F: util/chardev_open.c
>  F: docs/devel/vfio-iommufd.rst
>  
> diff --git a/include/hw/iommu.h b/include/hw/iommu.h
> new file mode 100644
> index 0000000000..3c1c08f05d
> --- /dev/null
> +++ b/include/hw/iommu.h
> @@ -0,0 +1,14 @@
> +/*
> + * General vIOMMU capabilities, flags, etc
> + *
> + * Copyright (C) 2025 Intel Corporation.
> + *
> + * SPDX-License-Identifier: GPL-2.0-or-later
> + */
> +
> +#ifndef HW_IOMMU_H
> +#define HW_IOMMU_H
> +
> +#define VIOMMU_CAP_STAGE1    BIT_ULL(0)
I think you shall rather introduce the header and the first enum value
in the previous patch.

Eric
> +
> +#endif /* HW_IOMMU_H */
> diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
> index f0b1f90eff..702973da5c 100644
> --- a/hw/i386/intel_iommu.c
> +++ b/hw/i386/intel_iommu.c
> @@ -24,6 +24,7 @@
>  #include "qemu/main-loop.h"
>  #include "qapi/error.h"
>  #include "hw/sysbus.h"
> +#include "hw/iommu.h"
>  #include "intel_iommu_internal.h"
>  #include "hw/pci/pci.h"
>  #include "hw/pci/pci_bus.h"
> @@ -4412,6 +4413,16 @@ static void vtd_dev_unset_iommu_device(PCIBus *bus, void *opaque, int devfn)
>      vtd_iommu_unlock(s);
>  }
>  
> +static uint64_t vtd_get_viommu_cap(void *opaque)
> +{
> +    IntelIOMMUState *s = opaque;
> +    uint64_t caps;
> +
> +    caps = s->flts ? VIOMMU_CAP_STAGE1 : 0;
> +
> +    return caps;
> +}
> +
>  /* Unmap the whole range in the notifier's scope. */
>  static void vtd_address_space_unmap(VTDAddressSpace *as, IOMMUNotifier *n)
>  {
> @@ -4734,6 +4745,7 @@ static PCIIOMMUOps vtd_iommu_ops = {
>      .get_address_space = vtd_host_dma_iommu,
>      .set_iommu_device = vtd_dev_set_iommu_device,
>      .unset_iommu_device = vtd_dev_unset_iommu_device,
> +    .get_viommu_cap = vtd_get_viommu_cap,
>  };
>  
>  static bool vtd_decide_config(IntelIOMMUState *s, Error **errp)