Re: [PATCH v6 31/33] Extend get_cap() callback to support PASID

["Cédric Le Goater" <clg@redhat.com>]

On 11/20/25 14:22, Shameer Kolothum wrote:
> Modify get_cap() callback so that it can return cap via an output
> uint64_t param. And add support for generic iommu hw capability
> info and max_pasid_log2(pasid width).

This is doing multiple changes. Please split.

Thanks,

C.


> Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
> Signed-off-by: Shameer Kolothum <skolothumtho@nvidia.com>
> ---
>   backends/iommufd.c                 | 23 ++++++++++++++++++-----
>   hw/i386/intel_iommu.c              |  8 +++++---
>   hw/vfio/container-legacy.c         |  8 ++++++--
>   include/system/host_iommu_device.h | 18 ++++++++++++------
>   4 files changed, 41 insertions(+), 16 deletions(-)
> 
> diff --git a/backends/iommufd.c b/backends/iommufd.c
> index 6381f9664b..718d63f5cf 100644
> --- a/backends/iommufd.c
> +++ b/backends/iommufd.c
> @@ -523,19 +523,32 @@ bool host_iommu_device_iommufd_detach_hwpt(HostIOMMUDeviceIOMMUFD *idev,
>       return idevc->detach_hwpt(idev, errp);
>   }
>   
> -static int hiod_iommufd_get_cap(HostIOMMUDevice *hiod, int cap, Error **errp)
> +static int hiod_iommufd_get_cap(HostIOMMUDevice *hiod, int cap_id,
> +                                uint64_t *out_cap, Error **errp)
>   {
>       HostIOMMUDeviceCaps *caps = &hiod->caps;
>   
> -    switch (cap) {
> +    g_assert(out_cap);
> +
> +    switch (cap_id) {
>       case HOST_IOMMU_DEVICE_CAP_IOMMU_TYPE:
> -        return caps->type;
> +        *out_cap = caps->type;
> +        break;
>       case HOST_IOMMU_DEVICE_CAP_AW_BITS:
> -        return vfio_device_get_aw_bits(hiod->agent);
> +        *out_cap = vfio_device_get_aw_bits(hiod->agent);
> +        break;
> +    case HOST_IOMMU_DEVICE_CAP_GENERIC_HW:
> +        *out_cap = caps->hw_caps;
> +        break;
> +    case HOST_IOMMU_DEVICE_CAP_MAX_PASID_LOG2:
> +        *out_cap = caps->max_pasid_log2;
> +        break;
>       default:
> -        error_setg(errp, "%s: unsupported capability %x", hiod->name, cap);
> +        *out_cap = 0;
> +        error_setg(errp, "%s: unsupported capability %x", hiod->name, cap_id);
>           return -EINVAL;
>       }
> +    return 0;
>   }
>   
>   static void hiod_iommufd_class_init(ObjectClass *oc, const void *data)
> diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
> index 78b142ccea..d5c131a814 100644
> --- a/hw/i386/intel_iommu.c
> +++ b/hw/i386/intel_iommu.c
> @@ -4605,6 +4605,7 @@ static bool vtd_check_hiod(IntelIOMMUState *s, HostIOMMUDevice *hiod,
>                              Error **errp)
>   {
>       HostIOMMUDeviceClass *hiodc = HOST_IOMMU_DEVICE_GET_CLASS(hiod);
> +    uint64_t out_cap;
>       int ret;
>   
>       if (!hiodc->get_cap) {
> @@ -4613,12 +4614,13 @@ static bool vtd_check_hiod(IntelIOMMUState *s, HostIOMMUDevice *hiod,
>       }
>   
>       /* Common checks */
> -    ret = hiodc->get_cap(hiod, HOST_IOMMU_DEVICE_CAP_AW_BITS, errp);
> +    ret = hiodc->get_cap(hiod, HOST_IOMMU_DEVICE_CAP_AW_BITS, &out_cap, errp);
>       if (ret < 0) {
>           return false;
>       }
> -    if (s->aw_bits > ret) {
> -        error_setg(errp, "aw-bits %d > host aw-bits %d", s->aw_bits, ret);
> +    if (s->aw_bits > out_cap) {
> +        error_setg(errp, "aw-bits %d > host aw-bits 0x%" PRIx64, s->aw_bits,
> +                   out_cap);
>           return false;
>       }
>   
> diff --git a/hw/vfio/container-legacy.c b/hw/vfio/container-legacy.c
> index 32c260b345..1acf063762 100644
> --- a/hw/vfio/container-legacy.c
> +++ b/hw/vfio/container-legacy.c
> @@ -1203,15 +1203,19 @@ static bool hiod_legacy_vfio_realize(HostIOMMUDevice *hiod, void *opaque,
>   }
>   
>   static int hiod_legacy_vfio_get_cap(HostIOMMUDevice *hiod, int cap,
> -                                    Error **errp)
> +                                    uint64_t *out_cap, Error **errp)
>   {
> +    g_assert(out_cap);
> +
>       switch (cap) {
>       case HOST_IOMMU_DEVICE_CAP_AW_BITS:
> -        return vfio_device_get_aw_bits(hiod->agent);
> +        *out_cap = vfio_device_get_aw_bits(hiod->agent);
> +        break;
>       default:
>           error_setg(errp, "%s: unsupported capability %x", hiod->name, cap);
>           return -EINVAL;
>       }
> +    return 0;
>   }
>   
>   static GList *
> diff --git a/include/system/host_iommu_device.h b/include/system/host_iommu_device.h
> index bfb2b60478..4e891e5225 100644
> --- a/include/system/host_iommu_device.h
> +++ b/include/system/host_iommu_device.h
> @@ -88,19 +88,21 @@ struct HostIOMMUDeviceClass {
>        * @get_cap: check if a host IOMMU device capability is supported.
>        *
>        * Optional callback, if not implemented, hint not supporting query
> -     * of @cap.
> +     * of @cap_id.
>        *
>        * @hiod: pointer to a host IOMMU device instance.
>        *
> -     * @cap: capability to check.
> +     * @cap_id: capability to check.
> +     *
> +     * @out_cap: 0 if a @cap_id is unsupported or else the capability
> +     * value for @cap_id.
>        *
>        * @errp: pass an Error out when fails to query capability.
>        *
> -     * Returns: <0 on failure, 0 if a @cap is unsupported, or else
> -     * 1 or some positive value for some special @cap,
> -     * i.e., HOST_IOMMU_DEVICE_CAP_AW_BITS.
> +     * Returns: <0 if @cap_id is not supported, 0 on success.
>        */
> -    int (*get_cap)(HostIOMMUDevice *hiod, int cap, Error **errp);
> +    int (*get_cap)(HostIOMMUDevice *hiod, int cap_id, uint64_t *out_cap,
> +                   Error **errp);
>       /**
>        * @get_iova_ranges: Return the list of usable iova_ranges along with
>        * @hiod Host IOMMU device
> @@ -123,6 +125,10 @@ struct HostIOMMUDeviceClass {
>    */
>   #define HOST_IOMMU_DEVICE_CAP_IOMMU_TYPE        0
>   #define HOST_IOMMU_DEVICE_CAP_AW_BITS           1
> +/* Generic IOMMU HW capability info */
> +#define HOST_IOMMU_DEVICE_CAP_GENERIC_HW        2
> +/* PASID width */
> +#define HOST_IOMMU_DEVICE_CAP_MAX_PASID_LOG2    3
>   
>   #define HOST_IOMMU_DEVICE_CAP_AW_BITS_MAX       64
>   #endif