Re: [PATCH v3 05/19] backends/host_iommu_device: Introduce HostIOMMUDeviceCaps

[Cédric Le Goater]

On 4/29/24 08:50, Zhenzhong Duan wrote:
> HostIOMMUDeviceCaps's elements map to the host IOMMU's capabilities.
> Different platform IOMMU can support different elements.
>
> Currently only two elements, type and aw_bits, type hints the host
> platform IOMMU type, i.e., INTEL vtd, ARM smmu, etc; aw_bits hints
> host IOMMU address width.
>
> Introduce .check_cap() handler to check if HOST_IOMMU_DEVICE_CAP_XXX
> is supported.
>
> Introduce a HostIOMMUDevice API host_iommu_device_check_cap() which
> is a wrapper of .check_cap().
>
> Introduce a HostIOMMUDevice API host_iommu_device_check_cap_common()
> to check common capabalities of different host platform IOMMUs.
>
> Suggested-by: Cédric Le Goater <clg@redhat.com>
> Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
> ---
>   include/sysemu/host_iommu_device.h | 44 ++++++++++++++++++++++++++++++
>   backends/host_iommu_device.c       | 29 ++++++++++++++++++++
>   2 files changed, 73 insertions(+)
>
> diff --git a/include/sysemu/host_iommu_device.h 
> b/include/sysemu/host_iommu_device.h
> index 2b58a94d62..12b6afb463 100644
> --- a/include/sysemu/host_iommu_device.h
> +++ b/include/sysemu/host_iommu_device.h
> @@ -14,12 +14,27 @@
>   
>   #include "qom/object.h"
>   #include "qapi/error.h"
> +#include "linux/iommufd.h"
> +
> +/**
> + * struct HostIOMMUDeviceCaps - Define host IOMMU device capabilities.
> + *
> + * @type: host platform IOMMU type.
> + *
> + * @aw_bits: host IOMMU address width. 0xff if no limitation.
> + */
> +typedef struct HostIOMMUDeviceCaps {
> +    enum iommu_hw_info_type type;
> +    uint8_t aw_bits;
> +} HostIOMMUDeviceCaps;
>   
>   #define TYPE_HOST_IOMMU_DEVICE "host-iommu-device"
>   OBJECT_DECLARE_TYPE(HostIOMMUDevice, HostIOMMUDeviceClass, HOST_IOMMU_DEVICE)
>   
>   struct HostIOMMUDevice {
>       Object parent_obj;
> +
> +    HostIOMMUDeviceCaps caps;
>   };
>   
>   /**
> @@ -47,5 +62,34 @@ struct HostIOMMUDeviceClass {
>        * Returns: true on success, false on failure.
>        */
>       bool (*realize)(HostIOMMUDevice *hiod, void *opaque, Error **errp);
> +    /**
> +     * @check_cap: check if a host IOMMU device capability is supported.
> +     *
> +     * Optional callback, if not implemented, hint not supporting query
> +     * of @cap.
> +     *
> +     * @hiod: pointer to a host IOMMU device instance.
> +     *
> +     * @cap: capability to check.
> +     *
> +     * @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.
> +     */
> +    int (*check_cap)(HostIOMMUDevice *hiod, int cap, Error **errp);
>   };
> +
> +/*
> + * Host IOMMU device capability list.
> + */
> +#define HOST_IOMMU_DEVICE_CAP_IOMMUFD       0
> +#define HOST_IOMMU_DEVICE_CAP_IOMMU_TYPE    1
> +#define HOST_IOMMU_DEVICE_CAP_AW_BITS       2
> +
> +
> +int host_iommu_device_check_cap(HostIOMMUDevice *hiod, int cap, Error **errp);
> +int host_iommu_device_check_cap_common(HostIOMMUDevice *hiod, int cap,
> +                                       Error **errp);
>   #endif
> diff --git a/backends/host_iommu_device.c b/backends/host_iommu_device.c
> index 41f2fdce20..b97d008cc7 100644
> --- a/backends/host_iommu_device.c
> +++ b/backends/host_iommu_device.c
> @@ -28,3 +28,32 @@ static void host_iommu_device_init(Object *obj)
>   static void host_iommu_device_finalize(Object *obj)
>   {
>   }
> +
> +/* Wrapper of HostIOMMUDeviceClass:check_cap */
> +int host_iommu_device_check_cap(HostIOMMUDevice *hiod, int cap, Error **errp)

Since we have an 'Error **errp', we could return a bool instead,
unless this is a 'get_cap' routine ?

Thanks,

C.


> +{
> +    HostIOMMUDeviceClass *hiodc = HOST_IOMMU_DEVICE_GET_CLASS(hiod);
> +    if (!hiodc->check_cap) {
> +        error_setg(errp, ".check_cap() not implemented");
> +        return -EINVAL;
> +    }
> +
> +    return hiodc->check_cap(hiod, cap, errp);
> +}
> +
> +/* Implement check on common IOMMU capabilities */
> +int host_iommu_device_check_cap_common(HostIOMMUDevice *hiod, int cap,
> +                                       Error **errp)
> +{
> +    HostIOMMUDeviceCaps *caps = &hiod->caps;
> +
> +    switch (cap) {
> +    case HOST_IOMMU_DEVICE_CAP_IOMMU_TYPE:
> +        return caps->type;
> +    case HOST_IOMMU_DEVICE_CAP_AW_BITS:
> +        return caps->aw_bits;
> +    default:
> +        error_setg(errp, "Not support query cap %x", cap);
> +        return -EINVAL;
> +    }
> +}