>-----Original Message-----
>From: Cédric Le Goater <c...@redhat.com>
>Subject: Re: [PATCH v3 05/19] backends/host_iommu_device: Introduce
>HostIOMMUDeviceCaps
>
>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 <c...@redhat.com>
>> Signed-off-by: Zhenzhong Duan <zhenzhong.d...@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 ?
Maybe better to name it host_iommu_device_get_cap()?
Because not all results are bool, some are integer, i.e., aw_bits.
Thanks
Zhenzhong
>
>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;
>> + }
>> +}
