>-----Original Message-----
>From: Joao Martins <joao.m.mart...@oracle.com>
>Subject: Re: [PATCH 1/5] vfio/iommufd: Save host iommu capabilities in
>VFIODevice.caps
>
>On 11/04/2025 11:17, Zhenzhong Duan wrote:
>> The saved caps copy can be used to check dirty tracking capability.
>>
>> The capabilities is gotten through IOMMUFD interface, so define a
>> new structure HostIOMMUDeviceIOMMUFDCaps which contains vendor
>> caps raw data in "include/system/iommufd.h".
>>
>> This is a prepare work for moving .realize() after .attach_device().
>>
>> Suggested-by: Cédric Le Goater <c...@redhat.com>
>> Suggested-by: Eric Auger <eric.au...@redhat.com>
>> Suggested-by: Nicolin Chen <nicol...@nvidia.com>
>> Signed-off-by: Zhenzhong Duan <zhenzhong.d...@intel.com>
>> ---
>> include/hw/vfio/vfio-device.h | 1 +
>> include/system/iommufd.h | 22 ++++++++++++++++++++++
>> hw/vfio/iommufd.c | 10 +++++++++-
>> 3 files changed, 32 insertions(+), 1 deletion(-)
>>
>> diff --git a/include/hw/vfio/vfio-device.h b/include/hw/vfio/vfio-device.h
>> index 66797b4c92..09a7af891a 100644
>> --- a/include/hw/vfio/vfio-device.h
>> +++ b/include/hw/vfio/vfio-device.h
>> @@ -77,6 +77,7 @@ typedef struct VFIODevice {
>> bool dirty_tracking; /* Protected by BQL */
>> bool iommu_dirty_tracking;
>> HostIOMMUDevice *hiod;
>> + HostIOMMUDeviceIOMMUFDCaps caps;
>> int devid;
>> IOMMUFDBackend *iommufd;
>> VFIOIOASHwpt *hwpt;
>> diff --git a/include/system/iommufd.h b/include/system/iommufd.h
>> index cbab75bfbf..0f337585c9 100644
>> --- a/include/system/iommufd.h
>> +++ b/include/system/iommufd.h
>> @@ -18,6 +18,9 @@
>> #include "exec/hwaddr.h"
>> #include "exec/cpu-common.h"
>> #include "system/host_iommu_device.h"
>> +#ifdef CONFIG_LINUX
>> +#include <linux/iommufd.h>
>> +#endif
>>
>> #define TYPE_IOMMUFD_BACKEND "iommufd"
>> OBJECT_DECLARE_TYPE(IOMMUFDBackend, IOMMUFDBackendClass,
>IOMMUFD_BACKEND)
>> @@ -63,4 +66,23 @@ bool
>iommufd_backend_get_dirty_bitmap(IOMMUFDBackend *be, uint32_t hwpt_id,
>> Error **errp);
>>
>> #define TYPE_HOST_IOMMU_DEVICE_IOMMUFD
>TYPE_HOST_IOMMU_DEVICE "-iommufd"
>> +
>> +typedef union VendorCaps {
>> + struct iommu_hw_info_vtd vtd;
>> + struct iommu_hw_info_arm_smmuv3 smmuv3;
>> +} VendorCaps;
>> +
>> +/**
>> + * struct HostIOMMUDeviceIOMMUFDCaps - Define host IOMMU device
>capabilities.
>> + *
>> + * @type: host platform IOMMU type.
>> + *
>> + * @hw_caps: host platform IOMMU capabilities (e.g. on IOMMUFD this
>represents
>> + * the @out_capabilities value returned from IOMMU_GET_HW_INFO
>ioctl)
>> + */
>> +typedef struct HostIOMMUDeviceIOMMUFDCaps {
>> + uint32_t type;
>> + uint64_t hw_caps;
>> + VendorCaps vendor_caps;
>> +} HostIOMMUDeviceIOMMUFDCaps;
>> #endif
>> diff --git a/hw/vfio/iommufd.c b/hw/vfio/iommufd.c
>> index 48db105422..530cde6740 100644
>> --- a/hw/vfio/iommufd.c
>> +++ b/hw/vfio/iommufd.c
>> @@ -324,7 +324,7 @@ static bool
>iommufd_cdev_autodomains_get(VFIODevice *vbasedev,
>> * vfio_migration_realize() may decide to use VF dirty tracking
>> * instead.
>> */
>> - if (vbasedev->hiod->caps.hw_caps & IOMMU_HW_CAP_DIRTY_TRACKING) {
>> + if (vbasedev->caps.hw_caps & IOMMU_HW_CAP_DIRTY_TRACKING) {
>> flags = IOMMU_HWPT_ALLOC_DIRTY_TRACKING;
>> }
>>
>> @@ -475,6 +475,7 @@ static bool iommufd_cdev_attach(const char *name,
>VFIODevice *vbasedev,
>> int ret, devfd;
>> uint32_t ioas_id;
>> Error *err = NULL;
>> + HostIOMMUDeviceIOMMUFDCaps *caps = &vbasedev->caps;
>> const VFIOIOMMUClass *iommufd_vioc =
>>
>VFIO_IOMMU_CLASS(object_class_by_name(TYPE_VFIO_IOMMU_IOMMUFD));
>>
>> @@ -505,6 +506,13 @@ static bool iommufd_cdev_attach(const char *name,
>VFIODevice *vbasedev,
>> goto err_alloc_ioas;
>> }
>>
>> + if (!iommufd_backend_get_device_info(vbasedev->iommufd, vbasedev-
>>devid,
>> + &caps->type, &caps->vendor_caps,
>> + sizeof(VendorCaps), &caps->hw_caps,
>> + errp)) {
>> + goto err_alloc_ioas;
>> + }
>> +
>
>I think this will fail on mdev (and thus fail the attachment mistakengly as
>there's no IOMMUFDDevice with mdev) ? In case it fails, you can just do:
>
> if (!vbasedev->mdev && !iommufd_backend_get_device_info(...)) {
Indeed, thanks for caching this.
BRs,
Zhenzhong
