Re: [PATCH v5 01/19] backends: Introduce HostIOMMUDevice abstract

["Cédric Le Goater" <clg@redhat.com>]

On 5/13/24 12:28, Duan, Zhenzhong wrote:
> Hi Cédric,
> 
>> -----Original Message-----
>> From: Cédric Le Goater <clg@redhat.com>
>> Subject: Re: [PATCH v5 01/19] backends: Introduce HostIOMMUDevice
>> abstract
>>
>> Hello Zhenzhong,
>>
>> On 5/8/24 11:03, Zhenzhong Duan wrote:
>>> Introduce HostIOMMUDevice as an abstraction of host IOMMU device.
>>>
>>> Introduce .realize() to initialize HostIOMMUDevice further after
>>> instance init.
>>>
>>> Introduce a macro CONFIG_HOST_IOMMU_DEVICE to define the usage
>>> for VFIO, and VDPA in the future.
>>
>> This looks like a way to work around some other problem, like
>> avoiding exposing Linux definitions on windows build.
> 
> Yes, I have used this MACRO in patch19 to fix build failure on windows.
> Also need change HostIOMMUDeviceCaps::type to be uint32_t type.

Routine host_iommu_device_get_cap() could be open coded in vtd_check_hdev()
to avoid CONFIG_HOST_IOMMU_DEVICE.

Thanks,

C.



> 
>>
>> Thanks,
>>
>> C.
>>
>>
>>
>>
>>>
>>> Suggested-by: Cédric Le Goater <clg@redhat.com>
>>> Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
>>> ---
>>>    MAINTAINERS                        |  2 ++
>>>    include/sysemu/host_iommu_device.h | 51
>> ++++++++++++++++++++++++++++++
>>>    backends/host_iommu_device.c       | 30 ++++++++++++++++++
>>>    backends/Kconfig                   |  5 +++
>>>    backends/meson.build               |  1 +
>>>    5 files changed, 89 insertions(+)
>>>    create mode 100644 include/sysemu/host_iommu_device.h
>>>    create mode 100644 backends/host_iommu_device.c
>>>
>>> diff --git a/MAINTAINERS b/MAINTAINERS
>>> index 84391777db..5dab60bd04 100644
>>> --- a/MAINTAINERS
>>> +++ b/MAINTAINERS
>>> @@ -2191,6 +2191,8 @@ M: Zhenzhong Duan
>> <zhenzhong.duan@intel.com>
>>>    S: Supported
>>>    F: backends/iommufd.c
>>>    F: include/sysemu/iommufd.h
>>> +F: backends/host_iommu_device.c
>>> +F: include/sysemu/host_iommu_device.h
>>>    F: include/qemu/chardev_open.h
>>>    F: util/chardev_open.c
>>>    F: docs/devel/vfio-iommufd.rst
>>> diff --git a/include/sysemu/host_iommu_device.h
>> b/include/sysemu/host_iommu_device.h
>>> new file mode 100644
>>> index 0000000000..2b58a94d62
>>> --- /dev/null
>>> +++ b/include/sysemu/host_iommu_device.h
>>> @@ -0,0 +1,51 @@
>>> +/*
>>> + * Host IOMMU device abstract declaration
>>> + *
>>> + * Copyright (C) 2024 Intel Corporation.
>>> + *
>>> + * Authors: Zhenzhong Duan <zhenzhong.duan@intel.com>
>>> + *
>>> + * This work is licensed under the terms of the GNU GPL, version 2.  See
>>> + * the COPYING file in the top-level directory.
>>> + */
>>> +
>>> +#ifndef HOST_IOMMU_DEVICE_H
>>> +#define HOST_IOMMU_DEVICE_H
>>> +
>>> +#include "qom/object.h"
>>> +#include "qapi/error.h"
>>> +
>>> +#define TYPE_HOST_IOMMU_DEVICE "host-iommu-device"
>>> +OBJECT_DECLARE_TYPE(HostIOMMUDevice, HostIOMMUDeviceClass,
>> HOST_IOMMU_DEVICE)
>>> +
>>> +struct HostIOMMUDevice {
>>> +    Object parent_obj;
>>> +};
>>> +
>>> +/**
>>> + * struct HostIOMMUDeviceClass - The base class for all host IOMMU
>> devices.
>>> + *
>>> + * Different type of host devices (e.g., VFIO or VDPA device) or devices
>>> + * with different backend (e.g., VFIO legacy container or IOMMUFD
>> backend)
>>> + * can have different sub-classes.
>>> + */
>>> +struct HostIOMMUDeviceClass {
>>> +    ObjectClass parent_class;
>>> +
>>> +    /**
>>> +     * @realize: initialize host IOMMU device instance further.
>>> +     *
>>> +     * Mandatory callback.
>>> +     *
>>> +     * @hiod: pointer to a host IOMMU device instance.
>>> +     *
>>> +     * @opaque: pointer to agent device of this host IOMMU device,
>>> +     *          i.e., for VFIO, pointer to VFIODevice
>>> +     *
>>> +     * @errp: pass an Error out when realize fails.
>>> +     *
>>> +     * Returns: true on success, false on failure.
>>> +     */
>>> +    bool (*realize)(HostIOMMUDevice *hiod, void *opaque, Error **errp);
>>> +};
>>> +#endif
>>> diff --git a/backends/host_iommu_device.c
>> b/backends/host_iommu_device.c
>>> new file mode 100644
>>> index 0000000000..41f2fdce20
>>> --- /dev/null
>>> +++ b/backends/host_iommu_device.c
>>> @@ -0,0 +1,30 @@
>>> +/*
>>> + * Host IOMMU device abstract
>>> + *
>>> + * Copyright (C) 2024 Intel Corporation.
>>> + *
>>> + * Authors: Zhenzhong Duan <zhenzhong.duan@intel.com>
>>> + *
>>> + * This work is licensed under the terms of the GNU GPL, version 2.  See
>>> + * the COPYING file in the top-level directory.
>>> + */
>>> +
>>> +#include "qemu/osdep.h"
>>> +#include "sysemu/host_iommu_device.h"
>>> +
>>> +OBJECT_DEFINE_ABSTRACT_TYPE(HostIOMMUDevice,
>>> +                            host_iommu_device,
>>> +                            HOST_IOMMU_DEVICE,
>>> +                            OBJECT)
>>> +
>>> +static void host_iommu_device_class_init(ObjectClass *oc, void *data)
>>> +{
>>> +}
>>> +
>>> +static void host_iommu_device_init(Object *obj)
>>> +{
>>> +}
>>> +
>>> +static void host_iommu_device_finalize(Object *obj)
>>> +{
>>> +}
>>> diff --git a/backends/Kconfig b/backends/Kconfig
>>> index 2cb23f62fa..34ab29e994 100644
>>> --- a/backends/Kconfig
>>> +++ b/backends/Kconfig
>>> @@ -3,3 +3,8 @@ source tpm/Kconfig
>>>    config IOMMUFD
>>>        bool
>>>        depends on VFIO
>>> +
>>> +config HOST_IOMMU_DEVICE
>>> +    bool
>>> +    default y
>>> +    depends on VFIO
>>> diff --git a/backends/meson.build b/backends/meson.build
>>> index 8b2b111497..2e975d641e 100644
>>> --- a/backends/meson.build
>>> +++ b/backends/meson.build
>>> @@ -25,6 +25,7 @@ if have_vhost_user
>>>    endif
>>>    system_ss.add(when: 'CONFIG_VIRTIO_CRYPTO', if_true: files('cryptodev-
>> vhost.c'))
>>>    system_ss.add(when: 'CONFIG_IOMMUFD', if_true: files('iommufd.c'))
>>> +system_ss.add(when: 'CONFIG_HOST_IOMMU_DEVICE', if_true:
>> files('host_iommu_device.c'))
>>
>> Euh. Why is that ?
> 
> Tried to reduce qemu binary size a bit.
> When CONFIG_VFIO=n such as on windows,  CONFIG_HOST_IOMMU_DEVICE=n.
> There is no user of host_iommu_device.c, so no need to build it.
> But this way need to add '#ifdef CONFIG_HOST_IOMMU_DEVICE' in vtd_check_hdev() in intel_iommu.c.
> 
> The other way is to drop this build configuration, then there is no need to add '#ifdef CONFIG_HOST_IOMMU_DEVICE' in vtd_check_hdev() in intel_iommu.c, because
> host_iommu_device.c is always built.
> 
> This series works in 1st way, I can change to 2nd way if you prefer.
> 
> Thanks
> Zhenzhong
> 
> 
>