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From: "Duan, Zhenzhong" <zhenzhong.duan@intel.com>
To: "Cédric Le Goater" <clg@redhat.com>,
	"qemu-devel@nongnu.org" <qemu-devel@nongnu.org>
Cc: "alex.williamson@redhat.com" <alex.williamson@redhat.com>,
	"eric.auger@redhat.com" <eric.auger@redhat.com>,
	"mst@redhat.com" <mst@redhat.com>,
	"peterx@redhat.com" <peterx@redhat.com>,
	"jasowang@redhat.com" <jasowang@redhat.com>,
	"jgg@nvidia.com" <jgg@nvidia.com>,
	"nicolinc@nvidia.com" <nicolinc@nvidia.com>,
	"joao.m.martins@oracle.com" <joao.m.martins@oracle.com>,
	"Tian, Kevin" <kevin.tian@intel.com>,
	"Liu, Yi L" <yi.l.liu@intel.com>,
	"Peng, Chao P" <chao.p.peng@intel.com>
Subject: RE: [PATCH v3 11/19] backends/iommufd: Implement HostIOMMUDeviceClass::check_cap() handler
Date: Mon, 6 May 2024 01:47:12 +0000	[thread overview]
Message-ID: <SJ0PR11MB6744798B79008487584F84F3921C2@SJ0PR11MB6744.namprd11.prod.outlook.com> (raw)
In-Reply-To: <241f5575-b177-4d38-91e5-e6f3ad276a05@redhat.com>

>-----Original Message-----
>From: Cédric Le Goater <clg@redhat.com>
>Subject: Re: [PATCH v3 11/19] backends/iommufd: Implement
>HostIOMMUDeviceClass::check_cap() handler
>
>>>>>> +static int hiod_iommufd_check_cap(HostIOMMUDevice *hiod, int
>cap,
>>>>> Error **errp)
>>>>>> +{
>>>>>> +    switch (cap) {
>>>>>> +    case HOST_IOMMU_DEVICE_CAP_IOMMUFD:
>>>>>> +        return 1;
>>>>>
>>>>> I don't understand this value.
>>>>
>>>> 1 means this host iommu device is attached to IOMMUFD backend,
>>>> or else 0 if attached to legacy backend.
>>>
>>> Hmm, this looks hacky to me and it is not used anywhere in the patchset.
>>> Let's reconsider when there is actually a use for it. Until then, please
>>> drop. My feeling is that a new HostIOMMUDeviceClass
>handler/attributed
>>> should be introduced instead.
>>
>> Got it, will drop it in this series.
>>
>> Is "return 1" directly the concern on your side?
>
>I don't know yet why the implementation would need to know if the host
>IOMMU device is of type IOMMUFD. If that's the case, there are alternative
>ways, like using OBJECT_CHECK( ..., TYPE_HOST_IOMMU_DEVICE_IOMMUFD)
>or
>a class attribute defined at build time but that's a bit the same. Let's
>see when the need arises.

Got it, let's revisit it in nesting series, will drop it for now.

Thanks
Zhenzhong

  reply	other threads:[~2024-05-06  1:48 UTC|newest]

Thread overview: 59+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-04-29  6:50 [PATCH v3 00/19] Add a host IOMMU device abstraction to check with vIOMMU Zhenzhong Duan
2024-04-29  6:50 ` [PATCH v3 01/19] backends: Introduce HostIOMMUDevice abstract Zhenzhong Duan
2024-04-29  6:50 ` [PATCH v3 02/19] vfio/container: Introduce HostIOMMUDeviceLegacyVFIO device Zhenzhong Duan
2024-04-30  7:51   ` Cédric Le Goater
2024-04-30  9:13     ` Duan, Zhenzhong
2024-04-30 12:00       ` Cédric Le Goater
2024-04-29  6:50 ` [PATCH v3 03/19] backends/iommufd: Introduce abstract HostIOMMUDeviceIOMMUFD device Zhenzhong Duan
2024-04-29  6:50 ` [PATCH v3 04/19] vfio/iommufd: Introduce HostIOMMUDeviceIOMMUFDVFIO device Zhenzhong Duan
2024-04-30  7:52   ` Cédric Le Goater
2024-04-30  9:25     ` Duan, Zhenzhong
2024-04-29  6:50 ` [PATCH v3 05/19] backends/host_iommu_device: Introduce HostIOMMUDeviceCaps Zhenzhong Duan
2024-04-30  9:41   ` Cédric Le Goater
2024-04-30  9:55     ` Duan, Zhenzhong
2024-04-30 12:01       ` Cédric Le Goater
2024-05-07  6:11   ` Cédric Le Goater
2024-05-07  6:24     ` Duan, Zhenzhong
2024-04-29  6:50 ` [PATCH v3 06/19] range: Introduce range_get_last_bit() Zhenzhong Duan
2024-04-30  9:41   ` Cédric Le Goater
2024-04-30  9:58     ` Duan, Zhenzhong
2024-05-02 10:30       ` Cédric Le Goater
2024-05-06  6:45         ` Duan, Zhenzhong
2024-04-29  6:50 ` [PATCH v3 07/19] vfio/container: Implement HostIOMMUDeviceClass::realize() handler Zhenzhong Duan
2024-04-30  9:41   ` Cédric Le Goater
2024-04-30  9:59     ` Duan, Zhenzhong
2024-04-29  6:50 ` [PATCH v3 08/19] backends/iommufd: Introduce helper function iommufd_backend_get_device_info() Zhenzhong Duan
2024-04-30  9:41   ` Cédric Le Goater
2024-04-30 10:06     ` Duan, Zhenzhong
2024-04-29  6:50 ` [PATCH v3 09/19] vfio/iommufd: Implement HostIOMMUDeviceClass::realize() handler Zhenzhong Duan
2024-04-29  6:50 ` [PATCH v3 10/19] vfio/container: Implement HostIOMMUDeviceClass::check_cap() handler Zhenzhong Duan
2024-04-29  6:50 ` [PATCH v3 11/19] backends/iommufd: " Zhenzhong Duan
2024-04-30  9:41   ` Cédric Le Goater
2024-04-30 10:06     ` Duan, Zhenzhong
2024-04-30 12:12       ` Cédric Le Goater
2024-05-01 12:34         ` Duan, Zhenzhong
2024-05-02  8:17           ` Cédric Le Goater
2024-05-06  1:47             ` Duan, Zhenzhong [this message]
2024-04-29  6:50 ` [PATCH v3 12/19] vfio: Introduce VFIOIOMMUClass::hiod_typename attribute Zhenzhong Duan
2024-04-29  6:50 ` [PATCH v3 13/19] vfio: Create host IOMMU device instance Zhenzhong Duan
2024-04-30  9:41   ` Cédric Le Goater
2024-04-30 10:16     ` Duan, Zhenzhong
2024-04-30 12:15       ` Cédric Le Goater
2024-04-29  6:50 ` [PATCH v3 14/19] hw/pci: Introduce helper function pci_device_get_iommu_bus_devfn() Zhenzhong Duan
2024-04-29  6:50 ` [PATCH v3 15/19] hw/pci: Introduce pci_device_[set|unset]_iommu_device() Zhenzhong Duan
2024-05-07  7:04   ` Cédric Le Goater
2024-05-07  7:48     ` Duan, Zhenzhong
2024-05-07 12:26       ` Cédric Le Goater
2024-05-08  6:24         ` Duan, Zhenzhong
2024-04-29  6:50 ` [PATCH v3 16/19] vfio/pci: Pass HostIOMMUDevice to vIOMMU Zhenzhong Duan
2024-04-29  6:50 ` [PATCH v3 17/19] intel_iommu: Extract out vtd_cap_init() to initialize cap/ecap Zhenzhong Duan
2024-04-29  6:50 ` [PATCH v3 18/19] intel_iommu: Implement [set|unset]_iommu_device() callbacks Zhenzhong Duan
2024-04-29  6:50 ` [PATCH v3 19/19] intel_iommu: Check compatibility with host IOMMU capabilities Zhenzhong Duan
2024-05-03 14:04 ` [PATCH v3 00/19] Add a host IOMMU device abstraction to check with vIOMMU Cédric Le Goater
2024-05-03 14:10   ` Jason Gunthorpe
2024-05-03 14:29     ` Cédric Le Goater
2024-05-06  2:30   ` Duan, Zhenzhong
2024-05-06 12:05     ` Jason Gunthorpe
2024-05-07  2:24       ` Duan, Zhenzhong
2024-05-07 11:58         ` Jason Gunthorpe
2024-05-08  6:36           ` Duan, Zhenzhong

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