Re: [RFC 00/18] vfio: Adopt iommufd

From: Yi Liu <yi.l.liu@intel.com>
To: "zhangfei.gao@foxmail.com" <zhangfei.gao@foxmail.com>,
	Jason Gunthorpe <jgg@nvidia.com>,
	Zhangfei Gao <zhangfei.gao@linaro.org>
Cc: <eric.auger@redhat.com>,
	Alex Williamson <alex.williamson@redhat.com>,
	Shameerali Kolothum Thodi  <shameerali.kolothum.thodi@huawei.com>,
	"cohuck@redhat.com" <cohuck@redhat.com>,
	"qemu-devel@nongnu.org" <qemu-devel@nongnu.org>,
	"david@gibson.dropbear.id.au" <david@gibson.dropbear.id.au>,
	"thuth@redhat.com" <thuth@redhat.com>,
	"farman@linux.ibm.com" <farman@linux.ibm.com>,
	"mjrosato@linux.ibm.com" <mjrosato@linux.ibm.com>,
	"akrowiak@linux.ibm.com" <akrowiak@linux.ibm.com>,
	"pasic@linux.ibm.com" <pasic@linux.ibm.com>,
	"jjherne@linux.ibm.com" <jjherne@linux.ibm.com>,
	"jasowang@redhat.com" <jasowang@redhat.com>,
	"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
	"nicolinc@nvidia.com" <nicolinc@nvidia.com>,
	"eric.auger.pro@gmail.com" <eric.auger.pro@gmail.com>,
	"kevin.tian@intel.com" <kevin.tian@intel.com>,
	"chao.p.peng@intel.com" <chao.p.peng@intel.com>,
	"yi.y.sun@intel.com" <yi.y.sun@intel.com>,
	"peterx@redhat.com" <peterx@redhat.com>
Subject: Re: [RFC 00/18] vfio: Adopt iommufd
Date: Tue, 17 May 2022 16:52:19 +0800	[thread overview]
Message-ID: <2e7d40ae-9449-36a2-2e3b-a5eb62e11aa6@intel.com> (raw)
In-Reply-To: <tencent_5823CCB7CFD4C49A90D3CC1A183AB406EB09@qq.com>

Hi Zhangfei,

On 2022/5/11 22:17, zhangfei.gao@foxmail.com wrote:
> 
> 
> On 2022/5/10 下午10:08, Yi Liu wrote:
>> On 2022/5/10 20:45, Jason Gunthorpe wrote:
>>> On Tue, May 10, 2022 at 08:35:00PM +0800, Zhangfei Gao wrote:
>>>> Thanks Yi and Eric,
>>>> Then will wait for the updated iommufd kernel for the PCI MMIO region.
>>>>
>>>> Another question,
>>>> How to get the iommu_domain in the ioctl.
>>>
>>> The ID of the iommu_domain (called the hwpt) it should be returned by
>>> the vfio attach ioctl.
>>
>> yes, hwpt_id is returned by the vfio attach ioctl and recorded in
>> qemu. You can query page table related capabilities with this id.
>>
>> https://lore.kernel.org/kvm/20220414104710.28534-16-yi.l.liu@intel.com/
>>
> Thanks Yi,
> 
> Do we use iommufd_hw_pagetable_from_id in kernel?
> 
> The qemu send hwpt_id via ioctl.
> Currently VFIOIOMMUFDContainer has hwpt_list,
> Which member is good to save hwpt_id, IOMMUTLBEntry?

currently, we don't make use of hwpt yet in the version we have
in the qemu branch. I have a change to make use of it. Also, it
would be used in future for nested translation setup and also
dirty page bit support query for a given domain.

> 
> In kernel ioctl: iommufd_vfio_ioctl
> @dev: Device to get an iommu_domain for
> iommufd_hw_pagetable_from_id(struct iommufd_ctx *ictx, u32 pt_id, struct 
> device *dev)
> But iommufd_vfio_ioctl seems no para dev?

there is. you can look at the vfio_group_set_iommufd(), it loops the
device_list provided by vfio. And the device info is passed to iommufd.

> Thanks
> 
> 
> 
> 

-- 
Regards,
Yi Liu