Re: [PATCH v3 14/15] iommufd: vfio container FD ioctl compatibility

From: Jason Gunthorpe <jgg@nvidia.com>
To: Baolu Lu <baolu.lu@linux.intel.com>
Cc: bpf@vger.kernel.org, Jonathan Corbet <corbet@lwn.net>,
	David Woodhouse <dwmw2@infradead.org>,
	iommu@lists.linux.dev, Joerg Roedel <joro@8bytes.org>,
	Kevin Tian <kevin.tian@intel.com>,
	linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org,
	llvm@lists.linux.dev, Nathan Chancellor <nathan@kernel.org>,
	Nick Desaulniers <ndesaulniers@google.com>,
	Miguel Ojeda <ojeda@kernel.org>,
	Robin Murphy <robin.murphy@arm.com>,
	Shuah Khan <shuah@kernel.org>,
	Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>,
	Tom Rix <trix@redhat.com>, Will Deacon <will@kernel.org>,
	Alex Williamson <alex.williamson@redhat.com>,
	Chaitanya Kulkarni <chaitanyak@nvidia.com>,
	Cornelia Huck <cohuck@redhat.com>,
	Daniel Jordan <daniel.m.jordan@oracle.com>,
	David Gibson <david@gibson.dropbear.id.au>,
	Eric Auger <eric.auger@redhat.com>,
	Eric Farman <farman@linux.ibm.com>,
	Jason Wang <jasowang@redhat.com>,
	Jean-Philippe Brucker <jean-philippe@linaro.org>,
	Joao Martins <joao.m.martins@oracle.com>,
	kvm@vger.kernel.org, Matthew Rosato <mjrosato@linux.ibm.com>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	Nicolin Chen <nicolinc@nvidia.com>,
	Niklas Schnelle <schnelle@linux.ibm.com>,
	Shameerali Kolothum Thodi <shameerali.kolothum.thodi@huawei.com>,
	Yi Liu <yi.l.liu@intel.com>, Keqian Zhu <zhukeqian1@huawei.com>
Subject: Re: [PATCH v3 14/15] iommufd: vfio container FD ioctl compatibility
Date: Mon, 7 Nov 2022 10:23:41 -0400	[thread overview]
Message-ID: <Y2kU7SCtOntzSfMh@nvidia.com> (raw)
In-Reply-To: <2d2b467b-da07-2b96-27c9-569b727dd8c9@linux.intel.com>

On Sat, Nov 05, 2022 at 08:07:24AM +0800, Baolu Lu wrote:

> If you fix the issue, kindly add following tag where applicable
> | Reported-by: kernel test robot <lkp@intel.com>
> 
> sparse warnings: (new ones prefixed by >>)
> >> drivers/iommu/iommufd/vfio_compat.c:294:17: sparse: sparse: cast removes
> address space '__user' of expression
> 
> vim +/__user +294 drivers/iommu/iommufd/vfio_compat.c
> 
>    288	
>    289	static int iommufd_fill_cap_iova(struct iommufd_ioas *ioas,
>    290					 struct vfio_info_cap_header __user *cur,
>    291					 size_t avail)
>    292	{
>    293		struct vfio_iommu_type1_info_cap_iova_range __user *ucap_iovas =
>  > 294			container_of(cur,
>    295				     struct vfio_iommu_type1_info_cap_iova_range __user,
>    296				     header);

I think this is correct as-written. Sparse is flagging the casting
inside container_of. I don't think ti is worth trying to fix

Jason