linux-kernel - Re: [PATCH v4 09/12] iommu/vt-d: Add iotlb flush for nested domain

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Date:   Mon, 7 Aug 2023 20:12:37 -0700
From:   Nicolin Chen <nicolinc@...dia.com>
To:     "Liu, Yi L" <yi.l.liu@...el.com>
CC:     "Tian, Kevin" <kevin.tian@...el.com>,
        "joro@...tes.org" <joro@...tes.org>,
        "alex.williamson@...hat.com" <alex.williamson@...hat.com>,
        "jgg@...dia.com" <jgg@...dia.com>,
        "robin.murphy@....com" <robin.murphy@....com>,
        "baolu.lu@...ux.intel.com" <baolu.lu@...ux.intel.com>,
        "cohuck@...hat.com" <cohuck@...hat.com>,
        "eric.auger@...hat.com" <eric.auger@...hat.com>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "mjrosato@...ux.ibm.com" <mjrosato@...ux.ibm.com>,
        "chao.p.peng@...ux.intel.com" <chao.p.peng@...ux.intel.com>,
        "yi.y.sun@...ux.intel.com" <yi.y.sun@...ux.intel.com>,
        "peterx@...hat.com" <peterx@...hat.com>,
        "jasowang@...hat.com" <jasowang@...hat.com>,
        "shameerali.kolothum.thodi@...wei.com" 
        <shameerali.kolothum.thodi@...wei.com>,
        "lulu@...hat.com" <lulu@...hat.com>,
        "suravee.suthikulpanit@....com" <suravee.suthikulpanit@....com>,
        "iommu@...ts.linux.dev" <iommu@...ts.linux.dev>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-kselftest@...r.kernel.org" <linux-kselftest@...r.kernel.org>,
        "Duan, Zhenzhong" <zhenzhong.duan@...el.com>
Subject: Re: [PATCH v4 09/12] iommu/vt-d: Add iotlb flush for nested domain

On Mon, Aug 07, 2023 at 03:08:29PM +0000, Liu, Yi L wrote:
> > > From: Liu, Yi L <yi.l.liu@...el.com>
> > > Sent: Monday, July 24, 2023 7:14 PM
> > >
> > > +static int intel_nested_cache_invalidate_user(struct iommu_domain
> > > *domain,
> > > +                                         void *user_data)
> > > +{
> > > +   struct iommu_hwpt_vtd_s1_invalidate_desc *req = user_data;
> > > +   struct iommu_hwpt_vtd_s1_invalidate *inv_info = user_data;
> > > +   struct dmar_domain *dmar_domain = to_dmar_domain(domain);
> > > +   unsigned int entry_size = inv_info->entry_size;
> > > +   u64 uptr = inv_info->inv_data_uptr;
> > > +   u64 nr_uptr = inv_info->entry_nr_uptr;
> > > +   struct device_domain_info *info;
> > > +   u32 entry_nr, index;
> > > +   unsigned long flags;
> > > +   int ret = 0;
> > > +
> > > +   if (get_user(entry_nr, (uint32_t __user *)u64_to_user_ptr(nr_uptr)))
> > > +           return -EFAULT;
> > > +
> > > +   for (index = 0; index < entry_nr; index++) {
> > > +           ret = copy_struct_from_user(req, sizeof(*req),
> > > +                                       u64_to_user_ptr(uptr + index *
> > > entry_size),
> > > +                                       entry_size);
> >
> > If continuing this direction then the driver should also check minsz etc.
> > for struct iommu_hwpt_vtd_s1_invalidate and iommu_hwpt_vtd_s1_invalidate_desc
> > since they are uAPI and subject to change.
> 
> Then needs to define size in the uapi data structure, and copy size first and
> check minsz before going forward. How about the structures for hwpt alloc
> like struct iommu_hwpt_vtd_s1? Should check minsz for them as well?

Assuming that every uAPI data structure needs a min_size, we can
either add a structure holding all min_sizes like iommufd main.c
or have another xx_min_len in iommu_/domain_ops.

Currently, we have the union of structures in iommu.h and also a
xx_data_len in iommu_ops. So, neither of the two places seem to
be optimal from my p.o.v... any suggestion?

Also, alloc allows data_len=0, so a min_size check will be only
applied to data_len > 0 case.

Thanks
Nic