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Date:   Wed, 6 Dec 2023 08:58:26 +0800
From:   Yan Zhao <yan.y.zhao@intel.com>
To:     Jason Gunthorpe <jgg@nvidia.com>
CC:     <iommu@lists.linux.dev>, <kvm@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>, <alex.williamson@redhat.com>,
        <pbonzini@redhat.com>, <seanjc@google.com>, <joro@8bytes.org>,
        <will@kernel.org>, <robin.murphy@arm.com>, <kevin.tian@intel.com>,
        <baolu.lu@linux.intel.com>, <dwmw2@infradead.org>,
        <yi.l.liu@intel.com>
Subject: Re: [RFC PATCH 12/42] iommufd: Introduce allocation data info and
 flag for KVM managed HWPT
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Reply-To: Yan Zhao <yan.y.zhao@intel.com>
References: <20231202091211.13376-1-yan.y.zhao@intel.com>
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On Tue, Dec 05, 2023 at 10:53:04AM -0400, Jason Gunthorpe wrote:
> On Tue, Dec 05, 2023 at 03:08:03PM +0800, Yan Zhao wrote:
> > On Mon, Dec 04, 2023 at 02:29:28PM -0400, Jason Gunthorpe wrote:
> > > On Sat, Dec 02, 2023 at 05:21:13PM +0800, Yan Zhao wrote:
> > > 
> > > > @@ -413,11 +422,13 @@ struct iommu_hwpt_arm_smmuv3 {
> > > >   * @IOMMU_HWPT_DATA_NONE: no data
> > > >   * @IOMMU_HWPT_DATA_VTD_S1: Intel VT-d stage-1 page table
> > > >   * @IOMMU_HWPT_DATA_ARM_SMMUV3: ARM SMMUv3 Context Descriptor Table
> > > > + * @IOMMU_HWPT_DATA_KVM: KVM managed stage-2 page table
> > > >   */
> > > >  enum iommu_hwpt_data_type {
> > > >  	IOMMU_HWPT_DATA_NONE,
> > > >  	IOMMU_HWPT_DATA_VTD_S1,
> > > >  	IOMMU_HWPT_DATA_ARM_SMMUV3,
> > > > +	IOMMU_HWPT_DATA_KVM,
> > > >  };
> > > 
> > > Definately no, the HWPT_DATA is for the *driver* - it should not be
> > > "kvm".
> > > 
> > > Add the kvm fd to the main structure
> > >
> > Do you mean add a "int kvm_fd" to "struct iommu_hwpt_alloc" ?
> > struct iommu_hwpt_alloc {
> >         __u32 size;
> >         __u32 flags;
> >         __u32 dev_id;
> >         __u32 pt_id;
> >         __u32 out_hwpt_id;
> >         __u32 __reserved;
> >         __u32 data_type;
> >         __u32 data_len;
> >         __aligned_u64 data_uptr;
> > };
> > 
> > Then always create the HWPT as IOMMUFD_OBJ_HWPT_KVM as long as kvm_fd > 0 ?
> 
> Yes, but 0 is a valid FD so you need to add a flag 'kvm_fd valid'

Got it, thanks!