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Date: Mon, 5 Mar 2018 17:11:19 +0800
From: "Liu, Yi L" <yi.l.liu@linux.intel.com>
Message-ID: <20180305091119.GH2482@sky-dev>
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Subject: Re: [Qemu-devel] [PATCH v3 11/12] intel_iommu: add framework for
 PASID AddressSpace management
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To: Paolo Bonzini <pbonzini@redhat.com>
Cc: qemu-devel@nongnu.org, mst@redhat.com, david@gibson.dropbear.id.au, kevin.tian@intel.com, yi.l.liu@intel.com, jasowang@redhat.com, peterx@redhat.com, alex.williamson@redhat.com, eric.auger.pro@gmail.com

On Fri, Mar 02, 2018 at 04:00:23PM +0100, Paolo Bonzini wrote:
> On 01/03/2018 11:33, Liu, Yi L wrote:
> > +struct VTDDeviceNode {
> > +    PCIBus *bus;
> > +    uint8_t devfn;
> > +    QLIST_ENTRY(VTDDeviceNode) next;
> > +};
> 
> Do you really need VTDDeviceNode?  I think can you simply put the
> QLIST_ENTRY in VTDAddressSpace (named e.g. next_by_pasid), since
> VTDAddressSpace already includes a (bus, devfn).

Existing VTDAddressSpace is actaully per-device. While for PASID tagged
address space, it is possible to have multiple devices tied to a single
PASID tagged address space. Reuse VTDAddressSpace could be a choice since
it is a per-device structure, but it may be missleading since there is
other fileds in VTDAddressSpace. This is why I proposed to have VTDDeviceNode.
But consolidation is possible here.

Thanks,
Yi Liu

> > +struct VTDPASIDAddressSpace {
> > +    AddressSpace as;
> > +    IOMMUSVAContext sva_ctx;
> > +    IntelIOMMUState *iommu_state;
> > +    /* list of devices binded to a pasid tagged address space */
> > +    QLIST_HEAD(, VTDDeviceNode) device_list;
> > +};
> > +
> 
>