[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Qemu-devel] [PATCH v2 7/7] intel_iommu: support passthrough (PT)

From: Peter Xu
Subject: Re: [Qemu-devel] [PATCH v2 7/7] intel_iommu: support passthrough (PT)
Date: Thu, 20 Apr 2017 15:04:20 +0800
User-agent: Mutt/1.5.24 (2015-08-30)

On Thu, Apr 20, 2017 at 06:36:16AM +0000, Liu, Yi L wrote:


> > > In my understanding, container->space->as->root cannot work here no
> > > matter passthru-mode is enabled or not. The code here is aiming to
> > > check if vIOMMU exists. After the vfio series, the vtd_dev_as->root is
> > > not initialized to be a iommu MemoryRegion. Compared with checking if
> > > it is system_memory(), I think adding a mechanism to get the iommu
> > MemoryRegion may be a better choice. Just like the current
> > pci_device_iommu_address_space().
> > 
> > Isn't pci_device_iommu_address_space() used to get that IOMMU memory region?

Again I should say s/memory region/address space/...

> It actually returns the AddressSpace, and the AddressSpace includes a memory 
> region.
> It is as->root. But after adding the vfio series, through the IOMMU memory 
> region
> is got, but it has no iommu_ops. Just as the following code shows. That's why 
> I said
> even without passthru-mode, Tianyu's that code snippet is not able to get the 
> correct
> check.
>         memory_region_init(&vtd_dev_as->root, OBJECT(s),
>                            "vtd_root", UINT64_MAX);
>         address_space_init(&vtd_dev_as->as, &vtd_dev_as->root, name);

The problem is, I am not sure whether there is always _only_ one IOMMU
region behind one device. E.g., IIUC ppc can have more than one IOMMU
memory regions, but translate for different address ranges.


Peter Xu

reply via email to

[Prev in Thread] Current Thread [Next in Thread]