Re: [Xen-devel] [PATCH 1/1] x86/AMD: Fix setup ssss:bb:dd:f for d0 failed

[Suravee Suthikulpanit <suravee.suthikulpanit@xxxxxxx>]

On 8/8/2013 1:38 AM, Jan Beulich wrote:
> > > > On 07.08.13 at 21:20, Suravee Suthikulanit <suravee.suthikulpanit@xxxxxxx> 
> > > > wrote:
> > On 8/7/2013 10:42 AM, Jan Beulich wrote:
> > > > > > On 07.08.13 at 17:31, Suravee Suthikulanit <suravee.suthikulpanit@xxxxxxx> 
> > > > > > wrote:
> > > > I am using the same logic here as in Intel's version in the
> > > > driver/passthrough/vtd/iommu/domain_context_map.
> > > No, not really: That code establishes a mapping for the upstream
> > > bridge of a legacy PCI device when handling that device. Your
> > > proposed code doesn't afaics. (This I understand is because
> > > bridges aren't expected to get assigned to guests, and hence
> > > otherwise the mapping for the bridge would never get established
> > > for a device behind it for other than Dom0.)
> > AFAICT from the domain_context_mapping() below, which get called when
> > the devices are assigned to domains
> >
> > static int domain_context_mapping(
> >       struct domain *domain, u8 devfn, const struct pci_dev *pdev)
> > {
> >       struct acpi_drhd_unit *drhd;
> >       int ret = 0;
> >       u8 seg = pdev->seg, bus = pdev->bus, secbus;
> >
> >       drhd = acpi_find_matched_drhd_unit(pdev);
> >       if ( !drhd )
> >           return -ENODEV;
> >
> >       ASSERT(spin_is_locked(&pcidevs_lock));
> >
> >       switch ( pdev->type )
> >       {
> >       case DEV_TYPE_PCIe_BRIDGE:
> >       case DEV_TYPE_PCIe2PCI_BRIDGE:
> >       case DEV_TYPE_LEGACY_PCI_BRIDGE:
> >           break;
> >
> > These bridges are actually not mapped(i.e. skipped).  That is why I
> > think the logic above is supposed to be doing the same thing.
> Just look a few lines down: There the bridges will get mappings
> established when a device behind them gets mapped.
>
> But since devices can't be behind host bridges, excluding those
> _may_ still be appropriate/desirable. Still waiting for Xiantao to
> voice his opinion...
>
> Jan
Sorry for didn't get a chance to follow up with this sooner.  Ok, I see 
the code you mentioned.
However, if I understand this correctly, it is also mapping the bridge 
to the domU
along with the end-device.  This is not the same as what you mentioned 
that the bridge should
be mapped to only Dom0.

Suravee


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