On Mon, Sep 01, 2014 at 09:29:16PM +0800, [email protected] wrote: > From: Gonglei <[email protected]> > > Root ports and downstream ports of switches are the hot > pluggable ports in a PCI Express hierarchy. > PCI Express supports chip-to-chip interconnect, a PCIe link can > only connect one pci device/Switch/EndPoint or PCI-bridge. > > 7.3. Configuration Transaction Rules (PCI Express specification 3.0) > 7.3.1. Device Number > > Downstream Ports that do not have ARI Forwarding enabled must > associate only Device 0 with the device attached to the Logical Bus > representing the Link from the Port. > > In QEMU, ARI Forwarding is enabled defualt at emulation of PCIe > ports. ARI Forwarding enable setting at firmware/OS Control handoff. > If the bit is Set when a non-ARI Device is present, the non-ARI > Device can respond to Configuration Space accesses under what it > interprets as being different Device Numbers, and its Functions can > be aliased under multiple Device Numbers, generally leading to > undesired behavior. > > So, for pci devices attached in pcie root ports or downstream pots, > we shoud assure that its slot is non-zero. For pcie devcies, which > ARP capbility is not enabled, we also should assure that its slot > is non-zero.
So what is this patchset about? Is there a broken configuration that this helps prevent? Can you show the command-line please? In particular, non-express devices behind an express bus shouldn't exist according to spec, but do in practice, and guests seem to be able to handle them. > Changes since v2: > - make patch 1/3 more simpler and safer.(Hu Tao) > - change check logic from pci.c to pcie.c and change function's name > - judge devcies' ARI capbility instead of PCIe ports' ARI Forwarding > (Michael) > - add trivial patch 3/3 > - update patch's commit messages and code comments. > > Thanks for your reviewing. > > Changes since v1: > - using object_dynamic_cast() instead of simple string comparing (Paolo) > - add ARI Forwarding enable bit check > - using pcie_cap_get_type() instead of simple string comparing (Marcel) > - fix some other comments. > > Gonglei (3): > qdev: Introduce a function to get qbus's parent > pcie: add check for ari capability of pcie devices > pcie: remove confused comments > > hw/core/qdev.c | 9 ++++++++ > hw/pci/pci.c | 4 ++++ > hw/pci/pcie.c | 59 > +++++++++++++++++++++++++++++++++++++++++++------- > include/hw/pci/pcie.h | 1 + > include/hw/qdev-core.h | 1 + > 5 files changed, 66 insertions(+), 8 deletions(-) > > -- > 1.7.12.4 >
