From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:56630) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1d0BQR-0003J7-2i for qemu-devel@nongnu.org; Mon, 17 Apr 2017 14:31:00 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1d0BQM-0006rr-F5 for qemu-devel@nongnu.org; Mon, 17 Apr 2017 14:30:59 -0400 Date: Mon, 17 Apr 2017 15:30:46 -0300 From: Eduardo Habkost Message-ID: <20170417183045.GA7078@thinpad.lan.raisama.net> References: <20170328021651.19350-1-david@gibson.dropbear.id.au> <20170328021651.19350-3-david@gibson.dropbear.id.au> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170328021651.19350-3-david@gibson.dropbear.id.au> Subject: Re: [Qemu-devel] [RFC for-2.10 2/3] pci: Allow host bridges to override PCI/PCIe hybrid device behaviour List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: David Gibson Cc: aik@ozlabs.ru, marcel@redhat.com, lersek@redhat.com, qemu-ppc@nongnu.org, qemu-devel@nongnu.org, mst@redhat.com On Tue, Mar 28, 2017 at 01:16:50PM +1100, David Gibson wrote: > Currently PCI/PCIe hybrid devices - that is, devices which can appear as > either plain PCI or PCIe depending on where they're attached - will only > appear in PCIe mode if they're attached to a PCIe bus via a root port or > downstream port. > > This is correct for "standard" PCIe setups, but there are some platforms > which need different behaviour (notably "pseries" whose paravirtualized > PCI host bridges have some idiosyncracies). > > This patch allows the host bridge to override the normal behaviour. > > Signed-off-by: David Gibson > --- > hw/pci/pci.c | 11 +++++++++-- > include/hw/pci/pci_host.h | 1 + > 2 files changed, 10 insertions(+), 2 deletions(-) > > diff --git a/hw/pci/pci.c b/hw/pci/pci.c > index 779787b..ac68065 100644 > --- a/hw/pci/pci.c > +++ b/hw/pci/pci.c > @@ -392,9 +392,16 @@ bool pci_bus_is_root(PCIBus *bus) > > bool pci_allow_hybrid_pcie(PCIDevice *pci_dev) Why are we asking the device about allowing hybrid pcie, and not the bus itself? Shouldn't we be able to query this before the device is plugged, and before pci_dev->bus is even set? In other words, why pci_allow_hyberid_pcie() and pci_device_get_bus() get a PCIDevice* argument instead of a PCIBus* argument? > { > - PCIBus *bus = pci_dev->bus; > + PCIHostState *host_bridge = PCI_HOST_BRIDGE(pci_device_root_bus(pci_dev)->qbus.parent); There's something I don't understand completely: what exactly guarantees that pci_device_root_bus(...)->qbus.parent is always going to be a PCI_HOST_BRIDGE? > + PCIHostBridgeClass *hc = PCI_HOST_BRIDGE_GET_CLASS(host_bridge); > + > + if (hc->allow_hybrid_pcie) { > + return hc->allow_hybrid_pcie(host_bridge, pci_dev); > + } else { > + PCIBus *bus = pci_dev->bus; > > - return pci_bus_is_express(bus) && !pci_bus_is_root(bus); > + return pci_bus_is_express(bus) && !pci_bus_is_root(bus); > + } > } > > void pci_bus_new_inplace(PCIBus *bus, size_t bus_size, DeviceState *parent, > diff --git a/include/hw/pci/pci_host.h b/include/hw/pci/pci_host.h > index ba31595..ad03cca 100644 > --- a/include/hw/pci/pci_host.h > +++ b/include/hw/pci/pci_host.h > @@ -54,6 +54,7 @@ typedef struct PCIHostBridgeClass { > SysBusDeviceClass parent_class; > > const char *(*root_bus_path)(PCIHostState *, PCIBus *); > + bool (*allow_hybrid_pcie)(PCIHostState *, PCIDevice *); > } PCIHostBridgeClass; > > /* common internal helpers for PCI/PCIe hosts, cut off overflows */ > -- > 2.9.3 > > -- Eduardo