On Mon, Dec 12, 2016 at 08:41:41PM +0200, Michael S. Tsirkin wrote:
> On Mon, Dec 12, 2016 at 05:29:15PM +0000, Stefan Hajnoczi wrote:
> > On Mon, Dec 12, 2016 at 01:34:05PM +0800, Cao jin wrote:
> > >
> > >
> > > On 12/10/2016 04:39 AM, Eduardo Habkost wrote:
> > > > Using latest qemu.git master:
> > > >
> > > > $ qemu-system-x86_64 -machine q35 -readconfig docs/q35-chipset.cfg
> > > > -monitor stdio
> > > > QEMU 2.7.93 monitor - type 'help' for more information
> > > > (qemu) device_add e1000e,bus=ich9-pcie-port-4,addr=00
> > > > (qemu) device_add e1000e,bus=ich9-pcie-port-4,addr=08
> > > > Segmentation fault (core dumped)
> > > >
> > > > It crashes at:
> > > >
> > > > #7 0x000055555598d7dc in do_pci_register_device
> > > > (errp=0x7fffffffbfd0, devfn=64, name=0x5555565df340 "e1000e",
> > > > bus=0x555558487380, pci_dev=0x5555589cd000)
> > > > at /home/ehabkost/rh/proj/virt/qemu/hw/pci/pci.c:983
> > > > 983 error_setg(errp, "PCI: slot %d function 0 already
> > > > ocuppied by %s,"
> > > > (gdb) l
> > > > 978 PCI_SLOT(devfn), PCI_FUNC(devfn), name,
> > > > 979 bus->devices[devfn]->name);
> > > > 980 return NULL;
> > > > 981 } else if (dev->hotplugged &&
> > > > 982 pci_get_function_0(pci_dev)) {
> > > > 983 error_setg(errp, "PCI: slot %d function 0 already
> > > > ocuppied by %s,"
> > > > 984 " new func %s cannot be exposed to guest.",
> > > > 985 PCI_SLOT(devfn),
> > > > 986 bus->devices[PCI_DEVFN(PCI_SLOT(devfn),
> > > > 0)]->name,
> > > > 987 name);
> > > >
> > >
> > > Thanks for informing me. I am kind of busy for now, so I suppose I will
> > > investigate it after 2.8 release.
> >
> > Please let me know if this should be considered a release blocker.
> >
> > The proposed QEMU 2.8 release date is tomorrow (December 13th)!
> >
> > Stefan
>
> I don't see how it's a blocker, it's an illegal configuration.
> Here's the fix. It's a rather obvious one.
> I'll target the fix for 2.9.
> Eduardo, I'd appreciate a tested-by tag.
I confirm the patch fixes the crash, but the error message seems
incorrect: the existing e1000e device is on slot 0 function 0,
not slot 8.
$ ./x86-kvm-build/x86_64-softmmu/qemu-system-x86_64 -machine q35 -readconfig
docs/q35-chipset.cfg -monitor stdio
QEMU 2.7.93 monitor - type 'help' for more information
(qemu) device_add e1000e,bus=ich9-pcie-port-4,addr=00
(qemu) device_add e1000e,bus=ich9-pcie-port-4,addr=08
PCI: slot 8 function 0 already ocuppied by e1000e, new func e1000e cannot be
exposed to guest.
^^^
>
> -->
>
> pci: fix error message for express slots
>
> PCI Express downstream slot has a single PCI slot
> behind it, using PCI_DEVFN(PCI_SLOT(devfn), 0)
> does not give you function 0 in cases such as ARI
> as well as some error cases.
>
> This is exactly what we are hitting:
> $ qemu-system-x86_64 -machine q35 -readconfig docs/q35-chipset.cfg
> -monitor stdio
> (qemu) device_add e1000e,bus=ich9-pcie-port-4,addr=00
> (qemu) device_add e1000e,bus=ich9-pcie-port-4,addr=08
> Segmentation fault (core dumped)
>
> The fix is to use the pci_get_function_0 API.
>
> Cc: qemu-sta...@nongnu.org
> Signed-off-by: Michael S. Tsirkin <m...@redhat.com>
> Reported-by: Eduardo Habkost <ehabk...@redhat.com>
> ---
>
> diff --git a/hw/pci/pci.c b/hw/pci/pci.c
> index 24fae16..339c531 100644
> --- a/hw/pci/pci.c
> +++ b/hw/pci/pci.c
> @@ -983,7 +983,7 @@ static PCIDevice *do_pci_register_device(PCIDevice
> *pci_dev, PCIBus *bus,
> error_setg(errp, "PCI: slot %d function 0 already ocuppied by %s,"
> " new func %s cannot be exposed to guest.",
> PCI_SLOT(devfn),
> - bus->devices[PCI_DEVFN(PCI_SLOT(devfn), 0)]->name,
> + pci_get_function_0(pci_dev)->name,
> name);
>
> return NULL;
>
> --
> MST
--
Eduardo
