| Message ID | 20141105202252.GB6168@google.com (mailing list archive) |
|---|---|
| State | Not Applicable, archived |
| Headers | show |
On Wednesday, November 05, 2014 01:22:52 PM Bjorn Helgaas wrote: > [+cc Chao, Joerg] > > On Thu, Oct 30, 2014 at 11:09:13AM -0600, Bjorn Helgaas wrote: > > [+cc Rafael, linux-acpi] > > > > On Wed, Oct 29, 2014 at 03:26:10PM -0700, Yinghai Lu wrote: > > > While enabling sriov for intel igb device got: > > > > > > sca05-0a81fda5:~ # echo 7 > /sys/bus/pci/devices/0000\:09\:00.0/sriov_numvfs > > > [ 729.612191] pci 0000:0a:10.0: [8086:1520] type 00 class 0x020000 > > > [ 729.619002] BUG: unable to handle kernel NULL pointer dereference at 00000000000000e8 > > > [ 729.627767] IP: [<ffffffff815901cb>] pci_get_hp_params+0x5b/0x640 > > > [ 729.634593] PGD 0 > > > [ 729.636844] Oops: 0000 [#1] SMP > > > [ 729.640466] Modules linked in: > > > ... > > > [ 729.795268] Call Trace: > > > [ 729.798007] [<ffffffff81ea0843>] ? pci_mmcfg_read+0x123/0x140 > > > [ 729.804519] [<ffffffff81ea0770>] ? pci_mmcfg_read+0x50/0x140 > > > [ 729.810942] [<ffffffff815692a3>] pci_configure_device+0x33/0x350 > > > [ 729.817744] [<ffffffff8156aba4>] pci_device_add+0x24/0x160 > > > [ 729.823965] [<ffffffff8158f3bb>] pci_enable_sriov+0x4db/0x7d0 > > > [ 729.830486] [<ffffffff81b63f54>] ? igb_pci_enable_sriov+0xe4/0x200 > > > [ 729.837481] [<ffffffff81b63f7f>] igb_pci_enable_sriov+0x10f/0x200 > > > [ 729.844386] [<ffffffff8155129c>] ? _kstrtoull+0x2c/0x80 > > > [ 729.850315] [<ffffffff81b640a5>] igb_pci_sriov_configure+0x35/0x40 > > > [ 729.857318] [<ffffffff815752b5>] sriov_numvfs_store+0xe5/0x140 > > > [ 729.863934] [<ffffffff817e1f88>] dev_attr_store+0x18/0x30 > > > [ 729.870063] [<ffffffff812624d8>] sysfs_kf_write+0x48/0x60 > > > [ 729.876186] [<ffffffff812617ef>] ? kernfs_fop_write+0xaf/0x170 > > > [ 729.882797] [<ffffffff81261827>] kernfs_fop_write+0xe7/0x170 > > > [ 729.889222] [<ffffffff811ef66b>] vfs_write+0xcb/0x1c0 > > > [ 729.894958] [<ffffffff811f0019>] SyS_write+0x49/0xb0 > > > ... > > > [ 729.943531] ---[ end trace 7cf0cdb66637665a ]--- > > > > > > and pci_get_hp_params+0x5b point to > > > 0xffffffff815901cb is in pci_get_hp_params (include/linux/device.h:815). > > > 810 #include <linux/pm_wakeup.h> > > > 811 > > > 812 static inline const char *dev_name(const struct device *dev) > > > 813 { > > > 814 /* Use the init name until the kobject becomes available */ > > > 815 if (dev->init_name) > > > 816 return dev->init_name; > > > 817 > > > 818 return kobject_name(&dev->kobj); > > > > > > The root cause: > > > Now pci_configure_device/pci_get_hp_params will be called for every pci_dev, > > > including VF that is under virtual bus. But virtual bus does not have bridge > > > set. So we can not refer pbus->self->dev directly. > > > > This raises the question of what the correct behavior should be. Your > > patch certainly avoids the NULL pointer dereference. It does so by making > > acpi_pci_get_bridge_handle() fail gracefully, which means we will not look > > for _HPP/_HPX for VF devices. > > I think I was mistaken about this. A VF device might be on a virtual bus. > And a virtual bus never has a bridge leading to it, i.e., its bus->self > pointer is NULL. But I think a virtual bus always has a *parent* bus, > i.e., for a VF, dev->bus->parent is always valid. This is because when > virtfn_add_bus() creates the virtual bus with "pci_add_new_bus(bus, NULL, > busnr)", the "bus" parameter (which becomes the parent bus of the virtual > bus) is a valid bus. > > So with your patch, I think we *will* actually look for _HPP and _HPX for > VF devices, because we'll look for the handle of the bridge leading to the > virtual bus (which will return NULL), then for the handle of the bridge > leading to the virtual bus' parent bus, etc. > > If you agree, Yinghai, I'll apply the patch below (same as what you posted, > with different changelog and a comment in the code). > > The acpi_pci_get_bridge_handle(struct pci_bus *) interface niggles at me a > little because I don't think there's any concept of an ACPI device for a > PCI *bus*, so it doesn't seem like a very good fit to say "find the handle > for this bus". But that's for later. To me it does what it says: Get me the handle of the bridge leading to this bus. > commit 32f638fc11db0526c706454d9ab4339d55ac89f3 > Author: Yinghai Lu <yinghai@kernel.org> > Date: Thu Oct 30 10:17:25 2014 -0600 > > PCI: Don't oops on virtual buses in acpi_pci_get_bridge_handle() > > acpi_pci_get_bridge_handle() returns the ACPI handle for the bridge device > (either a host bridge or a PCI-to-PCI bridge) leading to a PCI bus. But > SR-IOV virtual functions can be on a virtual bus with no bridge leading to > it. Return a NULL acpi_handle in this case instead of trying to > dereference the NULL pointer to the bridge. > > This fixes a NULL pointer dereference oops in pci_get_hp_params() when > adding SR-IOV VF devices on virtual buses. > > [bhelgaas: changelog, add comment in code] > Fixes: 6cd33649fa83 ("PCI: Add pci_configure_device() during enumeration") > Link: https://bugzilla.kernel.org/show_bug.cgi?id=87591 > Reported-by: Chao Zhou <chao.zhou@intel.com> > Reported-by: Joerg Roedel <joro@8bytes.org> > Signed-off-by: Yinghai Lu <yinghai@kernel.org> > Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> > > diff --git a/include/linux/pci-acpi.h b/include/linux/pci-acpi.h > index 64dacb7288a6..24c7728ca681 100644 > --- a/include/linux/pci-acpi.h > +++ b/include/linux/pci-acpi.h > @@ -41,8 +41,13 @@ static inline acpi_handle acpi_pci_get_bridge_handle(struct pci_bus *pbus) > > if (pci_is_root_bus(pbus)) > dev = pbus->bridge; > - else > + else { > + /* If pbus is a virtual bus, there is no bridge to it */ > + if (!pbus->self) > + return NULL; > + > dev = &pbus->self->dev; > + } > > return ACPI_HANDLE(dev); > } > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/
diff --git a/include/linux/pci-acpi.h b/include/linux/pci-acpi.h index 64dacb7288a6..24c7728ca681 100644 --- a/include/linux/pci-acpi.h +++ b/include/linux/pci-acpi.h @@ -41,8 +41,13 @@ static inline acpi_handle acpi_pci_get_bridge_handle(struct pci_bus *pbus) if (pci_is_root_bus(pbus)) dev = pbus->bridge; - else + else { + /* If pbus is a virtual bus, there is no bridge to it */ + if (!pbus->self) + return NULL; + dev = &pbus->self->dev; + } return ACPI_HANDLE(dev); }