On Tue, Mar 24, 2015 at 04:42:25PM +0100, Michael S. Tsirkin wrote: > Fam Zheng noticed that pci shutdown disables msi and msix of a device while > device is still active. This was intended to fix kexec with fusion devices but > had the unintended effect of breaking even regular shutdown when using virtio. > > As a result, people reported VMs being hung on shutdown, > with traces that look like this: > > ... > > [<ffffffff815f367b>] ? _raw_spin_unlock_irqrestore+0x1b/0x40 > [<ffffffff812e068f>] pci_bus_read_config_word+0x9f/0xb0 > [<ffffffff812e205c>] pci_read_config_word+0x1c/0x20 > [<ffffffff812e5ea3>] pci_intx+0x33/0xb0 > [<ffffffff81304ddd>] pci_msix_shutdown+0x8d/0x90 > [<ffffffff812ead26>] pci_device_shutdown+0x46/0x60 > [<ffffffff813b4258>] device_shutdown+0xc8/0x180 > [<ffffffff810761c5>] kernel_power_off+0x35/0x80 > [<ffffffff81077ceb>] SYSC_reboot+0x18b/0x260 > [<ffffffff811c5bb5>] ? d_free+0x55/0x60 > [<ffffffff811cf414>] ? mntput+0x24/0x40 > [<ffffffff811b1613>] ? __fput+0x183/0x270 > [<ffffffff81077dee>] SyS_reboot+0xe/0x10 > [<ffffffff815fc819>] system_call_fastpath+0x16/0x1b > > ... > > as well as the messages that look like this: > BUG: soft lockup - CPU#2 stuck for 22s! [poweroff:1964] > > The same problem would affect any driver which doesn't register > a level interrupt handler when using msix. > > I think the fix is to avoid touching device on shutdown: > we clear bus master anyway, so we won't get any more > msi interrupts, and bus reset will clear the msi/msix > state eventually. > > The patch that added the code in question is from > d52877c7b1afb8c37ebe17e2005040b79cb618b0: > "pci/irq: let pci_device_shutdown to call pci_msi_shutdown v2" > from 2008, but it turns out that in 2011 the following commit > commit d5dea7d95c48d7bc951cee4910a7fd9c0cd26fb0 > "PCI: msi: Disable msi interrupts when we initialize a pci device" > fixed the issue in a more robust way. The only thing left to do is to > fix configurations with CONFIG_PCI_MSI disabled, and then > d52877c7b1afb8c37ebe17e2005040b79cb618b0 can be reverted. > > Status: > > Patches 1-6 work well for me. > Given they affect all pci devices, and the bug has been there since 2.6 times, > I think there's no rush: we can merge them for 4.1. > > At the same time, once merged, patches 1-4 will likely make a good stable > candidate. > > Patches 7-10 compiled only, will need maintainer ack. > > Please review, and consider at least 1-6 for 4.1. > > Changes from v3: > move code from probe to device enumeration > add patches to unexport pci_msi_off > > Michael S. Tsirkin (10): > pci: export functions for msi/msix ctrl > pci: move pci_msi_init_pci_dev to pci.c > pci: drop some duplicate code > pci: don't disable msi/msix at shutdown > pci: make msi/msix shutdown functions static > virtio_pci: drop msi_off on probe > ntb: drop pci_msi_off call on probe > mic: drop pci_msi_off call on probe > pci: drop pci_msi_off calls from quirks > pci: unexport pci_msi_off > > drivers/pci/pci.h | 25 +++++++++++++-- > include/linux/pci.h | 5 --- > drivers/misc/mic/host/mic_intr.c | 2 -- > drivers/ntb/ntb_hw.c | 2 -- > drivers/pci/msi.c | 62 ++++++++------------------------------ > drivers/pci/pci-driver.c | 2 -- > drivers/pci/pci.c | 26 ++++------------ > drivers/pci/probe.c | 16 ++++++++++ > drivers/pci/quirks.c | 2 -- > drivers/virtio/virtio_pci_common.c | 3 -- > 10 files changed, 57 insertions(+), 88 deletions(-) <formletter> This is not the correct way to submit patches for inclusion in the stable kernel tree. Please read Documentation/stable_kernel_rules.txt for how to do this properly. </formletter> -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
