Bug 47451
| Summary: | need to re-load driver in guest to make a hot-plug VF work | ||
|---|---|---|---|
| Product: | Virtualization | Reporter: | Jay Ren (yongjie.ren) |
| Component: | kvm | Assignee: | virtualization_kvm |
| Status: | CLOSED UNREPRODUCIBLE | ||
| Severity: | normal | CC: | alex.williamson |
| Priority: | P1 | ||
| Hardware: | All | ||
| OS: | Linux | ||
| Kernel Version: | 3.5.0 | Subsystem: | |
| Regression: | Yes | Bisected commit-id: | |
The steps to reproduce don't indicate what you've done in the host to prepare the device. Is igbvf loaded in the host? Is the vf attached to igbvf or pci-stub or nothing? Can we narrow down the kvm.git commit range at all? The one provided is over 12k commits covering v3.4-rc3 to v3.5-rc6. Thanks (In reply to comment #1) > The steps to reproduce don't indicate what you've done in the host to prepare > the device. Is igbvf loaded in the host? No, I don't load igbvf driver in host. >Is the vf attached to igbvf or pci-stub or nothing? VF is attached to 'pci-stub' in host. >Can we narrow down the kvm.git commit range at all? The > one provided is over 12k commits covering v3.4-rc3 to v3.5-rc6. Thanks I did more testing. Do you remember the bug #43328 ( VT-d/SR-IOV totally doesn't work in guest)? Just use your fix commit for that bug, I'll meet this hot-plug issue. Is there a chance your patch fixed one bug but introduced another one? :) commit a76beb14123a69ca080f5a5425e28b786d62318d Author: Alex Williamson <alex.williamson@redhat.com> Date: Mon Jul 9 10:53:22 2012 -0600 KVM: Fix device assignment threaded irq handler (In reply to comment #2) > (In reply to comment #1) > >Can we narrow down the kvm.git commit range at all? The > > one provided is over 12k commits covering v3.4-rc3 to v3.5-rc6. Thanks > I did more testing. > Do you remember the bug #43328 ( VT-d/SR-IOV totally doesn't work in guest)? > Just use your fix commit for that bug, I'll meet this hot-plug issue. > Is there a chance your patch fixed one bug but introduced another one? :) > > commit a76beb14123a69ca080f5a5425e28b786d62318d > Author: Alex Williamson <alex.williamson@redhat.com> > Date: Mon Jul 9 10:53:22 2012 -0600 > > KVM: Fix device assignment threaded irq handler Thanks for the narrowing it down. It looks like perhaps that patch was ineffective at trying to keep us out of using IRQF_ONESHOT due to irq_setup_forced_threading() re-enabling it. Does the problem go away if you change the two calls to request_threaded_irq() in that commit to use IRQF_NO_THREAD for the flag value in place of 0? (In reply to comment #3) > (In reply to comment #2) > > (In reply to comment #1) > > >Can we narrow down the kvm.git commit range at all? The > > > one provided is over 12k commits covering v3.4-rc3 to v3.5-rc6. Thanks > > I did more testing. > > Do you remember the bug #43328 ( VT-d/SR-IOV totally doesn't work in > guest)? > > Just use your fix commit for that bug, I'll meet this hot-plug issue. > > Is there a chance your patch fixed one bug but introduced another one? :) > > > > commit a76beb14123a69ca080f5a5425e28b786d62318d > > Author: Alex Williamson <alex.williamson@redhat.com> > > Date: Mon Jul 9 10:53:22 2012 -0600 > > > > KVM: Fix device assignment threaded irq handler > > Thanks for the narrowing it down. It looks like perhaps that patch was > ineffective at trying to keep us out of using IRQF_ONESHOT due to > irq_setup_forced_threading() re-enabling it. Does the problem go away if you > change the two calls to request_threaded_irq() in that commit to use > IRQF_NO_THREAD for the flag value in place of 0? No, replacing flag value with 'IRQF_NO_THREAD' can't make PCIe NIC hot-plug work. Can you try with your commit "a76beb14123a6" ? BTW, sometimes, this bug is not so stable. Using '-m 512 -smp 2' option for qemu-kvm commandline to start a RHEL6.x guest will make it very easy to reproduce. I re-tested this bug against kvm.git next branch (commit:e6c7d321,kernel 3.7) and qemu-kvm.git master branch (commit:4d9367b7). I can't reproduce it now. It should have been fixed by some patches, but I don't know which patch fixed it. As this bug is unstable to reproduce, it's hard for me to do a bisect to find out the exact fix. close this bug as unreproducible. |
Environment: ------------ Host OS (ia32/ia32e/IA64):ia32e Guest OS (ia32/ia32e/IA64):ia32e Guest OS Type (Linux/Windows):Linux (RHEL6u3) kvm.git Commit:37e41afa97307a3e54b200a5c9179ada1632a844(master branch) qemu-kvm Commit:28c3a9b197900c88f27b14f8862a7a15c00dc7f0(master branch) Host Kernel Version:3.5.0-rc6 (Also exists in 3.6.0-rc3) Hardware:Romley-EP (SandyBridge system) Bug detailed description: -------------------------- After hot plugging a VF to a Linux guest (e.g.RHEL6.3) in qemu monitor, the VF cannot work in the guest by. I need to remove the VF driver (e.g. igbvf, ixgbevf) and probe it again, then the VF can work in guest. NIC: Intel 82599 NIC, Intel 82576 NIC It needn't reload VF driver in hot-plug case when using an old kernel. It's a regression in kernel. (commits are in kvm.git and qemu-kvm.git tree) kvm + qemu-kvm =result 37e41afa + 28c3a9b1 =bad 322728e5 + 28c3a9b1 =good Note: 1. When assigning a VF in qemu-kvm command line (not hot-plug), VF can work fine after boot-up. 2. It's easier to reproduce this in guest with 512/1024MB memory and 1/2 vCPUs. 3. Can't always reproduce with 2048MB and 2vCPUs. (Not very stable.) Reproduce steps: ---------------- 1.start up a host with kvm 2.qemu-system-x86_64 -m 512 smp 2 –net none –hda /root/rhel6u3.img 3.switch to qemu monitor (ctrl+Alt+2) 4.device_add pci-assign,host=02:10.0,id=mynic (02:10.0 is VF's BDF number.) 5.switch to guest (ctrl+Alt+1) 6.check network of the VF. (it can't work) 7. remove VF driver in guest ('rmmod igbvf') 8. re-probe VF driver in guest ('modprobe igbvf') 9. check network of the VF. (It should work this time.) Current result: ---------------- The VF cannot work in the guest by default. Need to re-load VF driver in guest. Expected result: ---------------- VF works well in the guest by default after hot-plug.