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[Xen-devel] Linux guests hitting VCPUOP_stop_singleshot_timer returning -EINVAL.

To: George.Dunlap@xxxxxxxxxxxxx, xen-devel@xxxxxxxxxxxxxxxxxxx

From: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>

Date: Wed, 8 May 2013 13:02:27 -0400

Delivery-date: Wed, 08 May 2013 17:02:51 +0000

List-id: Xen developer discussion <xen-devel.lists.xen.org>

Hey George, The issue I am hitting happens quite often but not always. And I hope you can help me understand the bootup part of PVHVM guests which I think is part of the problem. I can reproduce this way back to Xen 4.1 so I think this has been in the hypervisor for some time. First of the guest starts with just one VCPU: builder='hvm' device_model_version = 'qemu-xen-traditional' disk = [ 'file:/mnt/lab/latest/root_image.iso,hdc:cdrom,r'] memory = 2048 boot="d" maxvcpus=32 vcpus=1 serial='pty' vnclisten="0.0.0.0" name="latest" vif = [ 'mac=00:0F:4B:00:00:68, bridge=switch' ] And hit the issue when I try to add more VCPUs: xl vcpu-set latest 16 which triggers this bug in the Linux code (see below for the code): .. May 8 16:03:48 (none) udevd-work[2153]: error opening ATTR{/sys/devices/system/cpu/cpu1/online} for writing: No such file or directory [ 84.585905] CPU 1 got hotplugged [ 84.590192] installing Xen timer for CPU 1 [ 84.596371] SMP alternatives: lockdep: fixing up alternatives [ 84.603560] SMP alternatives: switching to SMP code [ 84.619508] smpboot: Booting Node 0 Processor 1 APIC 0x8 [ 84.639766] ------------[ cut here ]------------ [ 84.639766] WARNING: at /home/konrad/ssd/konrad/linux/arch/x86/xen/time.c:336 xen_vcpuop_set_mode+0xc2/0xd0() [ 84.639766] Hardware name: HVM domU [ 84.639766] VCPUOP_stop_singleshot_timer on CPU1 ret: -22 [ 84.639766] Modules linked in: dm_multipath dm_mod iscsi_boot_sysfs iscsi_tcp libiscsi_tcp libiscsi scsi_transport_iscsi libcrc32c crc32c sg sr_mod cdrom ata_generic crc32c_intel ata_piix libata scsi_mod xen_blkfront xen_netfront fb_sys_fops sysimgblt sysfillrect syscopyarea xen_kbdfront xenfs xen_privcmd [ 84.639766] Pid: 0, comm: swapper/1 Not tainted 3.9.0upstream-00022-g49c1bf1-dirty #6 [ 84.639766] Call Trace: [ 84.639766] [<ffffffff8109261a>] warn_slowpath_common+0x7a/0xc0 [ 84.639766] [<ffffffff81092701>] warn_slowpath_fmt+0x41/0x50 [ 84.639766] [<ffffffff810e8ae4>] ? tick_notify+0x114/0x420 [ 84.639766] [<ffffffff81044fe2>] xen_vcpuop_set_mode+0xc2/0xd0 [ 84.639766] [<ffffffff810e8385>] clockevents_set_mode+0x25/0x70 [ 84.639766] [<ffffffff810e83e6>] clockevents_shutdown+0x16/0x30 [ 84.639766] [<ffffffff810e84b7>] clockevents_exchange_device+0xb7/0x110 [ 84.639766] [<ffffffff810e8ae4>] ? tick_notify+0x114/0x420 [ 84.639766] [<ffffffff810e8b99>] tick_notify+0x1c9/0x420 [ 84.639766] [<ffffffff810e8221>] ? clockevents_register_device+0x31/0x170 [ 84.639766] [<ffffffff8169dddd>] notifier_call_chain+0x4d/0x70 [ 84.639766] [<ffffffff810be851>] raw_notifier_call_chain+0x11/0x20 [ 84.639766] [<ffffffff810e82d0>] clockevents_register_device+0xe0/0x170 [ 84.639766] [<ffffffff8104507c>] xen_setup_cpu_clockevents+0x2c/0x50 [ 84.639766] [<ffffffff810450b6>] xen_hvm_setup_cpu_clockevents+0x16/0x20 [ 84.639766] [<ffffffff8168d4af>] start_secondary+0x1ea/0x1f9 [ 84.639766] ---[ end trace f218984223a7067d ]--- [ 84.639766] ------------[ cut here ]------------ [ 84.639766] WARNING: at /home/konrad/ssd/konrad/linux/arch/x86/xen/time.c:338 xen_vcpuop_set_mode+0x9f/0xd0() [ 84.639766] Hardware name: HVM domU [ 84.639766] VCPUOP_stop_periodic_timer on CPU1 ret: -22 [ 84.639766] Modules linked in: dm_multipath dm_mod iscsi_boot_sysfs iscsi_tcp libiscsi_tcp libiscsi scsi_transport_iscsi libcrc32c crc32c sg sr_mod cdrom ata_generic crc32c_intel ata_piix libata scsi_mod xen_blkfront xen_netfront fb_sys_fops sysimgblt sysfillrect syscopyarea xen_kbdfront xenfs xen_privcmd [ 84.639766] Pid: 0, comm: swapper/1 Tainted: G W 3.9.0upstream-00022-g49c1bf1-dirty #6 [ 84.639766] Call Trace: [ 84.639766] [<ffffffff8109261a>] warn_slowpath_common+0x7a/0xc0 [ 84.639766] [<ffffffff81092701>] warn_slowpath_fmt+0x41/0x50 [ 84.639766] [<ffffffff810e8ae4>] ? tick_notify+0x114/0x420 [ 84.639766] [<ffffffff81044fbf>] xen_vcpuop_set_mode+0x9f/0xd0 [ 84.639766] [<ffffffff810e8385>] clockevents_set_mode+0x25/0x70 [ 84.639766] [<ffffffff810e83e6>] clockevents_shutdown+0x16/0x30 [ 84.639766] [<ffffffff810e84b7>] clockevents_exchange_device+0xb7/0x110 [ 84.639766] [<ffffffff810e8ae4>] ? tick_notify+0x114/0x420 [ 84.639766] [<ffffffff810e8b99>] tick_notify+0x1c9/0x420 [ 84.639766] [<ffffffff810e8221>] ? clockevents_register_device+0x31/0x170 [ 84.639766] [<ffffffff8169dddd>] notifier_call_chain+0x4d/0x70 [ 84.639766] [<ffffffff810be851>] raw_notifier_call_chain+0x11/0x20 [ 84.639766] [<ffffffff810e82d0>] clockevents_register_device+0xe0/0x170 [ 84.639766] [<ffffffff8104507c>] xen_setup_cpu_clockevents+0x2c/0x50 [ 84.639766] [<ffffffff810450b6>] xen_hvm_setup_cpu_clockevents+0x16/0x20 [ 84.639766] [<ffffffff8168d4af>] start_secondary+0x1ea/0x1f9 [ 84.639766] ---[ end trace f218984223a7067e ]--- [ 84.639766] ------------[ cut here ]------------ [ 84.639766] kernel BUG at /home/konrad/ssd/konrad/linux/arch/x86/xen/time.c:340! [ 84.639766] invalid opcode: 0000 [#1] SMP [ 84.639766] Modules linked in: dm_multipath dm_mod iscsi_boot_sysfs iscsi_tcp libiscsi_tcp libiscsi scsi_transport_iscsi libcrc32c crc32c sg sr_mod cdrom ata_generic crc32c_intel ata_piix libata scsi_mod xen_blkfront xen_netfront fb_sys_fops sysimgblt sysfillrect syscopyarea xen_kbdfront xenfs xen_privcmd [ 84.639766] CPU 1 [ 84.639766] Pid: 0, comm: swapper/1 Tainted: G W 3.9.0upstream-00022-g49c1bf1-dirty #6 Xen HVM domU [ 84.639766] RIP: 0010:[<ffffffff81044fbf>] [<ffffffff81044fbf>] xen_vcpuop_set_mode+0x9f/0xd0 [ 84.639766] RSP: 0000:ffff880073c6bd98 EFLAGS: 00010092 [ 84.639766] RAX: 0000000000000024 RBX: 0000000000000001 RCX: 0000000000000000 [ 84.639766] RDX: ffff880073c68300 RSI: 0000000000000000 RDI: 0000000000000009 [ 84.639766] RBP: ffff880073c6bdb8 R08: 0000000000000001 R09: 0000000000000000 [ 84.639766] R10: 0000000000000258 R11: 0000000000000000 R12: 00000000ffffffea [ 84.639766] R13: 0000000000000001 R14: 0000000000000000 R15: 0000000000000082 [ 84.639766] FS: 0000000000000000(0000) GS:ffff880074220000(0000) knlGS:0000000000000000 [ 84.639766] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 84.639766] CR2: 0000000000000000 CR3: 0000000001c0c000 CR4: 00000000000406e0 [ 84.639766] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 84.639766] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 [ 84.639766] Process swapper/1 (pid: 0, threadinfo ffff880073c6a000, task ffff880073c68300) [ 84.639766] Stack: [ 84.639766] 0000000000000000 ffff88007422be40 0000000000000001 0000000000000082 [ 84.639766] ffff880073c6bdd8 ffffffff810e8385 ffff88007422be40 ffff88007422be40 [ 84.639766] ffff880073c6bdf8 ffffffff810e83e6 ffff880073c6bdf8 0000000000000000 [ 84.639766] Call Trace: [ 84.639766] [<ffffffff810e8385>] clockevents_set_mode+0x25/0x70 [ 84.639766] [<ffffffff810e83e6>] clockevents_shutdown+0x16/0x30 [ 84.639766] [<ffffffff810e84b7>] clockevents_exchange_device+0xb7/0x110 [ 84.639766] [<ffffffff810e8ae4>] ? tick_notify+0x114/0x420 [ 84.639766] [<ffffffff810e8b99>] tick_notify+0x1c9/0x420 [ 84.639766] [<ffffffff810e8221>] ? clockevents_register_device+0x31/0x170 [ 84.639766] [<ffffffff8169dddd>] notifier_call_chain+0x4d/0x70 [ 84.639766] [<ffffffff810be851>] raw_notifier_call_chain+0x11/0x20 [ 84.639766] [<ffffffff810e82d0>] clockevents_register_device+0xe0/0x170 [ 84.639766] [<ffffffff8104507c>] xen_setup_cpu_clockevents+0x2c/0x50 [ 84.639766] [<ffffffff810450b6>] xen_hvm_setup_cpu_clockevents+0x16/0x20 [ 84.639766] [<ffffffff8168d4af>] start_secondary+0x1ea/0x1f9 [ 84.639766] Code: 00 48 c7 c7 f8 bc 9b 81 e8 bf d6 04 00 eb c9 89 d9 48 c7 c2 98 bd 9b 81 be 52 01 00 00 48 c7 c7 f8 bc 9b 81 31 c0 e8 01 d7 04 00 <0f> 0b eb fe 41 89 c0 89 d9 48 c7 c2 68 bd 9b 81 be 50 01 00 00 [ 84.639766] RIP [<ffffffff81044fbf>] xen_vcpuop_set_mode+0x9f/0xd0 [ 84.639766] RSP <ffff880073c6bd98> [ 84.639766] ---[ end trace f218984223a7067f ]--- [ 84.639766] Kernel panic - not syncing: Attempted to kill the idle task! Parsing config from /mnt/lab/latest/vm.cfg Daemon running with PID 7341 Here is the patch that I applied on v3.9 (along with some other patches to fix the VCPU hotplug path in there): diff --git a/arch/x86/xen/time.c b/arch/x86/xen/time.c index 3d88bfd..d2d1248 100644 --- a/arch/x86/xen/time.c +++ b/arch/x86/xen/time.c @@ -319,7 +319,7 @@ static void xen_vcpuop_set_mode(enum clock_event_mode mode, struct clock_event_device *evt) { int cpu = smp_processor_id(); - + int rc; switch (mode) { case CLOCK_EVT_MODE_PERIODIC: WARN_ON(1); /* unsupported */ @@ -332,9 +332,13 @@ static void xen_vcpuop_set_mode(enum clock_event_mode mode, case CLOCK_EVT_MODE_UNUSED: case CLOCK_EVT_MODE_SHUTDOWN: - if (HYPERVISOR_vcpu_op(VCPUOP_stop_singleshot_timer, cpu, NULL) || - HYPERVISOR_vcpu_op(VCPUOP_stop_periodic_timer, cpu, NULL)) + rc = HYPERVISOR_vcpu_op(VCPUOP_stop_singleshot_timer, cpu, NULL); + WARN(rc, "VCPUOP_stop_singleshot_timer on CPU%d ret: %d\n", cpu, rc); + rc |= HYPERVISOR_vcpu_op(VCPUOP_stop_periodic_timer, cpu, NULL); + WARN(rc, "VCPUOP_stop_periodic_timer on CPU%d ret: %d\n", cpu, rc); + if (rc) { BUG(); + } break; case CLOCK_EVT_MODE_RESUME: break; If you look in the kernel it says that it does on VCPU1, but the hypervisor (this is with another debug patch - this time attached), you can see: .. snip.. (XEN) irq.c:375: Dom5 callback via changed to Direct Vector 0xf3 (XEN) irq.c:270: Dom5 PCI link 0 changed 5 -> 0 (XEN) irq.c:270: Dom5 PCI link 1 changed 10 -> 0 (XEN) irq.c:270: Dom5 PCI link 2 changed 11 -> 0 (XEN) irq.c:270: Dom5 PCI link 3 changed 5 -> 0 ===> (XEN) d5 [`:-137435614851072] on VCPU4 <==== (XEN) d5v0: timer [singleshot] in 385066us vcpu_singleshot_timer_fn+0/0xb (XEN) d5v0 on CPU-1 - - 0 (XEN) d5v0: poll:0 not pending - (XEN) d5v1 on CPU-1 - - 0 (XEN) d5v1: poll:0 pending pending sel It thinks that 'current' is for VCPU4, not VCPU1! 1022 1023 case VCPUOP_stop_singleshot_timer: 1024 if ( v != current ) [v is VCPU1, current is VCPU4] 1025 return -EINVAL; 1026 1027 stop_timer(&v->singleshot_timer); 1028 1029 break; And if I run xentrace and xenalyze it confirms: 0.097606174 --x- d32767v2 runstate_change d7v4 offline->runnable Creating vcpu 4 for dom 7 ] 0.097606174 --x- d32767v2 22006(2:2:6) 1 [ 3 ] ] 0.097607074 --x- d32767v2 28004(2:8:4) 2 [ 7 4 ] 0.097607786 ---x d32767v3 pm_idle_end c1 0.097607995 --x- d32767v2 runstate_change d7v0 offline->runnable ] 0.097607995 --x- d32767v2 22006(2:2:6) 1 [ 1 ] ] 0.097608930 --x- d32767v2 28004(2:8:4) 2 [ 7 0 ] ] 0.097609486 ---x d32767v3 2800e(2:8:e) 2 [ 7fff 9a2abb ] ] 0.097609562 --x- d32767v2 2800e(2:8:e) 2 [ 7fff 49e9 ] ] 0.097609620 ---x d32767v3 2800f(2:8:f) 3 [ 7 8c2 1c9c380 ] 0.097609660 -x-- d32767v1 pm_idle_end c1 ] 0.097609690 --x- d32767v2 2800f(2:8:f) 3 [ 7 3d7 1c9c380 ] ] 0.097609780 ---x d32767v3 2800a(2:8:a) 4 [ 7fff 3 7 4 ] ] 0.097609845 --x- d32767v2 2800a(2:8:a) 4 [ 7fff 2 7 0 ] 0.097609933 ---x d32767v3 runstate_change d32767v3 running->runnable 0.097609998 --x d32767v2 runstate_change d32767v2 running->runnable 0.097610125 -- x d?v? runstate_change d7v4 runnable->running 0.097610168 --x| d?v? runstate_change d7v0 runnable->running 0.097612126 -x|| d32767v1 runstate_continue d32767v1 running->running 0.097612739 -x|| d32767v1 pm_idle_start c1 ! 0.097614366 --x| d7v0 vmentry ! 0.097615354 --|x d7v4 vmentry ] 0.097616526 --|x d7v4 vmexit exit_reason WBINVD eip 1 ] 0.097617403 --|x d7v4 vmentry cycles 2104 ] 0.097618322 --|x d7v4 vmexit exit_reason CPUID eip 1073 ] 0.097618322 --|x d7v4 cpuid [ 0 d 756e6547 6c65746e 49656e69 ] ] 0.097619549 --|x d7v4 vmentry cycles 2944 ] 0.097620297 --|x d7v4 vmexit exit_reason CPUID eip 10c0 ..blah blah.. bootup of the VCPU. Somehow it is using VCPU4 but the Linux guest thinks it is running in VCPU1. Please note that I can only cause this if maxvcpus != vcpus. And sometimes it works just great. Any ideas?

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