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+other: 0.892
+instruction: 0.842
+mistranslation: 0.842
+boot: 0.839
+semantic: 0.825
+
+[Qemu-devel] [BUG/RFC] Two cpus are not brought up normally in SLES11 sp3 VM after reboot
+
+Hi,
+
+Recently we encountered a problem in our project: 2 CPUs in VM are not brought 
+up normally after reboot.
+
+Our host is using KVM kmod 3.6 and QEMU 2.1.
+A SLES 11 sp3 VM configured with 8 vcpus,
+cpu model is configured with 'host-passthrough'.
+
+After VM's first time started up, everything seems to be OK.
+and then VM is paniced and rebooted.
+After reboot, only 6 cpus are brought up in VM, cpu1 and cpu7 are not online.
+
+This is the only message we can get from VM:
+VM dmesg shows:
+[    0.069867] Booting Node   0, Processors  #1
+[    5.060042] CPU1: Stuck ??
+[    5.060499]  #2
+[    5.088322] kvm-clock: cpu 2, msr 6:3fc90901, secondary cpu clock
+[    5.088335] KVM setup async PF for cpu 2
+[    5.092967] NMI watchdog enabled, takes one hw-pmu counter.
+[    5.094405]  #3
+[    5.108324] kvm-clock: cpu 3, msr 6:3fcd0901, secondary cpu clock
+[    5.108333] KVM setup async PF for cpu 3
+[    5.113553] NMI watchdog enabled, takes one hw-pmu counter.
+[    5.114970]  #4
+[    5.128325] kvm-clock: cpu 4, msr 6:3fd10901, secondary cpu clock
+[    5.128336] KVM setup async PF for cpu 4
+[    5.134576] NMI watchdog enabled, takes one hw-pmu counter.
+[    5.135998]  #5
+[    5.152324] kvm-clock: cpu 5, msr 6:3fd50901, secondary cpu clock
+[    5.152334] KVM setup async PF for cpu 5
+[    5.154764] NMI watchdog enabled, takes one hw-pmu counter.
+[    5.156467]  #6
+[    5.172327] kvm-clock: cpu 6, msr 6:3fd90901, secondary cpu clock
+[    5.172341] KVM setup async PF for cpu 6
+[    5.180738] NMI watchdog enabled, takes one hw-pmu counter.
+[    5.182173]  #7 Ok.
+[   10.170815] CPU7: Stuck ??
+[   10.171648] Brought up 6 CPUs
+[   10.172394] Total of 6 processors activated (28799.97 BogoMIPS).
+
+From host, we found that QEMU vcpu1 thread and vcpu7 thread were not consuming 
+any cpu (Should be in idle state),
+All of VCPUs' stacks in host is like bellow:
+
+[<ffffffffa07089b5>] kvm_vcpu_block+0x65/0xa0 [kvm]
+[<ffffffffa071c7c1>] __vcpu_run+0xd1/0x260 [kvm]
+[<ffffffffa071d508>] kvm_arch_vcpu_ioctl_run+0x68/0x1a0 [kvm]
+[<ffffffffa0709cee>] kvm_vcpu_ioctl+0x38e/0x580 [kvm]
+[<ffffffff8116be8b>] do_vfs_ioctl+0x8b/0x3b0
+[<ffffffff8116c251>] sys_ioctl+0xa1/0xb0
+[<ffffffff81468092>] system_call_fastpath+0x16/0x1b
+[<00002ab9fe1f99a7>] 0x2ab9fe1f99a7
+[<ffffffffffffffff>] 0xffffffffffffffff
+
+We looked into the kernel codes that could leading to the above 'Stuck' warning,
+and found that the only possible is the emulation of 'cpuid' instruct in 
+kvm/qemu has something wrong.
+But since we can’t reproduce this problem, we are not quite sure.
+Is there any possible that the cupid emulation in kvm/qemu has some bug ?
+
+Has anyone come across these problem before? Or any idea?
+
+Thanks,
+zhanghailiang
+
+On 06/07/2015 09:54, zhanghailiang wrote:
+>
+>
+From host, we found that QEMU vcpu1 thread and vcpu7 thread were not
+>
+consuming any cpu (Should be in idle state),
+>
+All of VCPUs' stacks in host is like bellow:
+>
+>
+[<ffffffffa07089b5>] kvm_vcpu_block+0x65/0xa0 [kvm]
+>
+[<ffffffffa071c7c1>] __vcpu_run+0xd1/0x260 [kvm]
+>
+[<ffffffffa071d508>] kvm_arch_vcpu_ioctl_run+0x68/0x1a0 [kvm]
+>
+[<ffffffffa0709cee>] kvm_vcpu_ioctl+0x38e/0x580 [kvm]
+>
+[<ffffffff8116be8b>] do_vfs_ioctl+0x8b/0x3b0
+>
+[<ffffffff8116c251>] sys_ioctl+0xa1/0xb0
+>
+[<ffffffff81468092>] system_call_fastpath+0x16/0x1b
+>
+[<00002ab9fe1f99a7>] 0x2ab9fe1f99a7
+>
+[<ffffffffffffffff>] 0xffffffffffffffff
+>
+>
+We looked into the kernel codes that could leading to the above 'Stuck'
+>
+warning,
+>
+and found that the only possible is the emulation of 'cpuid' instruct in
+>
+kvm/qemu has something wrong.
+>
+But since we can’t reproduce this problem, we are not quite sure.
+>
+Is there any possible that the cupid emulation in kvm/qemu has some bug ?
+Can you explain the relationship to the cpuid emulation?  What do the
+traces say about vcpus 1 and 7?
+
+Paolo
+
+On 2015/7/6 16:45, Paolo Bonzini wrote:
+On 06/07/2015 09:54, zhanghailiang wrote:
+From host, we found that QEMU vcpu1 thread and vcpu7 thread were not
+consuming any cpu (Should be in idle state),
+All of VCPUs' stacks in host is like bellow:
+
+[<ffffffffa07089b5>] kvm_vcpu_block+0x65/0xa0 [kvm]
+[<ffffffffa071c7c1>] __vcpu_run+0xd1/0x260 [kvm]
+[<ffffffffa071d508>] kvm_arch_vcpu_ioctl_run+0x68/0x1a0 [kvm]
+[<ffffffffa0709cee>] kvm_vcpu_ioctl+0x38e/0x580 [kvm]
+[<ffffffff8116be8b>] do_vfs_ioctl+0x8b/0x3b0
+[<ffffffff8116c251>] sys_ioctl+0xa1/0xb0
+[<ffffffff81468092>] system_call_fastpath+0x16/0x1b
+[<00002ab9fe1f99a7>] 0x2ab9fe1f99a7
+[<ffffffffffffffff>] 0xffffffffffffffff
+
+We looked into the kernel codes that could leading to the above 'Stuck'
+warning,
+and found that the only possible is the emulation of 'cpuid' instruct in
+kvm/qemu has something wrong.
+But since we can’t reproduce this problem, we are not quite sure.
+Is there any possible that the cupid emulation in kvm/qemu has some bug ?
+Can you explain the relationship to the cpuid emulation?  What do the
+traces say about vcpus 1 and 7?
+OK, we searched the VM's kernel codes with the 'Stuck' message, and  it is 
+located in
+do_boot_cpu(). It's in BSP context, the call process is:
+BSP executes start_kernel() -> smp_init() -> smp_boot_cpus() -> do_boot_cpu() 
+-> wakeup_secondary_via_INIT() to trigger APs.
+It will wait 5s for APs to startup, if some AP not startup normally, it will 
+print 'CPU%d Stuck' or 'CPU%d: Not responding'.
+
+If it prints 'Stuck', it means the AP has received the SIPI interrupt and 
+begins to execute the code
+'ENTRY(trampoline_data)' (trampoline_64.S) , but be stuck in some places before 
+smp_callin()(smpboot.c).
+The follow is the starup process of BSP and AP.
+BSP:
+start_kernel()
+  ->smp_init()
+     ->smp_boot_cpus()
+       ->do_boot_cpu()
+           ->start_ip = trampoline_address(); //set the address that AP will go 
+to execute
+           ->wakeup_secondary_cpu_via_init(); // kick the secondary CPU
+           ->for (timeout = 0; timeout < 50000; timeout++)
+               if (cpumask_test_cpu(cpu, cpu_callin_mask)) break;// check if AP 
+startup or not
+
+APs:
+ENTRY(trampoline_data) (trampoline_64.S)
+      ->ENTRY(secondary_startup_64) (head_64.S)
+         ->start_secondary() (smpboot.c)
+            ->cpu_init();
+            ->smp_callin();
+                ->cpumask_set_cpu(cpuid, cpu_callin_mask); ->Note: if AP comes 
+here, the BSP will not prints the error message.
+
+From above call process, we can be sure that, the AP has been stuck between 
+trampoline_data and the cpumask_set_cpu() in
+smp_callin(), we look through these codes path carefully, and only found a 
+'hlt' instruct that could block the process.
+It is located in trampoline_data():
+
+ENTRY(trampoline_data)
+        ...
+
+        call    verify_cpu              # Verify the cpu supports long mode
+        testl   %eax, %eax              # Check for return code
+        jnz     no_longmode
+
+        ...
+
+no_longmode:
+        hlt
+        jmp no_longmode
+
+For the process verify_cpu(),
+we can only find the 'cpuid' sensitive instruct that could lead VM exit from 
+No-root mode.
+This is why we doubt if cpuid emulation is wrong in KVM/QEMU that leading to 
+the fail in verify_cpu.
+
+From the message in VM, we know vcpu1 and vcpu7 is something wrong.
+[    5.060042] CPU1: Stuck ??
+[   10.170815] CPU7: Stuck ??
+[   10.171648] Brought up 6 CPUs
+
+Besides, the follow is the cpus message got from host.
+80FF72F5-FF6D-E411-A8C8-000000821800:/home/fsp/hrg # virsh qemu-monitor-command 
+instance-0000000
+* CPU #0: pc=0x00007f64160c683d thread_id=68570
+  CPU #1: pc=0xffffffff810301f1 (halted) thread_id=68573
+  CPU #2: pc=0xffffffff810301e2 (halted) thread_id=68575
+  CPU #3: pc=0xffffffff810301e2 (halted) thread_id=68576
+  CPU #4: pc=0xffffffff810301e2 (halted) thread_id=68577
+  CPU #5: pc=0xffffffff810301e2 (halted) thread_id=68578
+  CPU #6: pc=0xffffffff810301e2 (halted) thread_id=68583
+  CPU #7: pc=0xffffffff810301f1 (halted) thread_id=68584
+
+Oh, i also forgot to mention in the above message that, we have bond each vCPU 
+to different physical CPU in
+host.
+
+Thanks,
+zhanghailiang
+
+On 06/07/2015 11:59, zhanghailiang wrote:
+>
+>
+>
+Besides, the follow is the cpus message got from host.
+>
+80FF72F5-FF6D-E411-A8C8-000000821800:/home/fsp/hrg # virsh
+>
+qemu-monitor-command instance-0000000
+>
+* CPU #0: pc=0x00007f64160c683d thread_id=68570
+>
+CPU #1: pc=0xffffffff810301f1 (halted) thread_id=68573
+>
+CPU #2: pc=0xffffffff810301e2 (halted) thread_id=68575
+>
+CPU #3: pc=0xffffffff810301e2 (halted) thread_id=68576
+>
+CPU #4: pc=0xffffffff810301e2 (halted) thread_id=68577
+>
+CPU #5: pc=0xffffffff810301e2 (halted) thread_id=68578
+>
+CPU #6: pc=0xffffffff810301e2 (halted) thread_id=68583
+>
+CPU #7: pc=0xffffffff810301f1 (halted) thread_id=68584
+>
+>
+Oh, i also forgot to mention in the above message that, we have bond
+>
+each vCPU to different physical CPU in
+>
+host.
+Can you capture a trace on the host (trace-cmd record -e kvm) and send
+it privately?  Please note which CPUs get stuck, since I guess it's not
+always 1 and 7.
+
+Paolo
+
+On Mon, 6 Jul 2015 17:59:10 +0800
+zhanghailiang <address@hidden> wrote:
+
+>
+On 2015/7/6 16:45, Paolo Bonzini wrote:
+>
+>
+>
+>
+>
+> On 06/07/2015 09:54, zhanghailiang wrote:
+>
+>>
+>
+>>  From host, we found that QEMU vcpu1 thread and vcpu7 thread were not
+>
+>> consuming any cpu (Should be in idle state),
+>
+>> All of VCPUs' stacks in host is like bellow:
+>
+>>
+>
+>> [<ffffffffa07089b5>] kvm_vcpu_block+0x65/0xa0 [kvm]
+>
+>> [<ffffffffa071c7c1>] __vcpu_run+0xd1/0x260 [kvm]
+>
+>> [<ffffffffa071d508>] kvm_arch_vcpu_ioctl_run+0x68/0x1a0 [kvm]
+>
+>> [<ffffffffa0709cee>] kvm_vcpu_ioctl+0x38e/0x580 [kvm]
+>
+>> [<ffffffff8116be8b>] do_vfs_ioctl+0x8b/0x3b0
+>
+>> [<ffffffff8116c251>] sys_ioctl+0xa1/0xb0
+>
+>> [<ffffffff81468092>] system_call_fastpath+0x16/0x1b
+>
+>> [<00002ab9fe1f99a7>] 0x2ab9fe1f99a7
+>
+>> [<ffffffffffffffff>] 0xffffffffffffffff
+>
+>>
+>
+>> We looked into the kernel codes that could leading to the above 'Stuck'
+>
+>> warning,
+in current upstream there isn't any printk(...Stuck...) left since that code 
+path
+has been reworked.
+I've often seen this on over-committed host during guest CPUs up/down torture 
+test.
+Could you update guest kernel to upstream and see if issue reproduces?
+
+>
+>> and found that the only possible is the emulation of 'cpuid' instruct in
+>
+>> kvm/qemu has something wrong.
+>
+>> But since we can’t reproduce this problem, we are not quite sure.
+>
+>> Is there any possible that the cupid emulation in kvm/qemu has some bug ?
+>
+>
+>
+> Can you explain the relationship to the cpuid emulation?  What do the
+>
+> traces say about vcpus 1 and 7?
+>
+>
+OK, we searched the VM's kernel codes with the 'Stuck' message, and  it is
+>
+located in
+>
+do_boot_cpu(). It's in BSP context, the call process is:
+>
+BSP executes start_kernel() -> smp_init() -> smp_boot_cpus() -> do_boot_cpu()
+>
+-> wakeup_secondary_via_INIT() to trigger APs.
+>
+It will wait 5s for APs to startup, if some AP not startup normally, it will
+>
+print 'CPU%d Stuck' or 'CPU%d: Not responding'.
+>
+>
+If it prints 'Stuck', it means the AP has received the SIPI interrupt and
+>
+begins to execute the code
+>
+'ENTRY(trampoline_data)' (trampoline_64.S) , but be stuck in some places
+>
+before smp_callin()(smpboot.c).
+>
+The follow is the starup process of BSP and AP.
+>
+BSP:
+>
+start_kernel()
+>
+->smp_init()
+>
+->smp_boot_cpus()
+>
+->do_boot_cpu()
+>
+->start_ip = trampoline_address(); //set the address that AP will
+>
+go to execute
+>
+->wakeup_secondary_cpu_via_init(); // kick the secondary CPU
+>
+->for (timeout = 0; timeout < 50000; timeout++)
+>
+if (cpumask_test_cpu(cpu, cpu_callin_mask)) break;// check if
+>
+AP startup or not
+>
+>
+APs:
+>
+ENTRY(trampoline_data) (trampoline_64.S)
+>
+->ENTRY(secondary_startup_64) (head_64.S)
+>
+->start_secondary() (smpboot.c)
+>
+->cpu_init();
+>
+->smp_callin();
+>
+->cpumask_set_cpu(cpuid, cpu_callin_mask); ->Note: if AP
+>
+comes here, the BSP will not prints the error message.
+>
+>
+From above call process, we can be sure that, the AP has been stuck between
+>
+trampoline_data and the cpumask_set_cpu() in
+>
+smp_callin(), we look through these codes path carefully, and only found a
+>
+'hlt' instruct that could block the process.
+>
+It is located in trampoline_data():
+>
+>
+ENTRY(trampoline_data)
+>
+...
+>
+>
+call    verify_cpu              # Verify the cpu supports long mode
+>
+testl   %eax, %eax              # Check for return code
+>
+jnz     no_longmode
+>
+>
+...
+>
+>
+no_longmode:
+>
+hlt
+>
+jmp no_longmode
+>
+>
+For the process verify_cpu(),
+>
+we can only find the 'cpuid' sensitive instruct that could lead VM exit from
+>
+No-root mode.
+>
+This is why we doubt if cpuid emulation is wrong in KVM/QEMU that leading to
+>
+the fail in verify_cpu.
+>
+>
+From the message in VM, we know vcpu1 and vcpu7 is something wrong.
+>
+[    5.060042] CPU1: Stuck ??
+>
+[   10.170815] CPU7: Stuck ??
+>
+[   10.171648] Brought up 6 CPUs
+>
+>
+Besides, the follow is the cpus message got from host.
+>
+80FF72F5-FF6D-E411-A8C8-000000821800:/home/fsp/hrg # virsh
+>
+qemu-monitor-command instance-0000000
+>
+* CPU #0: pc=0x00007f64160c683d thread_id=68570
+>
+CPU #1: pc=0xffffffff810301f1 (halted) thread_id=68573
+>
+CPU #2: pc=0xffffffff810301e2 (halted) thread_id=68575
+>
+CPU #3: pc=0xffffffff810301e2 (halted) thread_id=68576
+>
+CPU #4: pc=0xffffffff810301e2 (halted) thread_id=68577
+>
+CPU #5: pc=0xffffffff810301e2 (halted) thread_id=68578
+>
+CPU #6: pc=0xffffffff810301e2 (halted) thread_id=68583
+>
+CPU #7: pc=0xffffffff810301f1 (halted) thread_id=68584
+>
+>
+Oh, i also forgot to mention in the above message that, we have bond each
+>
+vCPU to different physical CPU in
+>
+host.
+>
+>
+Thanks,
+>
+zhanghailiang
+>
+>
+>
+>
+>
+--
+>
+To unsubscribe from this list: send the line "unsubscribe kvm" in
+>
+the body of a message to address@hidden
+>
+More majordomo info at
+http://vger.kernel.org/majordomo-info.html
+
+On 2015/7/7 19:23, Igor Mammedov wrote:
+On Mon, 6 Jul 2015 17:59:10 +0800
+zhanghailiang <address@hidden> wrote:
+On 2015/7/6 16:45, Paolo Bonzini wrote:
+On 06/07/2015 09:54, zhanghailiang wrote:
+From host, we found that QEMU vcpu1 thread and vcpu7 thread were not
+consuming any cpu (Should be in idle state),
+All of VCPUs' stacks in host is like bellow:
+
+[<ffffffffa07089b5>] kvm_vcpu_block+0x65/0xa0 [kvm]
+[<ffffffffa071c7c1>] __vcpu_run+0xd1/0x260 [kvm]
+[<ffffffffa071d508>] kvm_arch_vcpu_ioctl_run+0x68/0x1a0 [kvm]
+[<ffffffffa0709cee>] kvm_vcpu_ioctl+0x38e/0x580 [kvm]
+[<ffffffff8116be8b>] do_vfs_ioctl+0x8b/0x3b0
+[<ffffffff8116c251>] sys_ioctl+0xa1/0xb0
+[<ffffffff81468092>] system_call_fastpath+0x16/0x1b
+[<00002ab9fe1f99a7>] 0x2ab9fe1f99a7
+[<ffffffffffffffff>] 0xffffffffffffffff
+
+We looked into the kernel codes that could leading to the above 'Stuck'
+warning,
+in current upstream there isn't any printk(...Stuck...) left since that code 
+path
+has been reworked.
+I've often seen this on over-committed host during guest CPUs up/down torture 
+test.
+Could you update guest kernel to upstream and see if issue reproduces?
+Hmm, Unfortunately, it is very hard to reproduce, and we are still trying to 
+reproduce it.
+
+For your test case, is it a kernel bug?
+Or is there any related patch could solve your test problem been merged into
+upstream ?
+
+Thanks,
+zhanghailiang
+and found that the only possible is the emulation of 'cpuid' instruct in
+kvm/qemu has something wrong.
+But since we can’t reproduce this problem, we are not quite sure.
+Is there any possible that the cupid emulation in kvm/qemu has some bug ?
+Can you explain the relationship to the cpuid emulation?  What do the
+traces say about vcpus 1 and 7?
+OK, we searched the VM's kernel codes with the 'Stuck' message, and  it is 
+located in
+do_boot_cpu(). It's in BSP context, the call process is:
+BSP executes start_kernel() -> smp_init() -> smp_boot_cpus() -> do_boot_cpu() 
+-> wakeup_secondary_via_INIT() to trigger APs.
+It will wait 5s for APs to startup, if some AP not startup normally, it will 
+print 'CPU%d Stuck' or 'CPU%d: Not responding'.
+
+If it prints 'Stuck', it means the AP has received the SIPI interrupt and 
+begins to execute the code
+'ENTRY(trampoline_data)' (trampoline_64.S) , but be stuck in some places before 
+smp_callin()(smpboot.c).
+The follow is the starup process of BSP and AP.
+BSP:
+start_kernel()
+    ->smp_init()
+       ->smp_boot_cpus()
+         ->do_boot_cpu()
+             ->start_ip = trampoline_address(); //set the address that AP will 
+go to execute
+             ->wakeup_secondary_cpu_via_init(); // kick the secondary CPU
+             ->for (timeout = 0; timeout < 50000; timeout++)
+                 if (cpumask_test_cpu(cpu, cpu_callin_mask)) break;// check if 
+AP startup or not
+
+APs:
+ENTRY(trampoline_data) (trampoline_64.S)
+        ->ENTRY(secondary_startup_64) (head_64.S)
+           ->start_secondary() (smpboot.c)
+              ->cpu_init();
+              ->smp_callin();
+                  ->cpumask_set_cpu(cpuid, cpu_callin_mask); ->Note: if AP 
+comes here, the BSP will not prints the error message.
+
+  From above call process, we can be sure that, the AP has been stuck between 
+trampoline_data and the cpumask_set_cpu() in
+smp_callin(), we look through these codes path carefully, and only found a 
+'hlt' instruct that could block the process.
+It is located in trampoline_data():
+
+ENTRY(trampoline_data)
+          ...
+
+        call    verify_cpu              # Verify the cpu supports long mode
+        testl   %eax, %eax              # Check for return code
+        jnz     no_longmode
+
+          ...
+
+no_longmode:
+        hlt
+        jmp no_longmode
+
+For the process verify_cpu(),
+we can only find the 'cpuid' sensitive instruct that could lead VM exit from 
+No-root mode.
+This is why we doubt if cpuid emulation is wrong in KVM/QEMU that leading to 
+the fail in verify_cpu.
+
+  From the message in VM, we know vcpu1 and vcpu7 is something wrong.
+[    5.060042] CPU1: Stuck ??
+[   10.170815] CPU7: Stuck ??
+[   10.171648] Brought up 6 CPUs
+
+Besides, the follow is the cpus message got from host.
+80FF72F5-FF6D-E411-A8C8-000000821800:/home/fsp/hrg # virsh qemu-monitor-command 
+instance-0000000
+* CPU #0: pc=0x00007f64160c683d thread_id=68570
+    CPU #1: pc=0xffffffff810301f1 (halted) thread_id=68573
+    CPU #2: pc=0xffffffff810301e2 (halted) thread_id=68575
+    CPU #3: pc=0xffffffff810301e2 (halted) thread_id=68576
+    CPU #4: pc=0xffffffff810301e2 (halted) thread_id=68577
+    CPU #5: pc=0xffffffff810301e2 (halted) thread_id=68578
+    CPU #6: pc=0xffffffff810301e2 (halted) thread_id=68583
+    CPU #7: pc=0xffffffff810301f1 (halted) thread_id=68584
+
+Oh, i also forgot to mention in the above message that, we have bond each vCPU 
+to different physical CPU in
+host.
+
+Thanks,
+zhanghailiang
+
+
+
+
+--
+To unsubscribe from this list: send the line "unsubscribe kvm" in
+the body of a message to address@hidden
+More majordomo info at
+http://vger.kernel.org/majordomo-info.html
+.
+
+On Tue, 7 Jul 2015 19:43:35 +0800
+zhanghailiang <address@hidden> wrote:
+
+>
+On 2015/7/7 19:23, Igor Mammedov wrote:
+>
+> On Mon, 6 Jul 2015 17:59:10 +0800
+>
+> zhanghailiang <address@hidden> wrote:
+>
+>
+>
+>> On 2015/7/6 16:45, Paolo Bonzini wrote:
+>
+>>>
+>
+>>>
+>
+>>> On 06/07/2015 09:54, zhanghailiang wrote:
+>
+>>>>
+>
+>>>>   From host, we found that QEMU vcpu1 thread and vcpu7 thread were not
+>
+>>>> consuming any cpu (Should be in idle state),
+>
+>>>> All of VCPUs' stacks in host is like bellow:
+>
+>>>>
+>
+>>>> [<ffffffffa07089b5>] kvm_vcpu_block+0x65/0xa0 [kvm]
+>
+>>>> [<ffffffffa071c7c1>] __vcpu_run+0xd1/0x260 [kvm]
+>
+>>>> [<ffffffffa071d508>] kvm_arch_vcpu_ioctl_run+0x68/0x1a0 [kvm]
+>
+>>>> [<ffffffffa0709cee>] kvm_vcpu_ioctl+0x38e/0x580 [kvm]
+>
+>>>> [<ffffffff8116be8b>] do_vfs_ioctl+0x8b/0x3b0
+>
+>>>> [<ffffffff8116c251>] sys_ioctl+0xa1/0xb0
+>
+>>>> [<ffffffff81468092>] system_call_fastpath+0x16/0x1b
+>
+>>>> [<00002ab9fe1f99a7>] 0x2ab9fe1f99a7
+>
+>>>> [<ffffffffffffffff>] 0xffffffffffffffff
+>
+>>>>
+>
+>>>> We looked into the kernel codes that could leading to the above 'Stuck'
+>
+>>>> warning,
+>
+> in current upstream there isn't any printk(...Stuck...) left since that
+>
+> code path
+>
+> has been reworked.
+>
+> I've often seen this on over-committed host during guest CPUs up/down
+>
+> torture test.
+>
+> Could you update guest kernel to upstream and see if issue reproduces?
+>
+>
+>
+>
+Hmm, Unfortunately, it is very hard to reproduce, and we are still trying to
+>
+reproduce it.
+>
+>
+For your test case, is it a kernel bug?
+>
+Or is there any related patch could solve your test problem been merged into
+>
+upstream ?
+I don't remember all prerequisite patches but you should be able to find
+http://marc.info/?l=linux-kernel&m=140326703108009&w=2
+"x86/smpboot: Initialize secondary CPU only if master CPU will wait for it"
+and then look for dependencies.
+
+
+>
+>
+Thanks,
+>
+zhanghailiang
+>
+>
+>>>> and found that the only possible is the emulation of 'cpuid' instruct in
+>
+>>>> kvm/qemu has something wrong.
+>
+>>>> But since we can’t reproduce this problem, we are not quite sure.
+>
+>>>> Is there any possible that the cupid emulation in kvm/qemu has some bug ?
+>
+>>>
+>
+>>> Can you explain the relationship to the cpuid emulation?  What do the
+>
+>>> traces say about vcpus 1 and 7?
+>
+>>
+>
+>> OK, we searched the VM's kernel codes with the 'Stuck' message, and  it is
+>
+>> located in
+>
+>> do_boot_cpu(). It's in BSP context, the call process is:
+>
+>> BSP executes start_kernel() -> smp_init() -> smp_boot_cpus() ->
+>
+>> do_boot_cpu() -> wakeup_secondary_via_INIT() to trigger APs.
+>
+>> It will wait 5s for APs to startup, if some AP not startup normally, it
+>
+>> will print 'CPU%d Stuck' or 'CPU%d: Not responding'.
+>
+>>
+>
+>> If it prints 'Stuck', it means the AP has received the SIPI interrupt and
+>
+>> begins to execute the code
+>
+>> 'ENTRY(trampoline_data)' (trampoline_64.S) , but be stuck in some places
+>
+>> before smp_callin()(smpboot.c).
+>
+>> The follow is the starup process of BSP and AP.
+>
+>> BSP:
+>
+>> start_kernel()
+>
+>>     ->smp_init()
+>
+>>        ->smp_boot_cpus()
+>
+>>          ->do_boot_cpu()
+>
+>>              ->start_ip = trampoline_address(); //set the address that AP
+>
+>> will go to execute
+>
+>>              ->wakeup_secondary_cpu_via_init(); // kick the secondary CPU
+>
+>>              ->for (timeout = 0; timeout < 50000; timeout++)
+>
+>>                  if (cpumask_test_cpu(cpu, cpu_callin_mask)) break;//
+>
+>> check if AP startup or not
+>
+>>
+>
+>> APs:
+>
+>> ENTRY(trampoline_data) (trampoline_64.S)
+>
+>>         ->ENTRY(secondary_startup_64) (head_64.S)
+>
+>>            ->start_secondary() (smpboot.c)
+>
+>>               ->cpu_init();
+>
+>>               ->smp_callin();
+>
+>>                   ->cpumask_set_cpu(cpuid, cpu_callin_mask); ->Note: if AP
+>
+>> comes here, the BSP will not prints the error message.
+>
+>>
+>
+>>   From above call process, we can be sure that, the AP has been stuck
+>
+>> between trampoline_data and the cpumask_set_cpu() in
+>
+>> smp_callin(), we look through these codes path carefully, and only found a
+>
+>> 'hlt' instruct that could block the process.
+>
+>> It is located in trampoline_data():
+>
+>>
+>
+>> ENTRY(trampoline_data)
+>
+>>           ...
+>
+>>
+>
+>>    call    verify_cpu              # Verify the cpu supports long mode
+>
+>>    testl   %eax, %eax              # Check for return code
+>
+>>    jnz     no_longmode
+>
+>>
+>
+>>           ...
+>
+>>
+>
+>> no_longmode:
+>
+>>    hlt
+>
+>>    jmp no_longmode
+>
+>>
+>
+>> For the process verify_cpu(),
+>
+>> we can only find the 'cpuid' sensitive instruct that could lead VM exit
+>
+>> from No-root mode.
+>
+>> This is why we doubt if cpuid emulation is wrong in KVM/QEMU that leading
+>
+>> to the fail in verify_cpu.
+>
+>>
+>
+>>   From the message in VM, we know vcpu1 and vcpu7 is something wrong.
+>
+>> [    5.060042] CPU1: Stuck ??
+>
+>> [   10.170815] CPU7: Stuck ??
+>
+>> [   10.171648] Brought up 6 CPUs
+>
+>>
+>
+>> Besides, the follow is the cpus message got from host.
+>
+>> 80FF72F5-FF6D-E411-A8C8-000000821800:/home/fsp/hrg # virsh
+>
+>> qemu-monitor-command instance-0000000
+>
+>> * CPU #0: pc=0x00007f64160c683d thread_id=68570
+>
+>>     CPU #1: pc=0xffffffff810301f1 (halted) thread_id=68573
+>
+>>     CPU #2: pc=0xffffffff810301e2 (halted) thread_id=68575
+>
+>>     CPU #3: pc=0xffffffff810301e2 (halted) thread_id=68576
+>
+>>     CPU #4: pc=0xffffffff810301e2 (halted) thread_id=68577
+>
+>>     CPU #5: pc=0xffffffff810301e2 (halted) thread_id=68578
+>
+>>     CPU #6: pc=0xffffffff810301e2 (halted) thread_id=68583
+>
+>>     CPU #7: pc=0xffffffff810301f1 (halted) thread_id=68584
+>
+>>
+>
+>> Oh, i also forgot to mention in the above message that, we have bond each
+>
+>> vCPU to different physical CPU in
+>
+>> host.
+>
+>>
+>
+>> Thanks,
+>
+>> zhanghailiang
+>
+>>
+>
+>>
+>
+>>
+>
+>>
+>
+>> --
+>
+>> To unsubscribe from this list: send the line "unsubscribe kvm" in
+>
+>> the body of a message to address@hidden
+>
+>> More majordomo info at
+http://vger.kernel.org/majordomo-info.html
+>
+>
+>
+>
+>
+> .
+>
+>
+>
+>
+>
+
+On 2015/7/7 20:21, Igor Mammedov wrote:
+On Tue, 7 Jul 2015 19:43:35 +0800
+zhanghailiang <address@hidden> wrote:
+On 2015/7/7 19:23, Igor Mammedov wrote:
+On Mon, 6 Jul 2015 17:59:10 +0800
+zhanghailiang <address@hidden> wrote:
+On 2015/7/6 16:45, Paolo Bonzini wrote:
+On 06/07/2015 09:54, zhanghailiang wrote:
+From host, we found that QEMU vcpu1 thread and vcpu7 thread were not
+consuming any cpu (Should be in idle state),
+All of VCPUs' stacks in host is like bellow:
+
+[<ffffffffa07089b5>] kvm_vcpu_block+0x65/0xa0 [kvm]
+[<ffffffffa071c7c1>] __vcpu_run+0xd1/0x260 [kvm]
+[<ffffffffa071d508>] kvm_arch_vcpu_ioctl_run+0x68/0x1a0 [kvm]
+[<ffffffffa0709cee>] kvm_vcpu_ioctl+0x38e/0x580 [kvm]
+[<ffffffff8116be8b>] do_vfs_ioctl+0x8b/0x3b0
+[<ffffffff8116c251>] sys_ioctl+0xa1/0xb0
+[<ffffffff81468092>] system_call_fastpath+0x16/0x1b
+[<00002ab9fe1f99a7>] 0x2ab9fe1f99a7
+[<ffffffffffffffff>] 0xffffffffffffffff
+
+We looked into the kernel codes that could leading to the above 'Stuck'
+warning,
+in current upstream there isn't any printk(...Stuck...) left since that code 
+path
+has been reworked.
+I've often seen this on over-committed host during guest CPUs up/down torture 
+test.
+Could you update guest kernel to upstream and see if issue reproduces?
+Hmm, Unfortunately, it is very hard to reproduce, and we are still trying to 
+reproduce it.
+
+For your test case, is it a kernel bug?
+Or is there any related patch could solve your test problem been merged into
+upstream ?
+I don't remember all prerequisite patches but you should be able to find
+http://marc.info/?l=linux-kernel&m=140326703108009&w=2
+"x86/smpboot: Initialize secondary CPU only if master CPU will wait for it"
+and then look for dependencies.
+Er, we have investigated this patch, and it is not related to our problem, :)
+
+Thanks.
+Thanks,
+zhanghailiang
+and found that the only possible is the emulation of 'cpuid' instruct in
+kvm/qemu has something wrong.
+But since we can’t reproduce this problem, we are not quite sure.
+Is there any possible that the cupid emulation in kvm/qemu has some bug ?
+Can you explain the relationship to the cpuid emulation?  What do the
+traces say about vcpus 1 and 7?
+OK, we searched the VM's kernel codes with the 'Stuck' message, and  it is 
+located in
+do_boot_cpu(). It's in BSP context, the call process is:
+BSP executes start_kernel() -> smp_init() -> smp_boot_cpus() -> do_boot_cpu() 
+-> wakeup_secondary_via_INIT() to trigger APs.
+It will wait 5s for APs to startup, if some AP not startup normally, it will 
+print 'CPU%d Stuck' or 'CPU%d: Not responding'.
+
+If it prints 'Stuck', it means the AP has received the SIPI interrupt and 
+begins to execute the code
+'ENTRY(trampoline_data)' (trampoline_64.S) , but be stuck in some places before 
+smp_callin()(smpboot.c).
+The follow is the starup process of BSP and AP.
+BSP:
+start_kernel()
+     ->smp_init()
+        ->smp_boot_cpus()
+          ->do_boot_cpu()
+              ->start_ip = trampoline_address(); //set the address that AP will 
+go to execute
+              ->wakeup_secondary_cpu_via_init(); // kick the secondary CPU
+              ->for (timeout = 0; timeout < 50000; timeout++)
+                  if (cpumask_test_cpu(cpu, cpu_callin_mask)) break;// check if 
+AP startup or not
+
+APs:
+ENTRY(trampoline_data) (trampoline_64.S)
+         ->ENTRY(secondary_startup_64) (head_64.S)
+            ->start_secondary() (smpboot.c)
+               ->cpu_init();
+               ->smp_callin();
+                   ->cpumask_set_cpu(cpuid, cpu_callin_mask); ->Note: if AP 
+comes here, the BSP will not prints the error message.
+
+   From above call process, we can be sure that, the AP has been stuck between 
+trampoline_data and the cpumask_set_cpu() in
+smp_callin(), we look through these codes path carefully, and only found a 
+'hlt' instruct that could block the process.
+It is located in trampoline_data():
+
+ENTRY(trampoline_data)
+           ...
+
+        call    verify_cpu              # Verify the cpu supports long mode
+        testl   %eax, %eax              # Check for return code
+        jnz     no_longmode
+
+           ...
+
+no_longmode:
+        hlt
+        jmp no_longmode
+
+For the process verify_cpu(),
+we can only find the 'cpuid' sensitive instruct that could lead VM exit from 
+No-root mode.
+This is why we doubt if cpuid emulation is wrong in KVM/QEMU that leading to 
+the fail in verify_cpu.
+
+   From the message in VM, we know vcpu1 and vcpu7 is something wrong.
+[    5.060042] CPU1: Stuck ??
+[   10.170815] CPU7: Stuck ??
+[   10.171648] Brought up 6 CPUs
+
+Besides, the follow is the cpus message got from host.
+80FF72F5-FF6D-E411-A8C8-000000821800:/home/fsp/hrg # virsh qemu-monitor-command 
+instance-0000000
+* CPU #0: pc=0x00007f64160c683d thread_id=68570
+     CPU #1: pc=0xffffffff810301f1 (halted) thread_id=68573
+     CPU #2: pc=0xffffffff810301e2 (halted) thread_id=68575
+     CPU #3: pc=0xffffffff810301e2 (halted) thread_id=68576
+     CPU #4: pc=0xffffffff810301e2 (halted) thread_id=68577
+     CPU #5: pc=0xffffffff810301e2 (halted) thread_id=68578
+     CPU #6: pc=0xffffffff810301e2 (halted) thread_id=68583
+     CPU #7: pc=0xffffffff810301f1 (halted) thread_id=68584
+
+Oh, i also forgot to mention in the above message that, we have bond each vCPU 
+to different physical CPU in
+host.
+
+Thanks,
+zhanghailiang
+
+
+
+
+--
+To unsubscribe from this list: send the line "unsubscribe kvm" in
+the body of a message to address@hidden
+More majordomo info at
+http://vger.kernel.org/majordomo-info.html
+.
+.
+