Re: [Qemu-devel] [PATCH for-2.8 00/18] pc: q35: x2APIC support in kvm_apic mode

[Chao Gao]

On Mon, Aug 08, 2016 at 11:18:20AM +0200, Igor Mammedov wrote:
>On Mon, 8 Aug 2016 15:41:23 +0800
>Chao Gao <address@hidden> wrote:
>
>> HI, everyone.
>> 
>> We have done some tests after merging this patch set into the lastest qemu
>> master. In kvm aspect, we use the lastest kvm linux-next branch. Here are
>> some problems we have met.
>> 
>> 1. We can't boot up a 288 vcpus linux guest with CLI:
>> qemu-system-x86_64 -boot c -m 4096 -sdl -monitor pty --enable-kvm \
>> -M kernel-irqchip=split -serial stdio -bios bios.bin -smp cpus=288 \
>> -hda vdisk.img -device intel-iommu,intremap=on -machine q35.
>> The problem exists, even after we only assign 32 vcpus to the linux guest.
>> Maybe the output "do_IRQ: 146.113 No irq handler for vector (irq -1)" is a 
>> clue.
>> The output of qemu and kernel is in attachments. Do you have any idea
>> about the problem and how to solve it?
>I don't think we ever looked at "kernel-irqchip=split" only in kernel variant's
>been targeted so far.
>Radim probably knows better whether it should work or not.
>
>Have you tried with smaller amount of CPUs but with APIC IDs above 254,
>like in test below?
>
>[...]
>
>> >Tested with following CLI:
>> > QEMU -M q35 -enable-kvm -smp 1,sockets=9,cores=32,threads=1,maxcpus=288 \
>> >      -device qemu64-x86_64-cpu,socket-id=8,core-id=30,thread-id=0       \
>> >      -bios x2apic_bios.bin

I test with CLI:
qemu-system-x86_64 -M q35 \
-enable-kvm -smp 1,sockets=9,cores=32,threads=1,maxcpus=288 \
-device qemu64-x86_64-cpu,socket-id=8,core-id=30,thread-id=0 \
-bios bios.bin -hda vdisk.img -serial stdio -m 4096 2>>qemu_and_guest.log >&2

But, I think there should have a cpu with initial apicid >255 
in /proc/cpuinfo. The log(in attachments) shows that the guest kernel 
treats the other cpu as a bad one. What do you think cause the problem?

# cat /proc/interrupts
localhost login:             CPU0       
   0:        125   IO-APIC-edge      timer
   1:        117   IO-APIC-edge      i8042
   4:        382   IO-APIC-edge      serial
   7:          0   IO-APIC-edge      parport0
   8:          1   IO-APIC-edge      rtc0
   9:          0   IO-APIC-fasteoi   acpi
  12:       1661   IO-APIC-edge      i8042
  16:          0   IO-APIC-fasteoi   i801_smbus
  22:         27   IO-APIC-fasteoi   enp0s2
  24:       7310   PCI-MSI-edge      0000:00:1f.2
 NMI:          0   Non-maskable interrupts
 LOC:       6401   Local timer interrupts
 SPU:          0   Spurious interrupts
 PMI:          0   Performance monitoring interrupts
 IWI:       3870   IRQ work interrupts
 RTR:          0   APIC ICR read retries
 RES:          0   Rescheduling interrupts
 CAL:          0   Function call interrupts
 TLB:          0   TLB shootdowns
 TRM:          0   Thermal event interrupts
 THR:          0   Threshold APIC interrupts
 MCE:          0   Machine check exceptions
 MCP:          1   Machine check polls
 ERR:          0
 MIS:          0

# cat /proc/cpuinfo
processor       : 0
vendor_id       : GenuineIntel
cpu family      : 6
model           : 6
model name      : QEMU Virtual CPU version 2.5+
stepping        : 3
microcode       : 0x1
cpu MHz         : 3591.682
cache size      : 4096 KB
physical id     : 0
siblings        : 1
core id         : 0
cpu cores       : 1
apicid          : 0
initial apicid  : 0
fpu             : yes
fpu_exception   : yes
cpuid level     : 13
wp              : yes
flags           : fpu de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov 
pse36 clflush mmx fxsr sse sse2 ht syscall nx lm rep_good nopl xtopology pni 
cx16 x2apic hypervisor lahf_lm
bogomips        : 7183.36
clflush size    : 64
cache_alignment : 64
address sizes   : 40 bits physical, 48 bits virtual
power management:

qemu_and_guest.log
Description: Text document