[Qemu-devel] [Bug 1661386] Re: Assertion `ret == cpu->kvm_msr_buf->nmsrs' failed

[Dr. David Alan Gilbert]

Hi,
  OK, lets see:

 kvm_put_msrs: ret=18 expected=105

so I think it's one of the MSRs around 18 that it's upset at:

kvm_msr_entry_add: @17 index=4b564d03 value=0

  41:#define MSR_KVM_STEAL_TIME  0x4b564d03

kvm_msr_entry_add: @18 index=38d value=0

     #define MSR_CORE_PERF_FIXED_CTR_CTRL    0x38d

So my guess is it's the steal time thing.

1) You didn't say what kernel your host was running - please tell me
  I think that steal time thing went into the kernel ~3.0
2) try starting qemu   with -cpu host,-kvm_steal_time and/or -cpu 
host,-perfctr_core
3) If those don't work, in kvm_put_msrs try hacking out the lines:

          if (env->features[FEAT_KVM] & (1 << KVM_FEATURE_STEAL_TIME)) {
            kvm_msr_entry_add(cpu, MSR_KVM_STEAL_TIME, env->steal_time_msr);
        }

and turning the :

        if (has_msr_architectural_pmu) {

into    if (0) {

Dave

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https://bugs.launchpad.net/bugs/1661386

Title:
  Assertion `ret == cpu->kvm_msr_buf->nmsrs' failed

Status in QEMU:
  New

Bug description:
  Hello,

  
  I see the following when try to run qemu from master as the following:

  # ./x86_64-softmmu/qemu-system-x86_64 --version
  QEMU emulator version 2.8.50 (v2.8.0-1006-g4e9f524)
  Copyright (c) 2003-2016 Fabrice Bellard and the QEMU Project developers
  # ./x86_64-softmmu/qemu-system-x86_64 -machine accel=kvm -nodefaults
  -no-reboot -nographic -cpu host -vga none  -kernel .build.kernel.kvm
  -initrd .build.initrd.kvm -append 'panic=1 no-kvmclock console=ttyS0
  loglevel=7' -m 1024 -serial stdio
  qemu-system-x86_64: /home/matwey/lab/qemu/target/i386/kvm.c:1849:
  kvm_put_msrs: Assertion `ret == cpu->kvm_msr_buf->nmsrs' failed.

  First broken commit has been bisected:

  commit 48e1a45c3166d659f781171a47dabf4a187ed7a5
  Author: Paolo Bonzini <address@hidden>
  Date:   Wed Mar 30 22:55:29 2016 +0200

      target-i386: assert that KVM_GET/SET_MSRS can set all requested MSRs
      
      This would have caught the bug in the previous patch.
      
      Signed-off-by: Paolo Bonzini <address@hidden>

  My cpuinfo is the following:

  processor       : 0
  vendor_id       : GenuineIntel
  cpu family      : 6
  model           : 44
  model name      : Intel(R) Xeon(R) CPU           X5675  @ 3.07GHz
  stepping        : 2
  microcode       : 0x14
  cpu MHz         : 3066.775
  cache size      : 12288 KB
  physical id     : 0
  siblings        : 2
  core id         : 0
  cpu cores       : 2
  apicid          : 0
  initial apicid  : 0
  fpu             : yes
  fpu_exception   : yes
  cpuid level     : 11
  wp              : yes
  flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca 
cmov pat pse36 clflush dts mmx fxsr sse sse2 ss ht syscall nx rdtscp lm 
constant_tsc arch_perfmon pebs bts nopl xtopology tsc_reliable nonstop_tsc 
aperfmperf pni pclmulqdq vmx ssse3 cx16 sse4_1 sse4_2 popcnt aes hypervisor 
lahf_lm ida arat epb dtherm tpr_shadow vnmi ept vpid
  bugs            :
  bogomips        : 6133.55
  clflush size    : 64
  cache_alignment : 64
  address sizes   : 40 bits physical, 48 bits virtual
  power management:

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