Re: [Qemu-devel] 3.1.0-rc{0,1} doesn't start

[Dr. David Alan Gilbert]

cc'ing in Paolo, Eduardo and Robert

* address@hidden (address@hidden) wrote:
> hello
> 
> I'm building qemu from source and happily using it since a bit
> (2.3.0)
> 
> Since 3.1.0-rc0 (including latest 3.1.0-rc1) I'm no more able to start
> qemu, getting:
> 
>     ----8<----
>     install:115> qemu
>     qemu: error: failed to set MSR 0x10a to 0x0
>     qemu: 
> /home/balducci/tmp/install-us-d/qemu-3.1.0-rc1.d/qemu-3.1.0-rc0/target/i386/kvm.c:2185:
>  kvm_put_msrs: Assertion `ret == cpu->kvm_msr_buf->nmsrs' failed.
>     Aborted
>     ---->8----
> 
> I have no idea about what the reason might be, apologies.

Thanks for the detailed error report.
MSR 0x10a is one of the new ones from the recent round of security
things:
    #define MSR_IA32_ARCH_CAPABILITIES      0x10a

That only went in recently so is probably why you're seeing it
in 3.1.

> Actually, I have found a recent (2018-10-16) post which might be
> related to this (it mentions the same error message from qemu):
> https://lkml.org/lkml/2018/10/16/440; but I'm not in the position to
> go through. AFAICS, the commit mentioned in the link is present in the
> 4.19.2 kernel I'm using, so...?

That's a different MSR number so is probably unrelated.

> I can add that 3.0.0 works nicely (everything else unchanged,
> including running kernel 4.19.2)
> 
> OTOH, 3.1.0-rc0 dumps the same error message if I boot into 4.17.14 or
> 4.18.16 kernels.
> 
> I enclose my specs hoping that somebody can spot where the problem
> might be. I will be happy to send any other detail which might be
> useful.
> 
> I suspect that this might be some problem on my side, as I couldn't
> find any similar report (apart some old (qemu-2.8.50) threads, that
> didn't help)

Not necessarily; can you tell me:
  a) At what point does it fail - immediately when booting the guest?
     Some time during the boot? Later?
  b) What guest does it happen on?

> thanks a lot in advance for any hint/help
> 
> ciao
> gabriele
> 
> 
> Here are my specs:
> 
> # --------------------------------
> # command to run qemu is:
> qemu -m 2G /opt/windog  \
>     -accel kvm,thread=multi \
>     -netdev user,id=net0,smb=/home/balducci \
>     -device rtl8139,netdev=net0
> 
> # --------------------------------
> # qemu build configuration:
> --prefix=/opt/stow.d/versions/qemu-3.1.0-rc1/usr
> --libdir=/opt/stow.d/versions/qemu-3.1.0-rc1/usr/lib64
> --sysconfdir=/opt/stow.d/versions/qemu-3.1.0-rc1/etc
> --localstatedir=/var/run
> --docdir=/opt/stow.d/versions/qemu-3.1.0-rc1/usr/share/doc/qemu
> --target-list=x86_64-softmmu
> --audio-drv-list=alsa
> 
> 
> # --------------------------------
> install:154> uname -sr
> Linux 4.19.2
> 
> # --------------------------------
> install:155> cat /proc/cpuinfo
> processor       : 0
> vendor_id       : AuthenticAMD
> cpu family      : 21
> model           : 48
> model name      : AMD Athlon(tm) X4 860K Quad Core Processor

OK, older AMD cpu, so a little less tested perhaps, maybe why
others haven't sene it.

> stepping        : 1
> microcode       : 0x6003106
> cpu MHz         : 3473.492
> cache size      : 2048 KB
> physical id     : 0
> siblings        : 4
> core id         : 0
> cpu cores       : 2
> apicid          : 16
> initial apicid  : 0
> fpu             : yes
> fpu_exception   : yes
> cpuid level     : 13
> wp              : yes
> flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca 
> cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt 
> pdpe1gb rdtscp lm constant_tsc rep_good nopl nonstop_tsc cpuid extd_apicid 
> aperfmperf pni pclmulqdq monitor ssse3 fma cx16 sse4_1 sse4_2 popcnt aes 
> xsave avx f16c lahf_lm cmp_legacy svm extapic cr8_legacy abm sse4a 
> misalignsse 3dnowprefetch osvw ibs xop skinit wdt lwp fma4 tce nodeid_msr tbm 
> topoext perfctr_core perfctr_nb bpext ptsc cpb hw_pstate ssbd vmmcall 
> fsgsbase bmi1 xsaveopt arat npt lbrv svm_lock nrip_save tsc_scale vmcb_clean 
> flushbyasid decodeassists pausefilter pfthreshold overflow_recov
> bugs            : fxsave_leak sysret_ss_attrs null_seg spectre_v1 spectre_v2 
> spec_store_bypass
> bogomips        : 7380.73
> TLB size        : 1536 4K pages
> clflush size    : 64
> cache_alignment : 64
> address sizes   : 48 bits physical, 48 bits virtual
> power management: ts ttp tm 100mhzsteps hwpstate cpb eff_freq_ro [13]
> 
> [...cpus 1 2 3 omitted...]
> 
> 
> # --------------------------------
> install:156> egrep KVM .config-4.19.2
> CONFIG_HAVE_KVM=y
> CONFIG_HAVE_KVM_IRQCHIP=y
> CONFIG_HAVE_KVM_IRQFD=y
> CONFIG_HAVE_KVM_IRQ_ROUTING=y
> CONFIG_HAVE_KVM_EVENTFD=y
> CONFIG_KVM_MMIO=y
> CONFIG_KVM_ASYNC_PF=y
> CONFIG_HAVE_KVM_MSI=y
> CONFIG_HAVE_KVM_CPU_RELAX_INTERCEPT=y
> CONFIG_KVM_VFIO=y
> CONFIG_KVM_GENERIC_DIRTYLOG_READ_PROTECT=y
> CONFIG_KVM_COMPAT=y
> CONFIG_HAVE_KVM_IRQ_BYPASS=y
> CONFIG_KVM=y
> # CONFIG_KVM_INTEL is not set
> CONFIG_KVM_AMD=y
> 
> [of course, I can send the whole kernel configuration file, if needed]

Dave

> 
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK