[Qemu-devel] [Bug 1318091] Re: Perfctr MSRs not available to Guest OS on AMD Phenom II

[Thomas Huth]

Triaging old bug tickets... can you still reproduce this issue with the
latest version of QEMU? Or could we close this ticket nowadays?

** Changed in: qemu
       Status: New => Incomplete

-- 
You received this bug notification because you are a member of qemu-
devel-ml, which is subscribed to QEMU.
https://bugs.launchpad.net/bugs/1318091

Title:
  Perfctr MSRs not available to Guest OS on AMD Phenom II

Status in QEMU:
  Incomplete

Bug description:
  The  AMD Phenom(tm) II X4 965 Processor (family 16, model 4, stepping
  3) has the 4 architecturally supported perf counters at MSRs.  The
  selectors are c001000-c001003, and the counters are c001004-c001007.
  I've verified that the MSRs are there and working by manually setting
  the MSRs with msr-tools to count cycles.

  The processor does not support the extended perfctr or the perfctr_nb.
  These are in cpuid leaf 8000_0001.  Qemu also sees that these cpuid
  flags are not set, when I try launching with  -cpu
  host,perfctr_core,check.  However, this flag is only for the extended
  perfctr MSRs, which also happen to map the original four counters at
  c0010200.

  When I run a Guest OS, that OS is unable to use the perf counter
  registers from c001000-7.  rdmsr and wrmsr complete, but the results
  are always 0.  By contrast, a wrmsr to one of the c0010200 registers
  causes a general protection fault (as it should, since those aren't
  supported).

  Kernel: 3.14.0-gentoo
  Qemu: 2.0.0 (gentoo) and also with 2.0.50 (commit 06b4f00d5)
  Qemu command: qemu-system-x86_64 -enable-kvm -cpu host -smp 8 -m 1024 
-nographic -monitor /dev/pts/4 mnt/hdd.img
  cat /proc/cpuinfo:
  processor     : 3
  vendor_id     : AuthenticAMD
  cpu family    : 16
  model         : 4
  model name    : AMD Phenom(tm) II X4 965 Processor
  stepping      : 3
  cpu MHz               : 800.000
  cache size    : 512 KB
  physical id   : 0
  siblings      : 4
  core id               : 3
  cpu cores     : 4
  apicid                : 3
  initial apicid        : 3
  fpu           : yes
  fpu_exception : yes
  cpuid level   : 5
  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 3dnowext 3dnow constant_tsc rep_good nopl nonstop_tsc extd_apicid pni 
monitor cx16 popcnt lahf_lm cmp_legacy svm extapic cr8_legacy abm sse4a 
misalignsse 3dnowprefetch osvw ibs skinit wdt hw_pstate npt lbrv svm_lock 
nrip_save
  bogomips      : 6803.79
  TLB size      : 1024 4K pages
  clflush size  : 64
  cache_alignment       : 64
  address sizes : 48 bits physical, 48 bits virtual
  power management: ts ttp tm stc 100mhzsteps hwpstate

  thanks.

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1318091/+subscriptions