1. 14 Nov, 2014 3 commits
  2. 13 Nov, 2014 1 commit
    • Chris J Arges's avatar
      kvm: svm: move WARN_ON in svm_adjust_tsc_offset · d913b904
      Chris J Arges authored
      When running the tsc_adjust kvm-unit-test on an AMD processor with the
      IA32_TSC_ADJUST feature enabled, the WARN_ON in svm_adjust_tsc_offset can be
      triggered. This WARN_ON checks for a negative adjustment in case __scale_tsc
      is called; however it may trigger unnecessary warnings.
      
      This patch moves the WARN_ON to trigger only if __scale_tsc will actually be
      called from svm_adjust_tsc_offset. In addition make adj in kvm_set_msr_common
      s64 since this can have signed values.
      Signed-off-by: default avatarChris J Arges <chris.j.arges@canonical.com>
      Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      d913b904
  3. 12 Nov, 2014 2 commits
    • Andy Lutomirski's avatar
      x86, kvm, vmx: Don't set LOAD_IA32_EFER when host and guest match · 54b98bff
      Andy Lutomirski authored
      There's nothing to switch if the host and guest values are the same.
      I am unable to find evidence that this makes any difference
      whatsoever.
      Signed-off-by: default avatarAndy Lutomirski <luto@amacapital.net>
      [I could see a difference on Nehalem.  From 5 runs:
      
       userspace exit, guest!=host   12200 11772 12130 12164 12327
       userspace exit, guest=host    11983 11780 11920 11919 12040
       lightweight exit, guest!=host  3214  3220  3238  3218  3337
       lightweight exit, guest=host   3178  3193  3193  3187  3220
      
       This passes the t-test with 99% confidence for userspace exit,
       98.5% confidence for lightweight exit. - Paolo]
      Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      54b98bff
    • Andy Lutomirski's avatar
      x86, kvm, vmx: Always use LOAD_IA32_EFER if available · f6577a5f
      Andy Lutomirski authored
      At least on Sandy Bridge, letting the CPU switch IA32_EFER is much
      faster than switching it manually.
      
      I benchmarked this using the vmexit kvm-unit-test (single run, but
      GOAL multiplied by 5 to do more iterations):
      
      Test                                  Before      After    Change
      cpuid                                   2000       1932    -3.40%
      vmcall                                  1914       1817    -5.07%
      mov_from_cr8                              13         13     0.00%
      mov_to_cr8                                19         19     0.00%
      inl_from_pmtimer                       19164      10619   -44.59%
      inl_from_qemu                          15662      10302   -34.22%
      inl_from_kernel                         3916       3802    -2.91%
      outl_to_kernel                          2230       2194    -1.61%
      mov_dr                                   172        176     2.33%
      ipi                                (skipped)  (skipped)
      ipi+halt                           (skipped)  (skipped)
      ple-round-robin                           13         13     0.00%
      wr_tsc_adjust_msr                       1920       1845    -3.91%
      rd_tsc_adjust_msr                       1892       1814    -4.12%
      mmio-no-eventfd:pci-mem                16394      11165   -31.90%
      mmio-wildcard-eventfd:pci-mem           4607       4645     0.82%
      mmio-datamatch-eventfd:pci-mem          4601       4610     0.20%
      portio-no-eventfd:pci-io               11507       7942   -30.98%
      portio-wildcard-eventfd:pci-io          2239       2225    -0.63%
      portio-datamatch-eventfd:pci-io         2250       2234    -0.71%
      
      I haven't explicitly computed the significance of these numbers,
      but this isn't subtle.
      Signed-off-by: default avatarAndy Lutomirski <luto@amacapital.net>
      [The results were reproducible on all of Nehalem, Sandy Bridge and
       Ivy Bridge.  The slowness of manual switching is because writing
       to EFER with WRMSR triggers a TLB flush, even if the only bit you're
       touching is SCE (so the page table format is not affected).  Doing
       the write as part of vmentry/vmexit, instead, does not flush the TLB,
       probably because all processors that have EPT also have VPID. - Paolo]
      Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      f6577a5f
  4. 10 Nov, 2014 1 commit
  5. 08 Nov, 2014 7 commits
  6. 07 Nov, 2014 23 commits
  7. 03 Nov, 2014 3 commits