Cpu utilization showing system time for kvm guests (performance) (sysstat)

[bugproxy]

== SRU Justification ==
All KVM guest cpu utilization is being reported as sys% time in the host.
It turns out Guest time accounting (CONFIG_VIRT_CPU_ACCOUNTING_GEN) has
been broken since v4.13 by commit 8b24e69fc47e436.

Commit 61bd0f66ff92 fixes this bug and is included in mainline as of v4.16-rc5.
The commit was cc'd to upstream stable, but has not yet landed in upstream 4.15.

== Fix ==
61bd0f66ff92 ("KVM: PPC: Book3S HV: Fix guest time accounting with VIRT_CPU_ACCOUNTING_GEN")

== Regression Potential ==
Low. Also cc'd to stable, so it has had additionl upstream review. Limited to powerpc.

== Test Case ==
A test kernel was built with this patch and tested by the original bug reporter.
The bug reporter states the test kernel resolved the bug.

== Comment: #0 - JENIFER HOPPER <email address hidden> - 2018-03-14 16:20:47 ==
+++ This bug was initially created as a clone of Bug #163375 +++

---Problem Description---
All KVM guest cpu utilization is being reported as sys% time in the host.
It turns out Guest time accounting (CONFIG_VIRT_CPU_ACCOUNTING_GEN) has been broken since v4.13 by commit:

commit 8b24e69fc47e43679bb29ddb481aa0e8dce2a3c5
Author: Paul Mackerras <email address hidden>
Date: Mon Jun 26 15:45:51 2017 +1000

KVM: PPC: Book3S HV: Close race with testing for signals on guest entry

---

That is now fixed and upstream accepted in Paulus' tree as git commit:

https://git.kernel.org/pub/scm/linux/kernel/git/paulus/powerpc.git/commit/?h=kvm-ppc-fixes&id=61bd0f66ff92d5ce765ff9850fd3cbfec773c560
("KVM: PPC: Book3S HV: Fix guest time accounting with VIRT_CPU_ACCOUNTING_GEN")

Please include this patch in Ubuntu so that guest cpu accounting is correct.

Contact Information = <email address hidden>

---uname output---
Linux ltc-b114 4.15.0-10-generic #11-Ubuntu SMP Tue Feb 13 18:21:52 UTC 2018 ppc64le ppc64le ppc64le GNU/Linux

Machine Type = 5104-22C

---Debugger---
A debugger is not configured

---Steps to Reproduce---
 Start a KVM guest, run something that generates cpu utilization in the guest, observe mpstat on the host.

[Joseph Salisbury (jsalisbury)]

I built a test kernel with commit 61bd0f66ff92. The test kernel can be downloaded from:
http://kernel.ubuntu.com/~jsalisbury/lp1755979

Can you test this kernel and see if it resolves this bug?

Note, to test this kernel, you need to install both the linux-image and linux-image-extra .deb packages.

Thanks in advance!

[bugproxy (bugproxy)]

------- Comment From <email address hidden> 2018-03-21 16:39 EDT-------
With this test kernel, I now see guest time reported correctly in the host:

03:32:17 PM CPU %usr %nice %sys %iowait %irq %soft %steal %guest %gnice %idle
03:32:19 PM all 0.00 0.00 0.91 0.00 0.00 0.02 0.00 64.58 0.00 34.48

4.15.0-12-generic #13~lp175597

[Joseph Salisbury (jsalisbury)]

SRU Request submitted:
https://lists.ubuntu.com/archives/kernel-team/2018-March/090973.html

[Brad Figg (brad-figg)]

This bug is awaiting verification that the kernel in -proposed solves the problem. Please test the kernel and update this bug with the results. If the problem is solved, change the tag 'verification-needed-artful' to 'verification-done-artful'. If the problem still exists, change the tag 'verification-needed-artful' to 'verification-failed-artful'.

If verification is not done by 5 working days from today, this fix will be dropped from the source code, and this bug will be closed.

See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you!

[bugproxy (bugproxy)]

------- Comment From <email address hidden> 2018-04-11 12:01 EDT-------
I verified the -proposed kernel fixes the issue:

10:59:35 AM CPU %usr %nice %sys %iowait %irq %soft %steal %guest %gnice %idle
10:59:37 AM all 0.01 0.00 0.08 0.00 0.00 0.01 0.00 20.68 0.00 79.21
10:59:37 AM 0 0.53 0.00 0.00 0.00 0.00 0.00 0.00 51.34 0.00 48.13
10:59:37 AM 1 0.00 0.00 0.00 0.00 0.00 0.00 0.00 76.00 0.00 24.00

Selected version '4.13.0.39.42' (Ubuntu:17.10/artful-proposed [ppc64el]) for 'linux-image-generic'

[Launchpad Janitor (janitor)]

This bug was fixed in the package linux - 4.15.0-15.16

---------------
linux (4.15.0-15.16) bionic; urgency=medium

  * linux: 4.15.0-15.16 -proposed tracker (LP: #1761177)

  * FFe: Enable configuring resume offset via sysfs (LP: #1760106)
    - PM / hibernate: Make passing hibernate offsets more friendly

  * /dev/bcache/by-uuid links not created after reboot (LP: #1729145)
    - SAUCE: (no-up) bcache: decouple emitting a cached_dev CHANGE uevent

  * Ubuntu18.04:POWER9:DD2.2 - Unable to start a KVM guest with default machine
    type(pseries-bionic) complaining "KVM implementation does not support
    Transactional Memory, try cap-htm=off" (kvm) (LP: #1752026)
    - powerpc: Use feature bit for RTC presence rather than timebase presence
    - powerpc: Book E: Remove unused CPU_FTR_L2CSR bit
    - powerpc: Free up CPU feature bits on 64-bit machines
    - powerpc: Add CPU feature bits for TM bug workarounds on POWER9 v2.2
    - powerpc/powernv: Provide a way to force a core into SMT4 mode
    - KVM: PPC: Book3S HV: Work around transactional memory bugs in POWER9
    - KVM: PPC: Book3S HV: Work around XER[SO] bug in fake suspend mode
    - KVM: PPC: Book3S HV: Work around TEXASR bug in fake suspend state

  * Important Kernel fixes to be backported for Power9 (kvm) (LP: #1758910)
    - powerpc/mm: Fixup tlbie vs store ordering issue on POWER9

  * Ubuntu 18.04 - IO Hang on some namespaces when running HTX with 16
    namespaces (Bolt / NVMe) (LP: #1757497)
    - powerpc/64s: Fix lost pending interrupt due to race causing lost update to
      irq_happened

  * fwts-efi-runtime-dkms 18.03.00-0ubuntu1: fwts-efi-runtime-dkms kernel module
    failed to build (LP: #1760876)
    - [Packaging] include the retpoline extractor in the headers

linux (4.15.0-14.15) bionic; urgency=medium

  * linux: 4.15.0-14.15 -proposed tracker (LP: #1760678)

  * [Bionic] mlx4 ETH - mlnx_qos failed when set some TC to vendor
    (LP: #1758662)
    - net/mlx4_en: Change default QoS settings

  * AT_BASE_PLATFORM in AUXV is absent on kernels available on Ubuntu 17.10
    (LP: #1759312)
    - powerpc/64s: Fix NULL AT_BASE_PLATFORM when using DT CPU features

  * Bionic update to 4.15.15 stable release (LP: #1760585)
    - net: dsa: Fix dsa_is_user_port() test inversion
    - openvswitch: meter: fix the incorrect calculation of max delta_t
    - qed: Fix MPA unalign flow in case header is split across two packets.
    - tcp: purge write queue upon aborting the connection
    - qed: Fix non TCP packets should be dropped on iWARP ll2 connection
    - sysfs: symlink: export sysfs_create_link_nowarn()
    - net: phy: relax error checking when creating sysfs link netdev->phydev
    - devlink: Remove redundant free on error path
    - macvlan: filter out unsupported feature flags
    - net: ipv6: keep sk status consistent after datagram connect failure
    - ipv6: old_dport should be a __be16 in __ip6_datagram_connect()
    - ipv6: sr: fix NULL pointer dereference when setting encap source address
    - ipv6: sr: fix scheduling in RCU when creating seg6 lwtunnel state
    - mlxsw: spectrum_buffers: Set a minimum quota for CPU port traffic
    - net: phy: Tell caller result ...

[Launchpad Janitor (janitor)]

This bug was fixed in the package linux - 4.13.0-39.44

---------------
linux (4.13.0-39.44) artful; urgency=medium

  * linux: 4.13.0-39.44 -proposed tracker (LP: #1761456)

  * intel-microcode 3.20180312.0 causes lockup at login screen(w/ linux-
    image-4.13.0-37-generic) (LP: #1759920) // CVE-2017-5715 (Spectre v2
    Intel) // CVE-2017-5754
    - x86/mm: Reinitialize TLB state on hotplug and resume

  * intel-microcode 3.20180312.0 causes lockup at login screen(w/ linux-
    image-4.13.0-37-generic) (LP: #1759920) // CVE-2017-5715 (Spectre v2 Intel)
    - Revert "x86/mm: Only set IBPB when the new thread cannot ptrace current
      thread"
    - x86/speculation: Use Indirect Branch Prediction Barrier in context switch

  * DKMS driver builds fail with: Cannot use CONFIG_STACK_VALIDATION=y, please
    install libelf-dev, libelf-devel or elfutils-libelf-devel (LP: #1760876)
    - [Packaging] include the retpoline extractor in the headers

  * retpoline hints: primary infrastructure and initial hints (LP: #1758856)
    - [Packaging] retpoline-extract: flag *0xNNN(%reg) branches
    - x86/speculation, objtool: Annotate indirect calls/jumps for objtool
    - x86/speculation, objtool: Annotate indirect calls/jumps for objtool on 32bit
    - x86/paravirt, objtool: Annotate indirect calls
    - [Packaging] retpoline -- add safe usage hint support
    - [Packaging] retpoline-check -- only report additions
    - [Packaging] retpoline -- widen indirect call/jmp detection
    - [Packaging] retpoline -- elide %rip relative indirections
    - [Packaging] retpoline -- clear hint information from packages
    - KVM: x86: Make indirect calls in emulator speculation safe
    - KVM: VMX: Make indirect call speculation safe
    - x86/boot, objtool: Annotate indirect jump in secondary_startup_64()
    - SAUCE: early/late -- annotate indirect calls in early/late initialisation
      code
    - SAUCE: vga_set_mode -- avoid jump tables
    - [Config] retpoline -- switch to new format
    - [Packaging] retpoline hints -- handle missing files when RETPOLINE not
      enabled
    - [Packaging] final-checks -- remove check for empty retpoline files

  * retpoline: ignore %cs:0xNNN constant indirections (LP: #1752655)
    - [Packaging] retpoline -- elide %cs:0xNNNN constants on i386

  * zfs system process hung on container stop/delete (LP: #1754584)
    - SAUCE: Fix non-prefaulted page deadlock (LP: #1754584)

  * zfs-linux 0.6.5.11-1ubuntu5 ADT test failure with linux 4.15.0-1.2
    (LP: #1737761)
    - SAUCE: (noup) Update zfs to 0.6.5.11-1ubuntu3.2

  * AT_BASE_PLATFORM in AUXV is absent on kernels available on Ubuntu 17.10
    (LP: #1759312)
    - powerpc/64s: Fix NULL AT_BASE_PLATFORM when using DT CPU features

  * btrfs and tar sparse truncate archives (LP: #1757565)
    - Btrfs: move definition of the function btrfs_find_new_delalloc_bytes
    - Btrfs: fix reported number of inode blocks after buffered append writes

  * efifb broken on ThunderX-based Gigabyte nodes (LP: #1758375)
    - drivers/fbdev/efifb: Allow BAR to be moved instead of claiming it

  * Intel i40e PF reset due to incorrect MDD detection (continues...)
    (LP: #1723127)
    - i40e/i40ev...