kernel: Fix arch random implementation

[bugproxy]

== SRU Justification ==
IBM reports that arch_get_random_seed_long() invocations may slow down the
interrupt handling on heavy interrupt producing loads.

The existing random device driver calls arch_get_random_seed_long() in
interrupt context. The current implementation of this function uses the
PRNO(TRNG) instruction to provide good entropy. This instruction is
relatively slow and expensive and may slow down the capacity of interrupts which can be handled per cpu.

This fix reworks the arch_get_random_seed implementation. It introduces a
buffer concept to decouple the delivery of random data via
arch_get_random_seed*() from the generation of new random bytes and so
does not limit the interrupt handling per cpu any more.

== Fix ==
966f53e750ae ("s390/archrandom: Rework arch random implementation.")

== Regression Potential ==
Low. This fix is limited to s390.

== Test Case ==
Verified upfront by IBM during upstream integration

Description: kernel: Fix arch random implementation
Symptom: arch_get_random_seed_long() invocations may slow down the
              interrupt handling on heavy interrupt producing loads.
Problem: The existing random device driver calls
              arch_get_random_seed_long() in interrupt context. The
              current implementation of this function uses the
              PRNO(TRNG) instruction to provide good entropy. This
              instruction is relatively slow and expensive and may
              slow down the capacity of interrupts which can be handled
              per cpu.
Solution: This fix reworks the arch_get_random_seed implementation.
              It introduces a buffer concept to decouple the delivery
              of random data via arch_get_random_seed*() from the
              generation of new random bytes and so does not limit
              the interrupt handling per cpu any more.
Reproduction: Systems with heavy irq load show performance decrease.
Component: kernel

Upstream commit(s): kernel 4.18
966f53e750aedc5f59f9ccae6bbfb8f671c7c842

[bugproxy (bugproxy)]

Default Comment by Bridge

[Joseph Salisbury (jsalisbury)]

I built a test kernel with commit 966f53e750aedc5f59f9ccae6bbfb8f671c7c842. The test kernel can be downloaded from:
http://kernel.ubuntu.com/~jsalisbury/lp1775391

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

Note about installing test kernels:
• If the test kernel is prior to 4.15(Bionic) you need to install the linux-image and linux-image-extra .deb packages.
• If the test kernel is 4.15(Bionic) or newer, you need to install the linux-modules, linux-modules-extra and linux-image-unsigned .deb packages.

Thanks in advance!

[bugproxy (bugproxy)]

------- Comment From <email address hidden> 2018-06-13 03:53 EDT-------
Verified upfront by IBM during upstream integration

[Joseph Salisbury (jsalisbury)]

SRU request submitted:
https://lists.ubuntu.com/archives/kernel-team/2018-June/093312.html

[Launchpad Janitor (janitor)]

This bug was fixed in the package linux - 4.17.0-6.7

---------------
linux (4.17.0-6.7) cosmic; urgency=medium

  * linux: 4.17.0-6.7 -proposed tracker (LP: #1783396)

  * [Regression] EXT4-fs error (device sda2): ext4_validate_block_bitmap:383:
    comm stress-ng: bg 4705: bad block bitmap checksum (LP: #1781709)
    - SAUCE: Revert "UBUNTU: SAUCE: ext4: fix ext4_validate_inode_bitmap: comm
      stress-ng: Corrupt inode bitmap"
    - SAUCE: ext4: check for allocation block validity with block group locked

  * Cosmic update to 4.17.9 stable release (LP: #1783201)
    - userfaultfd: hugetlbfs: fix userfaultfd_huge_must_wait() pte access
    - mm: hugetlb: yield when prepping struct pages
    - mm: teach dump_page() to correctly output poisoned struct pages
    - PCI / ACPI / PM: Resume bridges w/o drivers on suspend-to-RAM
    - ACPICA: Drop leading newlines from error messages
    - ACPI / battery: Safe unregistering of hooks
    - drm/amdgpu: Make struct amdgpu_atif private to amdgpu_acpi.c
    - tracing: Avoid string overflow
    - tracing: Fix missing return symbol in function_graph output
    - scsi: sg: mitigate read/write abuse
    - scsi: aacraid: Fix PD performance regression over incorrect qd being set
    - scsi: target: Fix truncated PR-in ReadKeys response
    - s390: Correct register corruption in critical section cleanup
    - drbd: fix access after free
    - vfio: Use get_user_pages_longterm correctly
    - ARM: dts: imx51-zii-rdu1: fix touchscreen pinctrl
    - ARM: dts: omap3: Fix am3517 mdio and emac clock references
    - ARM: dts: dra7: Disable metastability workaround for USB2
    - cifs: Fix use after free of a mid_q_entry
    - cifs: Fix memory leak in smb2_set_ea()
    - cifs: Fix slab-out-of-bounds in send_set_info() on SMB2 ACE setting
    - cifs: Fix infinite loop when using hard mount option
    - drm: Use kvzalloc for allocating blob property memory
    - drm/udl: fix display corruption of the last line
    - drm/amdgpu: Add amdgpu_atpx_get_dhandle()
    - drm/amdgpu: Dynamically probe for ATIF handle (v2)
    - jbd2: don't mark block as modified if the handle is out of credits
    - ext4: add corruption check in ext4_xattr_set_entry()
    - ext4: always verify the magic number in xattr blocks
    - ext4: make sure bitmaps and the inode table don't overlap with bg
      descriptors
    - ext4: always check block group bounds in ext4_init_block_bitmap()
    - ext4: only look at the bg_flags field if it is valid
    - ext4: verify the depth of extent tree in ext4_find_extent()
    - ext4: include the illegal physical block in the bad map ext4_error msg
    - ext4: clear i_data in ext4_inode_info when removing inline data
    - ext4: never move the system.data xattr out of the inode body
    - ext4: avoid running out of journal credits when appending to an inline file
    - ext4: add more inode number paranoia checks
    - ext4: add more mount time checks of the superblock
    - ext4: check superblock mapped prior to committing
    - HID: i2c-hid: Fix "incomplete report" noise
    - HID: hiddev: fix potential Spectre v1
    - HID: debug: check length before copy_to_user()
    - HID: core: allow concurrent registr...

[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-bionic' to 'verification-done-bionic'. If the problem still exists, change the tag 'verification-needed-bionic' to 'verification-failed-bionic'.

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> 2018-08-08 08:18 EDT-------
Verified upfront by IBM during upstream integration.
No further test by IBM.

[Frank Heimes (fheimes)]

Adjusted the tags according to comment #7.

[Joseph Salisbury (jsalisbury)]

Confirmed patch is in Ubuntu-4.15.0-31.33~527 as commit:

c1072b71e9bf s390/archrandom: Rework arch random implementation.

[Launchpad Janitor (janitor)]

This bug was fixed in the package linux - 4.15.0-33.36

---------------
linux (4.15.0-33.36) bionic; urgency=medium

  * linux: 4.15.0-33.36 -proposed tracker (LP: #1787149)

  * RTNL assertion failure on ipvlan (LP: #1776927)
    - ipvlan: drop ipv6 dependency
    - ipvlan: use per device spinlock to protect addrs list updates
    - SAUCE: fix warning from "ipvlan: drop ipv6 dependency"

  * ubuntu_bpf_jit test failed on Bionic s390x systems (LP: #1753941)
    - test_bpf: flag tests that cannot be jited on s390

  * HDMI/DP audio can't work on the laptop of Dell Latitude 5495 (LP: #1782689)
    - drm/nouveau: fix nouveau_dsm_get_client_id()'s return type
    - drm/radeon: fix radeon_atpx_get_client_id()'s return type
    - drm/amdgpu: fix amdgpu_atpx_get_client_id()'s return type
    - platform/x86: apple-gmux: fix gmux_get_client_id()'s return type
    - ALSA: hda: use PCI_BASE_CLASS_DISPLAY to replace PCI_CLASS_DISPLAY_VGA
    - vga_switcheroo: set audio client id according to bound GPU id

  * locking sockets broken due to missing AppArmor socket mediation patches
    (LP: #1780227)
    - UBUNTU SAUCE: apparmor: fix apparmor mediating locking non-fs, unix sockets

  * Update2 for ocxl driver (LP: #1781436)
    - ocxl: Fix page fault handler in case of fault on dying process

  * netns: unable to follow an interface that moves to another netns
    (LP: #1774225)
    - net: core: Expose number of link up/down transitions
    - dev: always advertise the new nsid when the netns iface changes
    - dev: advertise the new ifindex when the netns iface changes

  * [Bionic] Disk IO hangs when using BFQ as io scheduler (LP: #1780066)
    - block, bfq: fix occurrences of request finish method's old name
    - block, bfq: remove batches of confusing ifdefs
    - block, bfq: add requeue-request hook

  * HP ProBook 455 G5 needs mute-led-gpio fixup (LP: #1781763)
    - ALSA: hda: add mute led support for HP ProBook 455 G5

  * [Bionic] bug fixes to improve stability of the ThunderX2 i2c driver
    (LP: #1781476)
    - i2c: xlp9xx: Fix issue seen when updating receive length
    - i2c: xlp9xx: Make sure the transfer size is not more than
      I2C_SMBUS_BLOCK_SIZE

  * x86/kvm: fix LAPIC timer drift when guest uses periodic mode (LP: #1778486)
    - x86/kvm: fix LAPIC timer drift when guest uses periodic mode

  * Please include ax88179_178a and r8152 modules in d-i udeb (LP: #1771823)
    - [Config:] d-i: Add ax88179_178a and r8152 to nic-modules

  * Nvidia fails after switching its mode (LP: #1778658)
    - PCI: Restore config space on runtime resume despite being unbound

  * Kernel error "task zfs:pid blocked for more than 120 seconds" (LP: #1781364)
    - SAUCE: (noup) zfs to 0.7.5-1ubuntu16.3

  * CVE-2018-12232
    - PATCH 1/1] socket: close race condition between sock_close() and
      sockfs_setattr()

  * CVE-2018-10323
    - xfs: set format back to extents if xfs_bmap_extents_to_btree

  * change front mic location for more lenovo m7/8/9xx machines (LP: #1781316)
    - ALSA: hda/realtek - Fix the problem of two front mics on more machines
    - ALSA: hda/realtek - two more lenovo models need fixup of MIC_LOCATION

  * Cephfs + fscache: unab...