** Changed in: ubuntu-z-systems
Status: In Progress => Fix Committed
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https://bugs.launchpad.net/bugs/1962578
Title:
[UBUNTU 20.04] Fix SIGP processing on KVM/s390
Status in Ubuntu on IBM z Systems:
Fix Committed
Status in linux package in Ubuntu:
Fix Released
Status in linux source package in Focal:
Fix Committed
Status in linux source package in Impish:
Fix Committed
Bug description:
SRU Justification:
==================
[Impact]
* The SIGP processing on KVM/s390x is incorrect and not fully conform to
the 'Principles of Operations', the IBM Z architecture definition
and documentation.
* KVM: SIGP RESTART is reporting a CPU state 'stopped' after SIGP RESTART
was issued, while it should report a 'busy' condition until the CPU is
really started.
* The fix for this consists of three patches:
812de04661c4 "KVM: s390: Clarify SIGP orders versus STOP/RESTART"
435d17955519 "KVM: s390: Add a routine for setting userspace CPU state"
4563bcad46bf "KVM: s390: Simplify SIGP Set Arch handling"
whereas 812de04661c4 already landed via upstream stable,
hence only two are left and need to be cherry-picked:
[Fix]
* 67cf68b6a5ccac8bc7dfef0a220b59af4c83fd2c 67cf68b6a5cc "KVM: s390:
Add a routine for setting userspace CPU state"
* 8eeba194a32e0f50329354a696baaa2e3d9accc5 8eeba194a32e "KVM: s390:
Simplify SIGP Set Arch handling"
[Test Case]
* Install an LPAR on IBM Z (z13+) or LinuxONE (Emperor / Rockhopper)
with Ubuntu Server 20.04 using kernel standard kernel 5.4.
* Setup this LPAR as QEMU/KVM host and a focal VM as guest.
* The test itself is the following unit test:
https://lore.kernel.org/r/20220303210425.1693486-1-far...@linux.ibm.com/
* The test and verification will be done by the IBM Z team.
[Where problems could occur]
* A broken patch could harm KVM ioctl on s390x or the (virtual) CPU
state control in general.
* The SIGP handing (on s390x) can become broken, which could lead to
incorrect (virtual) CPU states.
* In worst case KVM can become broken on s390x entirely.
* The modified code is all s390x specific QEMU/KVM code,
no common code is touched.
[Other]
* The two remaining patches are upstream since 5.16,
the first one already landed in 5.4 via upstream stable bug LP#1959701
and in 5.13 via upstream stable bug LP#1960861.
* The patches already landed in jammy (master-next) based on LP#1959735,
hence only SRU to impish and focal is needed.
* This patches got discussed here:
https://lore.kernel.org/all/20211008203112.1979843-2-far...@linux.ibm.com/
* This not only fixes the SIGP processing, but is also important in terms of
long term maintainability.
__________
Description:
KVM: SIGP RESTART is reporting a CPU state 'stopped' after SIGP RESTART
was issued, while it should report a 'busy' condition until the CPU is really
started.
The patches to fix this have already been picked for jammy/master-
next:
812de04661c4 "KVM: s390: Clarify SIGP orders versus STOP/RESTART"
435d17955519 "KVM: s390: Add a routine for setting userspace CPU state"
4563bcad46bf "KVM: s390: Simplify SIGP Set Arch handling"
For Ubuntu 20.04 the focal/master-next already contains:
d74b0d2d38d3 KVM: s390: Clarify SIGP orders versus STOP/RESTART
so we additionally need the following two upstream commits in focal
67cf68b6a5cc KVM: s390: Add a routine for setting userspace CPU state
8eeba194a32e KVM: s390: Simplify SIGP Set Arch handling
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