ACK: [SRU][I][F][PATCH v2 0/2] Fix SIGP processing on KVM/s390 (LP: 1962578)
tim.gardner at canonical.com
Fri Mar 4 12:39:42 UTC 2022
Acked-by: Tim Gardner <tim.gardner at canonical.com>
On 3/4/22 00:22, frank.heimes at canonical.com wrote:
> BugLink: https://bugs.launchpad.net/bugs/1962578
> SRU Justification:
> * 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:
> * 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:
> * 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.
> * 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:
> * This not only fixes the SIGP processing, but is also important in terms of
> long term maintainability.
> v2: fixed typos and text of SRU justification
> Eric Farman (2):
> KVM: s390: Simplify SIGP Set Arch handling
> KVM: s390: Add a routine for setting userspace CPU state
> arch/s390/kvm/kvm-s390.c | 6 +++---
> arch/s390/kvm/kvm-s390.h | 9 +++++++++
> arch/s390/kvm/sigp.c | 14 +-------------
> 3 files changed, 13 insertions(+), 16 deletions(-)
More information about the kernel-team