------- Comment From nico.bo...@ibm.com 2023-03-07 04:01 EDT------- (In reply to comment #11) > Bug has been verified and is fixed with 5.4.0-145.162.
Please note that the QEMU fix from LP 1999885 is still missing. We recommend releasing both fixes at the same time. Otherwise customers may get this warning message: warning: Unable to set KVM guest TOD clock: Operation not supported -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1999882 Title: [UBUNTU 20.04] KVM: s390: pv: don't allow userspace to set the clock under PV - kernel part Status in Ubuntu on IBM z Systems: Fix Committed Status in linux package in Ubuntu: In Progress Status in linux source package in Focal: Fix Committed Status in linux source package in Jammy: Fix Committed Status in linux source package in Kinetic: Fix Committed Status in linux source package in Lunar: In Progress Bug description: Description: KVM: s390: pv: don't allow userspace to set the clock under PV Symptom: Timer issues and RCU stalls after suspending and resuming an IBM Secure Execution guest Problem: KVM and QEMU try to set the guest's TOD clock after resume under PV, even though that is not permitted under SE. Hence,their view of the guest clock may deviate from the ultravisor's, possibly causing KVM to re-dispatch the guest too late on clock comparator interrupts. Solution: Don't set the clock after resume under PV. Note that kernel and QEMU patches are required in lockstep, to avoid a warning message in QEMU. Reproduction: 1. Start SE guest using libvirt. 2. Pause the guest using "virsh suspend", wait for a few seconds, resume using "virsh resume". 3. Run "time sleep 1" in the guest. 4. The sleep will sleep much longer than one second. Upstream-ID: 6973091d1b50ab4042f6a2d495f59e9db3662ab8 Preventive fix: yes Author: Nico Boehr <n...@linux.ibm.com> Please note that fixing the described problem requires patches for the kernel as well as for QEMU. This bug covers the kernel part, whereas the required QEMU part is described and handled in the following related bug: Bug?200901 - [UBUNTU 20.04] KVM: s390: pv: don't allow userspace to set the clock under PV - qemu part Both parts, the kernel and the qemu patches should be applied / released at the same time to avoid problems resulting in the following warning message for customers: 'warning: Unable to set KVM guest TOD clock: Operation not supported' To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu-z-systems/+bug/1999882/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
