Converted to an FFe and subscribed the release Team to sign off on it. ** Description changed:
- Without support for channel path handling changes in the host's channel path for underlying CCW devices may go unnoticed by the guest. This could cause erroneous operation and lead to a crashing guest. Therefore it is necessary to ensure proper handling of channel paths in vfio-ccw, like passing through channel path operations and notification of channel path changes. - -> Enhance RAS characteristics of guests using passed-through CCW devices. + [Feature Freeze Exception] - Freature request for qemu contribution + 1. Feature: + + s390x is all about resilency, and one of the great features it provides is that on FICON stroage that even is mostly handled by the underlying layers. + Think of it as multipathd not being in userspace/kernel but firmware. + Nowadays that can not yet all be transparently handled for KVM guests. + The feature proposed here is one that enables this for dasd's passed through via vfio-ccw. + + Without support for channel path handling changes in the host's channel + path for underlying CCW devices may go unnoticed by the guest. This + could cause erroneous operation and lead to a crashing guest. Therefore + it is necessary to ensure proper handling of channel paths in vfio-ccw, + like passing through channel path operations and notification of channel + path changes. + + This is one of the more visible drawbacks of KVM to the alternatives of + running in LPAR or as a z/VM guest. An example could be channel path + changes caused by the FICON fabric, or simply offlining and subsequently + onlining. This feature is critical to use vfio-ccw in production more + reliably. + + 2. Changes + https://git.qemu.org/?p=qemu.git;a=commit;h=f76b348ec7 + https://git.qemu.org/?p=qemu.git;a=commit;h=2a3b9cbaa7 + https://git.qemu.org/?p=qemu.git;a=commit;h=46ea3841ed + https://git.qemu.org/?p=qemu.git;a=commit;h=690e29b911 + https://git.qemu.org/?p=qemu.git;a=commit;h=f6dde1b012 + https://git.qemu.org/?p=qemu.git;a=commit;h=f030532f2a + + All of them apply cleanly on top of qemu 5.0 as it is in Groovy right + now. + + + 3. Regression risk + + All changes are s390x / vfio-ccw (which is exclusive to s390x) only. + So potential regressions of this late addition would be limited to the s390x which in the Form of the IBM Dev&Test teams is the requester of this addition. But if something unexpected happens then in the vfio-ccw use cases. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1887930 Title: [FFe][20.10 FEAT] KVM: Enable Channel Path Handling for vfio-ccw - qemu part To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu-z-systems/+bug/1887930/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
