Thanks for the ping sil2100, I have forgotten to move the thoughts I had into a proper SRU template.
** Description changed: + [Impact] + + * The kernel detects CPU types and enables/disables some features based + on that. With future HW this detection is broken as the csske facility + is no more available. + + * This is fixed upstream and here backported, the csske is ignored when + expanding the cpu model for the guest and thereby the issue avoided. + + [Test Case] + + * Start a kvm guest on s390x + * While doing so qemu/kvm will try to detect the host model + * Check what CPU it detects the model + * Note: this will work (regression check) on all s390x HW, but to prove + the fix and trigger the issue one would need experimental (not GA yet) + HW or a similator. Hence we are relying on the bug reporter for + verification. + * For the functionality of this check the initial commit adding the + core feature [1] which shows how the filtering works. + + [1]: https://github.com/qemu/qemu/commit/30e82de70 + + [Regression Potential] + + * If there would be a detection that depends on csske being available or + not that would be affected. But there is none that this is important + for. All existing machines still have csske, for those the issue never + existed and nothing should change. The behavior on new machines will + "change", but not regress. And in addition those new HW was never sold + yet, so even if that would be considered a regression it wouldn't + happen in the field. + + [Other Info] + + * n/a + + --- + A nested KVM hypervisor has problems to detect the cpu type as z10..z14 with no csske facility available. Instead it will fall back to z9. We need a backport of commit eaf6f642abf1d4d24791b70728d4068428fc4658 Author: Christian Borntraeger <[email protected]> AuthorDate: Mon Apr 29 05:02:43 2019 -0400 Commit: Cornelia Huck <[email protected]> CommitDate: Tue May 21 16:59:16 2019 +0200 - s390x/cpumodel: ignore csske for expansion - - ... - - Signed-off-by: Christian Borntraeger <[email protected]> - Cc: [email protected] - Reviewed-by: David Hildenbrand <[email protected]> - Message-Id: <[email protected]> - Signed-off-by: Cornelia Huck <[email protected]> + s390x/cpumodel: ignore csske for expansion + + ... + + Signed-off-by: Christian Borntraeger <[email protected]> + Cc: [email protected] + Reviewed-by: David Hildenbrand <[email protected]> + Message-Id: <[email protected]> + Signed-off-by: Cornelia Huck <[email protected]> diff --git a/target/s390x/cpu_models.c b/target/s390x/cpu_models.c index e5afa15512..b4bb5de635 100644 --- a/target/s390x/cpu_models.c +++ b/target/s390x/cpu_models.c @@ -1322,6 +1322,8 @@ static void init_ignored_base_feat(void) - S390_FEAT_KM_TDEA_192, - S390_FEAT_KIMD_SHA_1, - S390_FEAT_KLMD_SHA_1, + S390_FEAT_KM_TDEA_192, + S390_FEAT_KIMD_SHA_1, + S390_FEAT_KLMD_SHA_1, + /* CSSKE is deprecated on newer generations */ + S390_FEAT_CONDITIONAL_SSKE, - }; - int i; + }; + int i; This patch is also needed for Ubuntu 18.04 and 19.04. 18.10 will be out of service in July..... -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1830704 Title: [UBUNTU] QEMU toleration patch to ensure cpu detection in a nested KVM To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu-z-systems/+bug/1830704/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
