On Wed, 2017-01-25 at 15:50 -0800, Eric Wheeler wrote: > Hello All, > > We discovered guests hanging when using the 4.1.y kernel after 4.1.16 with > live migration after CentOS applied this patch to the latest version of > qemu-kvm user space: > https://git.centos.org/blob/rpms!!qemu-kvm.git/34b32196890e2c41b0aee042e600ba422f29db17/SOURCES!kvm-target-i386-get-put-MSR_TSC_AUX-across-reset-and-mig.patch > > Please also see this Bugzilla entry: > https://bugzilla.redhat.com/show_bug.cgi?id=1408333 > > After a bisect, We found this commit to be causing the hang: > 8a3185c54d650a86dafc8d8bcafa124b50944315 KVM: x86: expose MSR_TSC_AUX to userspace > > It turns out that this is not actually the problem, but rather these > commits need to be pulled in as well to support the 8a31 commit: > 609e36d372a KVM: x86: pass host_initiated to functions that read MSRs > 81b1b9ca6d5 KVM: VMX: Fix host initiated access to guest MSR_TSC_AUX > > Thus, we need to either: > 1. Revert commit 8a3185c54d650a86dafc8d8bcafa124b50944315 > - or - > 2. Merge commits 609e36d372a and 81b1b9ca6d5 into 4.1.y. > > If you choose the latter options, then please see below for the backport > patch of 81b1b9ca6d5 (609e36d372a cherry-picks just fine). > > What do you believe would be best? For 3.2 and 3.16, I will revert the change. Thanks for tracking this down. Ben. -- Ben Hutchings Unix is many things to many people, but it's never been everything to anybody.
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