SRU request submitted for Artful and Bionic:
https://lists.ubuntu.com/archives/kernel-team/2018-January/089404.html
** Description changed:
+ == SRU Justification ==
+ The following mainline commit introduced a regression in v4.12-rc1:
+ 2c82878b0cb3 ("KVM: VMX: require virtual NMI support")
+
+ This regression caused the kvm-intel module fail to load with the following
error:
+ "modprobe: ERROR: could not insert 'kvm_intel': Input/output error"
+
+ This error would happen because suppor for CPUs without virtual NMI was
removed
+ by commit 2c82878b0cb3.
+
+ Mainline commit 8a1b43922d0d fixes this regression and was added to
+ mainline in v4.15-rc1.
+
+
+ == Fix ==
+ commit 8a1b43922d0d1279e7936ba85c4c2a870403c95f
+ Author: Paolo Bonzini <pbonz...@redhat.com>
+ Date: Mon Nov 6 13:31:12 2017 +0100
+
+ kvm: vmx: Reinstate support for CPUs without virtual NMI
+
+ == Regression Potential ==
+ Low. This patch fixes a current regression. It was cc'd to upstream stable
+ so had additional upstream review.
+
+
+ ## Original Bug Description ##
Since upgrading from zesty to artful, I'm not longer able to use KVM on my
server:
# modprobe kvm-intel
modprobe: ERROR: could not insert 'kvm_intel': Input/output error
Searching tells me this is caused by requiring Virtual NMI support[1]
Running the script provided on the mailing list[1] to check virtualization
features confirms my CPU (Xeon E5345) doesn't support Virtual NMIs:
# python features.py | grep NMI
- NMI exiting yes
- Virtual NMIs no
- NMI-window exiting no
+ NMI exiting yes
+ Virtual NMIs no
+ NMI-window exiting no
Virtual NMI support was required in v4.12[1] and later reverted in
v4.14.3[2] as some models (including Xeons) don't support it, even if
others with the same core do.
-
[1] https://bugzilla.redhat.com/show_bug.cgi?id=1490803
[2] https://lkml.org/lkml/2017/8/7/231
[3]
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git/commit/arch/x86/kvm/vmx.c?h=linux-4.13.y&id=2c82878b0cb38fd516fd612c67852a6bbf282003
[4]
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git/commit/arch/x86/kvm/vmx.c?h=linux-4.14.y&id=a77360e989f3dc06e4f177a0837d533d13a20d91
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https://bugs.launchpad.net/bugs/1741655
Title:
Regression: KVM no longer supports Intel CPUs without Virtual NMI
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