From mboxrd@z Thu Jan 1 00:00:00 1970
From: bugzilla-daemon@bugzilla.kernel.org
Subject: [Bug 103321] New: NPT page attribute support causes extreme slowdown
Date: Sat, 22 Aug 2015 22:16:12 +0000
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https://bugzilla.kernel.org/show_bug.cgi?id=103321
Bug ID: 103321
Summary: NPT page attribute support causes extreme slowdown
Product: Virtualization
Version: unspecified
Kernel Version: 4.2-rc3+
Hardware: x86-64
OS: Linux
Tree: Mainline
Status: NEW
Severity: normal
Priority: P1
Component: kvm
Assignee: virtualization_kvm@kernel-bugs.osdl.org
Reporter: dracon@ewetel.net
Regression: No
Created attachment 185501
--> https://bugzilla.kernel.org/attachment.cgi?id=185501&action=edit
dmesg
For some reason the new NPT attribute support that has been introduced with
4.3-RC3 causes my VM to run awfully slow, I managed to track this issue to
commit 3c2e7f7de3 ("KVM: SVM: use NPT page attributes").
The VM runs Win7 64bit via Qemu and uses PCI passthrough with several devices
(primary GPU, USB, audio) on a AMD 970/SB950 based Asrock 970 EXTREME3 2.0
motherboard and an AMD Phenom II X6 CPU.
There are no error/warning messages whatsoever, booting the VM takes several
minutes just to get past the first boot screen.
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