[Bug 103321] New: NPT page attribute support causes extreme slowdown

[bugzilla-daemon@bugzilla.kernel.org]

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.

-- 
You are receiving this mail because:
You are watching the assignee of the bug.