On Mon, Mar 11, 2013 at 09:09:13AM +0100, Stefan Hajnoczi wrote: > On Sat, Mar 09, 2013 at 12:43:32PM -0700, Earl Marwil wrote: > > Hi, > > > > I'm looking for some guidance on how to get to the root cause of an > > issue that I am observing with a win2k guest that won't boot under > > Fedora 18 on one system but will boot on another. A few days ago I > > posted on the fedora forum: > > > > http://forums.fedoraforum.org/showthread.php?t=289401 > > > > I can repeat the details in this thread if requested. The issue is that, > > with a fresh build of Fedora 18, updated to the most recent kernel and > > packages on an external USB ssd, my win2k VM boots on my laptop (Core > > i73720QM processor) but does not boot on my desktop system (Core i7-870 > > processor). > > > > I'm not sure whether this is a kvm issue or a kernel issue. I'll be glad > > to dig deeper, just let me what information is needed. > > Hi Earl, > >From your forum post: > > KVM internal error. Suberror: 1 > emulation failure > EAX=63700200 EBX=0000e6f5 ECX=0000000f EDX=00000936 > ... > Code=74 1d b0 37 e6 70 eb 00 e4 71 eb 00 32 e4 c1 c0 04 c0 c8 04 <d5> 0a 3d 13 0 > 0 75 04 b8 7a 15 c3 b8 00 00 c3 55 8b ec 1e 06 56 57 8b 46 04 8e d8 8b 76 06 > > Here is my guess: > > Laptop has a CPU from 2012. Desktop has a CPU from 2009. > > Intel added "unrestricted guest" support to VMX. This feature allows > the CPU to run real mode code in guest mode. > > CPUs that do not support "unrestricted guest" (your desktop?) use an > emulator implemented in software inside the kvm.ko kernel module. > > The emulator may be unable to handle the real mode instruction in the > particular kernel version you are running. > > The laptop doesn't hit this issue because it supports "unrestricted > guest" while the desktop falls back to the emulator inside kvm.ko where > it hits the bug. > > You may find that changing kernel versions on the desktop will make it > work. > > The best would be to compile a vanilla Linux kernel for the desktop > machine to verify that this issue still happens. If so, please post the > full "KVM internal error" output to this mailing list and hopefully > someone can fix the emulator. > > Problem with my theory: I haven't figured out how to check which Intel > CPU models support "unrestricted guest", so I'm not 100% sure this is > the issue. > Your theory is correct. This is the same as [1] which is fixed in 3.9. Depending on your kernel emulate_invalid_guest_state = 0 may help, or may make things even worse :( [1] https://bugzilla.kernel.org/show_bug.cgi?id=50921 -- Gleb. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
