On Tue, Mar 12, 2013 at 01:09:44PM -0600, Earl Marwil wrote: > > On 03/11/2013 02:27 AM, Gleb Natapov wrote: > > 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. > > > Thank you Stephan and Gleb. You are both right. I tried setting the > kvm_intel module parameter as Gleb suggested. Running under kernel > 3.7.9-205.fc18.x86_64, my VM failed to start with the log message: > Yes, emulate_invalid_guest_state = 0 was broke in 3.7. 3.9, when released, should work without it. -- 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
