[adding lkml and linux-x86_64] On 1/7/19 2:25 AM, Kirill A. Shutemov wrote: > On Fri, Jan 04, 2019 at 05:44:11AM +0000, Wei Huang wrote: >> In some old AMD KVM implementation, guest's EFER.LME bit is cleared by KVM >> when the hypervsior detects guest sets CR0.PG to 0. This causes guest OS >> to reboot when it tries to return from 32-bit trampoline code because CPU >> is in incorrect state: CR4.PAE=1, CR0.PG=1, CS.L=1, but EFER.LME=0. >> As a precaution, this patch sets EFER.LME=1 as part of long mode >> activation procedure. This extra step won't cause any harm when Linux is >> booting on bare-metal machine. >> >> Signed-off-by: Wei Huang <wei@xxxxxxxxxx> > > Thanks for tracking this down. BTW I think this patch _might_ be related the recent reboot issue reported in https://lkml.org/lkml/2018/7/1/836 since the symptoms are exactly the same. > > Acked-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx> > Fixes: 34bbb0009f3b ("x86/boot/compressed: Enable 5-level paging during decompression stage") >
