2016-12-21 16:09 GMT+08:00 Ladi Prosek <lprosek@xxxxxxxxxx>: > On Wed, Dec 21, 2016 at 8:31 AM, Wanpeng Li <kernellwp@xxxxxxxxx> wrote: >> 2016-11-30 23:03 GMT+08:00 Ladi Prosek <lprosek@xxxxxxxxxx>: >>> KVM does not correctly handle L1 hypervisors that emulate L2 real mode with >>> PAE and EPT, such as Hyper-V. In this mode, the L1 hypervisor populates guest >>> PDPTE VMCS fields and leaves guest CR3 uninitialized because it is not used >> >> How L1 hypervisor populates guest PDPTE VMCS fields if undereference CR3？ > > L2 is free to write anything to CR3. From its perspective it's still > running in real mode so CR3 is effectively a general purpose register. > If L1 intercepts CR3 accesses, it just shadows the value in the guest > CR3 VMCS field so it's preserved across vmexists. It does not and > should not dereference it. > > Let me know if I misunderstood the question. I just confuse how PDPTE VMCS field is set when CR3 is uninitialized, I think it should be from something like ept_identity_map_addr in Hyper-V. Regards, Wanpeng Li -- 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
