Re: [PATCH 2/2] x86/cpu: Handle GUEST_MAXPHYADDR < HOST_MAXPHYADDR for hosts that don't support it

[Paolo Bonzini]

On 09/07/20 21:13, Eduardo Habkost wrote:
>> Doesn't this require intercepting MOV-to-CR3 when the guest is in PAE
>> mode, so that the hypervisor can validate the high bits in the PDPTEs?
> If the fix has additional overhead, is the additional overhead
> bad enough to warrant making it optional?  Most existing
> GUEST_MAXPHYADDR < HOST_MAXPHYADDR guests already work today
> without the fix.

The problematic case is when host maxphyaddr is 52.  That case wouldn't
work at all without the fix.

Paolo