Re: [PATCH] KVM: nVMX: VMX instructions: fix segment checks when L1 is in long mode.

Paolo Bonzini
2016-06-23T16:04:30Z

On 18/06/2016 11:01, Quentin Casasnovas wrote:
> Cross-checking the KVM/VMX VMREAD emulation code with the Intel Software
> Developper Manual Volume 3C - "VMREAD - Read Field from Virtual-Machine
> Control Structure", I found that we're enforcing that the destination
> operand is NOT located in a read-only data segment or any code segment when
> the L1 is in long mode - BUT that check should only happen when it is in
> protected mode.
>
> Shuffling the code a bit to make our emulation follow the specification
> allows me to boot a Xen dom0 in a nested KVM and start HVM L2 guests
> without problems.

That's great, and I'm applying the patch, but it's also pretty weird. :)
Do you have a pointer to Xen source code that does a VMREAD into a
read-only data segment or a code segment?

Thanks,

Paolo