Re: [PATCH v5 19/19] KVM: selftests: Add test for KVM_SET_USER_MEMORY_REGION

Sean Christopherson
2020-02-06T23:11:27Z

On Thu, Feb 06, 2020 at 05:30:01PM -0500, Peter Xu wrote:
> On Tue, Jan 21, 2020 at 02:31:57PM -0800, Sean Christopherson wrote:
> > Add a KVM selftest to test moving the base gfn of a userspace memory
> > region. Although the basic concept of moving memory regions is not x86
> > specific, the assumptions regarding large pages and MMIO shenanigans
> > used to verify the correctness make this x86_64 only for the time being.
> >
> > Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
>
> (I'm a bit curious why write 2 first before 1...)

To verify KVM actually relocated the memslot and didn't leave anything in
the TLB. If "2" isn't written, KVM could completely botch the MOVE but the
guest_code() would still signal pass because it would eventually see the
0-> transitions.

> Reviewed-by: Peter Xu <peterx@redhat.com>
>
> --
> Peter Xu
>