Re: [PATCH 30/30] x86, kaiser, xen: Dynamically disable KAISER when running under Xen PV

[Juergen Gross]

On 08/11/17 20:47, Dave Hansen wrote:
> From: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
> 
> If you paravirtualize the MMU, you can not use KAISER.  This boils down
> to the fact that KAISER needs to do CR3 writes in places that it is not
> feasible to do real hypercalls.
> 
> If we detect that Xen PV is in use, do not do the KAISER CR3 switches.
> 
> I don't think this too bug of a deal for Xen.  I was under the
> impression that the Xen guest kernel and Xen guest userspace didn't
> share an address space *anyway* so Xen PV is not normally even exposed
> to the kinds of things that KAISER protects against.
> 
> This allows KAISER=y kernels to deployed in environments that also
> require PARAVIRT=y.
> 
> Signed-off-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>

Acked-by: Juergen Gross <jgross@xxxxxxxx>


Juergen