Re: [PATCH 2/2] xen/pv: Call get_cpu_address_sizes to set x86_virt/phys_bits

[M. Vefa Bicakci]

On 07/21/2018 05:25 PM, Boris Ostrovsky wrote:
> On 07/21/2018 03:49 PM, M. Vefa Bicakci wrote:
> > diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c
> > index 439a94bf89ad..87afb000142a 100644
> > --- a/arch/x86/xen/enlighten_pv.c
> > +++ b/arch/x86/xen/enlighten_pv.c
> > @@ -1257,6 +1257,7 @@ asmlinkage __visible void __init xen_start_kernel(void)
> >   
> >   	/* Work out if we support NX */
> >   	get_cpu_cap(&boot_cpu_data);
> > +	get_cpu_address_sizes(&boot_cpu_data);
> >   	x86_configure_nx();
>
>
> Have you observed any problems without this call? get_cpu_cap() is only
> called here to set X86_FEATURE_NX, and is then called again, together
> with get_cpu_address_sizes(), from early_identify_cpu().

Hello Boris,

Thank you for the reviews! Without the call to get_cpu_address_sizes,
paravirtualized virtual machines do not boot up kernels with versions
4.17 and up at all; this includes dom0 and domU. No domU logs are
generated in dom0's /var/log/xen/console/ directory either, despite
having earlyprintk=xen on the kernel command line for my test domU.

(For the record, I am using the patched version of Xen 4.6.6 provided
by Qubes OS R3.2.)

Thank you,

Vefa