Re: [PATCH v13 11/19] xen/pvh: Secondary VCPU bringup (non-bootup CPUs)

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

On Mon, Jan 06, 2014 at 10:52:39AM +0000, David Vrabel wrote:
> On 03/01/14 19:38, Konrad Rzeszutek Wilk wrote:
> > From: Mukesh Rathor <mukesh.rathor@oracle.com>
> > 
> > The VCPU bringup protocol follows the PV with certain twists.
> > From xen/include/public/arch-x86/xen.h:
> > 
> > Also note that when calling DOMCTL_setvcpucontext and VCPU_initialise
> > for HVM and PVH guests, not all information in this structure is updated:
> > 
> >  - For HVM guests, the structures read include: fpu_ctxt (if
> >  VGCT_I387_VALID is set), flags, user_regs, debugreg[*]
> > 
> >  - PVH guests are the same as HVM guests, but additionally use ctrlreg[3] to
> >  set cr3. All other fields not used should be set to 0.
> > 
> > This is what we do. We piggyback on the 'xen_setup_gdt' - but modify
> > a bit - we need to call 'load_percpu_segment' so that 'switch_to_new_gdt'
> > can load per-cpu data-structures. It has no effect on the VCPU0.
> > 
> > We also piggyback on the %rdi register to pass in the CPU number - so
> > that when we bootup a new CPU, the cpu_bringup_and_idle will have
> > passed as the first parameter the CPU number (via %rdi for 64-bit).
> [...]
> > --- a/arch/x86/xen/enlighten.c
> > +++ b/arch/x86/xen/enlighten.c
> > @@ -1409,14 +1409,19 @@ static void __init xen_boot_params_init_edd(void)
> >   * Set up the GDT and segment registers for -fstack-protector.  Until
> >   * we do this, we have to be careful not to call any stack-protected
> >   * function, which is most of the kernel.
> > + *
> > + * Note, that it is refok - because the only caller of this after init
> 
> "Note, this is __ref because..."

Fixed.

Thank you.
> 
> David