Re: [Xen-devel] [PATCH RFC v1 61/74] xen/pvshim: support vCPU hotplug

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On Tue, Jan 09, 2018 at 03:16:38AM -0700, Jan Beulich wrote:
> >>> On 04.01.18 at 14:06, <wei.liu2@xxxxxxxxxx> wrote:
> > @@ -1303,22 +1320,20 @@ long do_vcpu_op(int cmd, unsigned int vcpuid, 
> > XEN_GUEST_HANDLE_PARAM(void) arg)
> >  
> >          break;
> >  
> > -    case VCPUOP_up: {
> > -        bool_t wake = 0;
> > -        domain_lock(d);
> > -        if ( !v->is_initialised )
> > -            rc = -EINVAL;
> 
> Shouldn't this check remain here? I realize this will complicate
> locking (luckily the domain lock is a recursive one, so it shouldn't
> be too bad), but I don't think pv_shim_cpu_up() can tolerate failing
> because of vcpu_up() failing.

I guess you mean that it's unfortunate to fail in pv_shim_cpu_up after
having brought up the physical CPU if it turns out that
!v->is_initialised. I can add a check at the top of pv_shim_cpu_up for
!v->is_initialised and change vcpu_up slightly.

Regarding the usage of long, continue_hypercall_on_cpu requires a
function that returns long, so I would rather keep things as they are
now for simplicity.

Thanks, Roger.

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