Re: [PATCH v2 08/17] x86/hyperv: handling hypercall page setup for root

[Wei Liu]

On Fri, Nov 13, 2020 at 03:33:33PM +0000, Wei Liu wrote:
> On Thu, Nov 12, 2020 at 04:51:09PM +0100, Vitaly Kuznetsov wrote:
> > Wei Liu <wei.liu@xxxxxxxxxx> writes:
> > 
> > > When Linux is running as the root partition, the hypercall page will
> > > have already been setup by Hyper-V. Copy the content over to the
> > > allocated page.
> > >
> > > The suspend, resume and cleanup paths remain untouched because they are
> > > not supported in this setup yet.
> > 
> > What about adding BUG_ONs there then?
> 
> I generally avoid cluttering code if I'm sure it definitely does not
> work.
> 
> In any case, adding BUG_ONs is not the right answer. Both hv_suspend and
> hv_resume can return an error code. I would rather just do
> 
>    if (hv_root_partition)
>        return -EPERM;
> 
> in both places.

Correction: hv_resume is void, so I won't add that code snippet. But we
should still be fine because hv_suspend will have already failed in the
first place.

Wei.