Re: [PATCH v4 2/9] virt: geniezone: Add GenieZone hypervisor support

[Trilok Soni]

On 7/21/2023 1:46 AM, Yi-De Wu (吳一德) wrote:
> On Fri, 2023-06-09 at 17:22 +0200, Krzysztof Kozlowski wrote:
> >   	
> > External email : Please do not click links or open attachments until
> > you have verified the sender or the content.
> >   On 09/06/2023 10:52, Yi-De Wu wrote:
> > > From: "Yingshiuan Pan" <yingshiuan.pan@xxxxxxxxxxxx>
> > >
> > > GenieZone is MediaTek hypervisor solution, and it is running in EL2
> > > stand alone as a type-I hypervisor. This patch exports a set of
> > ioctl
> > > interfaces for userspace VMM (e.g., crosvm) to operate guest VMs
> > > lifecycle (creation and destroy) on GenieZone.
> >
> > ...
> >
> > > +static int gzvm_drv_probe(void)
> > > +{
> > > +int ret;
> > > +
> > > +if (gzvm_arch_probe() != 0) {
> > > +pr_err("Not found available conduit\n");
> > > +return -ENODEV;
> > > +}
> > > +
> > > +ret = misc_register(&gzvm_dev);
> > > +if (ret)
> > > +return ret;
> > > +gzvm_debug_dev = &gzvm_dev;
> > > +
> > > +return 0;
> > > +}
> > > +
> > > +static int gzvm_drv_remove(void)
> > > +{
> > > +destroy_all_vm();
> > > +misc_deregister(&gzvm_dev);
> > > +return 0;
> > > +}
> > > +
> > > +static int gzvm_dev_init(void)
> > > +{
> > > +return gzvm_drv_probe();
> >
> > So for every system and architecture you want to: probe, run some SMC
> > and then print error that it is not othe system you wanted.
> >
> > I don't think this is what we want. You basically pollute all of
> > other
> > users just to have your hypervisor guest additions...
> >
> >
> > Best regards,
> > Krzysztof
>
>
> hi Krzysztof,
>
> After some back-and-forth discussion[1][2][3][4][5], we'd like to bring
> bakc all the attension of related issues in this thread.
>
> We're going to restore the dt solution on our next version, which means
> we would maintain a simple dt for discovering the hypervisor node and
> probe for the status of the device when needed.

.. see the comment below.

> The reasons are listed below for the record.
> - Although dt is for hardware, it's difficult to discover a specific
> hypervisor without probing on all subsystem and thus pollute all of
> other users[4] as a consequence.

I don't understand. Patches will help here to understand what exactly 
you are referring here.

> - The GenieZone hypervisor could be considered as a vendor model to
> assist platform virtualization whose implementation is independent from
> Linuxism.

Then why we are adding this hypervisor support in Linux?

> Please let us if there're any other concerns.
>
> Reference
>
> [1]
> https://android-review.googlesource.com/c/kernel/common/+/2447547/comment/495502f3_bb52344b/

Why we look at the ACK patches here on the LKML? Please submit them here 
if you would like to discuss and review?

---Trilok Soni