[PATCH v6 02/21] dt-bindings: Add binding for gunyah hypervisor

[Jassi Brar]

On Tue, Nov 1, 2022 at 3:35 PM Elliot Berman <quic_eberman at quicinc.com> wrote:
>
>
>
> On 11/1/2022 9:23 AM, Jassi Brar wrote:
> > On Mon, Oct 31, 2022 at 10:20 PM Elliot Berman <quic_eberman at quicinc.com> wrote:
> >>
> >> Hi Jassi,
> >>
> >> On 10/27/2022 7:33 PM, Jassi Brar wrote:
> >>   > On Wed, Oct 26, 2022 at 1:59 PM Elliot Berman
> >> <quic_eberman at quicinc.com> wrote:
> >>   > .....
> >>   >> +
> >>   >> +        gunyah-resource-mgr at 0 {
> >>   >> +            compatible = "gunyah-resource-manager-1-0",
> >> "gunyah-resource-manager";
> >>   >> +            interrupts = <GIC_SPI 3 IRQ_TYPE_EDGE_RISING>, /* TX
> >> full IRQ */
> >>   >> +                         <GIC_SPI 4 IRQ_TYPE_EDGE_RISING>; /* RX
> >> empty IRQ */
> >>   >> +            reg = <0x00000000 0x00000000>, <0x00000000 0x00000001>;
> >>   >> +                  /* TX, RX cap ids */
> >>   >> +        };
> >>   >>
> >>   > All these resources are used only by the mailbox controller driver.
> >>   > So, this should be the mailbox controller node, rather than the
> >>   > mailbox user.> One option is to load gunyah-resource-manager as a
> >> module that relies
> >>   > on the gunyah-mailbox provider. That would also avoid the "Allow
> >>   > direct registration to a channel" hack patch.
> >>
> >> A message queue to another guest VM wouldn't be known at boot time and
> >> thus couldn't be described on the devicetree.
> >>
> > I think you need to implement of_xlate() ... or please tell me what
> > exactly you need to specify in the dt.
>
> Dynamically created virtual machines can't be known on the dt, so there
> is nothing to specify in the DT. There couldn't be a devicetree node for
> the message queue client because that client is only exists once the VM
> is created by userspace.
>
The underlying "physical channel" is the synchronous SMC instruction,
which remains 1 irrespective of the number of mailbox instances
created.
So basically you are sharing one resource among users. Why doesn't the
RM request the "smc instruction" channel once and share it among
users?

-j