Re: Design doc of adding ACPI support for arm64 on Xen - version 2

[Julien Grall <julien.grall@citrix.com>]

On 11/08/15 03:09, Shannon Zhao wrote:
> Hi Julien,

Hi Shannon,

> On 2015/8/7 18:33, Julien Grall wrote:
>> Hi Shannon,
>>
>> Just some clarification questions.
>>
>> On 07/08/15 03:11, Shannon Zhao wrote:
>>> 3. Dom0 gets grant table and event channel irq information
>>> -----------------------------------------------------------
>>> As said above, we assign the hypervisor_id be "XenVMM" to tell Dom0 that
>>> it runs on Xen hypervisor.
>>>
>>> For grant table, add two new HVM_PARAMs: HVM_PARAM_GNTTAB_START_ADDRESS
>>> and HVM_PARAM_GNTTAB_SIZE.
>>>
>>> For event channel irq, reuse HVM_PARAM_CALLBACK_IRQ and add a new
>>> delivery type:
>>> val[63:56] == 3: val[15:8] is flag: val[7:0] is a PPI (ARM and ARM64
>>> only)
>>
>> Can you describe the content of flag?
>>
> 
> This needs definition as well. I think it could use the definition of
> xenv table. Bit 0 stands interrupt mode and bit 1 stands interrupt
> polarity. And explain it in the comment of HVM_PARAM_CALLBACK_IRQ.

That would be fine for me.

>>> When constructing Dom0 in Xen, save these values. Then Dom0 could get
>>> them through hypercall HVMOP_get_param.
>>>
>>> 4. Map MMIO regions
>>> -------------------
>>> Register a bus_notifier for platform and amba bus in Linux. Add a new
>>> XENMAPSPACE "XENMAPSPACE_dev_mmio". Within the register, check if the
>>> device is newly added, then call hypercall XENMEM_add_to_physmap to map
>>> the mmio regions.
>>>
>>> 5. Route device interrupts to Dom0
>>> ----------------------------------
>>> Route all the SPI interrupts to Dom0 before Dom0 booting.
>>
>> Not all the SPI will be routed to DOM0. Some are used by Xen and should
>> never be used by any guest. I have in mind the UART and SMMU interrupts.
>>
>> You will have to find away to skip them nicely. Note that not all the
>> IRQs used by Xen are properly registered when we build DOM0 (see the SMMU).
>>
> To uart, we can get the interrupt information from SPCR table and hide
> it from Dom0.

Can you clarify your meaning of "hide from DOM0"? Did you mean avoid to
route the SPI to DOM0?

> IIUC, currently Xen (as well as Linux) doesn't support use SMMU when
> booting with ACPI. When it supports, it could read the interrupts
> information from IORT table and Hide them from Dom0.

Well for Xen we don't even have ACPI supported upstream ;). For Linux
there is some on-going work. Anyway, this is not important right now.

-- 
Julien Grall