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Date:   Fri, 21 Jul 2023 18:29:19 -0700
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Subject: Re: [PATCH v4 2/9] virt: geniezone: Add GenieZone hypervisor support
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 <ea531ba80db67cccb03ea173e714fe868f869e91.camel@mediatek.com>
From:   Trilok Soni <quic_tsoni@quicinc.com>
In-Reply-To: <ea531ba80db67cccb03ea173e714fe868f869e91.camel@mediatek.com>
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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@mediatek.com>
>>>
>>> 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