From: Elliot Berman <quic_eberman@quicinc.com>
To: Arnd Bergmann <arnd@arndb.de>,
Bjorn Andersson <quic_bjorande@quicinc.com>,
Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Cc: Murali Nalajala <quic_mnalajal@quicinc.com>,
Trilok Soni <quic_tsoni@quicinc.com>,
Srivatsa Vaddagiri <quic_svaddagi@quicinc.com>,
Carl van Schaik <quic_cvanscha@quicinc.com>,
Prakruthi Deepak Heragu <quic_pheragu@quicinc.com>,
Andy Gross <agross@kernel.org>,
Jassi Brar <jassisinghbrar@gmail.com>,
<linux-arm-kernel@lists.infradead.org>,
"Mark Rutland" <mark.rutland@arm.com>,
Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
Sudeep Holla <sudeep.holla@arm.com>,
"Marc Zyngier" <maz@kernel.org>, Rob Herring <robh+dt@kernel.org>,
"Krzysztof Kozlowski" <krzysztof.kozlowski+dt@linaro.org>,
Jonathan Corbet <corbet@lwn.net>, Will Deacon <will@kernel.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Srinivas Kandagatla <srinivas.kandagatla@linaro.org>,
Amol Maheshwari <amahesh@qti.qualcomm.com>,
Kalle Valo <kvalo@kernel.org>, <devicetree@vger.kernel.org>,
<linux-doc@vger.kernel.org>, <linux-arm-msm@vger.kernel.org>,
<linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v6 13/21] gunyah: vm_mgr: Introduce basic VM Manager
Date: Thu, 3 Nov 2022 15:10:07 -0700 [thread overview]
Message-ID: <25174792-4b8e-9c0d-0272-8b5010406365@quicinc.com> (raw)
In-Reply-To: <a3754259-9989-495e-a6bd-5501daff06a2@app.fastmail.com>
On 11/3/2022 2:39 AM, Arnd Bergmann wrote:
> On Wed, Nov 2, 2022, at 19:44, Elliot Berman wrote:
>> On 11/2/2022 12:31 AM, Arnd Bergmann wrote:
>>>> +static long gh_dev_ioctl_create_vm(unsigned long arg)
>>>> +{
>>>> + struct gunyah_vm *ghvm;
>>>> + struct file *file;
>>>> + int fd, err;
>>>> +
>>>> + /* arg reserved for future use. */
>>>> + if (arg)
>>>> + return -EINVAL;
>>>
>>> Do you have something specific in mind here? If 'create'
>>> is the only command you support, and it has no arguments,
>>> it would be easier to do it implicitly during open() and
>>> have each fd opened from /dev/gunyah represent a new VM.
>>>
>>
>> I'd like the argument here to support different types of virtual
>> machines. I want to leave open what "different types" can be in case
>> something new comes up in the future, but immediately "different type"
>> would correspond to a few different authentication mechanisms for
>> virtual machines that Gunyah supports.
>>
>> In this series, I'm only supporting unauthenticated virtual machines
>> because they are the simplest to get up and running from a Linux
>> userspace. When I introduce the other authentication mechanisms, I'll
>> expand much more on how they work, but I'll give quick overview here.
>> Other authentication mechanisms that are currently supported by Gunyah
>> are "protected VM" and, on Qualcomm platforms, "PIL/carveout VMs".
>> Protected VMs are *loosely* similar to the protected firmware design for
>> KVM and intended to support Android virtualization use cases.
>> PIL/carevout VMs are special virtual machines that can run on Qualcomm
>> firmware which authenticate in a way similar to remoteproc firmware (MDT
>> loader).
>
> Ok, thanks for the background. Having different types of virtual
> machines does mean that you may need some complexity, but I would
> still lean towards using the simpler context management of opening
> the /dev/gunyah device node to get a new context, and then using
> ioctls on each fd to manage that context, instead of going through
> the extra indirection of having a secondary 'open context' command
> that always requires opening two file descriptors.
>
>>> I'm correct, you can just turn the entire bus/device/driver
>>> structure within your code into simple function calls, where
>>> the main code calls vm_mgr_probe() as an exported function
>>> instead of creating a device.
>>
>> Ack. I can do this, although I am nervous about this snowballing into a
>> situation where I have a mega-module.
>>
>> > Please stop beating everything in a single module.
>>
>> https://lore.kernel.org/all/250945d2-3940-9830-63e5-beec5f44010b@linaro.org/
>
> I see you concern, but I wasn't suggesting having everything
> in one module either. There are three common ways of splitting
> things into separate modules:
>
> - I suggested having the vm_mgr module as a library block that
> exports a few symbols which get used by the core module. The
> module doesn't do anything on its own, but loading the core
> module forces loading the vm_mgr.
>
Got the idea, I'll do this.
- Elliot
> - Alternatively one can do the opposite, and have symbols
> exported by the core module, with the vm_mgr module using
> it. This would make sense if you commonly have the core
> module loaded on virtual machines that do not need to manage
> other VMs.
>
> - The method you have is to have a lower "bus" level that
> abstracts device providers from consumers, with both sides
> hooking into the bus. This makes sense for physical buses
> like PCI or USB where both the host driver and the function
> driver are unaware of implementation details of the other,
> but in your case it does not seem like a good fit.
>
> Arnd
next prev parent reply other threads:[~2022-11-03 22:10 UTC|newest]
Thread overview: 68+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-26 18:58 [PATCH v6 00/21] Drivers for gunyah hypervisor Elliot Berman
2022-10-26 18:58 ` [PATCH v6 01/21] docs: gunyah: Introduce Gunyah Hypervisor Elliot Berman
2022-11-02 12:35 ` Bagas Sanjaya
2022-10-26 18:58 ` [PATCH v6 02/21] dt-bindings: Add binding for gunyah hypervisor Elliot Berman
2022-10-27 19:57 ` Krzysztof Kozlowski
2022-10-28 2:33 ` Jassi Brar
2022-11-01 3:19 ` Elliot Berman
2022-11-01 16:23 ` Jassi Brar
2022-11-01 20:35 ` Elliot Berman
2022-11-01 21:58 ` Jassi Brar
2022-11-02 0:12 ` Elliot Berman
2022-11-02 2:01 ` Jassi Brar
2022-11-02 18:05 ` Elliot Berman
2022-11-02 18:24 ` Jassi Brar
2022-11-02 23:23 ` Elliot Berman
2022-11-03 3:21 ` Jassi Brar
2022-11-03 19:45 ` Elliot Berman
2022-10-26 18:58 ` [PATCH v6 03/21] gunyah: Common types and error codes for Gunyah hypercalls Elliot Berman
2022-10-26 19:47 ` Dmitry Baryshkov
2022-10-26 18:58 ` [PATCH v6 04/21] arm64: smccc: Include alternative-macros.h Elliot Berman
2022-10-26 19:46 ` Dmitry Baryshkov
2022-10-26 20:23 ` Elliot Berman
2022-10-26 20:39 ` Dmitry Baryshkov
2022-10-26 18:58 ` [PATCH v6 05/21] virt: gunyah: Add hypercalls to identify Gunyah Elliot Berman
2022-10-26 18:58 ` [PATCH v6 06/21] virt: gunyah: Identify hypervisor version Elliot Berman
2022-10-26 18:58 ` [PATCH v6 07/21] mailbox: Allow direct registration to a channel Elliot Berman
2022-10-26 18:58 ` [PATCH v6 08/21] virt: gunyah: msgq: Add hypercalls to send and receive messages Elliot Berman
2022-10-26 18:58 ` [PATCH v6 09/21] mailbox: Add Gunyah message queue mailbox Elliot Berman
2022-10-27 13:55 ` Pavan Kondeti
2022-11-01 17:44 ` Elliot Berman
2022-10-26 18:58 ` [PATCH v6 10/21] gunyah: rsc_mgr: Add resource manager RPC core Elliot Berman
2022-11-01 18:02 ` Greg Kroah-Hartman
2022-11-02 0:12 ` Elliot Berman
2022-11-02 2:53 ` Greg Kroah-Hartman
2022-11-02 18:04 ` Elliot Berman
2022-11-03 0:22 ` Greg Kroah-Hartman
2022-11-03 22:07 ` Elliot Berman
2022-11-03 22:09 ` Elliot Berman
2022-10-26 18:58 ` [PATCH v6 11/21] gunyah: rsc_mgr: Add subdevices bus Elliot Berman
2022-10-26 18:58 ` [PATCH v6 12/21] gunyah: rsc_mgr: Add VM lifecycle RPC Elliot Berman
2022-10-26 18:58 ` [PATCH v6 13/21] gunyah: vm_mgr: Introduce basic VM Manager Elliot Berman
2022-11-02 5:14 ` Greg Kroah-Hartman
2022-11-02 18:45 ` Elliot Berman
2022-11-03 0:24 ` Greg Kroah-Hartman
2022-11-04 0:11 ` Elliot Berman
2022-11-04 8:10 ` Arnd Bergmann
2022-11-04 22:38 ` Elliot Berman
2022-11-05 4:19 ` Trilok Soni
2022-11-11 0:03 ` Elliot Berman
2022-11-11 6:24 ` Greg Kroah-Hartman
2022-11-11 17:08 ` Elliot Berman
2022-11-02 7:31 ` Arnd Bergmann
2022-11-02 18:44 ` Elliot Berman
2022-11-03 0:20 ` Greg Kroah-Hartman
2022-11-03 22:33 ` Elliot Berman
2022-11-03 9:39 ` Arnd Bergmann
2022-11-03 22:10 ` Elliot Berman [this message]
2022-10-26 18:58 ` [PATCH v6 14/21] gunyah: rsc_mgr: Add RPC for sharing memory Elliot Berman
2022-10-26 18:58 ` [PATCH v6 15/21] gunyah: vm_mgr: Add/remove user memory regions Elliot Berman
2022-10-26 18:58 ` [PATCH v6 16/21] gunyah: vm_mgr: Add ioctls to support basic non-proxy VM boot Elliot Berman
2022-10-26 18:58 ` [PATCH v6 17/21] samples: Add sample userspace Gunyah VM Manager Elliot Berman
2022-10-26 18:58 ` [PATCH v6 18/21] gunyah: rsc_mgr: Add platform ops on mem_lend/mem_reclaim Elliot Berman
2022-10-26 18:58 ` [PATCH v6 19/21] firmware: qcom_scm: Use fixed width src vm bitmap Elliot Berman
2022-10-26 18:58 ` [PATCH v6 20/21] firmware: qcom_scm: Register Gunyah platform ops Elliot Berman
2022-10-26 21:32 ` kernel test robot
2022-10-26 18:58 ` [PATCH v6 21/21] docs: gunyah: Document Gunyah VM Manager Elliot Berman
2022-11-02 13:05 ` Bagas Sanjaya
2022-11-02 18:04 ` Elliot Berman
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