From: "Arnd Bergmann" <arnd@arndb.de>
To: "Alex Elder" <alex.elder@linaro.org>,
"Elliot Berman" <quic_eberman@quicinc.com>,
"Srinivas Kandagatla" <srinivas.kandagatla@linaro.org>,
"Alex Elder" <elder@linaro.org>,
"Jonathan Corbet" <corbet@lwn.net>,
"Prakruthi Deepak Heragu" <quic_pheragu@quicinc.com>
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>,
"Dmitry Baryshkov" <dmitry.baryshkov@linaro.org>,
"Bjorn Andersson" <andersson@kernel.org>,
"Konrad Dybcio" <konrad.dybcio@linaro.org>,
"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
"Rob Herring" <robh+dt@kernel.org>,
"Krzysztof Kozlowski" <krzysztof.kozlowski+dt@linaro.org>,
"Bagas Sanjaya" <bagasdotme@gmail.com>,
"Catalin Marinas" <catalin.marinas@arm.com>,
"Jassi Brar" <jassisinghbrar@gmail.com>,
linux-arm-msm@vger.kernel.org, devicetree@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v10 10/26] gunyah: vm_mgr: Introduce basic VM Manager
Date: Tue, 28 Feb 2023 10:19:00 +0100 [thread overview]
Message-ID: <90bc1f6c-95c5-43a5-a39c-6a72bdf4a4f5@app.fastmail.com> (raw)
In-Reply-To: <fcd61f55-f445-9721-3490-ed70b7b30293@linaro.org>
On Tue, Feb 28, 2023, at 02:06, Alex Elder wrote:
> On 2/24/23 4:48 PM, Elliot Berman wrote:
>> I'd be open to making GH_CREATE_VM take a struct argument today, but I
>> really don't know what size or what needs to be in that struct. My hope
>> is that we can get away with just an integer for future needs. If
>> integer doesn't suit, then new ioctl would need to be created. I think
>> there's same problem if I pick some struct today (the struct may not
>> suit tomorrow and we need to create new ioctl for the new struct).
>
> I'd like someone to back me up (or tell me I'm wrong), but...
>
> I think you can still pass a void in/out pointer, which can
> be interpreted in an IOCTL-specific way, as long as it can
> be unambiguously processed.
>
> So if you passed a non-null pointer, what it referred to
> could contain a key that defines the way to interpret it.
>
> You can't take away a behavior you've once supported, but I
> *think* you can add a new behavior (with a new structure
> that identifies itself).
>
> So if that is correct, you can extend a single IOCTL. But
> sadly I can't tell you I'm sure this is correct.
In general you are correct that the behavior of an ioctl
command can be changed by reusing a combination of inputs that
was previously prohibited. I can't think of a case where that
would be a good idea though, as this just adds more complexity
than defining a new ioctl command code.
Interface versions and multiplexed ioctl commands are
all discouraged for the same reason.
Arnd
WARNING: multiple messages have this Message-ID (diff)
From: "Arnd Bergmann" <arnd@arndb.de>
To: "Alex Elder" <alex.elder@linaro.org>,
"Elliot Berman" <quic_eberman@quicinc.com>,
"Srinivas Kandagatla" <srinivas.kandagatla@linaro.org>,
"Alex Elder" <elder@linaro.org>,
"Jonathan Corbet" <corbet@lwn.net>,
"Prakruthi Deepak Heragu" <quic_pheragu@quicinc.com>
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>,
"Dmitry Baryshkov" <dmitry.baryshkov@linaro.org>,
"Bjorn Andersson" <andersson@kernel.org>,
"Konrad Dybcio" <konrad.dybcio@linaro.org>,
"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
"Rob Herring" <robh+dt@kernel.org>,
"Krzysztof Kozlowski" <krzysztof.kozlowski+dt@linaro.org>,
"Bagas Sanjaya" <bagasdotme@gmail.com>,
"Catalin Marinas" <catalin.marinas@arm.com>,
"Jassi Brar" <jassisinghbrar@gmail.com>,
linux-arm-msm@vger.kernel.org, devicetree@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v10 10/26] gunyah: vm_mgr: Introduce basic VM Manager
Date: Tue, 28 Feb 2023 10:19:00 +0100 [thread overview]
Message-ID: <90bc1f6c-95c5-43a5-a39c-6a72bdf4a4f5@app.fastmail.com> (raw)
In-Reply-To: <fcd61f55-f445-9721-3490-ed70b7b30293@linaro.org>
On Tue, Feb 28, 2023, at 02:06, Alex Elder wrote:
> On 2/24/23 4:48 PM, Elliot Berman wrote:
>> I'd be open to making GH_CREATE_VM take a struct argument today, but I
>> really don't know what size or what needs to be in that struct. My hope
>> is that we can get away with just an integer for future needs. If
>> integer doesn't suit, then new ioctl would need to be created. I think
>> there's same problem if I pick some struct today (the struct may not
>> suit tomorrow and we need to create new ioctl for the new struct).
>
> I'd like someone to back me up (or tell me I'm wrong), but...
>
> I think you can still pass a void in/out pointer, which can
> be interpreted in an IOCTL-specific way, as long as it can
> be unambiguously processed.
>
> So if you passed a non-null pointer, what it referred to
> could contain a key that defines the way to interpret it.
>
> You can't take away a behavior you've once supported, but I
> *think* you can add a new behavior (with a new structure
> that identifies itself).
>
> So if that is correct, you can extend a single IOCTL. But
> sadly I can't tell you I'm sure this is correct.
In general you are correct that the behavior of an ioctl
command can be changed by reusing a combination of inputs that
was previously prohibited. I can't think of a case where that
would be a good idea though, as this just adds more complexity
than defining a new ioctl command code.
Interface versions and multiplexed ioctl commands are
all discouraged for the same reason.
Arnd
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linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2023-02-28 9:19 UTC|newest]
Thread overview: 222+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-14 21:12 [PATCH v10 00/26] Drivers for Gunyah hypervisor Elliot Berman
2023-02-14 21:12 ` Elliot Berman
2023-02-14 21:12 ` [PATCH v10 01/26] docs: gunyah: Introduce Gunyah Hypervisor Elliot Berman
2023-02-14 21:12 ` Elliot Berman
2023-02-23 23:41 ` Alex Elder
2023-02-23 23:41 ` Alex Elder
2023-03-01 0:00 ` Elliot Berman
2023-03-01 0:00 ` Elliot Berman
2023-02-14 21:12 ` [PATCH v10 02/26] dt-bindings: Add binding for gunyah hypervisor Elliot Berman
2023-02-14 21:12 ` Elliot Berman
2023-02-14 21:12 ` [PATCH v10 03/26] gunyah: Common types and error codes for Gunyah hypercalls Elliot Berman
2023-02-14 21:12 ` Elliot Berman
2023-02-23 21:58 ` Alex Elder
2023-02-23 21:58 ` Alex Elder
2023-03-02 1:40 ` Elliot Berman
2023-03-02 1:40 ` Elliot Berman
2023-03-02 7:18 ` Arnd Bergmann
2023-03-02 7:18 ` Arnd Bergmann
2023-02-14 21:12 ` [PATCH v10 04/26] virt: gunyah: Add hypercalls to identify Gunyah Elliot Berman
2023-02-14 21:12 ` Elliot Berman
2023-02-20 13:59 ` Srinivas Kandagatla
2023-02-20 13:59 ` Srinivas Kandagatla
2023-02-24 0:09 ` Alex Elder
2023-02-24 0:09 ` Alex Elder
2023-03-02 1:21 ` Elliot Berman
2023-03-02 1:21 ` Elliot Berman
2023-02-14 21:18 ` Elliot Berman
2023-02-14 21:18 ` Elliot Berman
2023-02-14 21:21 ` [PATCH v10 05/26] virt: gunyah: Identify hypervisor version Elliot Berman
2023-02-14 21:21 ` Elliot Berman
2023-02-14 21:23 ` [PATCH v10 06/26] virt: gunyah: msgq: Add hypercalls to send and receive messages Elliot Berman
2023-02-14 21:23 ` Elliot Berman
2023-02-24 0:15 ` Alex Elder
2023-02-24 0:15 ` Alex Elder
2023-02-24 21:24 ` Elliot Berman
2023-02-24 21:24 ` Elliot Berman
2023-02-14 21:23 ` [PATCH v10 07/26] mailbox: Add Gunyah message queue mailbox Elliot Berman
2023-02-14 21:23 ` Elliot Berman
2023-02-16 4:07 ` kernel test robot
2023-02-16 4:07 ` kernel test robot
2023-02-20 13:59 ` Srinivas Kandagatla
2023-02-20 13:59 ` Srinivas Kandagatla
2023-02-23 0:15 ` Elliot Berman
2023-02-23 0:15 ` Elliot Berman
2023-02-23 10:25 ` Srinivas Kandagatla
2023-02-23 10:25 ` Srinivas Kandagatla
2023-02-23 23:15 ` Elliot Berman
2023-02-23 23:15 ` Elliot Berman
2023-02-24 7:49 ` Srinivas Kandagatla
2023-02-24 7:49 ` Srinivas Kandagatla
2023-02-23 18:24 ` Alex Elder
2023-02-23 18:24 ` Alex Elder
2023-02-23 21:11 ` Alex Elder
2023-02-23 21:11 ` Alex Elder
2023-02-24 21:57 ` Elliot Berman
2023-02-24 21:57 ` Elliot Berman
2023-02-14 21:23 ` [PATCH v10 08/26] gunyah: rsc_mgr: Add resource manager RPC core Elliot Berman
2023-02-14 21:23 ` Elliot Berman
2023-02-16 6:43 ` Greg Kroah-Hartman
2023-02-16 6:43 ` Greg Kroah-Hartman
2023-02-16 17:40 ` Elliot Berman
2023-02-16 17:40 ` Elliot Berman
2023-02-17 7:37 ` Greg Kroah-Hartman
2023-02-17 7:37 ` Greg Kroah-Hartman
2023-02-22 22:52 ` Elliot Berman
2023-02-22 22:52 ` Elliot Berman
2023-02-20 18:10 ` Srinivas Kandagatla
2023-02-20 18:10 ` Srinivas Kandagatla
2023-02-22 23:18 ` Elliot Berman
2023-02-22 23:18 ` Elliot Berman
2023-02-23 10:29 ` Srinivas Kandagatla
2023-02-23 10:29 ` Srinivas Kandagatla
2023-02-23 23:13 ` Elliot Berman
2023-02-23 23:13 ` Elliot Berman
2023-02-28 0:52 ` Alex Elder
2023-02-28 0:52 ` Alex Elder
2023-02-28 22:49 ` Elliot Berman
2023-02-28 22:49 ` Elliot Berman
2023-02-23 23:28 ` Alex Elder
2023-02-23 23:28 ` Alex Elder
2023-02-24 22:39 ` Elliot Berman
2023-02-24 22:39 ` Elliot Berman
2023-02-14 21:23 ` [PATCH v10 09/26] gunyah: rsc_mgr: Add VM lifecycle RPC Elliot Berman
2023-02-14 21:23 ` Elliot Berman
2023-02-16 6:39 ` Greg Kroah-Hartman
2023-02-16 6:39 ` Greg Kroah-Hartman
2023-02-16 17:18 ` Elliot Berman
2023-02-16 17:18 ` Elliot Berman
2023-02-21 7:50 ` Srinivas Kandagatla
2023-02-21 7:50 ` Srinivas Kandagatla
2023-02-23 21:36 ` Alex Elder
2023-02-23 21:36 ` Alex Elder
2023-02-23 23:10 ` Elliot Berman
2023-02-23 23:10 ` Elliot Berman
2023-02-14 21:23 ` [PATCH v10 10/26] gunyah: vm_mgr: Introduce basic VM Manager Elliot Berman
2023-02-14 21:23 ` Elliot Berman
2023-02-21 10:46 ` Srinivas Kandagatla
2023-02-21 10:46 ` Srinivas Kandagatla
2023-02-22 0:27 ` Elliot Berman
2023-02-22 0:27 ` Elliot Berman
2023-02-23 10:08 ` Srinivas Kandagatla
2023-02-23 10:08 ` Srinivas Kandagatla
2023-02-23 22:40 ` Elliot Berman
2023-02-23 22:40 ` Elliot Berman
2023-02-24 10:29 ` Srinivas Kandagatla
2023-02-24 10:29 ` Srinivas Kandagatla
2023-02-24 13:20 ` Arnd Bergmann
2023-02-24 13:20 ` Arnd Bergmann
2023-02-24 22:48 ` Elliot Berman
2023-02-24 22:48 ` Elliot Berman
2023-02-28 1:06 ` Alex Elder
2023-02-28 1:06 ` Alex Elder
2023-02-28 9:19 ` Arnd Bergmann [this message]
2023-02-28 9:19 ` Arnd Bergmann
2023-02-21 13:06 ` Srivatsa Vaddagiri
2023-02-21 13:06 ` Srivatsa Vaddagiri
2023-02-14 21:24 ` [PATCH v10 11/26] gunyah: rsc_mgr: Add RPC for sharing memory Elliot Berman
2023-02-14 21:24 ` Elliot Berman
2023-02-21 11:07 ` Srinivas Kandagatla
2023-02-21 11:07 ` Srinivas Kandagatla
2023-02-14 21:24 ` [PATCH v10 12/26] gunyah: vm_mgr: Add/remove user memory regions Elliot Berman
2023-02-14 21:24 ` Elliot Berman
2023-02-16 6:38 ` Greg Kroah-Hartman
2023-02-16 6:38 ` Greg Kroah-Hartman
2023-02-16 17:24 ` Elliot Berman
2023-02-16 17:24 ` Elliot Berman
2023-02-21 12:28 ` Srinivas Kandagatla
2023-02-21 12:28 ` Srinivas Kandagatla
2023-02-21 12:43 ` Srivatsa Vaddagiri
2023-02-21 12:43 ` Srivatsa Vaddagiri
2023-02-24 0:43 ` Elliot Berman
2023-02-24 0:43 ` Elliot Berman
2023-02-24 10:36 ` Srinivas Kandagatla
2023-02-24 10:36 ` Srinivas Kandagatla
2023-02-21 12:45 ` Srivatsa Vaddagiri
2023-02-21 12:45 ` Srivatsa Vaddagiri
2023-02-24 0:34 ` Alex Elder
2023-02-24 0:34 ` Alex Elder
2023-02-25 1:03 ` Elliot Berman
2023-02-25 1:03 ` Elliot Berman
2023-02-24 10:19 ` Fuad Tabba
2023-02-24 10:19 ` Fuad Tabba
2023-02-24 18:08 ` Elliot Berman
2023-02-24 18:08 ` Elliot Berman
2023-02-24 18:58 ` Sean Christopherson
2023-02-24 18:58 ` Sean Christopherson
2023-02-27 9:55 ` Fuad Tabba
2023-02-27 9:55 ` Fuad Tabba
2023-02-14 21:24 ` [PATCH v10 13/26] gunyah: vm_mgr: Add ioctls to support basic non-proxy VM boot Elliot Berman
2023-02-14 21:24 ` Elliot Berman
2023-02-16 6:35 ` Greg Kroah-Hartman
2023-02-16 6:35 ` Greg Kroah-Hartman
2023-02-16 17:20 ` Elliot Berman
2023-02-16 17:20 ` Elliot Berman
2023-02-20 9:15 ` Srivatsa Vaddagiri
2023-02-20 9:15 ` Srivatsa Vaddagiri
2023-02-20 9:54 ` Srivatsa Vaddagiri
2023-02-20 9:54 ` Srivatsa Vaddagiri
2023-02-21 13:06 ` Srivatsa Vaddagiri
2023-02-21 13:06 ` Srivatsa Vaddagiri
2023-02-21 14:17 ` Srinivas Kandagatla
2023-02-21 14:17 ` Srinivas Kandagatla
2023-02-23 0:50 ` Elliot Berman
2023-02-23 0:50 ` Elliot Berman
2023-02-23 9:21 ` Srinivas Kandagatla
2023-02-23 9:21 ` Srinivas Kandagatla
2023-02-14 21:24 ` [PATCH v10 14/26] samples: Add sample userspace Gunyah VM Manager Elliot Berman
2023-02-14 21:24 ` Elliot Berman
2023-02-14 21:24 ` [PATCH v10 15/26] gunyah: rsc_mgr: Add platform ops on mem_lend/mem_reclaim Elliot Berman
2023-02-14 21:24 ` Elliot Berman
2023-02-21 14:51 ` Srinivas Kandagatla
2023-02-21 14:51 ` Srinivas Kandagatla
2023-02-21 21:22 ` Elliot Berman
2023-02-21 21:22 ` Elliot Berman
2023-02-22 10:21 ` Srinivas Kandagatla
2023-02-22 10:21 ` Srinivas Kandagatla
2023-02-23 1:55 ` Elliot Berman
2023-02-23 1:55 ` Elliot Berman
2023-02-14 21:24 ` [PATCH v10 16/26] firmware: qcom_scm: Register Gunyah platform ops Elliot Berman
2023-02-14 21:24 ` Elliot Berman
2023-02-16 0:22 ` kernel test robot
2023-02-16 0:22 ` kernel test robot
2023-02-16 11:09 ` kernel test robot
2023-02-16 11:09 ` kernel test robot
2023-02-21 14:55 ` Srinivas Kandagatla
2023-02-21 14:55 ` Srinivas Kandagatla
2023-02-14 21:25 ` [PATCH v10 17/26] docs: gunyah: Document Gunyah VM Manager Elliot Berman
2023-02-14 21:25 ` Elliot Berman
2023-02-23 23:55 ` Alex Elder
2023-02-23 23:55 ` Alex Elder
2023-02-14 21:25 ` [PATCH v10 18/26] virt: gunyah: Translate gh_rm_hyp_resource into gunyah_resource Elliot Berman
2023-02-14 21:25 ` Elliot Berman
2023-02-21 17:47 ` Srinivas Kandagatla
2023-02-21 17:47 ` Srinivas Kandagatla
2023-02-14 21:25 ` [PATCH v10 19/26] gunyah: vm_mgr: Add framework to add VM Functions Elliot Berman
2023-02-14 21:25 ` Elliot Berman
2023-02-17 13:23 ` Srivatsa Vaddagiri
2023-02-17 13:23 ` Srivatsa Vaddagiri
2023-02-21 13:07 ` Srivatsa Vaddagiri
2023-02-21 13:07 ` Srivatsa Vaddagiri
2023-02-21 17:58 ` Srinivas Kandagatla
2023-02-21 17:58 ` Srinivas Kandagatla
2023-02-22 14:08 ` Srinivas Kandagatla
2023-02-22 14:08 ` Srinivas Kandagatla
2023-02-24 23:44 ` Elliot Berman
2023-02-24 23:44 ` Elliot Berman
2023-02-14 21:25 ` [PATCH v10 20/26] virt: gunyah: Add resource tickets Elliot Berman
2023-02-14 21:25 ` Elliot Berman
2023-02-14 21:25 ` [PATCH v10 21/26] virt: gunyah: Add IO handlers Elliot Berman
2023-02-14 21:25 ` Elliot Berman
2023-02-14 21:26 ` [PATCH v10 22/26] virt: gunyah: Add proxy-scheduled vCPUs Elliot Berman
2023-02-14 21:26 ` Elliot Berman
2023-02-14 21:26 ` [PATCH v10 23/26] virt: gunyah: Add hypercalls for sending doorbell Elliot Berman
2023-02-14 21:26 ` Elliot Berman
2023-02-14 21:26 ` [PATCH v10 24/26] virt: gunyah: Add irqfd interface Elliot Berman
2023-02-14 21:26 ` Elliot Berman
2023-02-14 21:26 ` [PATCH v10 25/26] virt: gunyah: Add ioeventfd Elliot Berman
2023-02-14 21:26 ` Elliot Berman
2023-02-14 21:26 ` [PATCH v10 26/26] MAINTAINERS: Add Gunyah hypervisor drivers section Elliot Berman
2023-02-14 21:26 ` Elliot Berman
2023-02-23 21:59 ` [PATCH v10 00/26] Drivers for Gunyah hypervisor Alex Elder
2023-02-23 21:59 ` Alex Elder
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