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From: Alex Elder <elder@linaro.org>
To: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>,
	Elliot Berman <quic_eberman@quicinc.com>,
	Bjorn Andersson <quic_bjorande@quicinc.com>,
	Murali Nalajala <quic_mnalajal@quicinc.com>
Cc: 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>,
	Dmitry Baryshkov <dmitry.baryshkov@linaro.org>,
	Arnd Bergmann <arnd@arndb.de>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Rob Herring <robh+dt@kernel.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
	Jonathan Corbet <corbet@lwn.net>,
	Bagas Sanjaya <bagasdotme@gmail.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>, Marc Zyngier <maz@kernel.org>,
	Jassi Brar <jassisinghbrar@gmail.com>,
	Sudeep Holla <sudeep.holla@arm.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 v9 10/27] gunyah: rsc_mgr: Add VM lifecycle RPC
Date: Mon, 6 Feb 2023 09:41:11 -0600	[thread overview]
Message-ID: <4a584563-1fb7-22fa-5e16-e0cf5e88b76b@linaro.org> (raw)
In-Reply-To: <4db1c760-10d9-3a22-106a-dda141dd5381@linaro.org>

On 2/2/23 6:46 AM, Srinivas Kandagatla wrote:
>> +    ret = gh_rm_call(rm, message_id, &req_payload, 
>> sizeof(req_payload), &resp, &resp_size);
>> +    if (!ret && resp_size) {
> 
> Am struggling to understand these type of checks in success case, when a 
> command is not expecting any response why are we checking for response 
> here, This sounds like a bug in either RM or hypervisor.
> 
> Or Is this something that happens due to some firmware behaviour?
> Could you elobrate on this.

What I think you're talking about is error checking even when
it's very clear something "can't happen."  It's a pattern I've
seen in Qualcomm downstream code, and I believe sometimes it
is done as "best practice" to avoid warnings from security scans.
(I might be wrong about this though.)

I think your underlying point though is that we can just assume
success means "truly successful," so there's no reason to do any
additional sanity checks.  We *assume* the hardware is doing the
correct thing (if it's not, we might as well assume it does
*nothing* right).

So as a very general statement, I think all checks of this type
should go away (and I think Srini would agree).

					-Alex

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  reply	other threads:[~2023-02-06 16:11 UTC|newest]

Thread overview: 76+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-01-20 22:45 [PATCH v9 00/27] Drivers for gunyah hypervisor Elliot Berman
2023-01-20 22:46 ` [PATCH v9 01/27] docs: gunyah: Introduce Gunyah Hypervisor Elliot Berman
2023-01-20 22:46 ` [PATCH v9 02/27] dt-bindings: Add binding for gunyah hypervisor Elliot Berman
2023-01-20 22:46 ` [PATCH v9 03/27] gunyah: Common types and error codes for Gunyah hypercalls Elliot Berman
2023-01-30  9:58   ` Greg Kroah-Hartman
2023-01-20 22:46 ` [PATCH v9 04/27] virt: gunyah: Add hypercalls to identify Gunyah Elliot Berman
2023-01-30 10:01   ` Greg Kroah-Hartman
2023-01-30 19:05     ` Elliot Berman
2023-01-20 22:46 ` [PATCH v9 05/27] virt: gunyah: Identify hypervisor version Elliot Berman
2023-01-20 22:46 ` [PATCH v9 06/27] mailbox: Allow direct registration to a channel Elliot Berman
2023-01-20 22:46 ` [PATCH v9 07/27] virt: gunyah: msgq: Add hypercalls to send and receive messages Elliot Berman
2023-01-31 16:16   ` Srinivas Kandagatla
2023-01-20 22:46 ` [PATCH v9 08/27] mailbox: Add Gunyah message queue mailbox Elliot Berman
2023-02-02  9:59   ` Srinivas Kandagatla
2023-02-06 14:00     ` Alex Elder
2023-02-08 20:46     ` Elliot Berman
2023-01-20 22:46 ` [PATCH v9 09/27] gunyah: rsc_mgr: Add resource manager RPC core Elliot Berman
2023-02-02 11:53   ` Srinivas Kandagatla
2023-02-06 14:14     ` Alex Elder
2023-01-20 22:46 ` [PATCH v9 10/27] gunyah: rsc_mgr: Add VM lifecycle RPC Elliot Berman
2023-01-25  6:12   ` Srivatsa Vaddagiri
2023-01-30 21:43     ` Elliot Berman
2023-02-02 12:46   ` Srinivas Kandagatla
2023-02-06 15:41     ` Alex Elder [this message]
2023-02-06 17:38       ` Elliot Berman
2023-01-20 22:46 ` [PATCH v9 11/27] gunyah: vm_mgr: Introduce basic VM Manager Elliot Berman
2023-02-02 12:54   ` Srinivas Kandagatla
2023-02-07  0:36     ` Elliot Berman
2023-01-20 22:46 ` [PATCH v9 12/27] gunyah: rsc_mgr: Add RPC for sharing memory Elliot Berman
2023-01-30 10:14   ` Srivatsa Vaddagiri
2023-01-30 21:45     ` Elliot Berman
2023-01-20 22:46 ` [PATCH v9 13/27] gunyah: vm_mgr: Add/remove user memory regions Elliot Berman
2023-01-25 13:34   ` Srivatsa Vaddagiri
2023-01-30 21:46     ` Elliot Berman
2023-02-06 16:12   ` Srinivas Kandagatla
2023-02-06 23:23     ` Elliot Berman
2023-01-20 22:46 ` [PATCH v9 14/27] gunyah: vm_mgr: Add ioctls to support basic non-proxy VM boot Elliot Berman
2023-01-30  8:53   ` Srivatsa Vaddagiri
2023-01-30 21:44     ` Elliot Berman
2023-01-30 21:45       ` Elliot Berman
2023-02-07 11:36   ` Srinivas Kandagatla
2023-02-08 21:04     ` Elliot Berman
2023-01-20 22:46 ` [PATCH v9 15/27] samples: Add sample userspace Gunyah VM Manager Elliot Berman
2023-01-20 22:46 ` [PATCH v9 16/27] gunyah: rsc_mgr: Add platform ops on mem_lend/mem_reclaim Elliot Berman
2023-01-20 22:46 ` [PATCH v9 17/27] firmware: qcom_scm: Use fixed width src vm bitmap Elliot Berman
2023-03-16  3:21   ` (subset) " Bjorn Andersson
2023-01-20 22:46 ` [PATCH v9 18/27] firmware: qcom_scm: Register Gunyah platform ops Elliot Berman
2023-01-31 15:18   ` Srivatsa Vaddagiri
2023-02-07 11:52   ` Srinivas Kandagatla
2023-02-08  1:06     ` Elliot Berman
2023-01-20 22:46 ` [PATCH v9 19/27] docs: gunyah: Document Gunyah VM Manager Elliot Berman
2023-01-20 22:46 ` [PATCH v9 20/27] virt: gunyah: Translate gh_rm_hyp_resource into gunyah_resource Elliot Berman
2023-01-20 22:46 ` [PATCH v9 21/27] gunyah: vm_mgr: Add framework to add VM Functions Elliot Berman
2023-02-03  9:37   ` Srivatsa Vaddagiri
2023-02-03 17:56     ` Srivatsa Vaddagiri
2023-02-07 13:15   ` Srinivas Kandagatla
2023-02-08 19:34     ` Elliot Berman
2023-01-20 22:46 ` [PATCH v9 22/27] virt: gunyah: Add resource tickets Elliot Berman
2023-02-06  9:50   ` Srivatsa Vaddagiri
2023-02-06 21:30     ` Elliot Berman
2023-01-20 22:46 ` [PATCH v9 23/27] virt: gunyah: Add IO handlers Elliot Berman
2023-02-06 10:46   ` Srivatsa Vaddagiri
2023-02-07  3:59     ` Elliot Berman
2023-02-07 12:19       ` Srivatsa Vaddagiri
2023-01-20 22:46 ` [PATCH v9 24/27] virt: gunyah: Add proxy-scheduled vCPUs Elliot Berman
2023-02-07 14:43   ` Srinivas Kandagatla
2023-02-08 18:36     ` Elliot Berman
2023-02-09 10:39   ` Srivatsa Vaddagiri
2023-02-10  6:54     ` Srivatsa Vaddagiri
2023-02-10 17:09       ` Elliot Berman
2023-01-20 22:46 ` [PATCH v9 25/27] virt: gunyah: Add hypercalls for sending doorbell Elliot Berman
2023-01-20 22:46 ` [PATCH v9 26/27] virt: gunyah: Add irqfd interface Elliot Berman
2023-02-07 14:30   ` Srinivas Kandagatla
2023-02-13  8:11   ` Srivatsa Vaddagiri
2023-01-20 22:46 ` [PATCH v9 27/27] virt: gunyah: Add ioeventfd Elliot Berman
2023-02-07 14:19   ` Srinivas Kandagatla

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