linux-kernel - Re: [PATCH v14 08/25] gunyah: rsc

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Date:   Sat, 5 Aug 2023 10:18:33 -0700
From:   Bjorn Andersson <andersson@...nel.org>
To:     Elliot Berman <quic_eberman@...cinc.com>
Cc:     Alex Elder <elder@...aro.org>,
        Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
        Prakruthi Deepak Heragu <quic_pheragu@...cinc.com>,
        Murali Nalajala <quic_mnalajal@...cinc.com>,
        Trilok Soni <quic_tsoni@...cinc.com>,
        Srivatsa Vaddagiri <quic_svaddagi@...cinc.com>,
        Carl van Schaik <quic_cvanscha@...cinc.com>,
        Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
        Konrad Dybcio <konrad.dybcio@...aro.org>,
        Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Jonathan Corbet <corbet@....net>,
        Bagas Sanjaya <bagasdotme@...il.com>,
        Will Deacon <will@...nel.org>, Andy Gross <agross@...nel.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Jassi Brar <jassisinghbrar@...il.com>,
        linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v14 08/25] gunyah: rsc_mgr: Add VM lifecycle RPC

On Tue, Jun 13, 2023 at 10:20:36AM -0700, Elliot Berman wrote:
> diff --git a/drivers/virt/gunyah/rsc_mgr_rpc.c b/drivers/virt/gunyah/rsc_mgr_rpc.c
[..]
> +/**
> + * gh_rm_alloc_vmid() - Allocate a new VM in Gunyah. Returns the VM identifier.
> + * @rm: Handle to a Gunyah resource manager
> + * @vmid: Use 0 to dynamically allocate a VM. A reserved VMID can be supplied
> + *        to request allocation of a platform-defined VM.
> + *
> + * Returns - the allocated VMID or negative value on error

kernel-doc Return:

> + */
> +int gh_rm_alloc_vmid(struct gh_rm *rm, u16 vmid)
> +{
> +	struct gh_rm_vm_common_vmid_req req_payload = {
> +		.vmid = cpu_to_le16(vmid),
> +	};
> +	struct gh_rm_vm_alloc_vmid_resp *resp_payload;
> +	size_t resp_size;
> +	void *resp;
> +	int ret;
> +
> +	ret = gh_rm_call(rm, GH_RM_RPC_VM_ALLOC_VMID, &req_payload, sizeof(req_payload), &resp,

Wrap lines at 80 characters, unless it improves readability, which is
doesn't here as you wrap it later anyways.

(The gh_rm_call() in gh_rm_common_vmid_call() above is a good example of
where going above 80 characters looks good)

> +			&resp_size);
> +	if (ret)
> +		return ret;
> +
> +	if (!vmid) {
> +		resp_payload = resp;
> +		ret = le16_to_cpu(resp_payload->vmid);
> +		kfree(resp);
> +	}

With vmid specified, will the call somehow not return a response buffer?
If this is the case please document it here with a comment.

Otherwise, you're leaking resp.

> +
> +	return ret;
> +}
> +
> +/**
> + * gh_rm_dealloc_vmid() - Dispose of a VMID
> + * @rm: Handle to a Gunyah resource manager
> + * @vmid: VM identifier allocated with gh_rm_alloc_vmid

Doesn't hurt to define the return value of all these apis.

> + */
> +int gh_rm_dealloc_vmid(struct gh_rm *rm, u16 vmid)
> +{
> +	return gh_rm_common_vmid_call(rm, GH_RM_RPC_VM_DEALLOC_VMID, vmid);
> +}
> +
> +/**
> + * gh_rm_vm_reset() - Reset a VM's resources
> + * @rm: Handle to a Gunyah resource manager
> + * @vmid: VM identifier allocated with gh_rm_alloc_vmid
> + *
> + * As part of tearing down the VM, request RM to clean up all the VM resources
> + * associated with the VM. Only after this, Linux can clean up all the

s/, Linux can/can Linux/

> + * references it maintains to resources.
> + */
> +int gh_rm_vm_reset(struct gh_rm *rm, u16 vmid)
> +{
> +	return gh_rm_common_vmid_call(rm, GH_RM_RPC_VM_RESET, vmid);
> +}
[..]
> +int gh_rm_get_hyp_resources(struct gh_rm *rm, u16 vmid,
> +				struct gh_rm_hyp_resources **resources)
> +{
> +	struct gh_rm_vm_common_vmid_req req_payload = {
> +		.vmid = cpu_to_le16(vmid),
> +	};
> +	struct gh_rm_hyp_resources *resp;
> +	size_t resp_size;
> +	int ret;
> +
> +	ret = gh_rm_call(rm, GH_RM_RPC_VM_GET_HYP_RESOURCES,
> +			 &req_payload, sizeof(req_payload),
> +			 (void **)&resp, &resp_size);
> +	if (ret)
> +		return ret;
> +
> +	if (!resp_size)
> +		return -EBADMSG;
> +
> +	if (resp_size < struct_size(resp, entries, 0) ||
> +		resp_size != struct_size(resp, entries, le32_to_cpu(resp->n_entries))) {

Indent wrapped expressions to match the previous start of that
expression.

> +		kfree(resp);
> +		return -EBADMSG;
> +	}
> +
> +	*resources = resp;
> +	return 0;
> +}
> +
> +/**
> + * gh_rm_get_vmid() - Retrieve VMID of this virtual machine
> + * @rm: Handle to a Gunyah resource manager
> + * @vmid: Filled with the VMID of this VM

In gh_rm_alloc_vmid() you return the vmid (or a errno), here you return
the value by reference. Pick one please. (Preferably return vmid)

> + */
> +int gh_rm_get_vmid(struct gh_rm *rm, u16 *vmid)
> +{
> +	static u16 cached_vmid = GH_VMID_INVAL;
> +	size_t resp_size;
> +	__le32 *resp;
> +	int ret;
> +
> +	if (cached_vmid != GH_VMID_INVAL) {
> +		*vmid = cached_vmid;
> +		return 0;
> +	}

Regards,
Bjorn