linux-kernel - Re: [PATCH v1 5/6] s390/uvdevice: Add List Secrets Ext IOCTL

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Message-Id: <D4KLU6A3D449.1P07EI9XL7IY2@linux.ibm.com>
Date: Tue, 01 Oct 2024 18:19:50 +0200
From: "Christoph Schlameuss" <schlameuss@...ux.ibm.com>
To: "Steffen Eiden" <seiden@...ux.ibm.com>, <linux-kernel@...r.kernel.org>,
        <linux-s390@...r.kernel.org>
Cc: "Ingo Franzki" <ifranzki@...ux.ibm.com>,
        "Harald Freudenberger"
 <freude@...ux.ibm.com>,
        "Janosch Frank" <frankja@...ux.ibm.com>,
        "Claudio
 Imbrenda" <imbrenda@...ux.ibm.com>
Subject: Re: [PATCH v1 5/6] s390/uvdevice: Add List Secrets Ext IOCTL

On Mon Sep 30, 2024 at 3:19 PM CEST, Steffen Eiden wrote:
> Add an extended List Secrets IOCTL. In contrast to the first list IOCTL
> this accepts an index as the first two bytes of the provided page as an
> input. This index is then taken as the index offset for the list UVC to
> receive later entries for the list.
>
> Signed-off-by: Steffen Eiden <seiden@...ux.ibm.com>

[...]

> +/* The actual list(_ext) IOCTL.
> + * If list_ext is true, the first two bytes of the user buffer set the starting index of the
> + * list-UVC
> + */
> +static int list_secrets(struct uvio_ioctl_cb *uv_ioctl, bool list_ext)
> +{
> +	void __user *user_buf_arg = (void __user *)uv_ioctl->argument_addr;
> +	u16 __user *user_index = (u16 __user *)uv_ioctl->argument_addr;
> +	u16 start_idx = 0;
> +	u8 *secrets = NULL;
> +	int ret;

nit: These can be reordered to reverse xmas tree.

> +
> +	if (uv_ioctl->argument_len != UVIO_LIST_SECRETS_LEN)
> +		return -EINVAL;
> +
> +	BUILD_BUG_ON(UVIO_LIST_SECRETS_LEN != PAGE_SIZE);
> +	secrets = (u8 *)get_zeroed_page(GFP_KERNEL);
> +	if (!secrets)
> +		return -ENOMEM;
> +
> +	// The extended call accepts an u16 index as input

Comments should use /* */

> +	ret = -EFAULT;
> +	if (list_ext) {
> +		if (get_user(start_idx, user_index))
> +			goto err;
> +	}
> +
> +	uv_list_secrets(secrets, start_idx, &uv_ioctl->uv_rc, &uv_ioctl->uv_rrc);
> +
> +	if (copy_to_user(user_buf_arg, secrets, UVIO_LIST_SECRETS_LEN))
> +		goto err;
> +	ret = 0;
> +
> +err:
> +	free_pages((unsigned long)secrets, 0);
> +	return ret;
> +}

[...]