Re: [PATCH v3 2/4] drivers/s390/char: Add Query Ultravisor Information to uvdevice

[Janosch Frank <frankja@linux.ibm.com>]

On 3/4/22 15:11, Steffen Eiden wrote:
> This patch enables userspace to call the Query Ultravisor Information
> Ultravisor Call using IOCTLs on the uvdevice.
> 
> The uvdevice will do some sanity checks first, build the UVCB,
> perform the UV call, and copy the result to userspace.
> 
> Signed-off-by: Steffen Eiden <seiden@linux.ibm.com>


Reviewed-by: Janosch Frank <frankja@linux.ibm.com>

> ---
>   arch/s390/include/uapi/asm/uvdevice.h |  2 +
>   drivers/s390/char/uvdevice.c          | 56 +++++++++++++++++++++++++++
>   2 files changed, 58 insertions(+)
> 
> diff --git a/arch/s390/include/uapi/asm/uvdevice.h b/arch/s390/include/uapi/asm/uvdevice.h
> index d40f69345c75..7520bdde3102 100644
> --- a/arch/s390/include/uapi/asm/uvdevice.h
> +++ b/arch/s390/include/uapi/asm/uvdevice.h
> @@ -42,10 +42,12 @@ struct uvio_attest {
>   #define UVIO_ATT_ARCB_MAX_LEN		0x100000
>   #define UVIO_ATT_MEASUREMENT_MAX_LEN	0x8000
>   #define UVIO_ATT_ADDITIONAL_MAX_LEN	0x8000
> +#define UVIO_QUI_MAX_LEN		0x8000
>   
>   #define UVIO_DEVICE_NAME "uv"
>   #define UVIO_TYPE_UVC 'u'
>   
>   #define UVIO_IOCTL_ATT _IOWR(UVIO_TYPE_UVC, 0x01, struct uvio_ioctl_cb)
> +#define UVIO_IOCTL_QUI _IOWR(UVIO_TYPE_UVC, 0x02, struct uvio_ioctl_cb)
>   
>   #endif  /* __S390X_ASM_UVDEVICE_H */
> diff --git a/drivers/s390/char/uvdevice.c b/drivers/s390/char/uvdevice.c
> index b720dc8d0bd9..cfce8c5999e6 100644
> --- a/drivers/s390/char/uvdevice.c
> +++ b/drivers/s390/char/uvdevice.c
> @@ -31,6 +31,55 @@
>   #include <asm/uvdevice.h>
>   #include <asm/uv.h>
>   
> +/**
> + * uvio_qui() - Perform a Query Ultravisor Information UVC.
> + *
> + * uv_ioctl: ioctl control block
> + *
> + * uvio_qui() does a Query Ultravisor Information (QUI) Ultravisor Call.
> + * It creates the uvc qui request and sends it to the Ultravisor. After that
> + * it copies the response to userspace and fills the rc and rrc of uv_ioctl
> + * uv_call with the response values of the Ultravisor.
> + *
> + * Create the UVC structure, send the UVC to UV and write the response in the ioctl struct.
> + *
> + * Return: 0 on success or a negative error code on error.
> + */
> +static int uvio_qui(struct uvio_ioctl_cb *uv_ioctl)
> +{
> +	u8 __user *user_buf_addr = (__user u8 *)uv_ioctl->argument_addr;
> +	size_t user_buf_len = uv_ioctl->argument_len;
> +	struct uv_cb_header *uvcb_qui = NULL;
> +	int ret;
> +
> +	/*
> +	 * Do not check for a too small buffer. If userspace provides a buffer
> +	 * that is too small the Ultravisor will complain.
> +	 */
> +	ret = -EINVAL;
> +	if (!user_buf_len || user_buf_len > UVIO_QUI_MAX_LEN)
> +		goto out;
> +	ret = -ENOMEM;
> +	uvcb_qui = kvzalloc(user_buf_len, GFP_KERNEL);
> +	if (!uvcb_qui)
> +		goto out;
> +	uvcb_qui->len = user_buf_len;
> +	uvcb_qui->cmd = UVC_CMD_QUI;
> +
> +	uv_call(0, (u64)uvcb_qui);
> +
> +	ret = -EFAULT;
> +	if (copy_to_user(user_buf_addr, uvcb_qui, uvcb_qui->len))
> +		goto out;
> +	uv_ioctl->uv_rc = uvcb_qui->rc;
> +	uv_ioctl->uv_rrc = uvcb_qui->rrc;
> +
> +	ret = 0;
> +out:
> +	kvfree(uvcb_qui);
> +	return ret;
> +}
> +
>   static int uvio_build_uvcb_attest(struct uv_cb_attest *uvcb_attest, u8 *arcb,
>   				  u8 *meas, u8 *add_data, struct uvio_attest *uvio_attest)
>   {
> @@ -217,6 +266,13 @@ static long uvio_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
>   			goto out;
>   		ret = uvio_attestation(uv_ioctl);
>   		break;
> +	case UVIO_IOCTL_QUI:
> +		ret = uvio_copy_and_check_ioctl(uv_ioctl, argp);
> +		if (ret)
> +			goto out;
> +		ret = uvio_qui(uv_ioctl);
> +		break;
> +
>   	default:
>   		ret = -ENOIOCTLCMD;
>   		break;