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

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Date:   Fri,  4 Mar 2022 09:11:39 -0500
From:   Steffen Eiden <seiden@...ux.ibm.com>
To:     linux-s390@...r.kernel.org
Cc:     Heiko Carstens <hca@...ux.ibm.com>,
        Vasily Gorbik <gor@...ux.ibm.com>,
        Christian Borntraeger <borntraeger@...ux.ibm.com>,
        Alexander Gordeev <agordeev@...ux.ibm.com>,
        Janosch Frank <frankja@...ux.ibm.com>,
        David Hildenbrand <david@...hat.com>,
        Claudio Imbrenda <imbrenda@...ux.ibm.com>,
        Shuah Khan <shuah@...nel.org>, Nico Boehr <nrb@...ux.ibm.com>,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        linux-kselftest@...r.kernel.org
Subject: [PATCH v3 2/4] drivers/s390/char: Add Query Ultravisor Information to uvdevice

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@...ux.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;
-- 
2.25.1