1 files changed, 352 insertions, 0 deletions
diff --git a/arch/powerpc/platforms/pseries/papr-sysparm.c b/arch/powerpc/platforms/pseries/papr-sysparm.c
new file mode 100644
index 000000000000..7063ce8884e4
--- /dev/null
+++ b/arch/powerpc/platforms/pseries/papr-sysparm.c
@@ -0,0 +1,352 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#define pr_fmt(fmt)	"papr-sysparm: " fmt
+
+#include <linux/anon_inodes.h>
+#include <linux/bug.h>
+#include <linux/file.h>
+#include <linux/fs.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/miscdevice.h>
+#include <linux/printk.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+#include <asm/machdep.h>
+#include <asm/papr-sysparm.h>
+#include <asm/rtas-work-area.h>
+#include <asm/rtas.h>
+
+struct papr_sysparm_buf *papr_sysparm_buf_alloc(void)
+{
+	struct papr_sysparm_buf *buf = kzalloc(sizeof(*buf), GFP_KERNEL);
+
+	return buf;
+}
+
+void papr_sysparm_buf_free(struct papr_sysparm_buf *buf)
+{
+	kfree(buf);
+}
+
+static size_t papr_sysparm_buf_get_length(const struct papr_sysparm_buf *buf)
+{
+	return be16_to_cpu(buf->len);
+}
+
+static void papr_sysparm_buf_set_length(struct papr_sysparm_buf *buf, size_t length)
+{
+	WARN_ONCE(length > sizeof(buf->val),
+		  "bogus length %zu, clamping to safe value", length);
+	length = min(sizeof(buf->val), length);
+	buf->len = cpu_to_be16(length);
+}
+
+/*
+ * For use on buffers returned from ibm,get-system-parameter before
+ * returning them to callers. Ensures the encoded length of valid data
+ * cannot overrun buf->val[].
+ */
+static void papr_sysparm_buf_clamp_length(struct papr_sysparm_buf *buf)
+{
+	papr_sysparm_buf_set_length(buf, papr_sysparm_buf_get_length(buf));
+}
+
+/*
+ * Perform some basic diligence on the system parameter buffer before
+ * submitting it to RTAS.
+ */
+static bool papr_sysparm_buf_can_submit(const struct papr_sysparm_buf *buf)
+{
+	/*
+	 * Firmware ought to reject buffer lengths that exceed the
+	 * maximum specified in PAPR, but there's no reason for the
+	 * kernel to allow them either.
+	 */
+	if (papr_sysparm_buf_get_length(buf) > sizeof(buf->val))
+		return false;
+
+	return true;
+}
+
+/**
+ * papr_sysparm_get() - Retrieve the value of a PAPR system parameter.
+ * @param: PAPR system parameter token as described in
+ *         7.3.16 "System Parameters Option".
+ * @buf: A &struct papr_sysparm_buf as returned from papr_sysparm_buf_alloc().
+ *
+ * Place the result of querying the specified parameter, if available,
+ * in @buf. The result includes a be16 length header followed by the
+ * value, which may be a string or binary data. See &struct papr_sysparm_buf.
+ *
+ * Since there is at least one parameter (60, OS Service Entitlement
+ * Status) where the results depend on the incoming contents of the
+ * work area, the caller-supplied buffer is copied unmodified into the
+ * work area before calling ibm,get-system-parameter.
+ *
+ * A defined parameter may not be implemented on a given system, and
+ * some implemented parameters may not be available to all partitions
+ * on a system. A parameter's disposition may change at any time due
+ * to system configuration changes or partition migration.
+ *
+ * Context: This function may sleep.
+ *
+ * Return: 0 on success, -errno otherwise. @buf is unmodified on error.
+ */
+int papr_sysparm_get(papr_sysparm_t param, struct papr_sysparm_buf *buf)
+{
+	const s32 token = rtas_function_token(RTAS_FN_IBM_GET_SYSTEM_PARAMETER);
+	struct rtas_work_area *work_area;
+	s32 fwrc;
+	int ret;
+
+	might_sleep();
+
+	if (WARN_ON(!buf))
+		return -EFAULT;
+
+	if (token == RTAS_UNKNOWN_SERVICE)
+		return -ENOENT;
+
+	if (!papr_sysparm_buf_can_submit(buf))
+		return -EINVAL;
+
+	work_area = rtas_work_area_alloc(sizeof(*buf));
+
+	memcpy(rtas_work_area_raw_buf(work_area), buf, sizeof(*buf));
+
+	do {
+		fwrc = rtas_call(token, 3, 1, NULL, param.token,
+				 rtas_work_area_phys(work_area),
+				 rtas_work_area_size(work_area));
+	} while (rtas_busy_delay(fwrc));
+
+	switch (fwrc) {
+	case 0:
+		ret = 0;
+		memcpy(buf, rtas_work_area_raw_buf(work_area), sizeof(*buf));
+		papr_sysparm_buf_clamp_length(buf);
+		break;
+	case -3: /* parameter not implemented */
+		ret = -EOPNOTSUPP;
+		break;
+	case -9002: /* this partition not authorized to retrieve this parameter */
+		ret = -EPERM;
+		break;
+	case -9999: /* "parameter error" e.g. the buffer is too small */
+		ret = -EINVAL;
+		break;
+	default:
+		pr_err("unexpected ibm,get-system-parameter result %d\n", fwrc);
+		fallthrough;
+	case -1: /* Hardware/platform error */
+		ret = -EIO;
+		break;
+	}
+
+	rtas_work_area_free(work_area);
+
+	return ret;
+}
+
+int papr_sysparm_set(papr_sysparm_t param, const struct papr_sysparm_buf *buf)
+{
+	const s32 token = rtas_function_token(RTAS_FN_IBM_SET_SYSTEM_PARAMETER);
+	struct rtas_work_area *work_area;
+	s32 fwrc;
+	int ret;
+
+	might_sleep();
+
+	if (WARN_ON(!buf))
+		return -EFAULT;
+
+	if (token == RTAS_UNKNOWN_SERVICE)
+		return -ENOENT;
+
+	if (!papr_sysparm_buf_can_submit(buf))
+		return -EINVAL;
+
+	work_area = rtas_work_area_alloc(sizeof(*buf));
+
+	memcpy(rtas_work_area_raw_buf(work_area), buf, sizeof(*buf));
+
+	do {
+		fwrc = rtas_call(token, 2, 1, NULL, param.token,
+				 rtas_work_area_phys(work_area));
+	} while (rtas_busy_delay(fwrc));
+
+	switch (fwrc) {
+	case 0:
+		ret = 0;
+		break;
+	case -3: /* parameter not supported */
+		ret = -EOPNOTSUPP;
+		break;
+	case -9002: /* this partition not authorized to modify this parameter */
+		ret = -EPERM;
+		break;
+	case -9999: /* "parameter error" e.g. invalid input data */
+		ret = -EINVAL;
+		break;
+	default:
+		pr_err("unexpected ibm,set-system-parameter result %d\n", fwrc);
+		fallthrough;
+	case -1: /* Hardware/platform error */
+		ret = -EIO;
+		break;
+	}
+
+	rtas_work_area_free(work_area);
+
+	return ret;
+}
+
+static struct papr_sysparm_buf *
+papr_sysparm_buf_from_user(const struct papr_sysparm_io_block __user *user_iob)
+{
+	struct papr_sysparm_buf *kern_spbuf;
+	long err;
+	u16 len;
+
+	/*
+	 * The length of valid data that userspace claims to be in
+	 * user_iob->data[].
+	 */
+	if (get_user(len, &user_iob->length))
+		return ERR_PTR(-EFAULT);
+
+	static_assert(sizeof(user_iob->data) >= PAPR_SYSPARM_MAX_INPUT);
+	static_assert(sizeof(kern_spbuf->val) >= PAPR_SYSPARM_MAX_INPUT);
+
+	if (len > PAPR_SYSPARM_MAX_INPUT)
+		return ERR_PTR(-EINVAL);
+
+	kern_spbuf = papr_sysparm_buf_alloc();
+	if (!kern_spbuf)
+		return ERR_PTR(-ENOMEM);
+
+	papr_sysparm_buf_set_length(kern_spbuf, len);
+
+	if (len > 0 && copy_from_user(kern_spbuf->val, user_iob->data, len)) {
+		err = -EFAULT;
+		goto free_sysparm_buf;
+	}
+
+	return kern_spbuf;
+
+free_sysparm_buf:
+	papr_sysparm_buf_free(kern_spbuf);
+	return ERR_PTR(err);
+}
+
+static int papr_sysparm_buf_to_user(const struct papr_sysparm_buf *kern_spbuf,
+				    struct papr_sysparm_io_block __user *user_iob)
+{
+	u16 len_out = papr_sysparm_buf_get_length(kern_spbuf);
+
+	if (put_user(len_out, &user_iob->length))
+		return -EFAULT;
+
+	static_assert(sizeof(user_iob->data) >= PAPR_SYSPARM_MAX_OUTPUT);
+	static_assert(sizeof(kern_spbuf->val) >= PAPR_SYSPARM_MAX_OUTPUT);
+
+	if (copy_to_user(user_iob->data, kern_spbuf->val, PAPR_SYSPARM_MAX_OUTPUT))
+		return -EFAULT;
+
+	return 0;
+}
+
+static long papr_sysparm_ioctl_get(struct papr_sysparm_io_block __user *user_iob)
+{
+	struct papr_sysparm_buf *kern_spbuf;
+	papr_sysparm_t param;
+	long ret;
+
+	if (get_user(param.token, &user_iob->parameter))
+		return -EFAULT;
+
+	kern_spbuf = papr_sysparm_buf_from_user(user_iob);
+	if (IS_ERR(kern_spbuf))
+		return PTR_ERR(kern_spbuf);
+
+	ret = papr_sysparm_get(param, kern_spbuf);
+	if (ret)
+		goto free_sysparm_buf;
+
+	ret = papr_sysparm_buf_to_user(kern_spbuf, user_iob);
+	if (ret)
+		goto free_sysparm_buf;
+
+	ret = 0;
+
+free_sysparm_buf:
+	papr_sysparm_buf_free(kern_spbuf);
+	return ret;
+}
+
+
+static long papr_sysparm_ioctl_set(struct papr_sysparm_io_block __user *user_iob)
+{
+	struct papr_sysparm_buf *kern_spbuf;
+	papr_sysparm_t param;
+	long ret;
+
+	if (get_user(param.token, &user_iob->parameter))
+		return -EFAULT;
+
+	kern_spbuf = papr_sysparm_buf_from_user(user_iob);
+	if (IS_ERR(kern_spbuf))
+		return PTR_ERR(kern_spbuf);
+
+	ret = papr_sysparm_set(param, kern_spbuf);
+	if (ret)
+		goto free_sysparm_buf;
+
+	ret = 0;
+
+free_sysparm_buf:
+	papr_sysparm_buf_free(kern_spbuf);
+	return ret;
+}
+
+static long papr_sysparm_ioctl(struct file *filp, unsigned int ioctl, unsigned long arg)
+{
+	void __user *argp = (__force void __user *)arg;
+	long ret;
+
+	switch (ioctl) {
+	case PAPR_SYSPARM_IOC_GET:
+		ret = papr_sysparm_ioctl_get(argp);
+		break;
+	case PAPR_SYSPARM_IOC_SET:
+		if (filp->f_mode & FMODE_WRITE)
+			ret = papr_sysparm_ioctl_set(argp);
+		else
+			ret = -EBADF;
+		break;
+	default:
+		ret = -ENOIOCTLCMD;
+		break;
+	}
+	return ret;
+}
+
+static const struct file_operations papr_sysparm_ops = {
+	.unlocked_ioctl = papr_sysparm_ioctl,
+};
+
+static struct miscdevice papr_sysparm_dev = {
+	.minor = MISC_DYNAMIC_MINOR,
+	.name = "papr-sysparm",
+	.fops = &papr_sysparm_ops,
+};
+
+static __init int papr_sysparm_init(void)
+{
+	if (!rtas_function_implemented(RTAS_FN_IBM_GET_SYSTEM_PARAMETER))
+		return -ENODEV;
+
+	return misc_register(&papr_sysparm_dev);
+}
+machine_device_initcall(pseries, papr_sysparm_init);