On 17/07/21 12:35 am, Fabiano Rosas wrote:

"Pratik R. Sampat" [off-list ref] writes:

quoted

+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/errno.h>
+#include <linux/init.h>
+#include <linux/seq_file.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+#include <linux/hugetlb.h>
+#include <asm/lppaca.h>
+#include <asm/hvcall.h>
+#include <asm/firmware.h>
+#include <asm/time.h>
+#include <asm/prom.h>
+#include <asm/vdso_datapage.h>
+#include <asm/vio.h>
+#include <asm/mmu.h>
+#include <asm/machdep.h>
+#include <asm/drmem.h>

Do you need all of these headers? Sorry to mention just now, I seem to have
dropped this comment from a previous review.

Ah yes, that was a TODO on my part I had missed as cleanups.
I'll verify if I do need all of them and get back to you.

quoted

+
+#include "pseries.h"
+
+/*
+ * Flag attributes to fetch either all or one attribute from the HCALL
+ * flag = BE(0) => fetch all attributes with firstAttributeId = 0
+ * flag = BE(1) => fetch a single attribute with firstAttributeId = id
+ */
+#define ESI_FLAGS_ALL		0
+#define ESI_FLAGS_SINGLE	PPC_BIT(0)
+
+#define MAX_ATTRS		3
+
+struct papr_attr {
+	u64 id;
+	struct kobj_attribute kobj_attr;
+};
+struct papr_group {
+	struct attribute_group pg;
+	struct papr_attr pgattrs[MAX_ATTRS];
+} *pgs;
+
+/* /sys/firmware/papr */
+struct kobject *papr_kobj;
+/* /sys/firmware/papr/energy_scale_info */
+struct kobject *esi_kobj;
+
+/*
+ * Extract and export the description of the energy scale attribute
+ *

Extra line here.

ack.

quoted

+ */
+static ssize_t papr_show_desc(struct kobject *kobj,
+			       struct kobj_attribute *kobj_attr,
+			       char *buf)
+{
+	struct papr_attr *pattr = container_of(kobj_attr, struct papr_attr,
+					       kobj_attr);
+	struct h_energy_scale_info_hdr *t_hdr;
+	struct energy_scale_attribute *t_esi;
+	char *t_buf;
+	int ret = 0;
+
+	t_buf = kmalloc(MAX_BUF_SZ, GFP_KERNEL);
+	if (t_buf == NULL)
+		return -ENOMEM;
+
+	ret = plpar_hcall_norets(H_GET_ENERGY_SCALE_INFO, ESI_FLAGS_SINGLE,
+				 pattr->id, virt_to_phys(t_buf),
+				 MAX_BUF_SZ);
+
+	if (ret != H_SUCCESS) {
+		pr_warn("hcall failed: H_GET_ENERGY_SCALE_INFO");
+		goto out;
+	}
+
+	t_hdr = (struct h_energy_scale_info_hdr *) t_buf;
+	t_esi = (struct energy_scale_attribute *)
+		(t_buf + be64_to_cpu(t_hdr->array_offset));
+
+	ret = snprintf(buf, sizeof(t_esi->desc), "%s\n", t_esi->desc);
+	if (ret < 0)
+		ret = -EIO;
+out:
+	kfree(t_buf);
+
+	return ret;
+}
+
+/*
+ * Extract and export the numeric value of the energy scale attributes
+ */
+static ssize_t papr_show_value(struct kobject *kobj,
+				struct kobj_attribute *kobj_attr,
+				char *buf)
+{
+	struct papr_attr *pattr = container_of(kobj_attr, struct papr_attr,
+					       kobj_attr);
+	struct h_energy_scale_info_hdr *t_hdr;
+	struct energy_scale_attribute *t_esi;
+	char *t_buf;
+	int ret = 0;
+
+	t_buf = kmalloc(MAX_BUF_SZ, GFP_KERNEL);
+	if (t_buf == NULL)
+		return -ENOMEM;
+
+	ret = plpar_hcall_norets(H_GET_ENERGY_SCALE_INFO, ESI_FLAGS_SINGLE,
+				 pattr->id, virt_to_phys(t_buf),
+				 MAX_BUF_SZ);
+
+	if (ret != H_SUCCESS) {
+		pr_warn("hcall failed: H_GET_ENERGY_SCALE_INFO");
+		goto out;
+	}
+
+	t_hdr = (struct h_energy_scale_info_hdr *) t_buf;
+	t_esi = (struct energy_scale_attribute *)
+		(t_buf + be64_to_cpu(t_hdr->array_offset));
+
+	ret = snprintf(buf, sizeof(t_esi->value), "%llu\n",
+		       be64_to_cpu(t_esi->value));
+	if (ret < 0)
+		ret = -EIO;
+out:
+	kfree(t_buf);
+
+	return ret;
+}
+
+/*
+ * Extract and export the value description in string format of the energy
+ * scale attributes
+ */
+static ssize_t papr_show_value_desc(struct kobject *kobj,
+				     struct kobj_attribute *kobj_attr,
+				     char *buf)
+{
+	struct papr_attr *pattr = container_of(kobj_attr, struct papr_attr,
+					       kobj_attr);
+	struct h_energy_scale_info_hdr *t_hdr;
+	struct energy_scale_attribute *t_esi;
+	char *t_buf;
+	int ret = 0;
+
+	t_buf = kmalloc(MAX_BUF_SZ, GFP_KERNEL);
+	if (t_buf == NULL)
+		return -ENOMEM;
+
+	ret = plpar_hcall_norets(H_GET_ENERGY_SCALE_INFO, ESI_FLAGS_SINGLE,
+				 pattr->id, virt_to_phys(t_buf),
+				 MAX_BUF_SZ);
+
+	if (ret != H_SUCCESS) {
+		pr_warn("hcall failed: H_GET_ENERGY_SCALE_INFO");
+		goto out;
+	}
+
+	t_hdr = (struct h_energy_scale_info_hdr *) t_buf;
+	t_esi = (struct energy_scale_attribute *)
+		(t_buf + be64_to_cpu(t_hdr->array_offset));
+
+	ret = snprintf(buf, sizeof(t_esi->value_desc), "%s\n",
+		       t_esi->value_desc);
+	if (ret < 0)
+		ret = -EIO;
+out:
+	kfree(t_buf);
+
+	return ret;
+}
+
+static struct papr_ops_info {
+	const char *attr_name;
+	ssize_t (*show)(struct kobject *kobj, struct kobj_attribute *kobj_attr,
+			char *buf);
+} ops_info[MAX_ATTRS] = {
+	{ "desc", papr_show_desc },
+	{ "value", papr_show_value },
+	{ "value_desc", papr_show_value_desc },
+};
+
+static void add_attr(u64 id, int index, struct papr_attr *attr)
+{
+	attr->id = id;
+	sysfs_attr_init(&attr->kobj_attr.attr);
+	attr->kobj_attr.attr.name = ops_info[index].attr_name;
+	attr->kobj_attr.attr.mode = 0444;
+	attr->kobj_attr.show = ops_info[index].show;
+}
+
+static int add_attr_group(u64 id, int len, struct papr_group *pg,
+			  bool show_val_desc)
+{
+	int i;
+
+	for (i = 0; i < len; i++) {

Could use MAX_ATTRS directly.

Sure, while writing this initially I wasn't sure how many attrs we'd have so it
passed as param, now I see that's not needed so I can remove that and use
MAX_ATTRS itself

quoted

+		if (!strcmp(ops_info[i].attr_name, "value_desc") &&
+		    !show_val_desc) {
+			continue;
+		}
+		add_attr(id, i, &pg->pgattrs[i]);
+		pg->pg.attrs[i] = &pg->pgattrs[i].kobj_attr.attr;
+	}
+
+	return sysfs_create_group(esi_kobj, &pg->pg);
+}
+
+static int __init papr_init(void)
+{
+	struct h_energy_scale_info_hdr *esi_hdr;
+	struct energy_scale_attribute *esi_attrs;
+	uint64_t num_attrs;
+	int ret, idx, i;
+	char *esi_buf;
+
+	if (!firmware_has_feature(FW_FEATURE_LPAR))
+		return -ENXIO;
+
+	esi_buf = kmalloc(MAX_BUF_SZ, GFP_KERNEL);
+	if (esi_buf == NULL)
+		return -ENOMEM;
+	/*
+	 * hcall(
+	 * uint64 H_GET_ENERGY_SCALE_INFO,  // Get energy scale info
+	 * uint64 flags,            // Per the flag request
+	 * uint64 firstAttributeId, // The attribute id
+	 * uint64 bufferAddress,    // Guest physical address of the output buffer
+	 * uint64 bufferSize);      // The size in bytes of the output buffer
+	 */
+	ret = plpar_hcall_norets(H_GET_ENERGY_SCALE_INFO, ESI_FLAGS_ALL, 0,
+				 virt_to_phys(esi_buf), MAX_BUF_SZ);
+	if (ret != H_SUCCESS) {
+		pr_warn("hcall failed: H_GET_ENERGY_SCALE_INFO");
+		goto out;
+	}
+
+	esi_hdr = (struct h_energy_scale_info_hdr *) esi_buf;
+	if (esi_hdr->data_header_version != ESI_VERSION) {
+		pr_warn("H_GET_ENERGY_SCALE_INFO VER MISMATCH - EXP: 0x%x, REC: 0x%x",
+			ESI_VERSION, esi_hdr->data_header_version);
+	}
+
+	num_attrs = be64_to_cpu(esi_hdr->num_attrs);
+	esi_attrs = (struct energy_scale_attribute *)
+		    (esi_buf + be64_to_cpu(esi_hdr->array_offset));
+
+	pgs = kcalloc(num_attrs, sizeof(*pgs), GFP_KERNEL);
+	if (!pgs)
+		goto out;
+
+	papr_kobj = kobject_create_and_add("papr", firmware_kobj);
+	if (!papr_kobj) {
+		pr_warn("kobject_create_and_add papr failed\n");
+		goto out_pgs;
+	}
+
+	esi_kobj = kobject_create_and_add("energy_scale_info", papr_kobj);
+	if (!esi_kobj) {
+		pr_warn("kobject_create_and_add energy_scale_info failed\n");
+		goto out_kobj;
+	}
+
+	for (idx = 0; idx < num_attrs; idx++) {
+		bool show_val_desc = true;
+
+		pgs[idx].pg.attrs = kcalloc(MAX_ATTRS + 1,
+					    sizeof(*pgs[idx].pg.attrs),
+					    GFP_KERNEL);
+		if (!pgs[idx].pg.attrs)
+			goto out_ekobj;

What about the attrs allocated during the previous iterations?

Yes, you're right that needs cleanups.
I could write the following to clean up old entries like I did when space for
name couldn't be allocated:
for (i = idx - 1; i >= 0; i++)
	kfree(pgs[i].pg.attrs);
Thanks for pointing that out.

quoted

+
+		pgs[idx].pg.name = kasprintf(GFP_KERNEL, "%lld",
+					     be64_to_cpu(esi_attrs[idx].id));
+		if (pgs[idx].pg.name == NULL) {
+			for (i = idx; i >= 0; i--)
+				kfree(pgs[i].pg.attrs);
+			goto out_ekobj;
+		}
+		/* Do not add the value description if it does not exist */
+		if (strlen(esi_attrs[idx].value_desc) == 0)

strnlen

ack

quoted

+			show_val_desc = false;
+
+		if (add_attr_group(be64_to_cpu(esi_attrs[idx].id),
+				   MAX_ATTRS, &pgs[idx], show_val_desc)) {
+			pr_warn("Failed to create papr attribute group %s\n",
+				pgs[idx].pg.name);
+			goto out_pgattrs;
+		}
+	}
+
+	kfree(esi_buf);
+	return 0;
+
+out_pgattrs:
+	for (i = 0; i < MAX_ATTRS ; i++) {

pgs is num_attrs long

Ah yes, you're right. It should loop over num_attrs

quoted

+		kfree(pgs[i].pg.attrs);
+		kfree(pgs[i].pg.name);
+	}
+out_ekobj:
+	kobject_put(esi_kobj);
+out_kobj:
+	kobject_put(papr_kobj);
+out_pgs:
+	kfree(pgs);
+out:
+	kfree(esi_buf);
+
+	return -ENOMEM;
+}
+
+machine_device_initcall(pseries, papr_init);