From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Date: Tue, 27 Feb 2018 01:13:00 +0000 (-0500)
Subject: Revert "x86/spec: Add 'lfence_enabled' in sysfs"
X-Git-Tag: v4.1.12-124.31.3~1118
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=df80b1408dfcaa524b2cf9afa8be58f94e925a0c;p=users%2Fjedix%2Flinux-maple.git

Revert "x86/spec: Add 'lfence_enabled' in sysfs"

This reverts commit d4ac621c1079ddd1b390ab2f56eedbda4aa8d1d7.

OraBug: 27601789
Reviewed-by: Mihai Carabas <mihai.carabas@oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
---

diff --git a/arch/x86/include/asm/spec_ctrl.h b/arch/x86/include/asm/spec_ctrl.h
index 1d5af4745446..4d3577c54e51 100644
--- a/arch/x86/include/asm/spec_ctrl.h
+++ b/arch/x86/include/asm/spec_ctrl.h
@@ -273,13 +273,6 @@ extern u32 sysctl_lfence_enabled;
 static inline void set_lfence_disabled(void)
 {
 	use_ibrs |= SPEC_CTRL_LFENCE_OFF;
-	sysctl_lfence_enabled = 0;
-}
-
-static inline void clear_lfence_disabled(void)
-{
-	use_ibrs &= ~SPEC_CTRL_LFENCE_OFF;
-	sysctl_lfence_enabled = 1;
 }
 
 /* indicate usage of IBPB to control execution speculation */
diff --git a/arch/x86/kernel/cpu/spec_ctrl.c b/arch/x86/kernel/cpu/spec_ctrl.c
index 93aa00cede93..ec3e307f0289 100644
--- a/arch/x86/kernel/cpu/spec_ctrl.c
+++ b/arch/x86/kernel/cpu/spec_ctrl.c
@@ -15,8 +15,6 @@
  */
 
 u32 sysctl_ibrs_enabled = 0, sysctl_ibpb_enabled = 0;
-/* By default it is enabled. */
-u32 sysctl_lfence_enabled = 1;
 EXPORT_SYMBOL(sysctl_ibrs_enabled);
 EXPORT_SYMBOL(sysctl_ibpb_enabled);
 
@@ -148,71 +146,12 @@ static const struct file_operations fops_ibpb_enabled = {
 	.llseek = default_llseek,
 };
 
-static ssize_t lfence_enabled_read(struct file *file, char __user *user_buf,
-                                 size_t count, loff_t *ppos)
-{
-	uint32_t dummy = 0;
-
-	if (ibrs_disabled)
-		return __enabled_read(file, user_buf, count, ppos, &sysctl_lfence_enabled);
-
-	return __enabled_read(file, user_buf, count, ppos, &dummy);
-}
-
-static ssize_t lfence_enabled_write(struct file *file,
-				  const char __user *user_buf,
-				  size_t count, loff_t *ppos)
-{
-	char buf[32];
-	ssize_t len;
-	unsigned int enable;
-
-	/* You have to disable IBRS first. */
-	if (ibrs_inuse || retpoline_enabled()) {
-		pr_warn("%s is enabled. Ignoring request to change lfence_enabled state.\n",
-			ibrs_inuse ? "IBRS" : "retpoline");
-		return -EINVAL;
-	}
-
-	len = min(count, sizeof(buf) - 1);
-	if (copy_from_user(buf, user_buf, len))
-		return -EFAULT;
-
-	buf[len] = '\0';
-	if (kstrtouint(buf, 0, &enable))
-		return -EINVAL;
-
-	/* Only 0 and 1 are allowed */
-	if (enable > 1)
-		return -EINVAL;
-
-	mutex_lock(&spec_ctrl_mutex);
-
-	if (!enable)
-		set_lfence_disabled();
-	else
-		clear_lfence_disabled();
-
-	refresh_set_spectre_v2_enabled();
-
-	mutex_unlock(&spec_ctrl_mutex);
-	return count;
-}
-
-static const struct file_operations fops_lfence_enabled = {
-	.read = lfence_enabled_read,
-	.write = lfence_enabled_write,
-	.llseek = default_llseek,
-};
-
 static int __init debugfs_spec_ctrl(void)
 {
         debugfs_create_file("ibrs_enabled", S_IRUSR | S_IWUSR,
                             arch_debugfs_dir, NULL, &fops_ibrs_enabled);
 	debugfs_create_file("ibpb_enabled", S_IRUSR | S_IWUSR,
 			    arch_debugfs_dir, NULL, &fops_ibpb_enabled);
-	debugfs_create_file("lfence_enabled", S_IRUSR | S_IWUSR,
-			    arch_debugfs_dir, NULL, &fops_lfence_enabled);
         return 0;
 }
 late_initcall(debugfs_spec_ctrl);