linux-kernel - [PATCH v4 10/16] x86/mtrr: get rid of mtrr

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Date:   Tue,  4 Oct 2022 10:10:17 +0200
From:   Juergen Gross <jgross@...e.com>
To:     linux-kernel@...r.kernel.org, x86@...nel.org
Cc:     Juergen Gross <jgross@...e.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "H. Peter Anvin" <hpa@...or.com>
Subject: [PATCH v4 10/16] x86/mtrr: get rid of mtrr_enabled bool

There is no need for keeping mtrr_enabled, as it can easily be replaced
by testing mtrr_if to be not NULL.

Signed-off-by: Juergen Gross <jgross@...e.com>
---
V4:
- new patch
---
 arch/x86/kernel/cpu/mtrr/mtrr.c | 24 +++++++++++-------------
 1 file changed, 11 insertions(+), 13 deletions(-)

diff --git a/arch/x86/kernel/cpu/mtrr/mtrr.c b/arch/x86/kernel/cpu/mtrr/mtrr.c
index 9e1b478ac896..7eed5387e828 100644
--- a/arch/x86/kernel/cpu/mtrr/mtrr.c
+++ b/arch/x86/kernel/cpu/mtrr/mtrr.c
@@ -59,7 +59,6 @@
 #define MTRR_TO_PHYS_WC_OFFSET 1000
 
 u32 num_var_ranges;
-static bool mtrr_enabled;
 
 unsigned int mtrr_usage_table[MTRR_MAX_VAR_RANGES];
 static DEFINE_MUTEX(mtrr_mutex);
@@ -299,7 +298,7 @@ int mtrr_add_page(unsigned long base, unsigned long size,
 	int i, replace, error;
 	mtrr_type ltype;
 
-	if (!mtrr_enabled)
+	if (!mtrr_if)
 		return -ENXIO;
 
 	error = mtrr_if->validate_add_page(base, size, type);
@@ -447,7 +446,7 @@ static int mtrr_check(unsigned long base, unsigned long size)
 int mtrr_add(unsigned long base, unsigned long size, unsigned int type,
 	     bool increment)
 {
-	if (!mtrr_enabled)
+	if (!mtrr_if)
 		return -ENODEV;
 	if (mtrr_check(base, size))
 		return -EINVAL;
@@ -476,7 +475,7 @@ int mtrr_del_page(int reg, unsigned long base, unsigned long size)
 	unsigned long lbase, lsize;
 	int error = -EINVAL;
 
-	if (!mtrr_enabled)
+	if (!mtrr_if)
 		return -ENODEV;
 
 	max = num_var_ranges;
@@ -536,7 +535,7 @@ int mtrr_del_page(int reg, unsigned long base, unsigned long size)
  */
 int mtrr_del(int reg, unsigned long base, unsigned long size)
 {
-	if (!mtrr_enabled)
+	if (!mtrr_if)
 		return -ENODEV;
 	if (mtrr_check(base, size))
 		return -EINVAL;
@@ -562,7 +561,7 @@ int arch_phys_wc_add(unsigned long base, unsigned long size)
 {
 	int ret;
 
-	if (pat_enabled() || !mtrr_enabled)
+	if (pat_enabled() || !mtrr_if)
 		return 0;  /* Success!  (We don't need to do anything.) */
 
 	ret = mtrr_add(base, size, MTRR_TYPE_WRCOMB, true);
@@ -751,22 +750,21 @@ void __init mtrr_bp_init(void)
 	}
 
 	if (mtrr_if) {
-		mtrr_enabled = true;
 		set_num_var_ranges(mtrr_if == &generic_mtrr_ops);
 		init_table();
 		if (mtrr_if == &generic_mtrr_ops) {
 			/* BIOS may override */
-			mtrr_enabled = get_mtrr_state();
-
-			if (mtrr_enabled) {
+			if (get_mtrr_state()) {
 				memory_caching_control |= CACHE_MTRR | CACHE_PAT;
 				changed_by_mtrr_cleanup = mtrr_cleanup(phys_addr);
 				cache_cpu_init();
+			} else {
+				mtrr_if = NULL;
 			}
 		}
 	}
 
-	if (!mtrr_enabled) {
+	if (!mtrr_if) {
 		pr_info("Disabled\n");
 
 		/*
@@ -807,7 +805,7 @@ void mtrr_save_state(void)
 {
 	int first_cpu;
 
-	if (!mtrr_enabled)
+	if (!mtrr_if)
 		return;
 
 	first_cpu = cpumask_first(cpu_online_mask);
@@ -852,7 +850,7 @@ void mtrr_bp_restore(void)
 
 static int __init mtrr_init_finialize(void)
 {
-	if (!mtrr_enabled)
+	if (!mtrr_if)
 		return 0;
 
 	if (memory_caching_control & CACHE_MTRR) {
-- 
2.35.3