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From:   Juergen Gross <jgross@suse.com>
To:     linux-kernel@vger.kernel.org, x86@kernel.org
Cc:     Juergen Gross <jgross@suse.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        "H. Peter Anvin" <hpa@zytor.com>
Subject: [PATCH v4 03/16] x86/mtrr: replace use_intel() with a local flag
Date:   Tue,  4 Oct 2022 10:10:10 +0200
Message-Id: <20221004081023.32402-4-jgross@suse.com>
In-Reply-To: <20221004081023.32402-1-jgross@suse.com>
References: <20221004081023.32402-1-jgross@suse.com>
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In MTRR code use_intel() is only used in one source file, and the
relevant use_intel_if member of struct mtrr_ops is set only in
generic_mtrr_ops.

Replace use_intel() with a single flag in cacheinfo.c, which can be set
when assigning generic_mtrr_ops to mtrr_if. This allows to drop
use_intel_if from mtrr_ops, while preparing to support PAT without
MTRR. As another preparation for the PAT/MTRR decoupling use a bit for
MTRR control and one for PAT control. For now set both bits together,
this can be changed later.

As the new flag will be set only if mtrr_enabled is set, the test for
mtrr_enabled can be dropped at some places.

At the same time drop the local mtrr_enabled() function and rename
the __mtrr_enabled flag to mtrr_enabled.

Signed-off-by: Juergen Gross <jgross@suse.com>
---
V2:
- new patch
V4:
- rename cache_generic to memory_caching_control (Borislav Petkov)
- rename CACHE_GENERIC_* to CACHE_* (Borislav Petkov)
- get rid of use_generic in mtrr_bp_init() (Borislav Petkov)
---
 arch/x86/include/asm/cacheinfo.h   |  5 +++
 arch/x86/kernel/cpu/cacheinfo.c    |  3 ++
 arch/x86/kernel/cpu/mtrr/generic.c |  1 -
 arch/x86/kernel/cpu/mtrr/mtrr.c    | 55 +++++++++++++-----------------
 arch/x86/kernel/cpu/mtrr/mtrr.h    |  2 --
 5 files changed, 32 insertions(+), 34 deletions(-)

diff --git a/arch/x86/include/asm/cacheinfo.h b/arch/x86/include/asm/cacheinfo.h
index 86b2e0dcc4bf..c3873962a7cd 100644
--- a/arch/x86/include/asm/cacheinfo.h
+++ b/arch/x86/include/asm/cacheinfo.h
@@ -2,6 +2,11 @@
 #ifndef _ASM_X86_CACHEINFO_H
 #define _ASM_X86_CACHEINFO_H
 
+/* Kernel controls MTRR and/or PAT MSRs. */
+extern unsigned int memory_caching_control;
+#define CACHE_MTRR 0x01
+#define CACHE_PAT  0x02
+
 void cacheinfo_amd_init_llc_id(struct cpuinfo_x86 *c, int cpu);
 void cacheinfo_hygon_init_llc_id(struct cpuinfo_x86 *c, int cpu);
 
diff --git a/arch/x86/kernel/cpu/cacheinfo.c b/arch/x86/kernel/cpu/cacheinfo.c
index 66556833d7af..5228fb9a3798 100644
--- a/arch/x86/kernel/cpu/cacheinfo.c
+++ b/arch/x86/kernel/cpu/cacheinfo.c
@@ -35,6 +35,9 @@ DEFINE_PER_CPU_READ_MOSTLY(cpumask_var_t, cpu_llc_shared_map);
 /* Shared L2 cache maps */
 DEFINE_PER_CPU_READ_MOSTLY(cpumask_var_t, cpu_l2c_shared_map);
 
+/* Kernel controls MTRR and/or PAT MSRs. */
+unsigned int memory_caching_control __ro_after_init = 0;
+
 struct _cache_table {
 	unsigned char descriptor;
 	char cache_type;
diff --git a/arch/x86/kernel/cpu/mtrr/generic.c b/arch/x86/kernel/cpu/mtrr/generic.c
index cd64eab02393..81742870ecc5 100644
--- a/arch/x86/kernel/cpu/mtrr/generic.c
+++ b/arch/x86/kernel/cpu/mtrr/generic.c
@@ -917,7 +917,6 @@ int positive_have_wrcomb(void)
  * Generic structure...
  */
 const struct mtrr_ops generic_mtrr_ops = {
-	.use_intel_if		= 1,
 	.set_all		= generic_set_all,
 	.get			= generic_get_mtrr,
 	.get_free_region	= generic_get_free_region,
diff --git a/arch/x86/kernel/cpu/mtrr/mtrr.c b/arch/x86/kernel/cpu/mtrr/mtrr.c
index 2746cac9d8a9..dacb537da126 100644
--- a/arch/x86/kernel/cpu/mtrr/mtrr.c
+++ b/arch/x86/kernel/cpu/mtrr/mtrr.c
@@ -46,6 +46,7 @@
 #include <linux/syscore_ops.h>
 #include <linux/rcupdate.h>
 
+#include <asm/cacheinfo.h>
 #include <asm/cpufeature.h>
 #include <asm/e820/api.h>
 #include <asm/mtrr.h>
@@ -58,12 +59,7 @@
 #define MTRR_TO_PHYS_WC_OFFSET 1000
 
 u32 num_var_ranges;
-static bool __mtrr_enabled;
-
-static bool mtrr_enabled(void)
-{
-	return __mtrr_enabled;
-}
+static bool mtrr_enabled;
 
 unsigned int mtrr_usage_table[MTRR_MAX_VAR_RANGES];
 static DEFINE_MUTEX(mtrr_mutex);
@@ -119,11 +115,11 @@ static int have_wrcomb(void)
 }
 
 /*  This function returns the number of variable MTRRs  */
-static void __init set_num_var_ranges(void)
+static void __init set_num_var_ranges(bool use_generic)
 {
 	unsigned long config = 0, dummy;
 
-	if (use_intel())
+	if (use_generic)
 		rdmsr(MSR_MTRRcap, config, dummy);
 	else if (is_cpu(AMD) || is_cpu(HYGON))
 		config = 2;
@@ -303,7 +299,7 @@ int mtrr_add_page(unsigned long base, unsigned long size,
 	int i, replace, error;
 	mtrr_type ltype;
 
-	if (!mtrr_enabled())
+	if (!mtrr_enabled)
 		return -ENXIO;
 
 	error = mtrr_if->validate_add_page(base, size, type);
@@ -451,7 +447,7 @@ 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_enabled)
 		return -ENODEV;
 	if (mtrr_check(base, size))
 		return -EINVAL;
@@ -480,7 +476,7 @@ int mtrr_del_page(int reg, unsigned long base, unsigned long size)
 	unsigned long lbase, lsize;
 	int error = -EINVAL;
 
-	if (!mtrr_enabled())
+	if (!mtrr_enabled)
 		return -ENODEV;
 
 	max = num_var_ranges;
@@ -540,7 +536,7 @@ 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_enabled)
 		return -ENODEV;
 	if (mtrr_check(base, size))
 		return -EINVAL;
@@ -566,7 +562,7 @@ int arch_phys_wc_add(unsigned long base, unsigned long size)
 {
 	int ret;
 
-	if (pat_enabled() || !mtrr_enabled())
+	if (pat_enabled() || !mtrr_enabled)
 		return 0;  /* Success!  (We don't need to do anything.) */
 
 	ret = mtrr_add(base, size, MTRR_TYPE_WRCOMB, true);
@@ -755,15 +751,17 @@ void __init mtrr_bp_init(void)
 	}
 
 	if (mtrr_if) {
-		__mtrr_enabled = true;
-		set_num_var_ranges();
+		mtrr_enabled = true;
+		set_num_var_ranges(mtrr_if == &generic_mtrr_ops);
 		init_table();
-		if (use_intel()) {
+		if (mtrr_if == &generic_mtrr_ops) {
 			/* BIOS may override */
-			__mtrr_enabled = get_mtrr_state();
+			mtrr_enabled = get_mtrr_state();
 
-			if (mtrr_enabled())
+			if (mtrr_enabled) {
 				mtrr_bp_pat_init();
+				memory_caching_control |= CACHE_MTRR | CACHE_PAT;
+			}
 
 			if (mtrr_cleanup(phys_addr)) {
 				changed_by_mtrr_cleanup = 1;
@@ -772,7 +770,7 @@ void __init mtrr_bp_init(void)
 		}
 	}
 
-	if (!mtrr_enabled()) {
+	if (!mtrr_enabled) {
 		pr_info("Disabled\n");
 
 		/*
@@ -786,10 +784,7 @@ void __init mtrr_bp_init(void)
 
 void mtrr_ap_init(void)
 {
-	if (!mtrr_enabled())
-		return;
-
-	if (!use_intel() || mtrr_aps_delayed_init)
+	if (!memory_caching_control || mtrr_aps_delayed_init)
 		return;
 
 	/*
@@ -816,7 +811,7 @@ void mtrr_save_state(void)
 {
 	int first_cpu;
 
-	if (!mtrr_enabled())
+	if (!mtrr_enabled)
 		return;
 
 	first_cpu = cpumask_first(cpu_online_mask);
@@ -825,9 +820,7 @@ void mtrr_save_state(void)
 
 void set_mtrr_aps_delayed_init(void)
 {
-	if (!mtrr_enabled())
-		return;
-	if (!use_intel())
+	if (!memory_caching_control)
 		return;
 
 	mtrr_aps_delayed_init = true;
@@ -838,7 +831,7 @@ void set_mtrr_aps_delayed_init(void)
  */
 void mtrr_aps_init(void)
 {
-	if (!use_intel() || !mtrr_enabled())
+	if (!memory_caching_control)
 		return;
 
 	/*
@@ -855,7 +848,7 @@ void mtrr_aps_init(void)
 
 void mtrr_bp_restore(void)
 {
-	if (!use_intel() || !mtrr_enabled())
+	if (!memory_caching_control)
 		return;
 
 	mtrr_if->set_all();
@@ -863,10 +856,10 @@ void mtrr_bp_restore(void)
 
 static int __init mtrr_init_finialize(void)
 {
-	if (!mtrr_enabled())
+	if (!mtrr_enabled)
 		return 0;
 
-	if (use_intel()) {
+	if (memory_caching_control & CACHE_MTRR) {
 		if (!changed_by_mtrr_cleanup)
 			mtrr_state_warn();
 		return 0;
diff --git a/arch/x86/kernel/cpu/mtrr/mtrr.h b/arch/x86/kernel/cpu/mtrr/mtrr.h
index 2ac99e561181..88b1c4b6174a 100644
--- a/arch/x86/kernel/cpu/mtrr/mtrr.h
+++ b/arch/x86/kernel/cpu/mtrr/mtrr.h
@@ -14,7 +14,6 @@ extern unsigned int mtrr_usage_table[MTRR_MAX_VAR_RANGES];
 
 struct mtrr_ops {
 	u32	vendor;
-	u32	use_intel_if;
 	void	(*set)(unsigned int reg, unsigned long base,
 		       unsigned long size, mtrr_type type);
 	void	(*set_all)(void);
@@ -61,7 +60,6 @@ extern u64 size_or_mask, size_and_mask;
 extern const struct mtrr_ops *mtrr_if;
 
 #define is_cpu(vnd)	(mtrr_if && mtrr_if->vendor == X86_VENDOR_##vnd)
-#define use_intel()	(mtrr_if && mtrr_if->use_intel_if == 1)
 
 extern unsigned int num_var_ranges;
 extern u64 mtrr_tom2;
-- 
2.35.3