[tip: x86/msr] x86/cpu: Stop using 32-bit MSR interfaces

["tip-bot2 for Juergen Gross" <tip-bot2@linutronix.de>]

The following commit has been merged into the x86/msr branch of tip:

Commit-ID:     2e9e6edbad45fe9078dfb2d35d1213c9969de49d
Gitweb:        https://git.kernel.org/tip/2e9e6edbad45fe9078dfb2d35d1213c9969de49d
Author:        Juergen Gross <jgross@suse.com>
AuthorDate:    Mon, 29 Jun 2026 08:05:10 +02:00
Committer:     Ingo Molnar <mingo@kernel.org>
CommitterDate: Thu, 02 Jul 2026 11:54:52 +02:00

x86/cpu: Stop using 32-bit MSR interfaces

The 32-bit MSR interfaces rdmsr() and wrmsr() are planned to be
removed. Use the related 64-bit variants instead.

Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://patch.msgid.link/20260629060526.3638272-20-jgross@suse.com
---
 arch/x86/kernel/cpu/centaur.c   | 35 ++++++++++++++++----------------
 arch/x86/kernel/cpu/common.c    | 12 ++++++-----
 arch/x86/kernel/cpu/intel.c     |  8 +++----
 arch/x86/kernel/cpu/transmeta.c |  9 ++++----
 arch/x86/kernel/cpu/zhaoxin.c   | 12 ++++-------
 5 files changed, 39 insertions(+), 37 deletions(-)

diff --git a/arch/x86/kernel/cpu/centaur.c b/arch/x86/kernel/cpu/centaur.c
index 681d2da..513fa1f 100644
--- a/arch/x86/kernel/cpu/centaur.c
+++ b/arch/x86/kernel/cpu/centaur.c
@@ -22,7 +22,7 @@
 
 static void init_c3(struct cpuinfo_x86 *c)
 {
-	u32  lo, hi;
+	u64 msr;
 
 	/* Test for Centaur Extended Feature Flags presence */
 	if (cpuid_eax(0xC0000000) >= 0xC0000001) {
@@ -30,17 +30,17 @@ static void init_c3(struct cpuinfo_x86 *c)
 
 		/* enable ACE unit, if present and disabled */
 		if ((tmp & (ACE_PRESENT | ACE_ENABLED)) == ACE_PRESENT) {
-			rdmsr(MSR_VIA_FCR, lo, hi);
-			lo |= ACE_FCR;		/* enable ACE unit */
-			wrmsr(MSR_VIA_FCR, lo, hi);
+			rdmsrq(MSR_VIA_FCR, msr);
+			/* enable ACE unit */
+			wrmsrq(MSR_VIA_FCR, msr | ACE_FCR);
 			pr_info("CPU: Enabled ACE h/w crypto\n");
 		}
 
 		/* enable RNG unit, if present and disabled */
 		if ((tmp & (RNG_PRESENT | RNG_ENABLED)) == RNG_PRESENT) {
-			rdmsr(MSR_VIA_RNG, lo, hi);
-			lo |= RNG_ENABLE;	/* enable RNG unit */
-			wrmsr(MSR_VIA_RNG, lo, hi);
+			rdmsrq(MSR_VIA_RNG, msr);
+			/* enable RNG unit */
+			wrmsrq(MSR_VIA_RNG, msr | RNG_ENABLE);
 			pr_info("CPU: Enabled h/w RNG\n");
 		}
 
@@ -52,9 +52,8 @@ static void init_c3(struct cpuinfo_x86 *c)
 #ifdef CONFIG_X86_32
 	/* Cyrix III family needs CX8 & PGE explicitly enabled. */
 	if (c->x86_model >= 6 && c->x86_model <= 13) {
-		rdmsr(MSR_VIA_FCR, lo, hi);
-		lo |= (1<<1 | 1<<7);
-		wrmsr(MSR_VIA_FCR, lo, hi);
+		rdmsrq(MSR_VIA_FCR, msr);
+		wrmsrq(MSR_VIA_FCR, msr | (1 << 1 | 1 << 7));
 		set_cpu_cap(c, X86_FEATURE_CX8);
 	}
 
@@ -115,8 +114,9 @@ static void init_centaur(struct cpuinfo_x86 *c)
 	char *name;
 	u32  fcr_set = 0;
 	u32  fcr_clr = 0;
-	u32  lo, hi, newlo;
+	u32  newlo;
 	u32  aa, bb, cc, dd;
+	struct msr val;
 #endif
 	early_init_centaur(c);
 	init_intel_cacheinfo(c);
@@ -169,15 +169,16 @@ static void init_centaur(struct cpuinfo_x86 *c)
 			name = "??";
 		}
 
-		rdmsr(MSR_IDT_FCR1, lo, hi);
-		newlo = (lo|fcr_set) & (~fcr_clr);
+		rdmsrq(MSR_IDT_FCR1, val.q);
+		newlo = (val.l | fcr_set) & (~fcr_clr);
 
-		if (newlo != lo) {
+		if (newlo != val.l) {
 			pr_info("Centaur FCR was 0x%X now 0x%X\n",
-				lo, newlo);
-			wrmsr(MSR_IDT_FCR1, newlo, hi);
+				val.l, newlo);
+			val.l = newlo;
+			wrmsrq(MSR_IDT_FCR1, val.q);
 		} else {
-			pr_info("Centaur FCR is 0x%X\n", lo);
+			pr_info("Centaur FCR is 0x%X\n", val.l);
 		}
 		/* Emulate MTRRs using Centaur's MCR. */
 		set_cpu_cap(c, X86_FEATURE_CENTAUR_MCR);
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index a3df21d..cbef2c6 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -339,16 +339,16 @@ bool cpuid_feature(void)
 
 static void squash_the_stupid_serial_number(struct cpuinfo_x86 *c)
 {
-	unsigned long lo, hi;
+	struct msr val;
 
 	if (!cpu_has(c, X86_FEATURE_PN) || !disable_x86_serial_nr)
 		return;
 
 	/* Disable processor serial number: */
 
-	rdmsr(MSR_IA32_BBL_CR_CTL, lo, hi);
-	lo |= 0x200000;
-	wrmsr(MSR_IA32_BBL_CR_CTL, lo, hi);
+	rdmsrq(MSR_IA32_BBL_CR_CTL, val.q);
+	val.l |= 0x200000;
+	wrmsrq(MSR_IA32_BBL_CR_CTL, val.q);
 
 	pr_notice("CPU serial number disabled.\n");
 	clear_cpu_cap(c, X86_FEATURE_PN);
@@ -2299,8 +2299,10 @@ static inline void idt_syscall_init(void)
 /* May not be marked __init: used by software suspend */
 void syscall_init(void)
 {
+	struct msr val = { .h = (__USER32_CS << 16) | __KERNEL_CS };
+
 	/* The default user and kernel segments */
-	wrmsr(MSR_STAR, 0, (__USER32_CS << 16) | __KERNEL_CS);
+	wrmsrq(MSR_STAR, val.q);
 
 	/*
 	 * Except the IA32_STAR MSR, there is NO need to setup SYSCALL and
diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c
index abb3984..076bdd0 100644
--- a/arch/x86/kernel/cpu/intel.c
+++ b/arch/x86/kernel/cpu/intel.c
@@ -542,12 +542,12 @@ static void init_intel(struct cpuinfo_x86 *c)
 		set_cpu_cap(c, X86_FEATURE_LFENCE_RDTSC);
 
 	if (boot_cpu_has(X86_FEATURE_DS)) {
-		unsigned int l1, l2;
+		u64 l;
 
-		rdmsr(MSR_IA32_MISC_ENABLE, l1, l2);
-		if (!(l1 & MSR_IA32_MISC_ENABLE_BTS_UNAVAIL))
+		rdmsrq(MSR_IA32_MISC_ENABLE, l);
+		if (!(l & MSR_IA32_MISC_ENABLE_BTS_UNAVAIL))
 			set_cpu_cap(c, X86_FEATURE_BTS);
-		if (!(l1 & MSR_IA32_MISC_ENABLE_PEBS_UNAVAIL))
+		if (!(l & MSR_IA32_MISC_ENABLE_PEBS_UNAVAIL))
 			set_cpu_cap(c, X86_FEATURE_PEBS);
 	}
 
diff --git a/arch/x86/kernel/cpu/transmeta.c b/arch/x86/kernel/cpu/transmeta.c
index 1fdcd69..c670fbb 100644
--- a/arch/x86/kernel/cpu/transmeta.c
+++ b/arch/x86/kernel/cpu/transmeta.c
@@ -24,7 +24,8 @@ static void early_init_transmeta(struct cpuinfo_x86 *c)
 
 static void init_transmeta(struct cpuinfo_x86 *c)
 {
-	unsigned int cap_mask, uk, max, dummy;
+	u64 msr;
+	unsigned int max, dummy;
 	unsigned int cms_rev1, cms_rev2;
 	unsigned int cpu_rev, cpu_freq = 0, cpu_flags, new_cpu_rev;
 	char cpu_info[65];
@@ -86,10 +87,10 @@ static void init_transmeta(struct cpuinfo_x86 *c)
 	}
 
 	/* Unhide possibly hidden capability flags */
-	rdmsr(0x80860004, cap_mask, uk);
-	wrmsr(0x80860004, ~0, uk);
+	rdmsrq(0x80860004, msr);
+	wrmsrq(0x80860004, msr | ~0U);
 	c->x86_capability[CPUID_1_EDX] = cpuid_edx(0x00000001);
-	wrmsr(0x80860004, cap_mask, uk);
+	wrmsrq(0x80860004, msr);
 
 	/* All Transmeta CPUs have a constant TSC */
 	set_cpu_cap(c, X86_FEATURE_CONSTANT_TSC);
diff --git a/arch/x86/kernel/cpu/zhaoxin.c b/arch/x86/kernel/cpu/zhaoxin.c
index 761aef5..fe504fd 100644
--- a/arch/x86/kernel/cpu/zhaoxin.c
+++ b/arch/x86/kernel/cpu/zhaoxin.c
@@ -21,7 +21,7 @@
 
 static void init_zhaoxin_cap(struct cpuinfo_x86 *c)
 {
-	u32  lo, hi;
+	u64 msr;
 
 	/* Test for Extended Feature Flags presence */
 	if (cpuid_eax(0xC0000000) >= 0xC0000001) {
@@ -29,19 +29,17 @@ static void init_zhaoxin_cap(struct cpuinfo_x86 *c)
 
 		/* Enable ACE unit, if present and disabled */
 		if ((tmp & (ACE_PRESENT | ACE_ENABLED)) == ACE_PRESENT) {
-			rdmsr(MSR_ZHAOXIN_FCR57, lo, hi);
+			rdmsrq(MSR_ZHAOXIN_FCR57, msr);
 			/* Enable ACE unit */
-			lo |= ACE_FCR;
-			wrmsr(MSR_ZHAOXIN_FCR57, lo, hi);
+			wrmsrq(MSR_ZHAOXIN_FCR57, msr | ACE_FCR);
 			pr_info("CPU: Enabled ACE h/w crypto\n");
 		}
 
 		/* Enable RNG unit, if present and disabled */
 		if ((tmp & (RNG_PRESENT | RNG_ENABLED)) == RNG_PRESENT) {
-			rdmsr(MSR_ZHAOXIN_FCR57, lo, hi);
+			rdmsrq(MSR_ZHAOXIN_FCR57, msr);
 			/* Enable RNG unit */
-			lo |= RNG_ENABLE;
-			wrmsr(MSR_ZHAOXIN_FCR57, lo, hi);
+			wrmsrq(MSR_ZHAOXIN_FCR57, msr | RNG_ENABLE);
 			pr_info("CPU: Enabled h/w RNG\n");
 		}