[PATCH 04/32] acpi: Stop using 32-bit MSR interfaces

From: Juergen Gross

Date: Mon Jun 29 2026 - 02:06:47 EST


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

In processor_throttling.c drop needless initializers.

Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
---
arch/x86/kernel/acpi/sleep.c | 20 ++++++++------------
drivers/acpi/processor_perflib.c | 11 ++++++-----
drivers/acpi/processor_throttling.c | 14 ++------------
3 files changed, 16 insertions(+), 29 deletions(-)

diff --git a/arch/x86/kernel/acpi/sleep.c b/arch/x86/kernel/acpi/sleep.c
index 91fa262f0e30..8dfe98784bf9 100644
--- a/arch/x86/kernel/acpi/sleep.c
+++ b/arch/x86/kernel/acpi/sleep.c
@@ -61,6 +61,7 @@ int x86_acpi_suspend_lowlevel(void)
{
struct wakeup_header *header =
(struct wakeup_header *) __va(real_mode_header->wakeup_header);
+ struct msr val;

if (header->signature != WAKEUP_HEADER_SIGNATURE) {
printk(KERN_ERR "wakeup header does not match\n");
@@ -82,13 +83,10 @@ int x86_acpi_suspend_lowlevel(void)
* with 2-MB L2 Cache and Intel® Processor A100 and A110 on 90
* nm process with 512-KB L2 Cache Specification Update".
*/
- if (!rdmsr_safe(MSR_EFER,
- &header->pmode_efer_low,
- &header->pmode_efer_high) &&
- !wrmsr_safe(MSR_EFER,
- header->pmode_efer_low,
- header->pmode_efer_high))
+ if (!rdmsrq_safe(MSR_EFER, &val.q) && !wrmsrq_safe(MSR_EFER, val.q))
header->pmode_behavior |= (1 << WAKEUP_BEHAVIOR_RESTORE_EFER);
+ header->pmode_efer_low = val.l;
+ header->pmode_efer_high = val.h;
#endif /* !CONFIG_64BIT */

header->pmode_cr0 = read_cr0();
@@ -96,14 +94,12 @@ int x86_acpi_suspend_lowlevel(void)
header->pmode_cr4 = __read_cr4();
header->pmode_behavior |= (1 << WAKEUP_BEHAVIOR_RESTORE_CR4);
}
- if (!rdmsr_safe(MSR_IA32_MISC_ENABLE,
- &header->pmode_misc_en_low,
- &header->pmode_misc_en_high) &&
- !wrmsr_safe(MSR_IA32_MISC_ENABLE,
- header->pmode_misc_en_low,
- header->pmode_misc_en_high))
+ if (!rdmsrq_safe(MSR_IA32_MISC_ENABLE, &val.q) &&
+ !wrmsrq_safe(MSR_IA32_MISC_ENABLE, val.q))
header->pmode_behavior |=
(1 << WAKEUP_BEHAVIOR_RESTORE_MISC_ENABLE);
+ header->pmode_misc_en_low = val.l;
+ header->pmode_misc_en_high = val.h;
header->realmode_flags = acpi_realmode_flags;
header->real_magic = 0x12345678;

diff --git a/drivers/acpi/processor_perflib.c b/drivers/acpi/processor_perflib.c
index fdf55c285c9a..9e25d6124efd 100644
--- a/drivers/acpi/processor_perflib.c
+++ b/drivers/acpi/processor_perflib.c
@@ -287,7 +287,8 @@ static int acpi_processor_get_performance_control(struct acpi_processor *pr)
*/
static void amd_fixup_frequency(struct acpi_processor_px *px, int i)
{
- u32 hi, lo, fid, did;
+ struct msr val;
+ u32 fid, did;
int index = px->control & 0x00000007;

if (boot_cpu_data.x86_vendor != X86_VENDOR_AMD)
@@ -295,16 +296,16 @@ static void amd_fixup_frequency(struct acpi_processor_px *px, int i)

if ((boot_cpu_data.x86 == 0x10 && boot_cpu_data.x86_model < 10) ||
boot_cpu_data.x86 == 0x11) {
- rdmsr(MSR_AMD_PSTATE_DEF_BASE + index, lo, hi);
+ rdmsrq(MSR_AMD_PSTATE_DEF_BASE + index, val.q);
/*
* MSR C001_0064+:
* Bit 63: PstateEn. Read-write. If set, the P-state is valid.
*/
- if (!(hi & BIT(31)))
+ if (!(val.h & BIT(31)))
return;

- fid = lo & 0x3f;
- did = (lo >> 6) & 7;
+ fid = val.l & 0x3f;
+ did = (val.l >> 6) & 7;
if (boot_cpu_data.x86 == 0x10)
px->core_frequency = (100 * (fid + 0x10)) >> did;
else
diff --git a/drivers/acpi/processor_throttling.c b/drivers/acpi/processor_throttling.c
index c0f92b93747d..d1605e0ab61f 100644
--- a/drivers/acpi/processor_throttling.c
+++ b/drivers/acpi/processor_throttling.c
@@ -698,20 +698,13 @@ static int acpi_processor_get_throttling_fadt(struct acpi_processor *pr)
#ifdef CONFIG_X86
static int acpi_throttling_rdmsr(u64 *value)
{
- u64 msr_high, msr_low;
- u64 msr = 0;
int ret = -1;

if ((this_cpu_read(cpu_info.x86_vendor) != X86_VENDOR_INTEL) ||
!this_cpu_has(X86_FEATURE_ACPI)) {
pr_err("HARDWARE addr space,NOT supported yet\n");
} else {
- msr_low = 0;
- msr_high = 0;
- rdmsr_safe(MSR_IA32_THERM_CONTROL,
- (u32 *)&msr_low, (u32 *) &msr_high);
- msr = (msr_high << 32) | msr_low;
- *value = (u64) msr;
+ rdmsrq_safe(MSR_IA32_THERM_CONTROL, value);
ret = 0;
}
return ret;
@@ -720,15 +713,12 @@ static int acpi_throttling_rdmsr(u64 *value)
static int acpi_throttling_wrmsr(u64 value)
{
int ret = -1;
- u64 msr;

if ((this_cpu_read(cpu_info.x86_vendor) != X86_VENDOR_INTEL) ||
!this_cpu_has(X86_FEATURE_ACPI)) {
pr_err("HARDWARE addr space,NOT supported yet\n");
} else {
- msr = value;
- wrmsr_safe(MSR_IA32_THERM_CONTROL,
- msr & 0xffffffff, msr >> 32);
+ wrmsrq_safe(MSR_IA32_THERM_CONTROL, value);
ret = 0;
}
return ret;
--
2.54.0