arch_post_acpi_subsys_init() reads MSR_K8_INT_PENDING_MSG with rdmsr()
into a lo/hi pair but only uses the low 32 bits: K8_INTP_C1E_ACTIVE_MASK
(0x18000000) lies entirely within them. The 'hi' half is never consumed,
which triggers a -Wunused-but-set-variable warning under W=1:

  arch/x86/kernel/process.c: In function 'arch_post_acpi_subsys_init':
  arch/x86/kernel/process.c:972:17: warning: variable 'hi' set but not used

Read the full MSR into a single u64 with rdmsrq() and test the mask
against it, dropping the now-unnecessary lo/hi variables.

No functional change intended.

Signed-off-by: HyeongJun An <sammiee5311@gmail.com>
---
 arch/x86/kernel/process.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 4c718f8adc59..a554f19c9973 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -969,7 +969,7 @@ void amd_e400_c1e_apic_setup(void)
 
 void __init arch_post_acpi_subsys_init(void)
 {
-	u32 lo, hi;
+	u64 val;
 
 	if (!boot_cpu_has_bug(X86_BUG_AMD_E400))
 		return;
@@ -979,8 +979,8 @@ void __init arch_post_acpi_subsys_init(void)
 	 * the machine is affected K8_INTP_C1E_ACTIVE_MASK bits are set in
 	 * MSR_K8_INT_PENDING_MSG.
 	 */
-	rdmsr(MSR_K8_INT_PENDING_MSG, lo, hi);
-	if (!(lo & K8_INTP_C1E_ACTIVE_MASK))
+	rdmsrq(MSR_K8_INT_PENDING_MSG, val);
+	if (!(val & K8_INTP_C1E_ACTIVE_MASK))
 		return;
 
 	boot_cpu_set_bug(X86_BUG_AMD_APIC_C1E);
-- 
2.43.0

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

Commit-ID:     10a5d65856b9dbea0d63118e226b6fd820ee1d9d
Gitweb:        https://git.kernel.org/tip/10a5d65856b9dbea0d63118e226b6fd820ee1d9d
Author:        HyeongJun An <sammiee5311@gmail.com>
AuthorDate:    Fri, 05 Jun 2026 00:00:52 +09:00
Committer:     Ingo Molnar <mingo@kernel.org>
CommitterDate: Fri, 05 Jun 2026 12:07:11 +02:00

x86/process: Convert rdmsr() to rdmsrq() in arch_post_acpi_subsys_init() to address W=1 warning

arch_post_acpi_subsys_init() reads MSR_K8_INT_PENDING_MSG with rdmsr()
into a lo/hi pair but only uses the low 32 bits: K8_INTP_C1E_ACTIVE_MASK
(0x18000000) lies entirely within them. The 'hi' half is never consumed,
which triggers a -Wunused-but-set-variable warning under W=1:

  arch/x86/kernel/process.c: In function 'arch_post_acpi_subsys_init':
  arch/x86/kernel/process.c:972:17: warning: variable 'hi' set but not used

Read the full MSR into a single u64 with rdmsrq() and test the mask
against it, dropping the now-unnecessary lo/hi variables.

No functional change intended.

Signed-off-by: HyeongJun An <sammiee5311@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Jürgen Groß <jgross@suse.com>
Link: https://patch.msgid.link/20260604150052.3337246-1-sammiee5311@gmail.com
---
 arch/x86/kernel/process.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 4c718f8..a554f19 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -969,7 +969,7 @@ void amd_e400_c1e_apic_setup(void)
 
 void __init arch_post_acpi_subsys_init(void)
 {
-	u32 lo, hi;
+	u64 val;
 
 	if (!boot_cpu_has_bug(X86_BUG_AMD_E400))
 		return;
@@ -979,8 +979,8 @@ void __init arch_post_acpi_subsys_init(void)
 	 * the machine is affected K8_INTP_C1E_ACTIVE_MASK bits are set in
 	 * MSR_K8_INT_PENDING_MSG.
 	 */
-	rdmsr(MSR_K8_INT_PENDING_MSG, lo, hi);
-	if (!(lo & K8_INTP_C1E_ACTIVE_MASK))
+	rdmsrq(MSR_K8_INT_PENDING_MSG, val);
+	if (!(val & K8_INTP_C1E_ACTIVE_MASK))
 		return;
 
 	boot_cpu_set_bug(X86_BUG_AMD_APIC_C1E);