linux-kernel - [RFC PATCH v1 01/15] x86/msr: Replace __wrmsr() with native

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Message-ID: <20250331082251.3171276-2-xin@zytor.com>
Date: Mon, 31 Mar 2025 01:22:37 -0700
From: "Xin Li (Intel)" <xin@...or.com>
To: linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org,
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Subject: [RFC PATCH v1 01/15] x86/msr: Replace __wrmsr() with native_wrmsrl()

__wrmsr() is the lowest level primitive MSR write API, and its direct
use is NOT preferred.  Use its wrapper function native_wrmsrl() instead.

No functional change intended.

Signed-off-by: Xin Li (Intel) <xin@...or.com>
---
 arch/x86/events/amd/brs.c                 | 2 +-
 arch/x86/include/asm/apic.h               | 2 +-
 arch/x86/include/asm/msr.h                | 6 ++++--
 arch/x86/kernel/cpu/mce/core.c            | 2 +-
 arch/x86/kernel/cpu/resctrl/pseudo_lock.c | 6 +++---
 5 files changed, 10 insertions(+), 8 deletions(-)

diff --git a/arch/x86/events/amd/brs.c b/arch/x86/events/amd/brs.c
index ec3427463382..4a47f3c108de 100644
--- a/arch/x86/events/amd/brs.c
+++ b/arch/x86/events/amd/brs.c
@@ -44,7 +44,7 @@ static inline unsigned int brs_to(int idx)
 static __always_inline void set_debug_extn_cfg(u64 val)
 {
 	/* bits[4:3] must always be set to 11b */
-	__wrmsr(MSR_AMD_DBG_EXTN_CFG, val | 3ULL << 3, val >> 32);
+	native_wrmsrl(MSR_AMD_DBG_EXTN_CFG, val | 3ULL << 3);
 }
 
 static __always_inline u64 get_debug_extn_cfg(void)
diff --git a/arch/x86/include/asm/apic.h b/arch/x86/include/asm/apic.h
index c903d358405d..3345a819c859 100644
--- a/arch/x86/include/asm/apic.h
+++ b/arch/x86/include/asm/apic.h
@@ -214,7 +214,7 @@ static inline void native_apic_msr_write(u32 reg, u32 v)
 
 static inline void native_apic_msr_eoi(void)
 {
-	__wrmsr(APIC_BASE_MSR + (APIC_EOI >> 4), APIC_EOI_ACK, 0);
+	native_wrmsrl(APIC_BASE_MSR + (APIC_EOI >> 4), APIC_EOI_ACK);
 }
 
 static inline u32 native_apic_msr_read(u32 reg)
diff --git a/arch/x86/include/asm/msr.h b/arch/x86/include/asm/msr.h
index 9397a319d165..27ea8793705d 100644
--- a/arch/x86/include/asm/msr.h
+++ b/arch/x86/include/asm/msr.h
@@ -144,10 +144,12 @@ static inline unsigned long long native_read_msr_safe(unsigned int msr,
 static inline void notrace
 native_write_msr(unsigned int msr, u32 low, u32 high)
 {
-	__wrmsr(msr, low, high);
+	u64 val = (u64)high << 32 | low;
+
+	native_wrmsrl(msr, val);
 
 	if (tracepoint_enabled(write_msr))
-		do_trace_write_msr(msr, ((u64)high << 32 | low), 0);
+		do_trace_write_msr(msr, val, 0);
 }
 
 /* Can be uninlined because referenced by paravirt */
diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c
index 1f14c3308b6b..0eaeaba12df2 100644
--- a/arch/x86/kernel/cpu/mce/core.c
+++ b/arch/x86/kernel/cpu/mce/core.c
@@ -1306,7 +1306,7 @@ static noinstr bool mce_check_crashing_cpu(void)
 		}
 
 		if (mcgstatus & MCG_STATUS_RIPV) {
-			__wrmsr(MSR_IA32_MCG_STATUS, 0, 0);
+			native_wrmsrl(MSR_IA32_MCG_STATUS, 0);
 			return true;
 		}
 	}
diff --git a/arch/x86/kernel/cpu/resctrl/pseudo_lock.c b/arch/x86/kernel/cpu/resctrl/pseudo_lock.c
index 01fa7890b43f..55536120c8d1 100644
--- a/arch/x86/kernel/cpu/resctrl/pseudo_lock.c
+++ b/arch/x86/kernel/cpu/resctrl/pseudo_lock.c
@@ -481,7 +481,7 @@ int resctrl_arch_pseudo_lock_fn(void *_plr)
 	 * cache.
 	 */
 	saved_msr = __rdmsr(MSR_MISC_FEATURE_CONTROL);
-	__wrmsr(MSR_MISC_FEATURE_CONTROL, prefetch_disable_bits, 0x0);
+	native_wrmsrl(MSR_MISC_FEATURE_CONTROL, prefetch_disable_bits);
 	closid_p = this_cpu_read(pqr_state.cur_closid);
 	rmid_p = this_cpu_read(pqr_state.cur_rmid);
 	mem_r = plr->kmem;
@@ -493,7 +493,7 @@ int resctrl_arch_pseudo_lock_fn(void *_plr)
 	 * pseudo-locked followed by reading of kernel memory to load it
 	 * into the cache.
 	 */
-	__wrmsr(MSR_IA32_PQR_ASSOC, rmid_p, plr->closid);
+	native_wrmsrl(MSR_IA32_PQR_ASSOC, (u64)plr->closid << 32 | rmid_p);
 
 	/*
 	 * Cache was flushed earlier. Now access kernel memory to read it
@@ -530,7 +530,7 @@ int resctrl_arch_pseudo_lock_fn(void *_plr)
 	 * Critical section end: restore closid with capacity bitmask that
 	 * does not overlap with pseudo-locked region.
 	 */
-	__wrmsr(MSR_IA32_PQR_ASSOC, rmid_p, closid_p);
+	native_wrmsrl(MSR_IA32_PQR_ASSOC, (u64)closid_p << 32 | rmid_p);
 
 	/* Re-enable the hardware prefetcher(s) */
 	wrmsrl(MSR_MISC_FEATURE_CONTROL, saved_msr);
-- 
2.49.0