Do FRED MSR writes with wrmsrns() rather than wrmsrl().

No functional change intended.

Signed-off-by: Xin Li (Intel) <xin@zytor.com>
---
 arch/x86/kernel/fred.c | 26 +++++++++++++-------------
 1 file changed, 13 insertions(+), 13 deletions(-)

diff --git a/arch/x86/kernel/fred.c b/arch/x86/kernel/fred.c
index 4bcd8791ad96..b202685b8e77 100644
--- a/arch/x86/kernel/fred.c
+++ b/arch/x86/kernel/fred.c
@@ -26,27 +26,27 @@ void cpu_init_fred_exceptions(void)
 	/* When FRED is enabled by default, remove this log message */
 	pr_info("Initialize FRED on CPU%d\n", smp_processor_id());
 
-	wrmsrl(MSR_IA32_FRED_CONFIG,
-	       /* Reserve for CALL emulation */
-	       FRED_CONFIG_REDZONE |
-	       FRED_CONFIG_INT_STKLVL(0) |
-	       FRED_CONFIG_ENTRYPOINT(asm_fred_entrypoint_user));
+	wrmsrns(MSR_IA32_FRED_CONFIG,
+		/* Reserve for CALL emulation */
+		FRED_CONFIG_REDZONE |
+		FRED_CONFIG_INT_STKLVL(0) |
+		FRED_CONFIG_ENTRYPOINT(asm_fred_entrypoint_user));
 
 	/*
 	 * The purpose of separate stacks for NMI, #DB and #MC *in the kernel*
 	 * (remember that user space faults are always taken on stack level 0)
 	 * is to avoid overflowing the kernel stack.
 	 */
-	wrmsrl(MSR_IA32_FRED_STKLVLS,
-	       FRED_STKLVL(X86_TRAP_DB,  FRED_DB_STACK_LEVEL) |
-	       FRED_STKLVL(X86_TRAP_NMI, FRED_NMI_STACK_LEVEL) |
-	       FRED_STKLVL(X86_TRAP_MC,  FRED_MC_STACK_LEVEL) |
-	       FRED_STKLVL(X86_TRAP_DF,  FRED_DF_STACK_LEVEL));
+	wrmsrns(MSR_IA32_FRED_STKLVLS,
+		FRED_STKLVL(X86_TRAP_DB,  FRED_DB_STACK_LEVEL) |
+		FRED_STKLVL(X86_TRAP_NMI, FRED_NMI_STACK_LEVEL) |
+		FRED_STKLVL(X86_TRAP_MC,  FRED_MC_STACK_LEVEL) |
+		FRED_STKLVL(X86_TRAP_DF,  FRED_DF_STACK_LEVEL));
 
 	/* The FRED equivalents to IST stacks... */
-	wrmsrl(MSR_IA32_FRED_RSP1, __this_cpu_ist_top_va(DB));
-	wrmsrl(MSR_IA32_FRED_RSP2, __this_cpu_ist_top_va(NMI));
-	wrmsrl(MSR_IA32_FRED_RSP3, __this_cpu_ist_top_va(DF));
+	wrmsrns(MSR_IA32_FRED_RSP1, __this_cpu_ist_top_va(DB));
+	wrmsrns(MSR_IA32_FRED_RSP2, __this_cpu_ist_top_va(NMI));
+	wrmsrns(MSR_IA32_FRED_RSP3, __this_cpu_ist_top_va(DF));
 
 	/* Enable FRED */
 	cr4_set_bits(X86_CR4_FRED);
-- 
2.45.2

On 7/3/24 01:54, Xin Li (Intel) wrote:
> Do FRED MSR writes with wrmsrns() rather than wrmsrl().

A longer changelog would be appreciated here.  The wrmsrns() is
presumably to avoid the WRMSR serialization overhead and the CR4 write
provides all of the serialization that we need.

I'm also not clear how this fits into the series other than being FRED
related.

> No functional change intended.

I think I know what this was trying to convey, but I'm not sure this
phrase is appropriate to use here.  Sure, WRMSR and WRMSRNS have the
same general purpose, but I'd never say they are functionally equivalent.