diff options
Diffstat (limited to 'arch/x86/include/asm/msr.h')
| -rw-r--r-- | arch/x86/include/asm/msr.h | 25 |
1 files changed, 11 insertions, 14 deletions
diff --git a/arch/x86/include/asm/msr.h b/arch/x86/include/asm/msr.h index d642037f9ed5..001853541f1e 100644 --- a/arch/x86/include/asm/msr.h +++ b/arch/x86/include/asm/msr.h @@ -99,19 +99,6 @@ static __always_inline void __wrmsr(unsigned int msr, u32 low, u32 high) : : "c" (msr), "a"(low), "d" (high) : "memory"); } -/* - * WRMSRNS behaves exactly like WRMSR with the only difference being - * that it is not a serializing instruction by default. - */ -static __always_inline void __wrmsrns(u32 msr, u32 low, u32 high) -{ - /* Instruction opcode for WRMSRNS; supported in binutils >= 2.40. */ - asm volatile("1: .byte 0x0f,0x01,0xc6\n" - "2:\n" - _ASM_EXTABLE_TYPE(1b, 2b, EX_TYPE_WRMSR) - : : "c" (msr), "a"(low), "d" (high)); -} - #define native_rdmsr(msr, val1, val2) \ do { \ u64 __val = __rdmsr((msr)); \ @@ -312,9 +299,19 @@ do { \ #endif /* !CONFIG_PARAVIRT_XXL */ +/* Instruction opcode for WRMSRNS supported in binutils >= 2.40 */ +#define WRMSRNS _ASM_BYTES(0x0f,0x01,0xc6) + +/* Non-serializing WRMSR, when available. Falls back to a serializing WRMSR. */ static __always_inline void wrmsrns(u32 msr, u64 val) { - __wrmsrns(msr, val, val >> 32); + /* + * WRMSR is 2 bytes. WRMSRNS is 3 bytes. Pad WRMSR with a redundant + * DS prefix to avoid a trailing NOP. + */ + asm volatile("1: " ALTERNATIVE("ds wrmsr", WRMSRNS, X86_FEATURE_WRMSRNS) + "2: " _ASM_EXTABLE_TYPE(1b, 2b, EX_TYPE_WRMSR) + : : "c" (msr), "a" ((u32)val), "d" ((u32)(val >> 32))); } /* |