On 14.09.23 06:47, Xin Li wrote:
Add an always inline API __wrmsrns() to embed the WRMSRNS instruction into the code. Tested-by: Shan Kang <shan.kang@xxxxxxxxx> Signed-off-by: Xin Li <xin3.li@xxxxxxxxx>
In order to avoid having to add paravirt support for WRMSRNS I think xen_init_capabilities() should gain: + setup_clear_cpu_cap(X86_FEATURE_WRMSRNS); Juergen
--- arch/x86/include/asm/msr.h | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/arch/x86/include/asm/msr.h b/arch/x86/include/asm/msr.h index 65ec1965cd28..c284ff9ebe67 100644 --- a/arch/x86/include/asm/msr.h +++ b/arch/x86/include/asm/msr.h @@ -97,6 +97,19 @@ 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)); \ @@ -297,6 +310,11 @@ do { \#endif /* !CONFIG_PARAVIRT_XXL */ +static __always_inline void wrmsrns(u32 msr, u64 val)+{ + __wrmsrns(msr, val, val >> 32); +} + /* * 64-bit version of wrmsr_safe(): */
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