On April 11, 2025 9:18:08 AM PDT, Xin Li <xin@xxxxxxxxx> wrote: >On 4/10/2025 4:24 PM, Sean Christopherson wrote: >>> +/* >>> + * Write EAX to MSR_IA32_SPEC_CTRL. >>> + * >>> + * Choose the best WRMSR instruction based on availability. >>> + * >>> + * Replace with 'wrmsrns' and 'wrmsrns %rax, $MSR_IA32_SPEC_CTRL' once binutils support them. >>> + */ >>> +.macro WRITE_EAX_TO_MSR_IA32_SPEC_CTRL >>> + ALTERNATIVE_2 __stringify(mov $MSR_IA32_SPEC_CTRL, %ecx; \ >>> + xor %edx, %edx; \ >>> + mov %edi, %eax; \ >>> + ds wrmsr), \ >>> + __stringify(mov $MSR_IA32_SPEC_CTRL, %ecx; \ >>> + xor %edx, %edx; \ >>> + mov %edi, %eax; \ >>> + ASM_WRMSRNS), \ >>> + X86_FEATURE_WRMSRNS, \ >>> + __stringify(xor %_ASM_AX, %_ASM_AX; \ >>> + mov %edi, %eax; \ >>> + ASM_WRMSRNS_RAX; .long MSR_IA32_SPEC_CTRL), \ >>> + X86_FEATURE_MSR_IMM >>> +.endm >> This is quite hideous. I have no objection to optimizing __vmx_vcpu_run(), but >> I would much prefer that a macro like this live in generic code, and that it be >> generic. It should be easy enough to provide an assembly friendly equivalent to >> __native_wrmsr_constant(). > >Will do. This should be coming anyway, right?
