RE: [PATCH v3 7/9] KVM: x86: Implement Intel Processor Trace MSRs read/write

[Kang, Luwei]

> > +           case MSR_IA32_RTIT_ADDR0_A ... MSR_IA32_RTIT_ADDR3_B: {
> > +                   u32 eax, ebx, ecx, edx;
> > +
> > +                   cpuid_count(0x14, 1, &eax, &ebx, &ecx, &edx);
> 
> Please cache the cpuid_count result, or do the cpuid_count after testing
> vmx_pt_supported() (which you can use instead of going through kvm_x86_ops).

Hi Paolo,
    Thanks for your reply. I have cache EAX in "struct pt_desc" and will 
initialize in vmx_vcpu_setup().
+struct pt_desc {
+       unsigned int addr_num;
+       struct pt_ctx host;
+       struct pt_ctx guest;
+}; 
    But kvm_init_msr_list() is invoked too early, I have to read from hardware. 
 So, what about change like this.

-                       cpuid_count(0x14, 1, &eax, &ebx, &ecx, &edx);
-                       if (!kvm_x86_ops->pt_supported() || msrs_to_save[i] -
-                                       MSR_IA32_RTIT_ADDR0_A >= (eax & 0x7))
+                       if (!kvm_x86_ops->pt_supported())
                                continue;
+                       cpuid_count(0x14, 1, &eax, &ebx, &ecx, &edx);
+                       if (msrs_to_save[i] -
+                               MSR_IA32_RTIT_ADDR0_A >= (eax & 0x7))
+                                       continue;

Thanks,
Luwei Kang

> 
> Thanks,
> 
> Paolo
> 
> > +                   if (!kvm_x86_ops->pt_supported() || msrs_to_save[i] -
> > +                                   MSR_IA32_RTIT_ADDR0_A >= (eax & 0x7))
> > +                           continue;
> > +                   break;