RE: [PATCH v2 09/25] KVM: VMX: Switch FRED RSP0 between host and guest

...

• if (unlikely(vmx->msr_host_fred_rsp0 == 0))
  

• 	vmx->msr_host_fred_rsp0 =
  

read_msr(MSR_IA32_FRED_RSP0);

can we just drop this and use "(unsigned long)task_stack_page(current) + THREAD_SIZE" as host fred rsp0?

I thought about it, however, don't see a strong reason that it's better, i.e., is RDMSR slower than reading 'stack' from current task_struct?

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• wrmsrl(MSR_IA32_FRED_RSP0, vmx->msr_guest_fred_rsp0);
  

any reason to not use wrmsrns?

Good call!

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• }

#else savesegment(fs, fs_sel); savesegment(gs, gs_sel); @@ -1381,6 +1391,11 @@ static void vmx_prepare_switch_to_host(struct

vcpu_vmx *vmx)

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invalidate_tss_limit(); #ifdef CONFIG_X86_64 wrmsrl(MSR_KERNEL_GS_BASE, vmx->msr_host_kernel_gs_base);

• if (guest_can_use(&vmx->vcpu, X86_FEATURE_FRED)) {

• vmx->msr_guest_fred_rsp0 = read_msr(MSR_IA32_FRED_RSP0);
  

• wrmsrl(MSR_IA32_FRED_RSP0, vmx->msr_host_fred_rsp0);
  

same question.

Will do!

Thanks! Xin