On Wed, Mar 03, 2021, Like Xu wrote: > New VMX controls bits for Arch LBR are added. When bit 21 in vmentry_ctrl > is set, VM entry will write the value from the "Guest IA32_LBR_CTL" guest > state field to IA32_LBR_CTL. When bit 26 in vmexit_ctrl is set, VM exit > will clear IA32_LBR_CTL after the value has been saved to the "Guest > IA32_LBR_CTL" guest state field. ... > @@ -2529,7 +2532,8 @@ static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf, > VM_EXIT_LOAD_IA32_EFER | > VM_EXIT_CLEAR_BNDCFGS | > VM_EXIT_PT_CONCEAL_PIP | > - VM_EXIT_CLEAR_IA32_RTIT_CTL; > + VM_EXIT_CLEAR_IA32_RTIT_CTL | > + VM_EXIT_CLEAR_IA32_LBR_CTL; So, how does MSR_ARCH_LBR_CTL get restored on the host? What if the host wants to keep _its_ LBR recording active while the guest is running? > if (adjust_vmx_controls(min, opt, MSR_IA32_VMX_EXIT_CTLS, > &_vmexit_control) < 0) > return -EIO; > @@ -2553,7 +2557,8 @@ static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf, > VM_ENTRY_LOAD_IA32_EFER | > VM_ENTRY_LOAD_BNDCFGS | > VM_ENTRY_PT_CONCEAL_PIP | > - VM_ENTRY_LOAD_IA32_RTIT_CTL; > + VM_ENTRY_LOAD_IA32_RTIT_CTL | > + VM_ENTRY_LOAD_IA32_LBR_CTL; > if (adjust_vmx_controls(min, opt, MSR_IA32_VMX_ENTRY_CTLS, > &_vmentry_control) < 0) > return -EIO; > -- > 2.29.2 >
