A minor optimization to WRMSR MSR_IA32_RTIT_CTL when necessary.
Opportunistically refine the comment to call out that KVM requires
VM_EXIT_CLEAR_IA32_RTIT_CTL to expose PT to the guest.
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
Message-Id: <
20210827070249.924633-2-xiaoyao.li@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
pt_load_msr(&vmx->pt_desc.host, vmx->pt_desc.addr_range);
}
- /* Reload host state (IA32_RTIT_CTL will be cleared on VM exit). */
- wrmsrl(MSR_IA32_RTIT_CTL, vmx->pt_desc.host.ctl);
+ /*
+ * KVM requires VM_EXIT_CLEAR_IA32_RTIT_CTL to expose PT to the guest,
+ * i.e. RTIT_CTL is always cleared on VM-Exit. Restore it if necessary.
+ */
+ if (vmx->pt_desc.host.ctl)
+ wrmsrl(MSR_IA32_RTIT_CTL, vmx->pt_desc.host.ctl);
}
void vmx_set_host_fs_gs(struct vmcs_host_state *host, u16 fs_sel, u16 gs_sel,