Commit 2e6e0d68 authored by Xiaoyao Li's avatar Xiaoyao Li Committed by Paolo Bonzini
Browse files

KVM: VMX: Restore host's MSR_IA32_RTIT_CTL when it's not zero 



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: default avatarSean Christopherson <seanjc@google.com>
Signed-off-by: default avatarXiaoyao Li <xiaoyao.li@intel.com>
Message-Id: <20210827070249.924633-2-xiaoyao.li@intel.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 2839180c

arch/x86/kvm/vmx/vmx.c

+6 −2
Original line number Diff line number Diff line
@@ -1074,7 +1074,11 @@ static void pt_guest_exit(struct vcpu_vmx *vmx) 
		pt_load_msr(&vmx->pt_desc.host, vmx->pt_desc.addr_range);

	}



	/* Reload host state (IA32_RTIT_CTL will be cleared on VM exit). */

	/*

	 * 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);

}