KVM: VMX: don't configure RM TSS for unrestricted guest

An unrestricted guest can run with CR0.PG==0 and/or CR0.PE==0,
e.g. it can run in Real Mode without requiring host emulation.
The RM TSS is only used for emulating RM, i.e. it will never
be used when unrestricted guest is enabled and so doesn't need
to be configured.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 5726cee43f4f4ed03b6cb1ad8499f5d0742dadae..a5d2c6977e3cda0d711ecb99bbbd1b94acf2954f 100644 (file)
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -6044,6 +6044,9 @@ static int vmx_set_tss_addr(struct kvm *kvm, unsigned int addr)
 {
        int ret;
 
+       if (enable_unrestricted_guest)
+               return 0;
+
        ret = x86_set_memory_region(kvm, TSS_PRIVATE_MEMSLOT, addr,
                                    PAGE_SIZE * 3);
        if (ret)