x86: MSR_IA32_BNDCFGS save/restore

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
Reviewed-by: Liu Jinsong <jinsong.liu@xxxxxxxxx>

--- a/xen/arch/x86/hvm/vmx/vmx.c
+++ b/xen/arch/x86/hvm/vmx/vmx.c
@@ -580,6 +580,55 @@ static int vmx_load_vmcs_ctxt(struct vcp
     return 0;
 }
 
+static unsigned int __init vmx_init_msr(void)
+{
+    return !!cpu_has_mpx;
+}
+
+static void vmx_save_msr(struct vcpu *v, struct hvm_msr *ctxt)
+{
+    vmx_vmcs_enter(v);
+
+    if ( cpu_has_mpx )
+    {
+        __vmread(GUEST_BNDCFGS, &ctxt->msr[ctxt->count].val);
+        if ( ctxt->msr[ctxt->count].val )
+            ctxt->msr[ctxt->count++].index = MSR_IA32_BNDCFGS;
+    }
+
+    vmx_vmcs_exit(v);
+}
+
+static int vmx_load_msr(struct vcpu *v, struct hvm_msr *ctxt)
+{
+    unsigned int i;
+    int err = 0;
+
+    vmx_vmcs_enter(v);
+
+    for ( i = 0; i < ctxt->count; ++i )
+    {
+        switch ( ctxt->msr[i].index )
+        {
+        case MSR_IA32_BNDCFGS:
+            if ( cpu_has_mpx )
+                __vmwrite(GUEST_BNDCFGS, ctxt->msr[i].val);
+            else
+                err = -ENXIO;
+            break;
+        default:
+            continue;
+        }
+        if ( err )
+            break;
+        ctxt->msr[i]._rsvd = 1;
+    }
+
+    vmx_vmcs_exit(v);
+
+    return err;
+}
+
 static void vmx_fpu_enter(struct vcpu *v)
 {
     vcpu_restore_fpu_lazy(v);
@@ -1607,6 +1656,9 @@ static struct hvm_function_table __initd
     .vcpu_destroy         = vmx_vcpu_destroy,
     .save_cpu_ctxt        = vmx_save_vmcs_ctxt,
     .load_cpu_ctxt        = vmx_load_vmcs_ctxt,
+    .init_msr             = vmx_init_msr,
+    .save_msr             = vmx_save_msr,
+    .load_msr             = vmx_load_msr,
     .get_interrupt_shadow = vmx_get_interrupt_shadow,
     .set_interrupt_shadow = vmx_set_interrupt_shadow,
     .guest_x86_mode       = vmx_guest_x86_mode,
--- a/xen/include/asm-x86/hvm/vmx/vmcs.h
+++ b/xen/include/asm-x86/hvm/vmx/vmcs.h
@@ -367,6 +367,8 @@ enum vmcs_field {
     GUEST_PDPTR2_HIGH               = 0x0000280f,
     GUEST_PDPTR3                    = 0x00002810,
     GUEST_PDPTR3_HIGH               = 0x00002811,
+    GUEST_BNDCFGS                   = 0x00002812,
+    GUEST_BNDCFGS_HIGH              = 0x00002813,
     HOST_PAT                        = 0x00002c00,
     HOST_PAT_HIGH                   = 0x00002c01,
     HOST_EFER                       = 0x00002c02,