x86/altp2m: add altp2mhvm HVM domain parameter

The altp2mhvm and nestedhvm parameters are mutually
exclusive and cannot be set together.

Signed-off-by: Ed White <edmund.h.white@intel.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Release-acked-by: Wei Liu <wei.liu2@citrix.com>

docs/man/xl.cfg.pod.5

@@ -1130,6 +1130,18 @@ enabled by default and you should usually omit it. It may be necessary
 to disable the HPET in order to improve compatibility with guest
 Operating Systems (X86 only)
 
+=item B<altp2mhvm=BOOLEAN>
+
+Enables or disables hvm guest access to alternate-p2m capability.
+Alternate-p2m allows a guest to manage multiple p2m guest physical
+"memory views" (as opposed to a single p2m). This option is
+disabled by default and is available only to hvm domains.
+You may want this option if you want to access-control/isolate
+access to specific guest physical memory pages accessed by
+the guest, e.g. for HVM domain memory introspection or
+for isolation/access-control of memory between components within
+a single guest hvm domain.
+
 =item B<nestedhvm=BOOLEAN>
 
 Enable or disables guest access to hardware virtualisation features,

tools/libxl/libxl.h

@@ -757,6 +757,12 @@ typedef struct libxl__ctx libxl_ctx;
  */
 #define LIBXL_HAVE_BUILDINFO_SERIAL_LIST 1
 
+/*
+ * LIBXL_HAVE_ALTP2M
+ * If this is defined, then libxl supports alternate p2m functionality.
+ */
+#define LIBXL_HAVE_ALTP2M 1
+
 /*
  * LIBXL_HAVE_REMUS
  * If this is defined, then libxl supports remus.

tools/libxl/libxl_create.c

@@ -287,6 +287,7 @@ int libxl__domain_build_info_setdefault(libxl__gc *gc,
         libxl_defbool_setdefault(&b_info->u.hvm.hpet,               true);
         libxl_defbool_setdefault(&b_info->u.hvm.vpt_align,          true);
         libxl_defbool_setdefault(&b_info->u.hvm.nested_hvm,         false);
+        libxl_defbool_setdefault(&b_info->u.hvm.altp2m,             false);
         libxl_defbool_setdefault(&b_info->u.hvm.usb,                false);
         libxl_defbool_setdefault(&b_info->u.hvm.xen_platform_pci,   true);
 

tools/libxl/libxl_dom.c

@@ -301,6 +301,8 @@ static void hvm_set_conf_params(xc_interface *handle, uint32_t domid,
                     libxl_defbool_val(info->u.hvm.vpt_align));
     xc_hvm_param_set(handle, domid, HVM_PARAM_NESTEDHVM,
                     libxl_defbool_val(info->u.hvm.nested_hvm));
+    xc_hvm_param_set(handle, domid, HVM_PARAM_ALTP2M,
+                    libxl_defbool_val(info->u.hvm.altp2m));
 }
 
 int libxl__build_pre(libxl__gc *gc, uint32_t domid,

tools/libxl/libxl_types.idl

@@ -474,6 +474,7 @@ libxl_domain_build_info = Struct("domain_build_info",[
                                        ("mmio_hole_memkb",  MemKB),
                                        ("timer_mode",       libxl_timer_mode),
                                        ("nested_hvm",       libxl_defbool),
+                                       ("altp2m",           libxl_defbool),
                                        ("smbios_firmware",  string),
                                        ("acpi_firmware",    string),
                                        ("hdtype",           libxl_hdtype),

tools/libxl/xl_cmdimpl.c

@@ -1566,6 +1566,16 @@ static void parse_config_data(const char *config_source,
 
         xlu_cfg_get_defbool(config, "nestedhvm", &b_info->u.hvm.nested_hvm, 0);
 
+        xlu_cfg_get_defbool(config, "altp2mhvm", &b_info->u.hvm.altp2m, 0);
+
+        if (!libxl_defbool_is_default(b_info->u.hvm.nested_hvm) &&
+            libxl_defbool_val(b_info->u.hvm.nested_hvm) &&
+            !libxl_defbool_is_default(b_info->u.hvm.altp2m) &&
+            libxl_defbool_val(b_info->u.hvm.altp2m)) {
+            fprintf(stderr, "ERROR: nestedhvm and altp2mhvm cannot be used together\n");
+            exit(1);
+        }
+
         xlu_cfg_replace_string(config, "smbios_firmware",
                                &b_info->u.hvm.smbios_firmware, 0);
         xlu_cfg_replace_string(config, "acpi_firmware",

xen/arch/x86/hvm/hvm.c

@@ -5866,6 +5866,7 @@ static int hvm_allow_set_param(struct domain *d,
     case HVM_PARAM_VIRIDIAN:
     case HVM_PARAM_IOREQ_SERVER_PFN:
     case HVM_PARAM_NR_IOREQ_SERVER_PAGES:
+    case HVM_PARAM_ALTP2M:
         if ( value != 0 && a->value != value )
             rc = -EEXIST;
         break;
@@ -5988,6 +5989,9 @@ static int hvmop_set_param(
          */
         if ( cpu_has_svm && !paging_mode_hap(d) && a.value )
             rc = -EINVAL;
+        if ( a.value &&
+             d->arch.hvm_domain.params[HVM_PARAM_ALTP2M] )
+            rc = -EINVAL;
         /* Set up NHVM state for any vcpus that are already up. */
         if ( a.value &&
              !d->arch.hvm_domain.params[HVM_PARAM_NESTEDHVM] )
@@ -5998,6 +6002,13 @@ static int hvmop_set_param(
             for_each_vcpu(d, v)
                 nestedhvm_vcpu_destroy(v);
         break;
+    case HVM_PARAM_ALTP2M:
+        if ( a.value > 1 )
+            rc = -EINVAL;
+        if ( a.value &&
+             d->arch.hvm_domain.params[HVM_PARAM_NESTEDHVM] )
+            rc = -EINVAL;
+        break;
     case HVM_PARAM_BUFIOREQ_EVTCHN:
         rc = -EINVAL;
         break;
@@ -6058,6 +6069,7 @@ static int hvm_allow_get_param(struct domain *d,
     case HVM_PARAM_STORE_EVTCHN:
     case HVM_PARAM_CONSOLE_PFN:
     case HVM_PARAM_CONSOLE_EVTCHN:
+    case HVM_PARAM_ALTP2M:
         break;
     /*
      * The following parameters must not be read by the guest
@@ -6178,6 +6190,12 @@ static int do_altp2m_op(
     switch ( a.cmd )
     {
     case HVMOP_altp2m_get_domain_state:
+        if ( !d->arch.hvm_domain.params[HVM_PARAM_ALTP2M] )
+        {
+            rc = -EINVAL;
+            break;
+        }
+
         a.u.domain_state.state = altp2m_active(d);
         rc = __copy_to_guest(arg, &a, 1) ? -EFAULT : 0;
         break;
@@ -6187,7 +6205,8 @@ static int do_altp2m_op(
         struct vcpu *v;
         bool_t ostate;
 
-        if ( nestedhvm_enabled(d) )
+        if ( !d->arch.hvm_domain.params[HVM_PARAM_ALTP2M] ||
+             nestedhvm_enabled(d) )
         {
             rc = -EINVAL;
             break;

xen/include/public/hvm/params.h

@@ -187,6 +187,9 @@
 /* Location of the VM Generation ID in guest physical address space. */
 #define HVM_PARAM_VM_GENERATION_ID_ADDR 34
 
-#define HVM_NR_PARAMS          35
+/* Boolean: Enable altp2m */
+#define HVM_PARAM_ALTP2M       35
+
+#define HVM_NR_PARAMS          36
 
 #endif /* __XEN_PUBLIC_HVM_PARAMS_H__ */