gnttab: allow setting max version per-domain

Introduce a new domain create field so that toolstack can specify the
maximum grant table version usable by the domain. This is plumbed into
xl and settable by the user as max_grant_version.

Previously this was only settable on a per host basis using the
gnttab command line option.

Note the version is specified using 4 bits, which leaves room to
specify up to grant table version 15. Given that we only have 2 grant
table versions right now, and a new version is unlikely in the near
future using 4 bits seems more than enough.

xenstored stubdomains are limited to grant table v1 because the
current MiniOS code used to build them only has support for grants v1.
There are existing limits set for xenstored stubdomains at creation
time that already match the defaults in MiniOS.

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Acked-by: Christian Lindig <christian.lindig@citrix.com>
Reviewed-by: Ian Jackson <iwj@xenproject.org>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Release-Acked-by: Ian Jackson <iwj@xenproject.org>

docs/man/xl.cfg.5.pod.in

@@ -580,6 +580,11 @@ to have. This value controls how many pages of foreign domains can be accessed
 via the grant mechanism by this domain. The default value is settable via
 L<xl.conf(5)>.
 
+=item B<max_grant_version=NUMBER>
+
+Specify the maximum grant table version the domain is allowed to use. The
+default value is settable via L<xl.conf(5)>.
+
 =item B<nomigrate=BOOLEAN>
 
 Disable migration of this domain.  This enables certain other features

docs/man/xl.conf.5.pod.in

@@ -101,6 +101,12 @@ Sets the default value for the C<max_maptrack_frames> domain config value.
 Default: value of Xen command line B<gnttab_max_maptrack_frames>
 parameter (or its default value if unspecified).
 
+=item B<max_grant_version=NUMBER>
+
+Sets the default value for the C<max_grant_version> domain config value.
+
+Default: maximum grant version supported by the hypervisor.
+
 =item B<vif.default.script="PATH">
 
 Configures the default hotplug script used by virtual network devices.

tools/helpers/init-xenstore-domain.c

@@ -85,9 +85,11 @@ static int build(xc_interface *xch)
          * 1 grant frame is enough: we don't need many grants.
          * Mini-OS doesn't like less than 4, though, so use 4.
          * 128 maptrack frames: 256 entries per frame, enough for 32768 domains.
+         * Currently Mini-OS only supports grant v1.
          */
         .max_grant_frames = 4,
         .max_maptrack_frames = 128,
+        .grant_opts = 1,
     };
 
     xs_fd = open("/dev/xen/xenbus_backend", O_RDWR);

tools/include/libxl.h

@@ -520,6 +520,13 @@
  */
 #define LIBXL_HAVE_PHYSINFO_CAP_GNTTAB 1
 
+/*
+ * LIBXL_HAVE_MAX_GRANT_VERSION indicates libxl_domain_build_info has a
+ * max_grant_version field for setting the max grant table version per
+ * domain.
+ */
+#define LIBXL_HAVE_MAX_GRANT_VERSION 1
+
 /*
  * libxl ABI compatibility
  *

tools/libs/light/libxl_create.c

@@ -454,6 +454,28 @@ int libxl__domain_build_info_setdefault(libxl__gc *gc,
         libxl_defbool_setdefault(&b_info->nested_hvm,               false);
     }
 
+    if (b_info->max_grant_version == LIBXL_MAX_GRANT_DEFAULT) {
+        libxl_physinfo info;
+
+        rc = libxl_get_physinfo(CTX, &info);
+        if (rc) {
+            LOG(ERROR, "failed to get hypervisor info");
+            return rc;
+        }
+
+        if (info.cap_gnttab_v2)
+            b_info->max_grant_version = 2;
+        else if (info.cap_gnttab_v1)
+            b_info->max_grant_version = 1;
+        else
+            /* No grant table support reported */
+            b_info->max_grant_version = 0;
+    } else if (b_info->max_grant_version & ~XEN_DOMCTL_GRANT_version_mask) {
+        LOG(ERROR, "max grant version %d out of range",
+            b_info->max_grant_version);
+        return -ERROR_INVAL;
+    }
+
     return 0;
 }
 
@@ -607,6 +629,7 @@ int libxl__domain_make(libxl__gc *gc, libxl_domain_config *d_config,
             .max_evtchn_port = b_info->event_channels,
             .max_grant_frames = b_info->max_grant_frames,
             .max_maptrack_frames = b_info->max_maptrack_frames,
+            .grant_opts = b_info->max_grant_version,
             .vmtrace_size = ROUNDUP(b_info->vmtrace_buf_kb << 10, XC_PAGE_SHIFT),
         };
 

tools/libs/light/libxl_dm.c

@@ -2320,6 +2320,7 @@ void libxl__spawn_stub_dm(libxl__egc *egc, libxl__stub_dm_spawn_state *sdss)
 
     dm_config->b_info.max_grant_frames = guest_config->b_info.max_grant_frames;
     dm_config->b_info.max_maptrack_frames = guest_config->b_info.max_maptrack_frames;
+    dm_config->b_info.max_grant_version = guest_config->b_info.max_grant_version;
 
     dm_config->b_info.u.pv.features = "";
 

tools/libs/light/libxl_types.idl

@@ -519,6 +519,7 @@ libxl_domain_build_info = Struct("domain_build_info",[
 
     ("max_grant_frames",    uint32, {'init_val': 'LIBXL_MAX_GRANT_DEFAULT'}),
     ("max_maptrack_frames", uint32, {'init_val': 'LIBXL_MAX_GRANT_DEFAULT'}),
+    ("max_grant_version",   integer, {'init_val': 'LIBXL_MAX_GRANT_DEFAULT'}),
     
     ("device_model_version", libxl_device_model_version),
     ("device_model_stubdomain", libxl_defbool),

tools/ocaml/libs/xc/xenctrl.ml

@@ -84,6 +84,7 @@ type domctl_create_config =
 	max_evtchn_port: int;
 	max_grant_frames: int;
 	max_maptrack_frames: int;
+	max_grant_version: int;
 	arch: arch_domainconfig;
 }
 

tools/ocaml/libs/xc/xenctrl.mli

@@ -76,6 +76,7 @@ type domctl_create_config = {
   max_evtchn_port: int;
   max_grant_frames: int;
   max_maptrack_frames: int;
+  max_grant_version: int;
   arch: arch_domainconfig;
 }
 

tools/ocaml/libs/xc/xenctrl_stubs.c

@@ -188,7 +188,8 @@ CAMLprim value stub_xc_domain_create(value xch, value wanted_domid, value config
 #define VAL_MAX_EVTCHN_PORT     Field(config, 5)
 #define VAL_MAX_GRANT_FRAMES    Field(config, 6)
 #define VAL_MAX_MAPTRACK_FRAMES Field(config, 7)
-#define VAL_ARCH                Field(config, 8)
+#define VAL_MAX_GRANT_VERSION   Field(config, 8)
+#define VAL_ARCH                Field(config, 9)
 
 	uint32_t domid = Int_val(wanted_domid);
 	int result;
@@ -198,6 +199,7 @@ CAMLprim value stub_xc_domain_create(value xch, value wanted_domid, value config
 		.max_evtchn_port = Int_val(VAL_MAX_EVTCHN_PORT),
 		.max_grant_frames = Int_val(VAL_MAX_GRANT_FRAMES),
 		.max_maptrack_frames = Int_val(VAL_MAX_MAPTRACK_FRAMES),
+		.grant_opts = Int_val(VAL_MAX_GRANT_VERSION),
 	};
 
 	domain_handle_of_uuid_string(cfg.handle, String_val(VAL_HANDLE));
@@ -251,6 +253,7 @@ CAMLprim value stub_xc_domain_create(value xch, value wanted_domid, value config
 	}
 
 #undef VAL_ARCH
+#undef VAL_MAX_GRANT_VERSION
 #undef VAL_MAX_MAPTRACK_FRAMES
 #undef VAL_MAX_GRANT_FRAMES
 #undef VAL_MAX_EVTCHN_PORT

tools/xl/xl.c

@@ -55,6 +55,7 @@ bool progress_use_cr = 0;
 bool timestamps = 0;
 int max_grant_frames = -1;
 int max_maptrack_frames = -1;
+int max_grant_version = LIBXL_MAX_GRANT_DEFAULT;
 libxl_domid domid_policy = INVALID_DOMID;
 
 xentoollog_level minmsglevel = minmsglevel_default;
@@ -219,6 +220,13 @@ static void parse_global_config(const char *configfile,
     else if (e != ESRCH)
         exit(1);
 
+    e = xlu_cfg_get_bounded_long (config, "max_grant_version", 0,
+                                  INT_MAX, &l, 1);
+    if (!e)
+        max_grant_version = l;
+    else if (e != ESRCH)
+        exit(1);
+
     libxl_cpu_bitmap_alloc(ctx, &global_vm_affinity_mask, 0);
     libxl_cpu_bitmap_alloc(ctx, &global_hvm_affinity_mask, 0);
     libxl_cpu_bitmap_alloc(ctx, &global_pv_affinity_mask, 0);

tools/xl/xl.h

@@ -282,6 +282,7 @@ extern char *default_colo_proxy_script;
 extern char *blkdev_start;
 extern int max_grant_frames;
 extern int max_maptrack_frames;
+extern int max_grant_version;
 extern libxl_bitmap global_vm_affinity_mask;
 extern libxl_bitmap global_hvm_affinity_mask;
 extern libxl_bitmap global_pv_affinity_mask;

tools/xl/xl_parse.c

@@ -1431,6 +1431,15 @@ void parse_config_data(const char *config_source,
     else
         exit(1);
 
+    e = xlu_cfg_get_bounded_long (config, "max_grant_version", 0,
+                                  INT_MAX, &l, 1);
+    if (e == ESRCH) /* not specified */
+        b_info->max_grant_version = max_grant_version;
+    else if (!e)
+        b_info->max_grant_version = l;
+    else
+        exit(1);
+
     libxl_defbool_set(&b_info->claim_mode, claim_mode);
 
     if (xlu_cfg_get_string (config, "on_poweroff", &buf, 0))

xen/arch/arm/domain_build.c

@@ -2967,6 +2967,7 @@ void __init create_domUs(void)
             .max_evtchn_port = -1,
             .max_grant_frames = -1,
             .max_maptrack_frames = -1,
+            .grant_opts = opt_gnttab_max_version,
         };
 
         if ( !dt_device_is_compatible(node, "xen,domain") )
@@ -3074,6 +3075,7 @@ void __init create_dom0(void)
         .max_evtchn_port = -1,
         .max_grant_frames = gnttab_dom0_frames(),
         .max_maptrack_frames = -1,
+        .grant_opts = opt_gnttab_max_version,
     };
 
     /* The vGIC for DOM0 is exactly emulating the hardware GIC */

xen/arch/x86/setup.c

@@ -755,6 +755,7 @@ static struct domain *__init create_dom0(const module_t *image,
         .max_evtchn_port = -1,
         .max_grant_frames = -1,
         .max_maptrack_frames = -1,
+        .grant_opts = opt_gnttab_max_version,
         .max_vcpus = dom0_max_vcpus(),
         .arch = {
             .misc_flags = opt_dom0_msr_relaxed ? XEN_X86_MSR_RELAXED : 0,

xen/common/domain.c

@@ -492,6 +492,12 @@ static int sanitise_domain_config(struct xen_domctl_createdomain *config)
         return -EINVAL;
     }
 
+    if ( config->grant_opts & ~XEN_DOMCTL_GRANT_version_mask )
+    {
+        dprintk(XENLOG_INFO, "Unknown grant options %#x\n", config->grant_opts);
+        return -EINVAL;
+    }
+
     if ( config->max_vcpus < 1 )
     {
         dprintk(XENLOG_INFO, "No vCPUS\n");
@@ -678,7 +684,8 @@ struct domain *domain_create(domid_t domid,
         init_status |= INIT_evtchn;
 
         if ( (err = grant_table_init(d, config->max_grant_frames,
-                                     config->max_maptrack_frames)) != 0 )
+                                     config->max_maptrack_frames,
+                                     config->grant_opts)) != 0 )
             goto fail;
         init_status |= INIT_gnttab;
 

xen/common/grant_table.c

@@ -53,6 +53,7 @@ struct grant_table {
     percpu_rwlock_t       lock;
     /* Lock protecting the maptrack limit */
     spinlock_t            maptrack_lock;
+    unsigned int          max_version;
     /*
      * Defaults to v1.  May be changed with GNTTABOP_set_version.  All other
      * values are invalid.
@@ -1917,11 +1918,26 @@ active_alloc_failed:
 }
 
 int grant_table_init(struct domain *d, int max_grant_frames,
-                     int max_maptrack_frames)
+                     int max_maptrack_frames, unsigned int options)
 {
     struct grant_table *gt;
+    unsigned int max_grant_version = options & XEN_DOMCTL_GRANT_version_mask;
     int ret = -ENOMEM;
 
+    if ( !max_grant_version )
+    {
+        dprintk(XENLOG_INFO, "%pd: invalid grant table version 0 requested\n",
+                d);
+        return -EINVAL;
+    }
+    if ( max_grant_version > opt_gnttab_max_version )
+    {
+        dprintk(XENLOG_INFO,
+                "%pd: requested grant version (%u) greater than supported (%u)\n",
+                d, max_grant_version, opt_gnttab_max_version);
+        return -EINVAL;
+    }
+
     /* Default to maximum value if no value was specified */
     if ( max_grant_frames < 0 )
         max_grant_frames = opt_max_grant_frames;
@@ -1947,6 +1963,7 @@ int grant_table_init(struct domain *d, int max_grant_frames,
     gt->gt_version = 1;
     gt->max_grant_frames = max_grant_frames;
     gt->max_maptrack_frames = max_maptrack_frames;
+    gt->max_version = max_grant_version;
 
     /* Install the structure early to simplify the error path. */
     gt->domain = d;
@@ -3076,7 +3093,7 @@ gnttab_set_version(XEN_GUEST_HANDLE_PARAM(gnttab_set_version_t) uop)
         goto out;
 
     res = -ENOSYS;
-    if ( op.version == 2 && opt_gnttab_max_version == 1 )
+    if ( op.version == 2 && gt->max_version == 1 )
         goto out; /* Behave as before set_version was introduced. */
 
     res = 0;

xen/include/public/domctl.h

@@ -97,6 +97,11 @@ struct xen_domctl_createdomain {
     int32_t max_grant_frames;
     int32_t max_maptrack_frames;
 
+/* Grant version, use low 4 bits. */
+#define XEN_DOMCTL_GRANT_version_mask    0xf
+
+    uint32_t grant_opts;
+
     /* Per-vCPU buffer size in bytes.  0 to disable. */
     uint32_t vmtrace_size;
 

xen/include/xen/grant_table.h

@@ -37,7 +37,7 @@ extern unsigned int opt_max_grant_frames;
 
 /* Create/destroy per-domain grant table context. */
 int grant_table_init(struct domain *d, int max_grant_frames,
-                     int max_maptrack_frames);
+                     int max_maptrack_frames, unsigned int options);
 void grant_table_destroy(
     struct domain *d);
 void grant_table_init_vcpu(struct vcpu *v);
@@ -69,8 +69,12 @@ int gnttab_acquire_resource(
 
 static inline int grant_table_init(struct domain *d,
                                    int max_grant_frames,
-                                   int max_maptrack_frames)
+                                   int max_maptrack_frames,
+                                   unsigned int options)
 {
+    if ( options )
+        return -EINVAL;
+
     return 0;
 }