libxl/xl: add cacheability option to iomem

Parse a new cacheability option for the iomem parameter, it can be
"devmem" for device memory mappings, which is the default, or "memory"
for normal memory mappings.

Store the parameter in a new field in libxl_iomem_range.

Pass the cacheability option to xc_domain_memory_mapping.

Signed-off-by: Stefano Stabellini <stefanos@xilinx.com>
CC: ian.jackson@eu.citrix.com
CC: wei.liu2@citrix.com

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

@@ -1271,7 +1271,7 @@ is given in hexadecimal format and may either be a range, e.g. C<2f8-2ff>
 It is recommended to only use this option for trusted VMs under
 administrator's control.
 
-=item B<iomem=[ "IOMEM_START,NUM_PAGES[@GFN]", "IOMEM_START,NUM_PAGES[@GFN]", ...]>
+=item B<iomem=[ "IOMEM_START,NUM_PAGES[@GFN],CACHEABILITY", "IOMEM_START,NUM_PAGES[@GFN],CACHEABILITY", ...]>
 
 Allow auto-translated domains to access specific hardware I/O memory pages.
 
@@ -1282,6 +1282,8 @@ B<GFN> is not specified, the mapping will be performed using B<IOMEM_START>
 as a start in the guest's address space, therefore performing a 1:1 mapping
 by default.
 All of these values must be given in hexadecimal format.
+B<CACHEABILITY> can be "devmem" for device memory, the default if not
+specified, or it can be "memory" for normal memory.
 
 Note that the IOMMU won't be updated with the mappings specified with this
 option. This option therefore should not be used to pass through any

tools/libs/light/libxl_create.c

@@ -491,6 +491,14 @@ static void init_console_info(libxl__gc *gc,
        Only 'channels' when mapped to consoles have a string name. */
 }
 
+static uint32_t libxl__cacheability_to_xc(libxl_cacheability c)
+{
+    if (c == LIBXL_CACHEABILITY_MEMORY)
+        return CACHEABILITY_MEMORY;
+    /* default to devmem */
+    return CACHEABILITY_DEVMEM;
+}
+
 int libxl__domain_build(libxl__gc *gc,
                         libxl_domain_config *d_config,
                         uint32_t domid,
@@ -1719,7 +1727,9 @@ static void domcreate_launch_dm(libxl__egc *egc, libxl__multidev *multidev,
         }
         ret = xc_domain_memory_mapping(CTX->xch, domid,
                                        io->gfn, io->start,
-                                       io->number, 1, CACHEABILITY_DEVMEM);
+                                       io->number, 1,
+                                       libxl__cacheability_to_xc(
+                                           io->cache_policy));
         if (ret < 0) {
             LOGED(ERROR, domid,
                   "failed to map to domain iomem range %"PRIx64"-%"PRIx64

tools/libs/light/libxl_types.idl

@@ -283,13 +283,20 @@ libxl_ioport_range = Struct("ioport_range", [
     ("number", uint32),
     ])
 
+libxl_cacheability = Enumeration("cacheability", [
+    (0, "devmem"),
+    (1, "memory"),
+    ], init_val = "LIBXL_CACHEABILITY_DEVMEM")
+
 libxl_iomem_range = Struct("iomem_range", [
     # start host frame number to be mapped to the guest
     ("start", uint64),
     # number of frames to be mapped
     ("number", uint64),
     # guest frame number used as a start for the mapping
     ("gfn", uint64, {'init_val': "LIBXL_INVALID_GFN"}),
+    # cacheability of the memory region
+    ("cache_policy", libxl_cacheability),
     ])
 
 libxl_vga_interface_info = Struct("vga_interface_info", [

tools/xl/xl_parse.c

@@ -1970,6 +1970,7 @@ void parse_config_data(const char *config_source,
         }
         for (i = 0; i < num_iomem; i++) {
             int used;
+            char cache[7];
 
             buf = xlu_cfg_get_listitem (iomem, i);
             if (!buf) {
@@ -1978,15 +1979,27 @@ void parse_config_data(const char *config_source,
                 exit(1);
             }
             libxl_iomem_range_init(&b_info->iomem[i]);
-            ret = sscanf(buf, "%" SCNx64",%" SCNx64"%n@%" SCNx64"%n",
+            ret = sscanf(buf, "%" SCNx64",%" SCNx64"%n@%" SCNx64"%n,%6s%n",
                          &b_info->iomem[i].start,
                          &b_info->iomem[i].number, &used,
-                         &b_info->iomem[i].gfn, &used);
+                         &b_info->iomem[i].gfn, &used,
+                         cache, &used);
             if (ret < 2 || buf[used] != '\0') {
                 fprintf(stderr,
                         "xl: Invalid argument parsing iomem: %s\n", buf);
                 exit(1);
             }
+            if (ret == 4) {
+                if (!strcmp(cache, "memory"))
+                    b_info->iomem[i].cache_policy = LIBXL_CACHEABILITY_MEMORY;
+                else if (!strcmp(cache, "devmem"))
+                    b_info->iomem[i].cache_policy = LIBXL_CACHEABILITY_DEVMEM;
+                else {
+                    fprintf(stderr,
+                            "xl: Invalid iomem cache parameter: %s\n", cache);
+                    exit(1);
+                }
+            }
         }
     }