[Xen-devel] [PATCH RFC v1 71/74] libxl: pvshim: Provide first-class config settings to enable shim mode

[Wei Liu <wei.liu2@xxxxxxxxxx>]

From: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>

** NOTE: This patch does not currently work! **

** NOTE: I intend to change the config names from "pvhshim" to "pvshim" **

This is API-compatible because old callers are supposed to call
libxl_*_init to initialise the struct; and the updated function clears
these members.

It is ABI-compatible because the new fields make this member of the
guest type union larger but only within the existing size of that
union.

For now, our config defaults are:
 * shim is disabled
 * if enabled, path is "xen-shim" in the xen firmware directory
 * if enabled, cmdline is the one we are currently debugging with

The debugging arguments will be rationalised in a moment.

Signed-off-by: Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>
---
 tools/libxl/libxl.h          |  8 ++++++++
 tools/libxl/libxl_create.c   | 48 +++++++++++++++++++++++++++++++++++++++++---
 tools/libxl/libxl_dom.c      | 10 ---------
 tools/libxl/libxl_internal.h |  2 ++
 tools/libxl/libxl_types.idl  |  3 +++
 5 files changed, 58 insertions(+), 13 deletions(-)

diff --git a/tools/libxl/libxl.h b/tools/libxl/libxl.h
index 5e9aed739d..81dfcc80ad 100644
--- a/tools/libxl/libxl.h
+++ b/tools/libxl/libxl.h
@@ -1101,6 +1101,14 @@ void libxl_mac_copy(libxl_ctx *ctx, libxl_mac *dst, 
const libxl_mac *src);
  */
 #define LIBXL_HAVE_SET_PARAMETERS 1
 
+/*
+ * LIBXL_HAVE_PV_SHIM
+ *
+ * If this is defined, libxl_domain_build_info's pv type information
+ * contains members pvhshim, pvhshim_path, pvhshim_cmdline.
+ */
+#define LIBXL_HAVE_PV_SHIM 1
+
 typedef char **libxl_string_list;
 void libxl_string_list_dispose(libxl_string_list *sl);
 int libxl_string_list_length(const libxl_string_list *sl);
diff --git a/tools/libxl/libxl_create.c b/tools/libxl/libxl_create.c
index 6d910e4a09..cd98522b9b 100644
--- a/tools/libxl/libxl_create.c
+++ b/tools/libxl/libxl_create.c
@@ -369,6 +369,18 @@ int libxl__domain_build_info_setdefault(libxl__gc *gc,
         if (b_info->u.pv.slack_memkb == LIBXL_MEMKB_DEFAULT)
             b_info->u.pv.slack_memkb = 0;
 
+        libxl_defbool_setdefault(&b_info->u.pv.pvhshim, false);
+        if (libxl_defbool_val(b_info->u.pv.pvhshim)) {
+            if (!b_info->u.pv.pvhshim_path)
+                b_info->u.pv.pvhshim_path =
+                    libxl__sprintf(NOGC, "%s/%s",
+                                   libxl__xenfirmwaredir_path(),
+                                   PVSHIM_BASENAME);
+            if (!b_info->u.pv.pvhshim_cmdline)
+                b_info->u.pv.pvhshim_cmdline =
+                    libxl__strdup(NOGC, PVSHIM_CMDLINE);
+        }
+
         /* For compatibility, fill in b_info->kernel|ramdisk|cmdline
          * with the value in u.pv, later processing will use
          * b_info->kernel|ramdisk|cmdline only.
@@ -438,6 +450,9 @@ int libxl__domain_build(libxl__gc *gc,
     char **vments = NULL, **localents = NULL;
     struct timeval start_time;
     int i, ret;
+    libxl_domain_build_info shim_info;
+
+    libxl_domain_build_info_init(&shim_info);
 
     ret = libxl__build_pre(gc, domid, d_config, state);
     if (ret)
@@ -485,9 +500,35 @@ int libxl__domain_build(libxl__gc *gc,
 
         break;
     case LIBXL_DOMAIN_TYPE_PV:
-        ret = libxl__build_pv(gc, domid, info, state);
-        if (ret)
-            goto out;
+        if (libxl_defbool_val(info->u.pv.pvhshim)) {
+            /*
+             * The next bit seems like it might be thread-unsafe, but
+             * libxl_domain_create can already modify this struct so a
+             * config cannot be passed to libxl on different threads
+             * concurrently.  So we can set this to INVALID, as part
+             * of making copy with a different type.
+             */
+            libxl_domain_type shim_saved_type = info->type;
+            info->type = LIBXL_DOMAIN_TYPE_INVALID;
+            libxl_domain_build_info_copy(CTX, &shim_info, info);
+            info->type = shim_saved_type;
+
+            libxl_domain_build_info_init_type(&shim_info,
+                                              LIBXL_DOMAIN_TYPE_PVH);
+            ret = libxl__domain_build_info_setdefault_pvhhvm(gc, &shim_info);
+            if (ret) goto out;
+
+            state->shim_path = info->u.pv.pvhshim_path;
+            state->shim_cmdline = info->u.pv.pvhshim_cmdline;
+            ret = libxl__build_hvm(gc, domid,
+                                   d_config, &shim_info,
+                                   state);
+            if (ret) goto out;
+        } else {
+            ret = libxl__build_pv(gc, domid, info, state);
+            if (ret)
+                goto out;
+        }
 
         vments = libxl__calloc(gc, 11, sizeof(char *));
         i = 0;
@@ -525,6 +566,7 @@ int libxl__domain_build(libxl__gc *gc,
     }
     ret = libxl__build_post(gc, domid, info, state, vments, localents);
 out:
+    libxl_domain_build_info_dispose(&shim_info);
     return ret;
 }
 
diff --git a/tools/libxl/libxl_dom.c b/tools/libxl/libxl_dom.c
index bf509905a1..3b6c457ec0 100644
--- a/tools/libxl/libxl_dom.c
+++ b/tools/libxl/libxl_dom.c
@@ -1183,16 +1183,6 @@ int libxl__build_hvm(libxl__gc *gc, uint32_t domid,
 
     xc_dom_loginit(ctx->xch);
 
-    /* FIXME */
-#define LIBXL_PVSHIM_PATH "LIBXL_PVSHIM_PATH"
-#define LIBXL_PVSHIM_CMDLINE "LIBXL_PVSHIM_CMDLINE"
-    state->shim_path = getenv(LIBXL_PVSHIM_PATH);
-    if (state->shim_path) {
-        state->shim_cmdline = getenv(LIBXL_PVSHIM_CMDLINE);
-        LOG(WARN, "LIBXL_PVSHIM_PATH detected, using pv shim %s cmd %s",
-            state->shim_path, state->shim_cmdline);
-    }
-
     /* 
      * If PVH and we have a shim override, use the shim cmdline.
      * If PVH and no shim override, use the pv cmdline.
diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
index 174cf35d97..2897e7c3bb 100644
--- a/tools/libxl/libxl_internal.h
+++ b/tools/libxl/libxl_internal.h
@@ -118,6 +118,8 @@
 #define TAP_DEVICE_SUFFIX "-emu"
 #define DOMID_XS_PATH "domid"
 #define INVALID_DOMID ~0
+#define PVSHIM_BASENAME "xen-shim"
+#define PVSHIM_CMDLINE "pv-shim console=xen,pv sched=null loglvl=all 
guest_loglvl=all apic_verbosity=debug e820-verbose"
 
 /* Size macros. */
 #define __AC(X,Y)   (X##Y)
diff --git a/tools/libxl/libxl_types.idl b/tools/libxl/libxl_types.idl
index a239324341..a6ebea0178 100644
--- a/tools/libxl/libxl_types.idl
+++ b/tools/libxl/libxl_types.idl
@@ -591,6 +591,9 @@ libxl_domain_build_info = Struct("domain_build_info",[
                                       ("features", string, {'const': True}),
                                       # Use host's E820 for PCI passthrough.
                                       ("e820_host", libxl_defbool),
+                                      ("pvhshim", libxl_defbool),
+                                      ("pvhshim_path", string),
+                                      ("pvhshim_cmdline", string),
                                       ])),
                  ("pvh", None),
                  ("invalid", None),
-- 
2.11.0


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