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Re: [Qemu-devel] [v2][PATCH 2/2] libxl: introduce gfx_passthru_kind


From: Chen, Tiejun
Subject: Re: [Qemu-devel] [v2][PATCH 2/2] libxl: introduce gfx_passthru_kind
Date: Thu, 12 Mar 2015 11:18:46 +0800
User-agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:31.0) Gecko/20100101 Thunderbird/31.5.0

+
+        if (b_info->u.hvm.gfx_passthru_kind ==
+                LIBXL_GFX_PASSTHRU_KIND_DEFAULT) {
+            if (libxl__is_igd_vga_passthru(gc, guest_config))
+                machinearg = GCSPRINTF("%s,igd-passthru=on", machinearg);
+        } else if (b_info->u.hvm.gfx_passthru_kind ==
+                        LIBXL_GFX_PASSTHRU_KIND_IGD) {
+                machinearg = GCSPRINTF("%s,igd-passthru=on", machinearg);
+        } else {
+            LOG(WARN, "gfx_passthru_kind is invalid so ignored.\n");
+        }

I think this whole block should be inside an:
         if (libxl_defbool_val(b_info->u.hvm.gfx_passthru)
the semantics should be that kind is ignored unless passthru is enabled.

and then the if/else chain could become a switch perhaps?

Okay.


I'm unsure what we should do if kind==DEFAULT but
libxl__is_igd_vga_passthru fails. At a minimum a warning seems
desirable. I'm not sure if it should warrant a failure or not.

I think a warning message plus abort() should be enough, and then user can determine what's next,

Please take a look at this,

+
+        if (libxl_defbool_val(b_info->u.hvm.gfx_passthru)) {
+            switch (b_info->u.hvm.gfx_passthru_kind) {
+            case LIBXL_GFX_PASSTHRU_KIND_DEFAULT:
+                if (libxl__is_igd_vga_passthru(gc, guest_config)) {
+ machinearg = GCSPRINTF("%s,igd-passthru=on", machinearg);
+                } else {
+                    LOG(WARN, "No supported IGD to passthru,"
+                        " or please force set gfx_passthru=\"igd\".\n");
+                    abort();
+                }
+                break;
+            case LIBXL_GFX_PASSTHRU_KIND_IGD:
+                machinearg = GCSPRINTF("%s,igd-passthru=on", machinearg);
+                break;
+            default:
+                LOG(WARN, "gfx_passthru_kind is invalid so ignored.\n");
+                break;
+            }
+        }
+


+
          flexarray_append(dm_args, machinearg);
          for (i = 0; b_info->extra_hvm && b_info->extra_hvm[i] != NULL; i++)
              flexarray_append(dm_args, b_info->extra_hvm[i]);
diff --git a/tools/libxl/libxl_pci.c b/tools/libxl/libxl_pci.c
index fc060c6..9a534cc 100644
--- a/tools/libxl/libxl_pci.c
+++ b/tools/libxl/libxl_pci.c
@@ -608,11 +608,11 @@ bool libxl__is_igd_vga_passthru(libxl__gc *gc,
              device = fixup_ids[j].device;

              if (pt_vendor == vendor &&  pt_device == device)
-                return 1;
+                return true;
          }
      }

-    return 0;
+    return false;

Please fold this into the previous patch. (You may retain the ack I
gave).

Thanks for your catch.

  }

  /*
diff --git a/tools/libxl/libxl_types.idl b/tools/libxl/libxl_types.idl
index 02be466..d64ad10 100644
--- a/tools/libxl/libxl_types.idl
+++ b/tools/libxl/libxl_types.idl
@@ -140,6 +140,11 @@ libxl_tsc_mode = Enumeration("tsc_mode", [
      (3, "native_paravirt"),
      ])

+libxl_gfx_passthru_kind = Enumeration("gfx_passthru_kind", [
+    (0, "default"),
+    (1, "igd"),
+    ])
+
  # Consistent with the values defined for HVM_PARAM_TIMER_MODE.
  libxl_timer_mode = Enumeration("timer_mode", [
      (-1, "unknown"),
@@ -430,6 +435,7 @@ libxl_domain_build_info = Struct("domain_build_info",[
                                         ("spice",            libxl_spice_info),

                                         ("gfx_passthru",     libxl_defbool),
+                                       ("gfx_passthru_kind", 
libxl_gfx_passthru_kind),

Please add a #define LIBXL_HAVE_... to libxl.h to indicate that this
functionality is now available. There is a comment near the top
explaining why etc and a bunch of examples.

Note that the #define is for 3rd party code only, there is no need to
actually use it in either libxl or xl code.

Like this,

@@ -720,6 +720,13 @@ void libxl_mac_copy(libxl_ctx *ctx, libxl_mac *dst, libxl_mac *src);
 #define LIBXL_HAVE_PSR_MBM 1
 #endif

+/*
+ * LIBXL_HAVE_GFX_PASSTHRU_KIND
+ *
+ * If this is defined, the Graphic Device Passthrough Override is supported.
+ */
+#define LIBXL_HAVE_GFX_PASSTHRU_KIND 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);
@@ -1501,6 +1508,11 @@ int libxl_psr_cmt_get_sample(libxl_ctx *ctx,
                              uint64_t *tsc_r);
 #endif

+#ifdef LIBXL_HAVE_GFX_PASSTHRU_KIND
+bool libxl__is_igd_vga_passthru(libxl__gc *gc,
+                                const libxl_domain_config *d_config);
+#endif
+
 /* misc */

 /* Each of these sets or clears the flag according to whether the

But looks libxl__gc{} is defined in the libxl_internal.h file... I guess we need a conversion, or other idea?


                                         ("serial",           string),
                                         ("boot",             string),
diff --git a/tools/libxl/xl_cmdimpl.c b/tools/libxl/xl_cmdimpl.c
index 440db78..d0d6ce3 100644
--- a/tools/libxl/xl_cmdimpl.c
+++ b/tools/libxl/xl_cmdimpl.c
@@ -1953,8 +1953,26 @@ skip_vfb:
          xlu_cfg_replace_string (config, "spice_streaming_video",
                                  &b_info->u.hvm.spice.streaming_video, 0);
          xlu_cfg_get_defbool(config, "nographic", &b_info->u.hvm.nographic, 0);
-        xlu_cfg_get_defbool(config, "gfx_passthru",
-                            &b_info->u.hvm.gfx_passthru, 0);
+        if (!xlu_cfg_get_long(config, "gfx_passthru", &l, 1)) {
+            if (!l) {
+                libxl_defbool_set(&b_info->u.hvm.gfx_passthru, false);
+            } else if (i == 1) {
+                libxl_defbool_set(&b_info->u.hvm.gfx_passthru, true);
+            } else {
+                fprintf(stderr,
+                        "ERROR: invalid value %ld for \"gfx_passthru\"\n", l);
+                exit (1);
+            }

The docs (xl.cfg man page) say, regarding booleans "A C<NUMBER>
interpreted as C<False> (C<0>) or C<True> (any other value)."

So just libxl_defbool_set(&b_info->u.hvm.gfx_passthru, l); should be
fine here.

+        } else if (!xlu_cfg_get_string(config, "gfx_passthru", &buf, 0)) {
+            if (libxl_gfx_passthru_kind_from_string(buf,
+                                        &b_info->u.hvm.gfx_passthru_kind)) {
+                fprintf(stderr,
+                        "ERROR: invalid value \"%s\" for \"gfx_passthru\"\n",
+                        buf);
+                exit (1);
+            }
+            libxl_defbool_set(&b_info->u.hvm.gfx_passthru, false);

Should be true, I see you wrote false in the commit message so I assume
this was my mistake from earlier as well, sorry about that.


Here I update this chunk of code based on your two comments:

@@ -1953,8 +1953,22 @@ skip_vfb:
         xlu_cfg_replace_string (config, "spice_streaming_video",
                                 &b_info->u.hvm.spice.streaming_video, 0);
xlu_cfg_get_defbool(config, "nographic", &b_info->u.hvm.nographic, 0);
-        xlu_cfg_get_defbool(config, "gfx_passthru",
-                            &b_info->u.hvm.gfx_passthru, 0);
+        if (!xlu_cfg_get_long(config, "gfx_passthru", &l, 1)) {
+            if (l) {
+                libxl_defbool_set(&b_info->u.hvm.gfx_passthru, true);
+            } else {
+                libxl_defbool_set(&b_info->u.hvm.gfx_passthru, false);
+            }
+        } else if (!xlu_cfg_get_string(config, "gfx_passthru", &buf, 0)) {
+            if (libxl_gfx_passthru_kind_from_string(buf,
+ &b_info->u.hvm.gfx_passthru_kind)) {
+                fprintf(stderr,
+ "ERROR: invalid value \"%s\" for \"gfx_passthru\"\n",
+                        buf);
+                exit (1);
+            }
+            libxl_defbool_set(&b_info->u.hvm.gfx_passthru, true);
+        }
         switch (xlu_cfg_get_list_as_string_list(config, "serial",

&b_info->u.hvm.serial_list,
                                                 1))

Thanks
Tiejun



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