[libvirt] [PATCH v5 4/9] libxl: do not enable nested HVM unless global nested_hvm option enabled

[Marek Marczykowski-Górecki]

Introduce global libxl option for enabling nested HVM feature, similar
to kvm module parameter. This will prevent enabling experimental feature
by mere presence of <cpu mode='host-passthrough'> element in domain
config, unless explicitly enabled. <cpu mode='host-passthrough'> element
may be used to configure other features, like NUMA, or CPUID.

Signed-off-by: Marek Marczykowski-Górecki <marmarek at invisiblethingslab.com>
---
Changes since v4:
 - add nested_hvm option to test_libvirtd_libxl.aug.in and libvirtd_libxl.aug
 - make it possible to override nested_hvm=0 with explicit <feature
   policy='require' name='vmx'/>
 - split xenconfig changes into separate commits
Changes since v3:
 - use config option nested_hvm, instead of requiring explicit <feature
   ...> entries
 - title changed from "libxl: do not enable nested HVM by mere presence
   of <cpu> element"
 - xenconfig: don't add <feature policy='force' name='vmx'/> since it is
   implied by presence of <cpu> element
 - xenconfig: produce <cpu> element even when converting on host not
   supporting vmx/svm, to not lose setting value
Changes since v2:
 - new patch
---
 src/libxl/libvirtd_libxl.aug         |  2 ++
 src/libxl/libxl.conf                 |  8 ++++++++
 src/libxl/libxl_conf.c               | 12 +++++++++++-
 src/libxl/libxl_conf.h               |  2 ++
 src/libxl/test_libvirtd_libxl.aug.in |  1 +
 tests/libxlxml2domconfigtest.c       |  3 +++
 6 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/src/libxl/libvirtd_libxl.aug b/src/libxl/libvirtd_libxl.aug
index b31cc07..58b9af3 100644
--- a/src/libxl/libvirtd_libxl.aug
+++ b/src/libxl/libvirtd_libxl.aug
@@ -28,12 +28,14 @@ module Libvirtd_libxl =
    let lock_entry = str_entry "lock_manager"
    let keepalive_interval_entry = int_entry "keepalive_interval"
    let keepalive_count_entry = int_entry "keepalive_count"
+   let nested_hvm_entry = bool_entry "nested_hvm"
 
    (* Each entry in the config is one of the following ... *)
    let entry = autoballoon_entry
              | lock_entry
              | keepalive_interval_entry
              | keepalive_count_entry
+             | nested_hvm_entry
 
    let comment = [ label "#comment" . del /#[ \t]*/ "# " .  store /([^ \t\n][^\n]*)?/ . del /\n/ "\n" ]
    let empty = [ label "#empty" . eol ]
diff --git a/src/libxl/libxl.conf b/src/libxl/libxl.conf
index 264af7c..72825a7 100644
--- a/src/libxl/libxl.conf
+++ b/src/libxl/libxl.conf
@@ -41,3 +41,11 @@
 #
 #keepalive_interval = 5
 #keepalive_count = 5
+
+# Nested HVM default control. In order to use nested HVM feature, this option
+# needs to be enabled, in addition to specifying <cpu mode='host-passthrough'>
+# in domain configuration. This can be overridden in domain configuration by
+# explicitly setting <feature policy='require' name='vmx'/> inside <cpu/>
+# element.
+# By default it is disabled.
+#nested_hvm = 0
diff --git a/src/libxl/libxl_conf.c b/src/libxl/libxl_conf.c
index 9301731..09264ce 100644
--- a/src/libxl/libxl_conf.c
+++ b/src/libxl/libxl_conf.c
@@ -366,7 +366,9 @@ libxlMakeDomBuildInfo(virDomainDefPtr def,
                 return -1;
             }
 
-            if (ARCH_IS_X86(def->os.arch)) {
+            /* enable nested HVM only if global nested_hvm option enable it and
+             * host support it*/
+            if (cfg->nested_hvm && ARCH_IS_X86(def->os.arch)) {
                 vmx = virCPUCheckFeature(caps->host.arch, caps->host.cpu, "vmx");
                 svm = virCPUCheckFeature(caps->host.arch, caps->host.cpu, "svm");
                 hasHwVirt = vmx | svm;
@@ -386,6 +388,11 @@ libxlMakeDomBuildInfo(virDomainDefPtr def,
 
                         case VIR_CPU_FEATURE_FORCE:
                         case VIR_CPU_FEATURE_REQUIRE:
+                            if ((vmx && STREQ(def->cpu->features[i].name, "vmx")) ||
+                                (svm && STREQ(def->cpu->features[i].name, "svm")))
+                                hasHwVirt = true;
+                            break;
+
                         case VIR_CPU_FEATURE_OPTIONAL:
                         case VIR_CPU_FEATURE_LAST:
                             break;
@@ -1699,6 +1706,9 @@ int libxlDriverConfigLoadFile(libxlDriverConfigPtr cfg,
     if (virConfGetValueUInt(conf, "keepalive_count", &cfg->keepAliveCount) < 0)
         goto cleanup;
 
+    if (virConfGetValueBool(conf, "nested_hvm", &cfg->nested_hvm) < 0)
+        goto cleanup;
+
     ret = 0;
 
  cleanup:
diff --git a/src/libxl/libxl_conf.h b/src/libxl/libxl_conf.h
index ce9db26..27cfc1a 100644
--- a/src/libxl/libxl_conf.h
+++ b/src/libxl/libxl_conf.h
@@ -88,6 +88,8 @@ struct _libxlDriverConfig {
     int keepAliveInterval;
     unsigned int keepAliveCount;
 
+    bool nested_hvm;
+
     /* Once created, caps are immutable */
     virCapsPtr caps;
 
diff --git a/src/libxl/test_libvirtd_libxl.aug.in b/src/libxl/test_libvirtd_libxl.aug.in
index 63558e5..9106abe 100644
--- a/src/libxl/test_libvirtd_libxl.aug.in
+++ b/src/libxl/test_libvirtd_libxl.aug.in
@@ -6,3 +6,4 @@ module Test_libvirtd_libxl =
 { "lock_manager" = "lockd" }
 { "keepalive_interval" = "5" }
 { "keepalive_count" = "5" }
+{ "nested_hvm" = "1" }
diff --git a/tests/libxlxml2domconfigtest.c b/tests/libxlxml2domconfigtest.c
index cfbc37c..8819032 100644
--- a/tests/libxlxml2domconfigtest.c
+++ b/tests/libxlxml2domconfigtest.c
@@ -76,6 +76,9 @@ testCompareXMLToDomConfig(const char *xmlfile,
     if (!(log = (xentoollog_logger *)xtl_createlogger_stdiostream(stderr, XTL_DEBUG, 0)))
         goto cleanup;
 
+    /* for testing nested HVM */
+    cfg->nested_hvm = true;
+
     /* replace logger with stderr one */
     libxl_ctx_free(cfg->ctx);
 
-- 
git-series 0.9.1