Re: [libvirt] [PATCH v6.1 4/9] libxl: do not enable nested HVM unless global nested_hvm option enabled

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(a)invisiblethingslab.com&gt; Reviewed-by: Daniel P. Berrangé <berrange(a)redhat.com&gt; --- Changes since v6: - really allow per-domain override 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 dcfdd67..ed8506d 100644 --- a/src/libxl/libxl_conf.c +++ b/src/libxl/libxl_conf.c @@ -360,10 +360,12 @@ libxlMakeDomBuildInfo(virDomainDefPtr def, bool hasHwVirt = false; bool svm = false, vmx = false; + /* enable nested HVM only if global nested_hvm option enable it and + * host support it*/ if (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; + hasHwVirt = cfg->nested_hvm && (vmx | svm); } if (def->cpu->nfeatures) { @@ -380,6 +382,11 @@ 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);