Re: [libvirt] [PATCH] Add new 'kvm' domain feature and ability to hide KVM signature

QEMU 2.1 added support for the kvm=off option to the -cpu command, allowing the KVM hypervisor signature to be hidden from the guest. This enables disabling of some paravirualization features in the guest as well as allowing certain drivers which test for the hypervisor to load. Domain XML syntax is as follows: <domain type='kvm> ... <features> ... <kvm> <hidden state='on'/> </kvm> </features> ... Signed-off-by: Alex Williamson <alex.williamson(a)redhat.com&gt; --- If it's not obvious, this patch is derived from copying and modifying the similar hyperv feature support. Hopefully I've found all the right pieces.

docs/formatdomain.html.in | 21 ++++ docs/schemas/domaincommon.rng | 18 +++- src/conf/domain_conf.c | 100 ++++++++++++++++++++ src/conf/domain_conf.h | 9 ++ src/qemu/qemu_command.c | 22 ++++ tests/qemuargv2xmltest.c | 2 .../qemuxml2argv-kvm-features-off.args | 5 + .../qemuxml2argv-kvm-features-off.xml | 27 +++++ .../qemuxml2argv-kvm-features.args | 5 + .../qemuxml2argvdata/qemuxml2argv-kvm-features.xml | 27 +++++ tests/qemuxml2argvtest.c | 3 + tests/qemuxml2xmltest.c | 3 + 12 files changed, 240 insertions(+), 2 deletions(-) create mode 100644 tests/qemuxml2argvdata/qemuxml2argv-kvm-features-off.args create mode 100644 tests/qemuxml2argvdata/qemuxml2argv-kvm-features-off.xml create mode 100644 tests/qemuxml2argvdata/qemuxml2argv-kvm-features.args create mode 100644 tests/qemuxml2argvdata/qemuxml2argv-kvm-features.xml diff --git a/docs/formatdomain.html.in b/docs/formatdomain.html.in index bd99ae0..32cc381 100644 --- a/docs/formatdomain.html.in +++ b/docs/formatdomain.html.in @@ -1232,6 +1232,9 @@ &lt;vapic state='on'/&gt; &lt;spinlocks state='on' retries='4096'/&gt; &lt;/hyperv&gt; + &lt;kvm&gt; + &lt;hidden state='on'/&gt; + &lt;/kvm&gt; &lt;pvspinlock/&gt; &lt;/features&gt; @@ -1310,7 +1313,23 @@ can be explicitly disabled by using <code>state='off'</code> attribute. </dd> - + <dt><code>kvm</code></dt> + <dd>Various features to change the behavior of the KVM hypervisor. + <table class="top_table"> + <tr> + <th>Feature</th> + <th>Description</th> + <th>Value</th> + <th>Since</th> + </tr> + <tr> + <td>hidden</td> + <td>Hide the KVM hypervisor from standard MSR based discovery</td> + <td> on, off</td> + <td><span class="since">2.1.0 (QEMU only)</span></td> + </tr> + </table> + </dd> </dl>

diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c index 8a69976..77a84cc 100644 --- a/src/qemu/qemu_command.c +++ b/src/qemu/qemu_command.c @@ -6228,6 +6228,25 @@ qemuBuildCpuArgStr(virQEMUDriverPtr driver, } } + if (def->features[VIR_DOMAIN_FEATURE_KVM] == VIR_TRISTATE_SWITCH_ON) { + if (!have_cpu) { + virBufferAdd(&buf, default_model, -1); + have_cpu = true; + } + + for (i = 0; i < VIR_DOMAIN_KVM_LAST; i++) { + switch ((virDomainKVM) i) { + case VIR_DOMAIN_KVM_HIDDEN: + if (def->kvm_features[i] == VIR_TRISTATE_SWITCH_ON) + virBufferAsprintf(&buf, ",kvm=off"); + break; +