On recent Intel CPUs, some of the CPU features (mostly vmx-* subfeatures) are listed and controlled via the MSRs (Model Specific Registers) instead of the traditional CPUID instruction method. To be able to read the MSR's values, the kernel module msr has to be loaded and the values can be read via /dev/cpu/*/msr. This commit introduces following changes: - install modules-load file for msr this is only enabled: - On x86 arch - If user asks for it explicitly via a build option: meson -Dmsr_module_load=true build By default, it is disabled. - modify virt-host-validate to check of /dev/cpu/*/msr is available. Signed-off-by: Hector Cao <hector.cao@canonical.com> --- meson_options.txt | 1 + src/util/meson.build | 17 +++++++++++++++++ src/util/modules-load.d/msr.conf | 1 + tools/virt-host-validate-qemu.c | 7 +++++++ 4 files changed, 26 insertions(+) create mode 100644 src/util/modules-load.d/msr.conf diff --git a/meson_options.txt b/meson_options.txt index 3dc3e8667b..5a9e067407 100644 --- a/meson_options.txt +++ b/meson_options.txt @@ -135,3 +135,4 @@ option('sysctl_config', type: 'feature', value: 'auto', description: 'Whether to # dep:sysctl_config option('userfaultfd_sysctl', type: 'feature', value: 'auto', description: 'Whether to install sysctl config for enabling unprivileged userfaultfd') option('tls_priority', type: 'string', value: 'NORMAL', description: 'set the default TLS session priority string') +option('msr_module_load', type: 'boolean', value: true, description: 'Install modules-load.d file for msr module on x86') diff --git a/src/util/meson.build b/src/util/meson.build index 69ef49139a..5471a1e9ea 100644 --- a/src/util/meson.build +++ b/src/util/meson.build @@ -225,3 +225,20 @@ if conf.has('WITH_LIBVIRTD') endif util_inc_dir = include_directories('.') + +# Install the modules-load.d file to load the MSR module +# NB: For the file to taken into account and the module load to happen, users must trigger +# the modules-load.d reload (by reboot or restart the systemd-modules-load service). +msr_module_load = get_option('msr_module_load') +if msr_module_load and (host_machine.cpu_family() == 'x86' or host_machine.cpu_family() == 'x86_64') + message('msr_module_load: Enabling installation of modules-load.d/msr.conf for x86') + + install_data( + 'modules-load.d/msr.conf', + install_dir: join_paths(sysconfdir, 'modules-load.d') + ) +elif msr_module_load + message('msr_module_load: option enabled, but not x86/x86_64 : skipping') +else + message('msr_module_load: option disabled: skipping') +endif \ No newline at end of file diff --git a/src/util/modules-load.d/msr.conf b/src/util/modules-load.d/msr.conf new file mode 100644 index 0000000000..3e5ee7fa15 --- /dev/null +++ b/src/util/modules-load.d/msr.conf @@ -0,0 +1 @@ +msr diff --git a/tools/virt-host-validate-qemu.c b/tools/virt-host-validate-qemu.c index 833bb1b914..f582e1146e 100644 --- a/tools/virt-host-validate-qemu.c +++ b/tools/virt-host-validate-qemu.c @@ -95,6 +95,13 @@ int virHostValidateQEMU(void) virValidatePass(); } + if (arch == VIR_ARCH_X86_64) { + if (virHostValidateDeviceExists("QEMU", "/dev/cpu/0/msr", + VIR_HOST_VALIDATE_WARN, + _("Load the 'msr' module for better x86 CPU features detection")) < 0) + ret = -1; + } + if (virHostValidateDeviceExists("QEMU", "/dev/vhost-net", VIR_VALIDATE_WARN, _("Load the 'vhost_net' module to improve performance of virtio networking")) < 0) -- 2.45.2