[libvirt] [PATCH 1/9] target-i386: kvm: -cpu host: Use GET_SUPPORTED_CPUID for SVM features

The existing -cpu host code simply set every bit inside svm_features (initializing it to -1), and that makes it impossible to make the enforce/check options work properly when the user asks for SVM features explicitly in the command-line. So, instead of initializing svm_features to -1, use GET_SUPPORTED_CPUID to fill only the bits that are supported by the host (just like we do for all other CPUID feature words inside kvm_cpu_fill_host()). This will keep the existing behavior (as filter_features_for_kvm() already uses GET_SUPPORTED_CPUID to filter svm_features), but will allow us to properly check for KVM features inside kvm_check_features_against_host() later. For example, we will be able to make this: $ qemu-system-x86_64 -cpu ...,+pfthreshold,enforce refuse to start if the SVM "pfthreshold" feature is not supported by the host (after we fix kvm_check_features_against_host() to check SVM flags as well). Signed-off-by: Eduardo Habkost <ehabkost(a)redhat.com&gt; --- Changes v2: - Coding style (indentation) fix Cc: Gleb Natapov <gleb(a)redhat.com&gt; Cc: Marcelo Tosatti <mtosatti(a)redhat.com&gt; Cc: Joerg Roedel <joro(a)8bytes.org&gt; Cc: kvm(a)vger.kernel.org --- target-i386/cpu.c | 11 ++++------- 1 file changed, 4 insertions(+), 7 deletions(-) diff --git a/target-i386/cpu.c b/target-i386/cpu.c index ec877c7..649cfb2 100644 --- a/target-i386/cpu.c +++ b/target-i386/cpu.c @@ -906,13 +906,10 @@ static void kvm_cpu_fill_host(x86_def_t *x86_cpu_def) } } - /* - * Every SVM feature requires emulation support in KVM - so we can't just - * read the host features here. KVM might even support SVM features not - * available on the host hardware. Just set all bits and mask out the - * unsupported ones later. - */ - x86_cpu_def->svm_features = -1; + /* Other KVM-specific feature fields: */ + x86_cpu_def->svm_features = + kvm_arch_get_supported_cpuid(s, 0x8000000A, 0, R_EDX); + #endif /* CONFIG_KVM */ } -- 1.7.11.7