Commit fcb93c03 authored by Eduardo Habkost's avatar Eduardo Habkost Committed by Andreas Färber
Browse files

target-i386: kvm: -cpu host: Use GET_SUPPORTED_CPUID for SVM features 



The existing -cpu host code simply sets 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: default avatarEduardo Habkost <ehabkost@redhat.com>
Reviewed-by: default avatarGleb Natapov <gleb@redhat.com>
Signed-off-by: default avatarAndreas Färber <afaerber@suse.de>
parent 961f8395

target-i386/cpu.c

+4 −7
Original line number Diff line number Diff line
@@ -897,13 +897,10 @@ 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 */

}