On 1/24/22 14:05, Vitaly Kuznetsov wrote:
This is a backport of the recently merged "[PATCH v3 0/4] KVM: x86: Partially allow KVM_SET_CPUID{,2} after KVM_RUN for CPU hotplug" (https://lore.kernel.org/kvm/20220118141801.2219924-1-vkuznets@redhat.com/)
Original description:
Recently, KVM made it illegal to change CPUID after KVM_RUN but unfortunately this change is not fully compatible with existing VMMs. In particular, QEMU reuses vCPU fds for CPU hotplug after unplug and it calls KVM_SET_CPUID2. Relax the requirement by implementing an allowing KVM_SET_CPUID{,2} with the exact same data.
Vitaly Kuznetsov (4): KVM: x86: Do runtime CPUID update before updating vcpu->arch.cpuid_entries KVM: x86: Partially allow KVM_SET_CPUID{,2} after KVM_RUN KVM: selftests: Rename 'get_cpuid_test' to 'cpuid_test' KVM: selftests: Test KVM_SET_CPUID2 after KVM_RUN
arch/x86/kvm/cpuid.c | 90 ++++++++++++++----- arch/x86/kvm/x86.c | 19 ---- tools/testing/selftests/kvm/.gitignore | 2 +- tools/testing/selftests/kvm/Makefile | 4 +- .../selftests/kvm/include/x86_64/processor.h | 7 ++ .../selftests/kvm/lib/x86_64/processor.c | 33 ++++++- .../x86_64/{get_cpuid_test.c => cpuid_test.c} | 30 +++++++ 7 files changed, 139 insertions(+), 46 deletions(-) rename tools/testing/selftests/kvm/x86_64/{get_cpuid_test.c => cpuid_test.c} (83%)
Acked-by: Paolo Bonzini pbonzini@redhat.com