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@xxxxxxxxxx/)
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%)
--
2.34.1
