Expand x86's state test to load XSAVE state into a "dummy" vCPU prior to KVM_SET_CPUID2, and again with an empty guest CPUID model. Except for off-by-default features, i.e. AMX, KVM's ABI for KVM_SET_XSAVE is that userspace is allowed to load xfeatures so long as they are supported by the host. This is a regression test for a combination of KVM bugs where the state saved by KVM_GET_XSAVE{2} could not be loaded via KVM_SET_XSAVE if the saved xstate_bv would load guest-unsupported xfeatures.
Signed-off-by: Sean Christopherson seanjc@google.com --- .../testing/selftests/kvm/x86_64/state_test.c | 19 +++++++++++++++++-- 1 file changed, 17 insertions(+), 2 deletions(-)
diff --git a/tools/testing/selftests/kvm/x86_64/state_test.c b/tools/testing/selftests/kvm/x86_64/state_test.c index df3e93df4343..115b2cdf9279 100644 --- a/tools/testing/selftests/kvm/x86_64/state_test.c +++ b/tools/testing/selftests/kvm/x86_64/state_test.c @@ -231,9 +231,9 @@ static void __attribute__((__flatten__)) guest_code(void *arg) int main(int argc, char *argv[]) { vm_vaddr_t nested_gva = 0; - + struct kvm_cpuid2 empty_cpuid = {}; struct kvm_regs regs1, regs2; - struct kvm_vcpu *vcpu; + struct kvm_vcpu *vcpu, *vcpuN; struct kvm_vm *vm; struct kvm_x86_state *state; struct ucall uc; @@ -286,6 +286,21 @@ int main(int argc, char *argv[]) /* Restore state in a new VM. */ vcpu = vm_recreate_with_one_vcpu(vm); vcpu_load_state(vcpu, state); + + /* + * Restore XSAVE state in a dummy vCPU, first without doing + * KVM_SET_CPUID2, and then with an empty guest CPUID. Except + * for off-by-default xfeatures, e.g. AMX, KVM is supposed to + * allow KVM_SET_XSAVE regardless of guest CPUID. Manually + * load only XSAVE state, MSRs in particular have a much more + * convoluted ABI. + */ + vcpuN = __vm_vcpu_add(vm, vcpu->id + 1); + vcpu_xsave_set(vcpuN, state->xsave); + + vcpu_init_cpuid(vcpuN, &empty_cpuid); + vcpu_xsave_set(vcpuN, state->xsave); + kvm_x86_state_cleanup(state);
memset(®s2, 0, sizeof(regs2));