hdr.vmx.flags is meant for future extensions to the ABI, rejecting invalid flags is necessary to avoid broken half-loads of the nVMX state. Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx> --- arch/x86/kvm/vmx/nested.c | 3 +++ .../kvm/x86_64/vmx_set_nested_state_test.c | 13 +++++++++++++ 2 files changed, 16 insertions(+) diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c index 6a0e32a7418c..11e4df560018 100644 --- a/arch/x86/kvm/vmx/nested.c +++ b/arch/x86/kvm/vmx/nested.c @@ -6079,6 +6079,9 @@ static int vmx_set_nested_state(struct kvm_vcpu *vcpu, ~(KVM_STATE_NESTED_SMM_GUEST_MODE | KVM_STATE_NESTED_SMM_VMXON)) return -EINVAL; + if (kvm_state->hdr.vmx.flags & ~KVM_STATE_VMX_PREEMPTION_TIMER_DEADLINE) + return -EINVAL; + /* * SMM temporarily disables VMX, so we cannot be in guest mode, * nor can VMLAUNCH/VMRESUME be pending. Outside SMM, SMM flags diff --git a/tools/testing/selftests/kvm/x86_64/vmx_set_nested_state_test.c b/tools/testing/selftests/kvm/x86_64/vmx_set_nested_state_test.c index 94f28a657569..d59f3eb67c8f 100644 --- a/tools/testing/selftests/kvm/x86_64/vmx_set_nested_state_test.c +++ b/tools/testing/selftests/kvm/x86_64/vmx_set_nested_state_test.c @@ -146,6 +146,11 @@ void test_vmx_nested_state(struct kvm_vm *vm) state->hdr.vmx.smm.flags = 1; test_nested_state_expect_einval(vm, state); + /* Invalid flags are rejected. */ + set_default_vmx_state(state, state_sz); + state->hdr.vmx.flags = ~0; + test_nested_state_expect_einval(vm, state); + /* It is invalid to have vmxon_pa == -1ull and vmcs_pa != -1ull. */ set_default_vmx_state(state, state_sz); state->hdr.vmx.vmxon_pa = -1ull; @@ -206,6 +211,14 @@ void test_vmx_nested_state(struct kvm_vm *vm) state->flags = 0; test_nested_state(vm, state); + /* Invalid flags are rejected, even if no VMCS loaded. */ + set_default_vmx_state(state, state_sz); + state->size = sizeof(*state); + state->flags = 0; + state->hdr.vmx.vmcs12_pa = -1; + state->hdr.vmx.flags = ~0; + test_nested_state_expect_einval(vm, state); + /* vmxon_pa cannot be the same address as vmcs_pa. */ set_default_vmx_state(state, state_sz); state->hdr.vmx.vmxon_pa = 0; -- 2.26.2
