Setting nested state upon migration needs to happen after kvm_put_sregs2() to e.g. have EFER.SVME set. This, however, doesn't work for vCPU reset: when vCPU is in VMX root operation, certain CR bits are locked and kvm_put_sregs2() may fail. As nested state is fully cleaned up upon vCPU reset (kvm_arch_reset_vcpu() -> kvm_init_nested_state()), calling kvm_put_nested_state() before kvm_put_sregs2() is OK, this will ensure that vCPU is *not* in VMX root opertaion.
Signed-off-by: Vitaly Kuznetsov <[email protected]> --- target/i386/kvm/kvm.c | 20 ++++++++++++++++++-- 1 file changed, 18 insertions(+), 2 deletions(-) diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c index 4f8dacc1d4b5..73e3880fa57b 100644 --- a/target/i386/kvm/kvm.c +++ b/target/i386/kvm/kvm.c @@ -4529,18 +4529,34 @@ int kvm_arch_put_registers(CPUState *cpu, int level) assert(cpu_is_stopped(cpu) || qemu_cpu_is_self(cpu)); - /* must be before kvm_put_nested_state so that EFER.SVME is set */ + /* + * When resetting a vCPU, make sure to reset nested state first to + * e.g clear VMXON state and unlock certain CR4 bits. + */ + if (level == KVM_PUT_RESET_STATE) { + ret = kvm_put_nested_state(x86_cpu); + if (ret < 0) { + return ret; + } + } + ret = has_sregs2 ? kvm_put_sregs2(x86_cpu) : kvm_put_sregs(x86_cpu); if (ret < 0) { return ret; } - if (level >= KVM_PUT_RESET_STATE) { + /* + * When putting full CPU state, kvm_put_nested_state() must happen after + * kvm_put_sregs{,2} so that e.g. EFER.SVME is already set. + */ + if (level == KVM_PUT_FULL_STATE) { ret = kvm_put_nested_state(x86_cpu); if (ret < 0) { return ret; } + } + if (level >= KVM_PUT_RESET_STATE) { ret = kvm_put_msr_feature_control(x86_cpu); if (ret < 0) { return ret; -- 2.37.1
