* Liran Alon (liran.alon@xxxxxxxxxx) wrote:
> Kernel commit 8fcc4b5923af ("kvm: nVMX: Introduce KVM_CAP_NESTED_STATE")
> introduced new IOCTLs to extract and restore vCPU state related to
> Intel VMX & AMD SVM.
>
> Utilize these IOCTLs to add support for migration of VMs which are
> running nested hypervisors.
>
> Reviewed-by: Nikita Leshenko <nikita.leshchenko@xxxxxxxxxx>
> Signed-off-by: Liran Alon <liran.alon@xxxxxxxxxx>
> ---
> accel/kvm/kvm-all.c | 8 ++
> include/sysemu/kvm.h | 1 +
> target/i386/cpu.h | 3 +
> target/i386/kvm.c | 80 +++++++++++++++++
> target/i386/machine.c | 196 ++++++++++++++++++++++++++++++++++++++++++
> 5 files changed, 288 insertions(+)
>
> diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
> index 59a3aa3a40da..4fdf5b04b131 100644
> --- a/accel/kvm/kvm-all.c
> +++ b/accel/kvm/kvm-all.c
> @@ -88,6 +88,7 @@ struct KVMState
> #ifdef KVM_CAP_SET_GUEST_DEBUG
> QTAILQ_HEAD(, kvm_sw_breakpoint) kvm_sw_breakpoints;
> #endif
> + int max_nested_state_len;
> int many_ioeventfds;
> int intx_set_mask;
> bool sync_mmu;
> @@ -1678,6 +1679,8 @@ static int kvm_init(MachineState *ms)
> s->debugregs = kvm_check_extension(s, KVM_CAP_DEBUGREGS);
> #endif
>
> + s->max_nested_state_len = kvm_check_extension(s, KVM_CAP_NESTED_STATE);
> +
> #ifdef KVM_CAP_IRQ_ROUTING
> kvm_direct_msi_allowed = (kvm_check_extension(s, KVM_CAP_SIGNAL_MSI) > 0);
> #endif
> @@ -2245,6 +2248,11 @@ int kvm_has_debugregs(void)
> return kvm_state->debugregs;
> }
>
> +int kvm_max_nested_state_length(void)
> +{
> + return kvm_state->max_nested_state_len;
> +}
> +
> int kvm_has_many_ioeventfds(void)
> {
> if (!kvm_enabled()) {
> diff --git a/include/sysemu/kvm.h b/include/sysemu/kvm.h
> index 64f55e519df7..acd90aebb6c4 100644
> --- a/include/sysemu/kvm.h
> +++ b/include/sysemu/kvm.h
> @@ -210,6 +210,7 @@ bool kvm_has_sync_mmu(void);
> int kvm_has_vcpu_events(void);
> int kvm_has_robust_singlestep(void);
> int kvm_has_debugregs(void);
> +int kvm_max_nested_state_length(void);
> int kvm_has_pit_state2(void);
> int kvm_has_many_ioeventfds(void);
> int kvm_has_gsi_routing(void);
> diff --git a/target/i386/cpu.h b/target/i386/cpu.h
> index 79d9495ceb0c..a6bb71849869 100644
> --- a/target/i386/cpu.h
> +++ b/target/i386/cpu.h
> @@ -1350,6 +1350,9 @@ typedef struct CPUX86State {
> #if defined(CONFIG_KVM) || defined(CONFIG_HVF)
> void *xsave_buf;
> #endif
> +#if defined(CONFIG_KVM)
> + struct kvm_nested_state *nested_state;
> +#endif
> #if defined(CONFIG_HVF)
> HVFX86EmulatorState *hvf_emul;
> #endif
> diff --git a/target/i386/kvm.c b/target/i386/kvm.c
> index f43e2d69859e..5950c3ed0d1c 100644
> --- a/target/i386/kvm.c
> +++ b/target/i386/kvm.c
> @@ -931,6 +931,7 @@ int kvm_arch_init_vcpu(CPUState *cs)
> struct kvm_cpuid_entry2 *c;
> uint32_t signature[3];
> int kvm_base = KVM_CPUID_SIGNATURE;
> + int max_nested_state_len;
> int r;
> Error *local_err = NULL;
>
> @@ -1331,6 +1332,24 @@ int kvm_arch_init_vcpu(CPUState *cs)
> if (has_xsave) {
> env->xsave_buf = qemu_memalign(4096, sizeof(struct kvm_xsave));
> }
> +
> + max_nested_state_len = kvm_max_nested_state_length();
> + if (max_nested_state_len > 0) {
> + assert(max_nested_state_len >= offsetof(struct kvm_nested_state, data));
> + env->nested_state = g_malloc0(max_nested_state_len);
> +
> + env->nested_state->size = max_nested_state_len;
> +
> + if (IS_INTEL_CPU(env)) {
> + struct kvm_vmx_nested_state_hdr *vmx_hdr =
> + &env->nested_state->hdr.vmx;
> +
> + vmx_hdr->vmxon_pa = -1ull;
> + vmx_hdr->vmcs12_pa = -1ull;
> + }
> +
> + }
> +
> cpu->kvm_msr_buf = g_malloc0(MSR_BUF_SIZE);
>
> if (!(env->features[FEAT_8000_0001_EDX] & CPUID_EXT2_RDTSCP)) {
> @@ -1352,12 +1371,18 @@ int kvm_arch_init_vcpu(CPUState *cs)
> int kvm_arch_destroy_vcpu(CPUState *cs)
> {
> X86CPU *cpu = X86_CPU(cs);
> + CPUX86State *env = &cpu->env;
>
> if (cpu->kvm_msr_buf) {
> g_free(cpu->kvm_msr_buf);
> cpu->kvm_msr_buf = NULL;
> }
>
> + if (env->nested_state) {
> + g_free(env->nested_state);
> + env->nested_state = NULL;
> + }
> +
> return 0;
> }
>
> @@ -3072,6 +3097,52 @@ static int kvm_get_debugregs(X86CPU *cpu)
> return 0;
> }
>
> +static int kvm_put_nested_state(X86CPU *cpu)
> +{
> + CPUX86State *env = &cpu->env;
> + int max_nested_state_len = kvm_max_nested_state_length();
> +
> + if (max_nested_state_len <= 0) {
> + return 0;
> + }
> +
> + assert(env->nested_state->size <= max_nested_state_len);
> + return kvm_vcpu_ioctl(CPU(cpu), KVM_SET_NESTED_STATE, env->nested_state);
> +}
> +
> +static int kvm_get_nested_state(X86CPU *cpu)
> +{
> + CPUX86State *env = &cpu->env;
> + int max_nested_state_len = kvm_max_nested_state_length();
> + int ret;
> +
> + if (max_nested_state_len <= 0) {
> + return 0;
> + }
> +
> + /*
> + * It is possible that migration restored a smaller size into
> + * nested_state->hdr.size than what our kernel support.
> + * We preserve migration origin nested_state->hdr.size for
> + * call to KVM_SET_NESTED_STATE but wish that our next call
> + * to KVM_GET_NESTED_STATE will use max size our kernel support.
> + */
> + env->nested_state->size = max_nested_state_len;
> +
> + ret = kvm_vcpu_ioctl(CPU(cpu), KVM_GET_NESTED_STATE, env->nested_state);
> + if (ret < 0) {
> + return ret;
> + }
> +
> + if (env->nested_state->flags & KVM_STATE_NESTED_GUEST_MODE) {
> + env->hflags |= HF_GUEST_MASK;
> + } else {
> + env->hflags &= ~HF_GUEST_MASK;
> + }
> +
> + return ret;
> +}
> +
> int kvm_arch_put_registers(CPUState *cpu, int level)
> {
> X86CPU *x86_cpu = X86_CPU(cpu);
> @@ -3079,6 +3150,11 @@ int kvm_arch_put_registers(CPUState *cpu, int level)
>
> assert(cpu_is_stopped(cpu) || qemu_cpu_is_self(cpu));
>
> + 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) {
> @@ -3194,6 +3270,10 @@ int kvm_arch_get_registers(CPUState *cs)
> if (ret < 0) {
> goto out;
> }
> + ret = kvm_get_nested_state(cpu);
> + if (ret < 0) {
> + goto out;
> + }
> ret = 0;
> out:
> cpu_sync_bndcs_hflags(&cpu->env);
> diff --git a/target/i386/machine.c b/target/i386/machine.c
> index 225b5d433bc4..95299ebff44a 100644
> --- a/target/i386/machine.c
> +++ b/target/i386/machine.c
> @@ -231,6 +231,15 @@ static int cpu_pre_save(void *opaque)
> env->segs[R_SS].flags &= ~(env->segs[R_SS].flags & DESC_DPL_MASK);
> }
>
> +#ifdef CONFIG_KVM
> + /* Verify we have nested virtualization state from kernel if required */
> + if (cpu_has_nested_virt(env) && !env->nested_state) {
> + error_report("Guest enabled nested virtualization but kernel "
> + "does not support saving of nested state");
> + return -EINVAL;
> + }
> +#endif
> +
> return 0;
> }
>
> @@ -278,6 +287,16 @@ static int cpu_post_load(void *opaque, int version_id)
> env->hflags &= ~HF_CPL_MASK;
> env->hflags |= (env->segs[R_SS].flags >> DESC_DPL_SHIFT) & HF_CPL_MASK;
>
> +#ifdef CONFIG_KVM
> + if ((env->hflags & HF_GUEST_MASK) &&
> + (!env->nested_state ||
> + !(env->nested_state->flags & KVM_STATE_NESTED_GUEST_MODE))) {
> + error_report("vCPU set in guest-mode inconsistent with "
> + "migrated kernel nested state");
> + return -EINVAL;
> + }
> +#endif
> +
> env->fpstt = (env->fpus_vmstate >> 11) & 7;
> env->fpus = env->fpus_vmstate & ~0x3800;
> env->fptag_vmstate ^= 0xff;
> @@ -851,6 +870,180 @@ static const VMStateDescription vmstate_tsc_khz = {
> }
> };
>
> +#ifdef CONFIG_KVM
> +
> +static bool vmx_vmcs12_needed(void *opaque)
> +{
> + struct kvm_nested_state *nested_state = opaque;
> + return (nested_state->size >
> + offsetof(struct kvm_nested_state, data.vmx[0].vmcs12));
> +}
> +
> +static const VMStateDescription vmstate_vmx_vmcs12 = {
> + .name = "cpu/kvm_nested_state/vmx/vmcs12",
> + .version_id = 1,
> + .minimum_version_id = 1,
> + .needed = vmx_vmcs12_needed,
> + .fields = (VMStateField[]) {
> + VMSTATE_UINT8_ARRAY(data.vmx[0].vmcs12,
> + struct kvm_nested_state, 0x1000),
Where did that magic 0x1000 come from?
> + VMSTATE_END_OF_LIST()
> + }
> +};
> +
> +static bool vmx_shadow_vmcs12_needed(void *opaque)
> +{
> + struct kvm_nested_state *nested_state = opaque;
> + return (nested_state->size >
> + offsetof(struct kvm_nested_state, data.vmx[0].shadow_vmcs12));
> +}
> +
> +static const VMStateDescription vmstate_vmx_shadow_vmcs12 = {
> + .name = "cpu/kvm_nested_state/vmx/shadow_vmcs12",
> + .version_id = 1,
> + .minimum_version_id = 1,
> + .needed = vmx_shadow_vmcs12_needed,
> + .fields = (VMStateField[]) {
> + VMSTATE_UINT8_ARRAY(data.vmx[0].shadow_vmcs12,
> + struct kvm_nested_state, 0x1000),
> + VMSTATE_END_OF_LIST()
> + }
> +};
> +
> +static bool vmx_nested_state_needed(void *opaque)
> +{
> + struct kvm_nested_state *nested_state = opaque;
> +
> + return ((nested_state->format == KVM_STATE_NESTED_FORMAT_VMX) &&
> + ((nested_state->hdr.vmx.vmxon_pa != -1ull) ||
> + (nested_state->hdr.vmx.smm.flags & KVM_STATE_NESTED_SMM_VMXON)));
> +}
> +
> +static const VMStateDescription vmstate_vmx_nested_state = {
> + .name = "cpu/kvm_nested_state/vmx",
> + .version_id = 1,
> + .minimum_version_id = 1,
> + .needed = vmx_nested_state_needed,
> + .fields = (VMStateField[]) {
> + VMSTATE_U64(hdr.vmx.vmxon_pa, struct kvm_nested_state),
> + VMSTATE_U64(hdr.vmx.vmcs12_pa, struct kvm_nested_state),
> + VMSTATE_U16(hdr.vmx.smm.flags, struct kvm_nested_state),
> + VMSTATE_END_OF_LIST()
> + },
> + .subsections = (const VMStateDescription*[]) {
> + &vmstate_vmx_vmcs12,
> + &vmstate_vmx_shadow_vmcs12,
> + NULL,
> + }
> +};
> +
> +static bool svm_nested_state_needed(void *opaque)
> +{
> + struct kvm_nested_state *nested_state = opaque;
> +
> + return (nested_state->format == KVM_STATE_NESTED_FORMAT_SVM);
> +}
> +
> +static const VMStateDescription vmstate_svm_nested_state = {
> + .name = "cpu/kvm_nested_state/svm",
> + .version_id = 1,
> + .minimum_version_id = 1,
> + .needed = svm_nested_state_needed,
> + .fields = (VMStateField[]) {
> + VMSTATE_END_OF_LIST()
> + }
> +};
> +
> +static bool nested_state_needed(void *opaque)
> +{
> + X86CPU *cpu = opaque;
> + CPUX86State *env = &cpu->env;
> +
> + return (env->nested_state &&
> + (vmx_nested_state_needed(env->nested_state) ||
> + svm_nested_state_needed(env->nested_state)));
> +}
> +
> +static int nested_state_post_load(void *opaque, int version_id)
> +{
> + X86CPU *cpu = opaque;
> + CPUX86State *env = &cpu->env;
> + struct kvm_nested_state *nested_state = env->nested_state;
> + int min_nested_state_len = offsetof(struct kvm_nested_state, data);
> + int max_nested_state_len = kvm_max_nested_state_length();
> +
> + /*
> + * If our kernel don't support setting nested state
> + * and we have received nested state from migration stream,
> + * we need to fail migration
> + */
> + if (max_nested_state_len <= 0) {
> + error_report("Received nested state when kernel cannot restore it");
> + return -EINVAL;
> + }
> +
> + /*
> + * Verify that the size of received nested_state struct
> + * at least cover required header and is not larger
> + * than the max size that our kernel support
> + */
> + if (nested_state->size < min_nested_state_len) {
> + error_report("Received nested state size less than min: "
> + "len=%d, min=%d",
> + nested_state->size, min_nested_state_len);
> + return -EINVAL;
> + }
> + if (nested_state->size > max_nested_state_len) {
> + error_report("Recieved unsupported nested state size: "
> + "nested_state->size=%d, max=%d",
> + nested_state->size, max_nested_state_len);
> + return -EINVAL;
> + }
> +
> + /* Verify format is valid */
> + if ((nested_state->format != KVM_STATE_NESTED_FORMAT_VMX) &&
> + (nested_state->format != KVM_STATE_NESTED_FORMAT_SVM)) {
> + error_report("Received invalid nested state format: %d",
> + nested_state->format);
> + return -EINVAL;
> + }
> +
> + return 0;
> +}
> +
> +static const VMStateDescription vmstate_kvm_nested_state = {
> + .name = "cpu/kvm_nested_state",
> + .version_id = 1,
> + .minimum_version_id = 1,
> + .fields = (VMStateField[]) {
> + VMSTATE_U16(flags, struct kvm_nested_state),
> + VMSTATE_U16(format, struct kvm_nested_state),
> + VMSTATE_U32(size, struct kvm_nested_state),
> + VMSTATE_END_OF_LIST()
> + },
> + .subsections = (const VMStateDescription*[]) {
> + &vmstate_vmx_nested_state,
> + &vmstate_svm_nested_state,
> + NULL
> + }
> +};
> +
> +static const VMStateDescription vmstate_nested_state = {
> + .name = "cpu/nested_state",
> + .version_id = 1,
> + .minimum_version_id = 1,
> + .needed = nested_state_needed,
> + .post_load = nested_state_post_load,
> + .fields = (VMStateField[]) {
> + VMSTATE_STRUCT_POINTER(env.nested_state, X86CPU,
> + vmstate_kvm_nested_state,
> + struct kvm_nested_state),
> + VMSTATE_END_OF_LIST()
> + }
> +};
> +
> +#endif
> +
> static bool mcg_ext_ctl_needed(void *opaque)
> {
> X86CPU *cpu = opaque;
> @@ -1089,6 +1282,9 @@ VMStateDescription vmstate_x86_cpu = {
> &vmstate_msr_intel_pt,
> &vmstate_msr_virt_ssbd,
> &vmstate_svm_npt,
> +#ifdef CONFIG_KVM
> + &vmstate_nested_state,
> +#endif
> NULL
> }
> };
> --
> 2.20.1
>
--
Dr. David Alan Gilbert / dgilbert@xxxxxxxxxx / Manchester, UK
