On Tue, Mar 20, 2018 at 06:34:59PM +0100, Vitaly Kuznetsov wrote:
> KVM recently gained support for Hyper-V Reenlightenment MSRs which are
> required to make KVM-on-Hyper-V enable TSC page clocksource to its guests
> when INVTSC is not passed to it (and it is not passed by default in Qemu
> as it effectively blocks migration).
>
> Signed-off-by: Vitaly Kuznetsov <vkuzn...@redhat.com>
> ---
> Changes since v2:
> - add hv-reenlightenment CPU property [Roman Kagan, Paolo Bonzini]
> - add a comment to feature_word_info [Roman Kagan]
> ---
> target/i386/cpu.c | 4 +++-
> target/i386/cpu.h | 4 ++++
> target/i386/hyperv-proto.h | 9 ++++++++-
> target/i386/kvm.c | 39 ++++++++++++++++++++++++++++++++++++++-
> target/i386/machine.c | 24 ++++++++++++++++++++++++
> 5 files changed, 77 insertions(+), 3 deletions(-)
>
> diff --git a/target/i386/cpu.c b/target/i386/cpu.c
> index 6bb4ce8719..02579f8234 100644
> --- a/target/i386/cpu.c
> +++ b/target/i386/cpu.c
> @@ -407,7 +407,8 @@ static FeatureWordInfo feature_word_info[FEATURE_WORDS] =
> {
> NULL /* hv_vpindex_access */, NULL /* hv_msr_reset_access */,
> NULL /* hv_msr_stats_access */, NULL /* hv_reftsc_access */,
> NULL /* hv_msr_idle_access */, NULL /* hv_msr_frequency_access
> */,
> - NULL, NULL, NULL, NULL,
> + NULL /* hv_msr_debug_access */, NULL /*
> hv_msr_reenlightenment_access */,
> + NULL, NULL,
> NULL, NULL, NULL, NULL,
> NULL, NULL, NULL, NULL,
> NULL, NULL, NULL, NULL,
> @@ -4764,6 +4765,7 @@ static Property x86_cpu_properties[] = {
> DEFINE_PROP_BOOL("hv-runtime", X86CPU, hyperv_runtime, false),
> DEFINE_PROP_BOOL("hv-synic", X86CPU, hyperv_synic, false),
> DEFINE_PROP_BOOL("hv-stimer", X86CPU, hyperv_stimer, false),
> + DEFINE_PROP_BOOL("hv-reenlightenment", X86CPU, hyperv_reenlightenment,
> false),
Property is set to false by default, so compatibility is kept.
> DEFINE_PROP_BOOL("check", X86CPU, check_cpuid, true),
> DEFINE_PROP_BOOL("enforce", X86CPU, enforce_cpuid, false),
> DEFINE_PROP_BOOL("kvm", X86CPU, expose_kvm, true),
> diff --git a/target/i386/cpu.h b/target/i386/cpu.h
> index 2e2bab5ff3..98eed72937 100644
> --- a/target/i386/cpu.h
> +++ b/target/i386/cpu.h
> @@ -1174,6 +1174,9 @@ typedef struct CPUX86State {
> uint64_t msr_hv_synic_sint[HV_SINT_COUNT];
> uint64_t msr_hv_stimer_config[HV_STIMER_COUNT];
> uint64_t msr_hv_stimer_count[HV_STIMER_COUNT];
> + uint64_t msr_hv_reenlightenment_control;
> + uint64_t msr_hv_tsc_emulation_control;
> + uint64_t msr_hv_tsc_emulation_status;
>
> uint64_t msr_rtit_ctrl;
> uint64_t msr_rtit_status;
> @@ -1296,6 +1299,7 @@ struct X86CPU {
> bool hyperv_runtime;
> bool hyperv_synic;
> bool hyperv_stimer;
> + bool hyperv_reenlightenment;
> bool check_cpuid;
> bool enforce_cpuid;
> bool expose_kvm;
> diff --git a/target/i386/hyperv-proto.h b/target/i386/hyperv-proto.h
> index cb4d7f2b7a..93352ebd2a 100644
> --- a/target/i386/hyperv-proto.h
> +++ b/target/i386/hyperv-proto.h
> @@ -35,7 +35,7 @@
> #define HV_RESET_AVAILABLE (1u << 7)
> #define HV_REFERENCE_TSC_AVAILABLE (1u << 9)
> #define HV_ACCESS_FREQUENCY_MSRS (1u << 11)
> -
> +#define HV_ACCESS_REENLIGHTENMENTS_CONTROL (1u << 13)
>
> /*
> * HV_CPUID_FEATURES.EDX bits
> @@ -129,6 +129,13 @@
> #define HV_X64_MSR_CRASH_CTL 0x40000105
> #define HV_CRASH_CTL_NOTIFY (1ull << 63)
>
> +/*
> + * Reenlightenment notification MSRs
> + */
> +#define HV_X64_MSR_REENLIGHTENMENT_CONTROL 0x40000106
> +#define HV_X64_MSR_TSC_EMULATION_CONTROL 0x40000107
> +#define HV_X64_MSR_TSC_EMULATION_STATUS 0x40000108
> +
> /*
> * Hypercall status code
> */
> diff --git a/target/i386/kvm.c b/target/i386/kvm.c
> index d23fff12f5..7d9f9ca0b1 100644
> --- a/target/i386/kvm.c
> +++ b/target/i386/kvm.c
> @@ -90,6 +90,7 @@ static bool has_msr_hv_runtime;
> static bool has_msr_hv_synic;
> static bool has_msr_hv_stimer;
> static bool has_msr_hv_frequencies;
> +static bool has_msr_hv_reenlightenment;
> static bool has_msr_xss;
> static bool has_msr_spec_ctrl;
> static bool has_msr_smi_count;
> @@ -583,7 +584,8 @@ static bool hyperv_enabled(X86CPU *cpu)
> cpu->hyperv_vpindex ||
> cpu->hyperv_runtime ||
> cpu->hyperv_synic ||
> - cpu->hyperv_stimer);
> + cpu->hyperv_stimer ||
> + cpu->hyperv_reenlightenment);
> }
>
> static int kvm_arch_set_tsc_khz(CPUState *cs)
> @@ -654,6 +656,14 @@ static int hyperv_handle_properties(CPUState *cs)
> env->features[FEAT_HYPERV_EDX] |= HV_FREQUENCY_MSRS_AVAILABLE;
> }
> }
> + if (cpu->hyperv_reenlightenment) {
> + if (!has_msr_hv_reenlightenment) {
> + fprintf(stderr,
> + "Hyper-V Reenlightenment is not supported by kernel\n");
> + return -ENOSYS;
> + }
> + env->features[FEAT_HYPERV_EAX] |= HV_ACCESS_REENLIGHTENMENTS_CONTROL;
> + }
> if (cpu->hyperv_crash && has_msr_hv_crash) {
> env->features[FEAT_HYPERV_EDX] |= HV_GUEST_CRASH_MSR_AVAILABLE;
> }
> @@ -1185,6 +1195,9 @@ static int kvm_get_supported_msrs(KVMState *s)
> case HV_X64_MSR_TSC_FREQUENCY:
> has_msr_hv_frequencies = true;
> break;
> + case HV_X64_MSR_REENLIGHTENMENT_CONTROL:
> + has_msr_hv_reenlightenment = true;
> + break;
> case MSR_IA32_SPEC_CTRL:
> has_msr_spec_ctrl = true;
> break;
> @@ -1747,6 +1760,15 @@ static int kvm_put_msrs(X86CPU *cpu, int level)
> if (cpu->hyperv_time) {
> kvm_msr_entry_add(cpu, HV_X64_MSR_REFERENCE_TSC,
> env->msr_hv_tsc);
> +
> + if (has_msr_hv_reenlightenment) {
I see that the current code is inconsistent: some entries check
for has_msr_hv_*, other entries check cpu->hyperv_*.
I suggest changing all of them (including this one) to check
cpu->hyperv_* instead.
The difference between both approaches is that checking just
has_msr_hv_* would let a non-cooperating guest prevent itself
from being migrated to an older host by writing a non-zero value
to a MSR, even if hyperv support was not enabled in the VM
configuration at all. I don't think we want that.
> + kvm_msr_entry_add(cpu,
> HV_X64_MSR_REENLIGHTENMENT_CONTROL,
> + env->msr_hv_reenlightenment_control);
> + kvm_msr_entry_add(cpu, HV_X64_MSR_TSC_EMULATION_CONTROL,
> + env->msr_hv_tsc_emulation_control);
> + kvm_msr_entry_add(cpu, HV_X64_MSR_TSC_EMULATION_STATUS,
> + env->msr_hv_tsc_emulation_status);
The 3 MSRs are added by the same KVM commit, so setting all 3
based on the same has_msr_hv_*/cpu->hyperv_* flag is OK.
The rest of the patch looks good to me.
> + }
> }
> }
> if (cpu->hyperv_vapic) {
> @@ -2109,6 +2131,12 @@ static int kvm_get_msrs(X86CPU *cpu)
> }
> if (cpu->hyperv_time) {
> kvm_msr_entry_add(cpu, HV_X64_MSR_REFERENCE_TSC, 0);
> +
> + if (has_msr_hv_reenlightenment) {
> + kvm_msr_entry_add(cpu, HV_X64_MSR_REENLIGHTENMENT_CONTROL, 0);
> + kvm_msr_entry_add(cpu, HV_X64_MSR_TSC_EMULATION_CONTROL, 0);
> + kvm_msr_entry_add(cpu, HV_X64_MSR_TSC_EMULATION_STATUS, 0);
> + }
> }
> if (has_msr_hv_crash) {
> int j;
> @@ -2367,6 +2395,15 @@ static int kvm_get_msrs(X86CPU *cpu)
> env->msr_hv_stimer_count[(index - HV_X64_MSR_STIMER0_COUNT)/2] =
> msrs[i].data;
> break;
> + case HV_X64_MSR_REENLIGHTENMENT_CONTROL:
> + env->msr_hv_reenlightenment_control = msrs[i].data;
> + break;
> + case HV_X64_MSR_TSC_EMULATION_CONTROL:
> + env->msr_hv_tsc_emulation_control = msrs[i].data;
> + break;
> + case HV_X64_MSR_TSC_EMULATION_STATUS:
> + env->msr_hv_tsc_emulation_status = msrs[i].data;
> + break;
> case MSR_MTRRdefType:
> env->mtrr_deftype = msrs[i].data;
> break;
> diff --git a/target/i386/machine.c b/target/i386/machine.c
> index bd2d82e91b..fd99c0bbb4 100644
> --- a/target/i386/machine.c
> +++ b/target/i386/machine.c
> @@ -713,6 +713,29 @@ static const VMStateDescription
> vmstate_msr_hyperv_stimer = {
> }
> };
>
> +static bool hyperv_reenlightenment_enable_needed(void *opaque)
> +{
> + X86CPU *cpu = opaque;
> + CPUX86State *env = &cpu->env;
> +
> + return env->msr_hv_reenlightenment_control != 0 ||
> + env->msr_hv_tsc_emulation_control != 0 ||
> + env->msr_hv_tsc_emulation_status != 0;
> +}
> +
> +static const VMStateDescription vmstate_msr_hyperv_reenlightenment = {
> + .name = "cpu/msr_hyperv_reenlightenment",
> + .version_id = 1,
> + .minimum_version_id = 1,
> + .needed = hyperv_reenlightenment_enable_needed,
> + .fields = (VMStateField[]) {
> + VMSTATE_UINT64(env.msr_hv_reenlightenment_control, X86CPU),
> + VMSTATE_UINT64(env.msr_hv_tsc_emulation_control, X86CPU),
> + VMSTATE_UINT64(env.msr_hv_tsc_emulation_status, X86CPU),
> + VMSTATE_END_OF_LIST()
> + }
> +};
> +
> static bool avx512_needed(void *opaque)
> {
> X86CPU *cpu = opaque;
> @@ -1005,6 +1028,7 @@ VMStateDescription vmstate_x86_cpu = {
> &vmstate_msr_hyperv_runtime,
> &vmstate_msr_hyperv_synic,
> &vmstate_msr_hyperv_stimer,
> + &vmstate_msr_hyperv_reenlightenment,
> &vmstate_avx512,
> &vmstate_xss,
> &vmstate_tsc_khz,
> --
> 2.14.3
>
--
Eduardo
