Hi all, If the host doesn't support halt polling, this patch seems to break libvirt save/restore: " virsh # save halt-poll-vm halt-poll-vm.sav --running --verbose Save: [100 %] Domain halt-poll-vm saved to halt-poll-vm.sav virsh # restore halt-poll-vm.sav error: Failed to restore domain from halt-poll-vm.sav error: operation failed: guest CPU doesn't match specification " I believe this occurs because libvirt rejects the restore if there are filtered features, which is the case if halt polling is enabled on a host which doesn't support it (halt polling is enabled 'by default'). As such, I think we should only enable halt polling if it is supported on the host - see the attached patch. ...thoughts? Thanks, -Mark On 7/15/2019 4:23 AM, Paolo Bonzini wrote: > On 04/06/19 01:04, Marcelo Tosatti wrote: >> (CC'ing qemu devel) >> >> Add support for halt poll control MSR: save/restore, migration >> and new feature name. >> >> The purpose of this MSR is to allow the guest to disable >> host halt poll. >> >> Signed-off-by: Marcelo Tosatti >> >> diff --git a/include/standard-headers/asm-x86/kvm_para.h b/include/standard-headers/asm-x86/kvm_para.h >> index 35cd8d6..e171514 100644 >> --- a/include/standard-headers/asm-x86/kvm_para.h >> +++ b/include/standard-headers/asm-x86/kvm_para.h >> @@ -29,6 +29,7 @@ >> #define KVM_FEATURE_PV_TLB_FLUSH 9 >> #define KVM_FEATURE_ASYNC_PF_VMEXIT 10 >> #define KVM_FEATURE_PV_SEND_IPI 11 >> +#define KVM_FEATURE_POLL_CONTROL 12 >> >> #define KVM_HINTS_REALTIME 0 >> >> @@ -47,6 +48,7 @@ >> #define MSR_KVM_ASYNC_PF_EN 0x4b564d02 >> #define MSR_KVM_STEAL_TIME 0x4b564d03 >> #define MSR_KVM_PV_EOI_EN 0x4b564d04 >> +#define MSR_KVM_POLL_CONTROL 0x4b564d05 >> >> struct kvm_steal_time { >> uint64_t steal; >> diff --git a/target/i386/cpu.c b/target/i386/cpu.c >> index c1ab86d..1ca6944 100644 >> --- a/target/i386/cpu.c >> +++ b/target/i386/cpu.c >> @@ -903,7 +903,7 @@ static FeatureWordInfo feature_word_info[FEATURE_WORDS] = { >> "kvmclock", "kvm-nopiodelay", "kvm-mmu", "kvmclock", >> "kvm-asyncpf", "kvm-steal-time", "kvm-pv-eoi", "kvm-pv-unhalt", >> NULL, "kvm-pv-tlb-flush", NULL, "kvm-pv-ipi", >> - NULL, NULL, NULL, NULL, >> + "kvm-poll-control", NULL, NULL, NULL, >> NULL, NULL, NULL, NULL, >> NULL, NULL, NULL, NULL, >> "kvmclock-stable-bit", NULL, NULL, NULL, >> @@ -3001,6 +3001,7 @@ static PropValue kvm_default_props[] = { >> { "kvm-asyncpf", "on" }, >> { "kvm-steal-time", "on" }, >> { "kvm-pv-eoi", "on" }, >> + { "kvm-poll-control", "on" }, >> { "kvmclock-stable-bit", "on" }, >> { "x2apic", "on" }, >> { "acpi", "off" }, >> @@ -5660,6 +5661,8 @@ static void x86_cpu_initfn(Object *obj) >> object_property_add_alias(obj, "kvm_steal_time", obj, "kvm-steal-time", &error_abort); >> object_property_add_alias(obj, "kvm_pv_eoi", obj, "kvm-pv-eoi", &error_abort); >> object_property_add_alias(obj, "kvm_pv_unhalt", obj, "kvm-pv-unhalt", &error_abort); >> + object_property_add_alias(obj, "kvm_poll_control", obj, "kvm-poll-control", >> + &error_abort); >> object_property_add_alias(obj, "svm_lock", obj, "svm-lock", &error_abort); >> object_property_add_alias(obj, "nrip_save", obj, "nrip-save", &error_abort); >> object_property_add_alias(obj, "tsc_scale", obj, "tsc-scale", &error_abort); >> diff --git a/target/i386/cpu.h b/target/i386/cpu.h >> index bd06523..21ed2f8 100644 >> --- a/target/i386/cpu.h >> +++ b/target/i386/cpu.h >> @@ -1241,6 +1241,7 @@ typedef struct CPUX86State { >> uint64_t steal_time_msr; >> uint64_t async_pf_en_msr; >> uint64_t pv_eoi_en_msr; >> + uint64_t poll_control_msr; >> >> /* Partition-wide HV MSRs, will be updated only on the first vcpu */ >> uint64_t msr_hv_hypercall; >> diff --git a/target/i386/kvm.c b/target/i386/kvm.c >> index 3b29ce5..a5e9cdf 100644 >> --- a/target/i386/kvm.c >> +++ b/target/i386/kvm.c >> @@ -1369,6 +1369,8 @@ void kvm_arch_reset_vcpu(X86CPU *cpu) >> >> hyperv_x86_synic_reset(cpu); >> } >> + /* enabled by default */ >> + env->poll_control_msr = 1; >> } >> >> void kvm_arch_do_init_vcpu(X86CPU *cpu) >> @@ -2059,6 +2061,11 @@ static int kvm_put_msrs(X86CPU *cpu, int level) >> if (env->features[FEAT_KVM] & (1 << KVM_FEATURE_STEAL_TIME)) { >> kvm_msr_entry_add(cpu, MSR_KVM_STEAL_TIME, env->steal_time_msr); >> } >> + >> + if (env->features[FEAT_KVM] & (1 << KVM_FEATURE_POLL_CONTROL)) { >> + kvm_msr_entry_add(cpu, MSR_KVM_POLL_CONTROL, env->poll_control_msr); >> + } >> + >> if (has_architectural_pmu_version > 0) { >> if (has_architectural_pmu_version > 1) { >> /* Stop the counter. */ >> @@ -2443,6 +2450,9 @@ static int kvm_get_msrs(X86CPU *cpu) >> if (env->features[FEAT_KVM] & (1 << KVM_FEATURE_STEAL_TIME)) { >> kvm_msr_entry_add(cpu, MSR_KVM_STEAL_TIME, 0); >> } >> + if (env->features[FEAT_KVM] & (1 << KVM_FEATURE_POLL_CONTROL)) { >> + kvm_msr_entry_add(cpu, MSR_KVM_POLL_CONTROL, 1); >> + } >> if (has_architectural_pmu_version > 0) { >> if (has_architectural_pmu_version > 1) { >> kvm_msr_entry_add(cpu, MSR_CORE_PERF_FIXED_CTR_CTRL, 0); >> @@ -2677,6 +2687,10 @@ static int kvm_get_msrs(X86CPU *cpu) >> case MSR_KVM_STEAL_TIME: >> env->steal_time_msr = msrs[i].data; >> break; >> + case MSR_KVM_POLL_CONTROL: { >> + env->poll_control_msr = msrs[i].data; >> + break; >> + } >> case MSR_CORE_PERF_FIXED_CTR_CTRL: >> env->msr_fixed_ctr_ctrl = msrs[i].data; >> break; >> diff --git a/target/i386/machine.c b/target/i386/machine.c >> index 225b5d4..1c23e5e 100644 >> --- a/target/i386/machine.c >> +++ b/target/i386/machine.c >> @@ -323,6 +323,14 @@ static bool steal_time_msr_needed(void *opaque) >> return cpu->env.steal_time_msr != 0; >> } >> >> +/* Poll control MSR enabled by default */ >> +static bool poll_control_msr_needed(void *opaque) >> +{ >> + X86CPU *cpu = opaque; >> + >> + return cpu->env.poll_control_msr != 1; >> +} >> + >> static const VMStateDescription vmstate_steal_time_msr = { >> .name = "cpu/steal_time_msr", >> .version_id = 1, >> @@ -356,6 +364,17 @@ static const VMStateDescription vmstate_pv_eoi_msr = { >> } >> }; >> >> +static const VMStateDescription vmstate_poll_control_msr = { >> + .name = "cpu/poll_control_msr", >> + .version_id = 1, >> + .minimum_version_id = 1, >> + .needed = poll_control_msr_needed, >> + .fields = (VMStateField[]) { >> + VMSTATE_UINT64(env.poll_control_msr, X86CPU), >> + VMSTATE_END_OF_LIST() >> + } >> +}; >> + >> static bool fpop_ip_dp_needed(void *opaque) >> { >> X86CPU *cpu = opaque; >> @@ -1062,6 +1081,7 @@ VMStateDescription vmstate_x86_cpu = { >> &vmstate_async_pf_msr, >> &vmstate_pv_eoi_msr, >> &vmstate_steal_time_msr, >> + &vmstate_poll_control_msr, >> &vmstate_fpop_ip_dp, >> &vmstate_msr_tsc_adjust, >> &vmstate_msr_tscdeadline, >> > > Queued, thanks. Sorry for missing it until now. > > Paolo > >