| Message ID | 1447661048-31048-3-git-send-email-haozhong.zhang@intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Mon, Nov 16, 2015 at 04:04:08PM +0800, Haozhong Zhang wrote: > This patch enables migrating vcpu's TSC rate. If KVM on the destination > machine supports TSC scaling, guest programs will observe a consistent > TSC rate across the migration. > > If TSC scaling is not supported on the destination machine, the > migration will not be aborted and QEMU on the destination will not set > vcpu's TSC rate to the migrated value. > > If vcpu's TSC rate specified by CPU option 'tsc-freq' on the destination > machine is inconsistent with the migrated TSC rate, the migration will > be aborted. > > For backwards compatibility, the migration of vcpu's TSC rate is > disabled on pc-*-2.4 and older machine types. > > Signed-off-by: Haozhong Zhang <haozhong.zhang@intel.com> > --- > hw/i386/pc.c | 1 + > hw/i386/pc_piix.c | 1 + > hw/i386/pc_q35.c | 1 + > include/hw/i386/pc.h | 1 + > target-i386/cpu.c | 2 +- > target-i386/cpu.h | 1 + > target-i386/kvm.c | 26 ++++++++++++++++++++++++-- > target-i386/machine.c | 28 ++++++++++++++++++++++++++++ > 8 files changed, 58 insertions(+), 3 deletions(-) > > diff --git a/hw/i386/pc.c b/hw/i386/pc.c > index 0cb8afd..2f2fc93 100644 > --- a/hw/i386/pc.c > +++ b/hw/i386/pc.c > @@ -1952,6 +1952,7 @@ static void pc_machine_class_init(ObjectClass *oc, void *data) > HotplugHandlerClass *hc = HOTPLUG_HANDLER_CLASS(oc); > > pcmc->get_hotplug_handler = mc->get_hotplug_handler; > + pcmc->save_tsc_khz = true; > mc->get_hotplug_handler = pc_get_hotpug_handler; > mc->cpu_index_to_socket_id = pc_cpu_index_to_socket_id; > mc->default_boot_order = "cad"; > diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c > index 07d0baa..7c5b0d2 100644 > --- a/hw/i386/pc_piix.c > +++ b/hw/i386/pc_piix.c > @@ -489,6 +489,7 @@ static void pc_i440fx_2_4_machine_options(MachineClass *m) > m->alias = NULL; > m->is_default = 0; > pcmc->broken_reserved_end = true; > + pcmc->save_tsc_khz = false; > SET_MACHINE_COMPAT(m, PC_COMPAT_2_4); > } > > diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c > index 0fdae09..fd8efe3 100644 > --- a/hw/i386/pc_q35.c > +++ b/hw/i386/pc_q35.c > @@ -387,6 +387,7 @@ static void pc_q35_2_4_machine_options(MachineClass *m) > m->hw_version = "2.4.0"; > m->alias = NULL; > pcmc->broken_reserved_end = true; > + pcmc->save_tsc_khz = false; > SET_MACHINE_COMPAT(m, PC_COMPAT_2_4); > } > > diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h > index 4bbc0ff..fea0f28 100644 > --- a/include/hw/i386/pc.h > +++ b/include/hw/i386/pc.h > @@ -60,6 +60,7 @@ struct PCMachineClass { > > /*< public >*/ > bool broken_reserved_end; > + bool save_tsc_khz; > HotplugHandler *(*get_hotplug_handler)(MachineState *machine, > DeviceState *dev); > }; > diff --git a/target-i386/cpu.c b/target-i386/cpu.c > index e5f1c5b..98c6a4c 100644 > --- a/target-i386/cpu.c > +++ b/target-i386/cpu.c > @@ -1724,7 +1724,7 @@ static void x86_cpuid_set_tsc_freq(Object *obj, Visitor *v, void *opaque, > return; > } > > - cpu->env.tsc_khz = value / 1000; > + cpu->env.tsc_khz = cpu->env.user_tsc_khz = value / 1000; > } > > static void x86_cpuid_get_apic_id(Object *obj, Visitor *v, void *opaque, > diff --git a/target-i386/cpu.h b/target-i386/cpu.h > index fc4a605..1ad1da8 100644 > --- a/target-i386/cpu.h > +++ b/target-i386/cpu.h > @@ -973,6 +973,7 @@ typedef struct CPUX86State { > uint32_t sipi_vector; > bool tsc_valid; > int64_t tsc_khz; > + int64_t user_tsc_khz; > void *kvm_xsave_buf; > > uint64_t mcg_cap; > diff --git a/target-i386/kvm.c b/target-i386/kvm.c > index 9084b29..8448248 100644 > --- a/target-i386/kvm.c > +++ b/target-i386/kvm.c > @@ -2334,8 +2334,30 @@ static void kvm_arch_set_tsc_khz(CPUState *cs) > int r; > > /* > - * If no user-specified TSC frequency is present, we will try to > - * set env->tsc_khz to the value used by KVM. > + * For other cases of env->tsc_khz and env->user_tsc_khz: > + * > + * - We have eliminated all cases that satisfy > + * env->tsc_khz && env->user_tsc_khz && > + * env->tsc_khz != env->user_tsc_khz > + * in cpu_post_load(). > + * > + * - If env->user_tsc_khz is not zero, then it must be equal to > + * env->tsc_khz (if the latter is not zero) and has been set in > + * kvm_arch_init_vcpu(). > + */ > + if (env->tsc_khz && !env->user_tsc_khz) { > + r = kvm_check_extension(cs->kvm_state, KVM_CAP_TSC_CONTROL) ? > + kvm_vcpu_ioctl(cs, KVM_SET_TSC_KHZ, env->tsc_khz) : -ENOTSUP; Please don't duplicate the code from kvm_arch_init_vcpu(). We can handle both cases in kvm_arch_put_registers(KVM_PUT_FULL_STATE), can't we? > + if (r < 0) { > + error_report("warning: TSC frequency mismatch between VM and host, " > + "and TSC scaling unavailable"); > + } > + } > + > + /* > + * If neither the user-specified TSC frequency nor the migrated > + * TSC frequency is present, we will try to set env->tsc_khz > + * to the value used by KVM. > */ > if (!env->tsc_khz) { > r = kvm_check_extension(cs->kvm_state, KVM_CAP_GET_TSC_KHZ) ? > diff --git a/target-i386/machine.c b/target-i386/machine.c > index a18e16e..eb062d2 100644 > --- a/target-i386/machine.c > +++ b/target-i386/machine.c > @@ -331,6 +331,13 @@ static int cpu_post_load(void *opaque, int version_id) > CPUX86State *env = &cpu->env; > int i; > > + if (env->tsc_khz && env->user_tsc_khz && > + env->tsc_khz != env->user_tsc_khz) { > + fprintf(stderr, "Mismatch between user-specified TSC frequency and " > + "migrated TSC frequency"); > + return -1; > + } > + > /* > * Real mode guest segments register DPL should be zero. > * Older KVM version were setting it wrongly. > @@ -775,6 +782,26 @@ static const VMStateDescription vmstate_xss = { > } > }; > > +static bool tsc_khz_needed(void *opaque) > +{ > + X86CPU *cpu = opaque; > + CPUX86State *env = &cpu->env; > + MachineClass *mc = MACHINE_GET_CLASS(qdev_get_machine()); > + PCMachineClass *pcmc = PC_MACHINE_CLASS(mc); > + return env->tsc_khz && pcmc->save_tsc_khz; > +} > + > +static const VMStateDescription vmstate_tsc_khz = { > + .name = "cpu/tsc_khz", > + .version_id = 1, > + .minimum_version_id = 1, > + .needed = tsc_khz_needed, > + .fields = (VMStateField[]) { > + VMSTATE_INT64(env.tsc_khz, X86CPU), > + VMSTATE_END_OF_LIST() > + } > +}; > + > VMStateDescription vmstate_x86_cpu = { > .name = "cpu", > .version_id = 12, > @@ -895,6 +922,7 @@ VMStateDescription vmstate_x86_cpu = { > &vmstate_msr_hyperv_runtime, > &vmstate_avx512, > &vmstate_xss, > + &vmstate_tsc_khz, > NULL > } > }; > -- > 2.4.8 >
On 11/16/15 11:43, Eduardo Habkost wrote: > On Mon, Nov 16, 2015 at 04:04:08PM +0800, Haozhong Zhang wrote: > > This patch enables migrating vcpu's TSC rate. If KVM on the destination > > machine supports TSC scaling, guest programs will observe a consistent > > TSC rate across the migration. > > > > If TSC scaling is not supported on the destination machine, the > > migration will not be aborted and QEMU on the destination will not set > > vcpu's TSC rate to the migrated value. > > > > If vcpu's TSC rate specified by CPU option 'tsc-freq' on the destination > > machine is inconsistent with the migrated TSC rate, the migration will > > be aborted. > > > > For backwards compatibility, the migration of vcpu's TSC rate is > > disabled on pc-*-2.4 and older machine types. > > > > Signed-off-by: Haozhong Zhang <haozhong.zhang@intel.com> > > --- > > hw/i386/pc.c | 1 + > > hw/i386/pc_piix.c | 1 + > > hw/i386/pc_q35.c | 1 + > > include/hw/i386/pc.h | 1 + > > target-i386/cpu.c | 2 +- > > target-i386/cpu.h | 1 + > > target-i386/kvm.c | 26 ++++++++++++++++++++++++-- > > target-i386/machine.c | 28 ++++++++++++++++++++++++++++ > > 8 files changed, 58 insertions(+), 3 deletions(-) > > > > diff --git a/hw/i386/pc.c b/hw/i386/pc.c > > index 0cb8afd..2f2fc93 100644 > > --- a/hw/i386/pc.c > > +++ b/hw/i386/pc.c > > @@ -1952,6 +1952,7 @@ static void pc_machine_class_init(ObjectClass *oc, void *data) > > HotplugHandlerClass *hc = HOTPLUG_HANDLER_CLASS(oc); > > > > pcmc->get_hotplug_handler = mc->get_hotplug_handler; > > + pcmc->save_tsc_khz = true; > > mc->get_hotplug_handler = pc_get_hotpug_handler; > > mc->cpu_index_to_socket_id = pc_cpu_index_to_socket_id; > > mc->default_boot_order = "cad"; > > diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c > > index 07d0baa..7c5b0d2 100644 > > --- a/hw/i386/pc_piix.c > > +++ b/hw/i386/pc_piix.c > > @@ -489,6 +489,7 @@ static void pc_i440fx_2_4_machine_options(MachineClass *m) > > m->alias = NULL; > > m->is_default = 0; > > pcmc->broken_reserved_end = true; > > + pcmc->save_tsc_khz = false; > > SET_MACHINE_COMPAT(m, PC_COMPAT_2_4); > > } > > > > diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c > > index 0fdae09..fd8efe3 100644 > > --- a/hw/i386/pc_q35.c > > +++ b/hw/i386/pc_q35.c > > @@ -387,6 +387,7 @@ static void pc_q35_2_4_machine_options(MachineClass *m) > > m->hw_version = "2.4.0"; > > m->alias = NULL; > > pcmc->broken_reserved_end = true; > > + pcmc->save_tsc_khz = false; > > SET_MACHINE_COMPAT(m, PC_COMPAT_2_4); > > } > > > > diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h > > index 4bbc0ff..fea0f28 100644 > > --- a/include/hw/i386/pc.h > > +++ b/include/hw/i386/pc.h > > @@ -60,6 +60,7 @@ struct PCMachineClass { > > > > /*< public >*/ > > bool broken_reserved_end; > > + bool save_tsc_khz; > > HotplugHandler *(*get_hotplug_handler)(MachineState *machine, > > DeviceState *dev); > > }; > > diff --git a/target-i386/cpu.c b/target-i386/cpu.c > > index e5f1c5b..98c6a4c 100644 > > --- a/target-i386/cpu.c > > +++ b/target-i386/cpu.c > > @@ -1724,7 +1724,7 @@ static void x86_cpuid_set_tsc_freq(Object *obj, Visitor *v, void *opaque, > > return; > > } > > > > - cpu->env.tsc_khz = value / 1000; > > + cpu->env.tsc_khz = cpu->env.user_tsc_khz = value / 1000; > > } > > > > static void x86_cpuid_get_apic_id(Object *obj, Visitor *v, void *opaque, > > diff --git a/target-i386/cpu.h b/target-i386/cpu.h > > index fc4a605..1ad1da8 100644 > > --- a/target-i386/cpu.h > > +++ b/target-i386/cpu.h > > @@ -973,6 +973,7 @@ typedef struct CPUX86State { > > uint32_t sipi_vector; > > bool tsc_valid; > > int64_t tsc_khz; > > + int64_t user_tsc_khz; > > void *kvm_xsave_buf; > > > > uint64_t mcg_cap; > > diff --git a/target-i386/kvm.c b/target-i386/kvm.c > > index 9084b29..8448248 100644 > > --- a/target-i386/kvm.c > > +++ b/target-i386/kvm.c > > @@ -2334,8 +2334,30 @@ static void kvm_arch_set_tsc_khz(CPUState *cs) > > int r; > > > > /* > > - * If no user-specified TSC frequency is present, we will try to > > - * set env->tsc_khz to the value used by KVM. > > + * For other cases of env->tsc_khz and env->user_tsc_khz: > > + * > > + * - We have eliminated all cases that satisfy > > + * env->tsc_khz && env->user_tsc_khz && > > + * env->tsc_khz != env->user_tsc_khz > > + * in cpu_post_load(). > > + * > > + * - If env->user_tsc_khz is not zero, then it must be equal to > > + * env->tsc_khz (if the latter is not zero) and has been set in > > + * kvm_arch_init_vcpu(). > > + */ > > + if (env->tsc_khz && !env->user_tsc_khz) { > > + r = kvm_check_extension(cs->kvm_state, KVM_CAP_TSC_CONTROL) ? > > + kvm_vcpu_ioctl(cs, KVM_SET_TSC_KHZ, env->tsc_khz) : -ENOTSUP; > > Please don't duplicate the code from kvm_arch_init_vcpu(). We can > handle both cases in kvm_arch_put_registers(KVM_PUT_FULL_STATE), > can't we? > No. If KVM_SET_TSC_KHZ fails in kvm_arch_init_vcpu(), QEMU will exit. But if KVM_SET_TSC_KHZ fails in the migration, QEMU will not abort. And because the return value of kvm_arch_put_registers(KVM_PUT_FULL_STATE) is not checked by its caller do_kvm_cpu_synchronize_post_init(), I have to handle them in different ways. Haozhong > > + if (r < 0) { > > + error_report("warning: TSC frequency mismatch between VM and host, " > > + "and TSC scaling unavailable"); > > + } > > + } > > + > > + /* > > + * If neither the user-specified TSC frequency nor the migrated > > + * TSC frequency is present, we will try to set env->tsc_khz > > + * to the value used by KVM. > > */ > > if (!env->tsc_khz) { > > r = kvm_check_extension(cs->kvm_state, KVM_CAP_GET_TSC_KHZ) ? > > diff --git a/target-i386/machine.c b/target-i386/machine.c > > index a18e16e..eb062d2 100644 > > --- a/target-i386/machine.c > > +++ b/target-i386/machine.c > > @@ -331,6 +331,13 @@ static int cpu_post_load(void *opaque, int version_id) > > CPUX86State *env = &cpu->env; > > int i; > > > > + if (env->tsc_khz && env->user_tsc_khz && > > + env->tsc_khz != env->user_tsc_khz) { > > + fprintf(stderr, "Mismatch between user-specified TSC frequency and " > > + "migrated TSC frequency"); > > + return -1; > > + } > > + > > /* > > * Real mode guest segments register DPL should be zero. > > * Older KVM version were setting it wrongly. > > @@ -775,6 +782,26 @@ static const VMStateDescription vmstate_xss = { > > } > > }; > > > > +static bool tsc_khz_needed(void *opaque) > > +{ > > + X86CPU *cpu = opaque; > > + CPUX86State *env = &cpu->env; > > + MachineClass *mc = MACHINE_GET_CLASS(qdev_get_machine()); > > + PCMachineClass *pcmc = PC_MACHINE_CLASS(mc); > > + return env->tsc_khz && pcmc->save_tsc_khz; > > +} > > + > > +static const VMStateDescription vmstate_tsc_khz = { > > + .name = "cpu/tsc_khz", > > + .version_id = 1, > > + .minimum_version_id = 1, > > + .needed = tsc_khz_needed, > > + .fields = (VMStateField[]) { > > + VMSTATE_INT64(env.tsc_khz, X86CPU), > > + VMSTATE_END_OF_LIST() > > + } > > +}; > > + > > VMStateDescription vmstate_x86_cpu = { > > .name = "cpu", > > .version_id = 12, > > @@ -895,6 +922,7 @@ VMStateDescription vmstate_x86_cpu = { > > &vmstate_msr_hyperv_runtime, > > &vmstate_avx512, > > &vmstate_xss, > > + &vmstate_tsc_khz, > > NULL > > } > > }; > > -- > > 2.4.8 > > > > -- > Eduardo -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Mon, Nov 16, 2015 at 10:30:08PM +0800, Haozhong Zhang wrote: > On 11/16/15 11:43, Eduardo Habkost wrote: > > On Mon, Nov 16, 2015 at 04:04:08PM +0800, Haozhong Zhang wrote: > > > This patch enables migrating vcpu's TSC rate. If KVM on the destination > > > machine supports TSC scaling, guest programs will observe a consistent > > > TSC rate across the migration. > > > > > > If TSC scaling is not supported on the destination machine, the > > > migration will not be aborted and QEMU on the destination will not set > > > vcpu's TSC rate to the migrated value. > > > > > > If vcpu's TSC rate specified by CPU option 'tsc-freq' on the destination > > > machine is inconsistent with the migrated TSC rate, the migration will > > > be aborted. > > > > > > For backwards compatibility, the migration of vcpu's TSC rate is > > > disabled on pc-*-2.4 and older machine types. > > > > > > Signed-off-by: Haozhong Zhang <haozhong.zhang@intel.com> [...] > > > diff --git a/target-i386/kvm.c b/target-i386/kvm.c > > > index 9084b29..8448248 100644 > > > --- a/target-i386/kvm.c > > > +++ b/target-i386/kvm.c > > > @@ -2334,8 +2334,30 @@ static void kvm_arch_set_tsc_khz(CPUState *cs) > > > int r; > > > > > > /* > > > - * If no user-specified TSC frequency is present, we will try to > > > - * set env->tsc_khz to the value used by KVM. > > > + * For other cases of env->tsc_khz and env->user_tsc_khz: > > > + * > > > + * - We have eliminated all cases that satisfy > > > + * env->tsc_khz && env->user_tsc_khz && > > > + * env->tsc_khz != env->user_tsc_khz > > > + * in cpu_post_load(). > > > + * > > > + * - If env->user_tsc_khz is not zero, then it must be equal to > > > + * env->tsc_khz (if the latter is not zero) and has been set in > > > + * kvm_arch_init_vcpu(). > > > + */ > > > + if (env->tsc_khz && !env->user_tsc_khz) { > > > + r = kvm_check_extension(cs->kvm_state, KVM_CAP_TSC_CONTROL) ? > > > + kvm_vcpu_ioctl(cs, KVM_SET_TSC_KHZ, env->tsc_khz) : -ENOTSUP; > > > > Please don't duplicate the code from kvm_arch_init_vcpu(). We can > > handle both cases in kvm_arch_put_registers(KVM_PUT_FULL_STATE), > > can't we? > > > > No. If KVM_SET_TSC_KHZ fails in kvm_arch_init_vcpu(), QEMU will > exit. But if KVM_SET_TSC_KHZ fails in the migration, QEMU will not > abort. And because the return value of > kvm_arch_put_registers(KVM_PUT_FULL_STATE) is not checked by its > caller do_kvm_cpu_synchronize_post_init(), I have to handle them in > different ways. Reporting errors back in kvm_put_registers() may be difficult, I see, so handling user-provided TSC frequency in kvm_arch_init_vcpu() makes sense. But you can still avoid code duplication. Just reuse the same function in kvm_arch_init_vcpu() and kvm_put_registers(), but return errors back to the caller in kvm_arch_init_vcpu() in case env->user_tsc_khz is set. kvm_put_registers() can ignore the error, and just print a warning. But (on both cases) we should print a warning only if env->tsc_khz doesn't match KVM_GET_TSC_KHZ, because we don't want to print spurious warnings on every migration when TSC scaling isn't supported. (You even suggested changes to the example code that does that, at Message-ID: <20151106023244.GB24388@hzzhang-OptiPlex-9020.sh.intel.com>). Also, I believe it won't be a problem if we call KVM_SET_TSC_KHZ twice in the case of incoming migration, so there's no need to check user_tsc_khz in the kvm_arch_put_registers() path. Keeping the code simple is more important than avoiding one extra ioctl() on incoming migration, IMO.
On 11/16/15 13:35, Eduardo Habkost wrote: > On Mon, Nov 16, 2015 at 10:30:08PM +0800, Haozhong Zhang wrote: > > On 11/16/15 11:43, Eduardo Habkost wrote: > > > On Mon, Nov 16, 2015 at 04:04:08PM +0800, Haozhong Zhang wrote: > > > > This patch enables migrating vcpu's TSC rate. If KVM on the destination > > > > machine supports TSC scaling, guest programs will observe a consistent > > > > TSC rate across the migration. > > > > > > > > If TSC scaling is not supported on the destination machine, the > > > > migration will not be aborted and QEMU on the destination will not set > > > > vcpu's TSC rate to the migrated value. > > > > > > > > If vcpu's TSC rate specified by CPU option 'tsc-freq' on the destination > > > > machine is inconsistent with the migrated TSC rate, the migration will > > > > be aborted. > > > > > > > > For backwards compatibility, the migration of vcpu's TSC rate is > > > > disabled on pc-*-2.4 and older machine types. > > > > > > > > Signed-off-by: Haozhong Zhang <haozhong.zhang@intel.com> > [...] > > > > diff --git a/target-i386/kvm.c b/target-i386/kvm.c > > > > index 9084b29..8448248 100644 > > > > --- a/target-i386/kvm.c > > > > +++ b/target-i386/kvm.c > > > > @@ -2334,8 +2334,30 @@ static void kvm_arch_set_tsc_khz(CPUState *cs) > > > > int r; > > > > > > > > /* > > > > - * If no user-specified TSC frequency is present, we will try to > > > > - * set env->tsc_khz to the value used by KVM. > > > > + * For other cases of env->tsc_khz and env->user_tsc_khz: > > > > + * > > > > + * - We have eliminated all cases that satisfy > > > > + * env->tsc_khz && env->user_tsc_khz && > > > > + * env->tsc_khz != env->user_tsc_khz > > > > + * in cpu_post_load(). > > > > + * > > > > + * - If env->user_tsc_khz is not zero, then it must be equal to > > > > + * env->tsc_khz (if the latter is not zero) and has been set in > > > > + * kvm_arch_init_vcpu(). > > > > + */ > > > > + if (env->tsc_khz && !env->user_tsc_khz) { > > > > + r = kvm_check_extension(cs->kvm_state, KVM_CAP_TSC_CONTROL) ? > > > > + kvm_vcpu_ioctl(cs, KVM_SET_TSC_KHZ, env->tsc_khz) : -ENOTSUP; > > > > > > Please don't duplicate the code from kvm_arch_init_vcpu(). We can > > > handle both cases in kvm_arch_put_registers(KVM_PUT_FULL_STATE), > > > can't we? > > > > > > > No. If KVM_SET_TSC_KHZ fails in kvm_arch_init_vcpu(), QEMU will > > exit. But if KVM_SET_TSC_KHZ fails in the migration, QEMU will not > > abort. And because the return value of > > kvm_arch_put_registers(KVM_PUT_FULL_STATE) is not checked by its > > caller do_kvm_cpu_synchronize_post_init(), I have to handle them in > > different ways. > > Reporting errors back in kvm_put_registers() may be difficult, I > see, so handling user-provided TSC frequency in > kvm_arch_init_vcpu() makes sense. But you can still avoid code > duplication. Just reuse the same function in kvm_arch_init_vcpu() > and kvm_put_registers(), but return errors back to the caller in > kvm_arch_init_vcpu() in case env->user_tsc_khz is set. > Agree on using the same function to set TSC rate. I'll change in the next version. > kvm_put_registers() can ignore the error, and just print a > warning. But (on both cases) we should print a warning only if > env->tsc_khz doesn't match KVM_GET_TSC_KHZ, because we don't want > to print spurious warnings on every migration when TSC scaling > isn't supported. (You even suggested changes to the example code > that does that, at Message-ID: > <20151106023244.GB24388@hzzhang-OptiPlex-9020.sh.intel.com>). > I'll check whether env->tsc_khz == KVM_GET_TSC_KHZ in the next version. > Also, I believe it won't be a problem if we call KVM_SET_TSC_KHZ > twice in the case of incoming migration, so there's no need to > check user_tsc_khz in the kvm_arch_put_registers() path. Keeping > the code simple is more important than avoiding one extra ioctl() > on incoming migration, IMO. > I'll use tsc_khz only in the next version. Thanks, Haozhong -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/hw/i386/pc.c b/hw/i386/pc.c index 0cb8afd..2f2fc93 100644 --- a/hw/i386/pc.c +++ b/hw/i386/pc.c @@ -1952,6 +1952,7 @@ static void pc_machine_class_init(ObjectClass *oc, void *data) HotplugHandlerClass *hc = HOTPLUG_HANDLER_CLASS(oc); pcmc->get_hotplug_handler = mc->get_hotplug_handler; + pcmc->save_tsc_khz = true; mc->get_hotplug_handler = pc_get_hotpug_handler; mc->cpu_index_to_socket_id = pc_cpu_index_to_socket_id; mc->default_boot_order = "cad"; diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c index 07d0baa..7c5b0d2 100644 --- a/hw/i386/pc_piix.c +++ b/hw/i386/pc_piix.c @@ -489,6 +489,7 @@ static void pc_i440fx_2_4_machine_options(MachineClass *m) m->alias = NULL; m->is_default = 0; pcmc->broken_reserved_end = true; + pcmc->save_tsc_khz = false; SET_MACHINE_COMPAT(m, PC_COMPAT_2_4); } diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c index 0fdae09..fd8efe3 100644 --- a/hw/i386/pc_q35.c +++ b/hw/i386/pc_q35.c @@ -387,6 +387,7 @@ static void pc_q35_2_4_machine_options(MachineClass *m) m->hw_version = "2.4.0"; m->alias = NULL; pcmc->broken_reserved_end = true; + pcmc->save_tsc_khz = false; SET_MACHINE_COMPAT(m, PC_COMPAT_2_4); } diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h index 4bbc0ff..fea0f28 100644 --- a/include/hw/i386/pc.h +++ b/include/hw/i386/pc.h @@ -60,6 +60,7 @@ struct PCMachineClass { /*< public >*/ bool broken_reserved_end; + bool save_tsc_khz; HotplugHandler *(*get_hotplug_handler)(MachineState *machine, DeviceState *dev); }; diff --git a/target-i386/cpu.c b/target-i386/cpu.c index e5f1c5b..98c6a4c 100644 --- a/target-i386/cpu.c +++ b/target-i386/cpu.c @@ -1724,7 +1724,7 @@ static void x86_cpuid_set_tsc_freq(Object *obj, Visitor *v, void *opaque, return; } - cpu->env.tsc_khz = value / 1000; + cpu->env.tsc_khz = cpu->env.user_tsc_khz = value / 1000; } static void x86_cpuid_get_apic_id(Object *obj, Visitor *v, void *opaque, diff --git a/target-i386/cpu.h b/target-i386/cpu.h index fc4a605..1ad1da8 100644 --- a/target-i386/cpu.h +++ b/target-i386/cpu.h @@ -973,6 +973,7 @@ typedef struct CPUX86State { uint32_t sipi_vector; bool tsc_valid; int64_t tsc_khz; + int64_t user_tsc_khz; void *kvm_xsave_buf; uint64_t mcg_cap; diff --git a/target-i386/kvm.c b/target-i386/kvm.c index 9084b29..8448248 100644 --- a/target-i386/kvm.c +++ b/target-i386/kvm.c @@ -2334,8 +2334,30 @@ static void kvm_arch_set_tsc_khz(CPUState *cs) int r; /* - * If no user-specified TSC frequency is present, we will try to - * set env->tsc_khz to the value used by KVM. + * For other cases of env->tsc_khz and env->user_tsc_khz: + * + * - We have eliminated all cases that satisfy + * env->tsc_khz && env->user_tsc_khz && + * env->tsc_khz != env->user_tsc_khz + * in cpu_post_load(). + * + * - If env->user_tsc_khz is not zero, then it must be equal to + * env->tsc_khz (if the latter is not zero) and has been set in + * kvm_arch_init_vcpu(). + */ + if (env->tsc_khz && !env->user_tsc_khz) { + r = kvm_check_extension(cs->kvm_state, KVM_CAP_TSC_CONTROL) ? + kvm_vcpu_ioctl(cs, KVM_SET_TSC_KHZ, env->tsc_khz) : -ENOTSUP; + if (r < 0) { + error_report("warning: TSC frequency mismatch between VM and host, " + "and TSC scaling unavailable"); + } + } + + /* + * If neither the user-specified TSC frequency nor the migrated + * TSC frequency is present, we will try to set env->tsc_khz + * to the value used by KVM. */ if (!env->tsc_khz) { r = kvm_check_extension(cs->kvm_state, KVM_CAP_GET_TSC_KHZ) ? diff --git a/target-i386/machine.c b/target-i386/machine.c index a18e16e..eb062d2 100644 --- a/target-i386/machine.c +++ b/target-i386/machine.c @@ -331,6 +331,13 @@ static int cpu_post_load(void *opaque, int version_id) CPUX86State *env = &cpu->env; int i; + if (env->tsc_khz && env->user_tsc_khz && + env->tsc_khz != env->user_tsc_khz) { + fprintf(stderr, "Mismatch between user-specified TSC frequency and " + "migrated TSC frequency"); + return -1; + } + /* * Real mode guest segments register DPL should be zero. * Older KVM version were setting it wrongly. @@ -775,6 +782,26 @@ static const VMStateDescription vmstate_xss = { } }; +static bool tsc_khz_needed(void *opaque) +{ + X86CPU *cpu = opaque; + CPUX86State *env = &cpu->env; + MachineClass *mc = MACHINE_GET_CLASS(qdev_get_machine()); + PCMachineClass *pcmc = PC_MACHINE_CLASS(mc); + return env->tsc_khz && pcmc->save_tsc_khz; +} + +static const VMStateDescription vmstate_tsc_khz = { + .name = "cpu/tsc_khz", + .version_id = 1, + .minimum_version_id = 1, + .needed = tsc_khz_needed, + .fields = (VMStateField[]) { + VMSTATE_INT64(env.tsc_khz, X86CPU), + VMSTATE_END_OF_LIST() + } +}; + VMStateDescription vmstate_x86_cpu = { .name = "cpu", .version_id = 12, @@ -895,6 +922,7 @@ VMStateDescription vmstate_x86_cpu = { &vmstate_msr_hyperv_runtime, &vmstate_avx512, &vmstate_xss, + &vmstate_tsc_khz, NULL } };
This patch enables migrating vcpu's TSC rate. If KVM on the destination machine supports TSC scaling, guest programs will observe a consistent TSC rate across the migration. If TSC scaling is not supported on the destination machine, the migration will not be aborted and QEMU on the destination will not set vcpu's TSC rate to the migrated value. If vcpu's TSC rate specified by CPU option 'tsc-freq' on the destination machine is inconsistent with the migrated TSC rate, the migration will be aborted. For backwards compatibility, the migration of vcpu's TSC rate is disabled on pc-*-2.4 and older machine types. Signed-off-by: Haozhong Zhang <haozhong.zhang@intel.com> --- hw/i386/pc.c | 1 + hw/i386/pc_piix.c | 1 + hw/i386/pc_q35.c | 1 + include/hw/i386/pc.h | 1 + target-i386/cpu.c | 2 +- target-i386/cpu.h | 1 + target-i386/kvm.c | 26 ++++++++++++++++++++++++-- target-i386/machine.c | 28 ++++++++++++++++++++++++++++ 8 files changed, 58 insertions(+), 3 deletions(-)