| Message ID | 1504603805-180240-3-git-send-email-arei.gonglei@huawei.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tue, Sep 05, 2017 at 05:30:05PM +0800, Gonglei wrote: > Starting with Windows Server 2012 and Windows 8, if > CPUID.40000005.EAX contains a value of -1, Windows assumes specific > limit to the number of VPs. In this case, Windows Server 2012 > guest VMs may use more than 64 VPs, up to the maximum supported > number of processors applicable to the specific Windows > version being used. > > https://docs.microsoft.com/en-us/virtualization/hyper-v-on-windows/reference/tlfs > > For compatibility, Let's introduce a new property for X86CPU, > named "hv-cpuid-limits-eax" as Paolo's suggestion, and set it > to "on" before machine 2.10. > > Signed-off-by: Gonglei <arei.gonglei@huawei.com> > --- > include/hw/i386/pc.h | 5 +++++ > target/i386/cpu.c | 1 + > target/i386/cpu.h | 2 ++ > target/i386/kvm.c | 18 +++++++++++++++++- > 4 files changed, 25 insertions(+), 1 deletion(-) > > diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h > index 8226904..db32e58 100644 > --- a/include/hw/i386/pc.h > +++ b/include/hw/i386/pc.h > @@ -371,6 +371,11 @@ bool e820_get_entry(int, uint32_t, uint64_t *, uint64_t *); > > #define PC_COMPAT_2_10 \ > HW_COMPAT_2_10 \ > + {\ > + .driver = TYPE_X86_CPU,\ > + .property = "hv_cpuid_limits_eax",\ The property name is hv-cpuid-limits-eax. > + .value = "on",\ > + },\ > > #define PC_COMPAT_2_9 \ > HW_COMPAT_2_9 \ > diff --git a/target/i386/cpu.c b/target/i386/cpu.c > index 69676e1..0d47bdd 100644 > --- a/target/i386/cpu.c > +++ b/target/i386/cpu.c > @@ -4145,6 +4145,7 @@ static Property x86_cpu_properties[] = { > false), > DEFINE_PROP_BOOL("vmware-cpuid-freq", X86CPU, vmware_cpuid_freq, true), > DEFINE_PROP_BOOL("tcg-cpuid", X86CPU, expose_tcg, true), > + DEFINE_PROP_BOOL("hv-cpuid-limits-eax", X86CPU, hv_cpuid_limits_eax, false), The property name "hv-cpuid-limits-eax" doesn't say anything about what it does exactly when set to true. What about just making it int32? e.g.: DEFINE_PROP_INT32("x-hv-max-vps", X86CPU, hv_max_vps, -1) [...] {\ .driver = TYPE_X86_CPU,\ .property = "x-hv-max-vps",\ .value = "0x40",\ },\ [...] c->function = HYPERV_CPUID_IMPLEMENT_LIMITS; c->eax = cpu->hv_max_vps; (The "x-" prefix indicates that the property is not supposed to be a stable user interface.) > DEFINE_PROP_END_OF_LIST() > }; > > diff --git a/target/i386/cpu.h b/target/i386/cpu.h > index 525d35d..f8b455a 100644 > --- a/target/i386/cpu.h > +++ b/target/i386/cpu.h > @@ -1282,6 +1282,8 @@ struct X86CPU { > int32_t socket_id; > int32_t core_id; > int32_t thread_id; > + > + bool hv_cpuid_limits_eax; > }; > > static inline X86CPU *x86_env_get_cpu(CPUX86State *env) > diff --git a/target/i386/kvm.c b/target/i386/kvm.c > index 6db7783..cf6ef96 100644 > --- a/target/i386/kvm.c > +++ b/target/i386/kvm.c > @@ -751,7 +751,23 @@ int kvm_arch_init_vcpu(CPUState *cs) > > c = &cpuid_data.entries[cpuid_i++]; > c->function = HYPERV_CPUID_IMPLEMENT_LIMITS; > - c->eax = 0x40; > + > + if (!cpu->hv_cpuid_limits_eax) { > + /* > + * Starting with Windows Server 2012 and Windows 8, if > + * CPUID.40000005.EAX contains a value of -1, Windows > + * assumes specific limit to the number of VPs. In this case, > + * Windows Server 2012 guest VMs may use more than 64 VPs, > + * up to the maximum supported number of processors > + * applicable to the specific Windows version being used. That was a direct quote from a document, so I recommend citing the specific document you quoted. e.g.: /* * From "Requirements for Implementing the Microsoft * Hypervisor Interface": * https://docs.microsoft.com/en-us/virtualization/hyper-v-on-windows/reference/tlfs * * "Starting with Windows Server 2012 and Windows 8, if * CPUID.40000005.EAX contains a value of -1, Windows assumes * specific limit to the number of VPs. In this case, Windows * Server 2012 guest VMs may use more than 64 VPs, up to the * maximum supported number of processors applicable to the * specific Windows version being used." */ > + * > + * https://docs.microsoft.com/en-us/virtualization/ > + * hyper-v-on-windows/reference/tlfs IMO a long line is preferable to a broken URL. > + */ > + c->eax = -1; > + } else { > + c->eax = 0x40; > + } > c->ebx = 0x40; > > kvm_base = KVM_CPUID_SIGNATURE_NEXT; > -- > 1.8.3.1 > >
> -----Original Message----- > From: Eduardo Habkost [mailto:ehabkost@redhat.com] > Sent: Tuesday, September 05, 2017 9:17 PM > To: Gonglei (Arei) > Cc: qemu-devel@nongnu.org; mst@redhat.com; pbonzini@redhat.com; > rth@twiddle.net; mtosatti@redhat.com; vrozenfe@redhat.com; > Huangweidong (C) > Subject: Re: [PATCH 2/2] i386/cpu/hyperv: support over 64 vcpus for windows > guests > > On Tue, Sep 05, 2017 at 05:30:05PM +0800, Gonglei wrote: > > Starting with Windows Server 2012 and Windows 8, if > > CPUID.40000005.EAX contains a value of -1, Windows assumes specific > > limit to the number of VPs. In this case, Windows Server 2012 > > guest VMs may use more than 64 VPs, up to the maximum supported > > number of processors applicable to the specific Windows > > version being used. > > > > > https://docs.microsoft.com/en-us/virtualization/hyper-v-on-windows/referenc > e/tlfs > > > > For compatibility, Let's introduce a new property for X86CPU, > > named "hv-cpuid-limits-eax" as Paolo's suggestion, and set it > > to "on" before machine 2.10. > > > > Signed-off-by: Gonglei <arei.gonglei@huawei.com> > > --- > > include/hw/i386/pc.h | 5 +++++ > > target/i386/cpu.c | 1 + > > target/i386/cpu.h | 2 ++ > > target/i386/kvm.c | 18 +++++++++++++++++- > > 4 files changed, 25 insertions(+), 1 deletion(-) > > > > diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h > > index 8226904..db32e58 100644 > > --- a/include/hw/i386/pc.h > > +++ b/include/hw/i386/pc.h > > @@ -371,6 +371,11 @@ bool e820_get_entry(int, uint32_t, uint64_t *, > uint64_t *); > > > > #define PC_COMPAT_2_10 \ > > HW_COMPAT_2_10 \ > > + {\ > > + .driver = TYPE_X86_CPU,\ > > + .property = "hv_cpuid_limits_eax",\ > > The property name is hv-cpuid-limits-eax. > Make sense to me. > > + .value = "on",\ > > + },\ > > > > #define PC_COMPAT_2_9 \ > > HW_COMPAT_2_9 \ > > diff --git a/target/i386/cpu.c b/target/i386/cpu.c > > index 69676e1..0d47bdd 100644 > > --- a/target/i386/cpu.c > > +++ b/target/i386/cpu.c > > @@ -4145,6 +4145,7 @@ static Property x86_cpu_properties[] = { > > false), > > DEFINE_PROP_BOOL("vmware-cpuid-freq", X86CPU, > vmware_cpuid_freq, true), > > DEFINE_PROP_BOOL("tcg-cpuid", X86CPU, expose_tcg, true), > > + DEFINE_PROP_BOOL("hv-cpuid-limits-eax", X86CPU, > hv_cpuid_limits_eax, false), > > The property name "hv-cpuid-limits-eax" doesn't say anything > about what it does exactly when set to true. > > What about just making it int32? e.g.: > > DEFINE_PROP_INT32("x-hv-max-vps", X86CPU, hv_max_vps, -1) > [...] > {\ > .driver = TYPE_X86_CPU,\ > .property = "x-hv-max-vps",\ > .value = "0x40",\ > },\ > [...] > c->function = HYPERV_CPUID_IMPLEMENT_LIMITS; > c->eax = cpu->hv_max_vps; > > > (The "x-" prefix indicates that the property is not supposed to > be a stable user interface.) > I thought about this as well. but actually we can't assure that users set the x-hv-max-vps an invalid value if we use this method. Do we really need to expose eax directly? > > > DEFINE_PROP_END_OF_LIST() > > }; > > > > diff --git a/target/i386/cpu.h b/target/i386/cpu.h > > index 525d35d..f8b455a 100644 > > --- a/target/i386/cpu.h > > +++ b/target/i386/cpu.h > > @@ -1282,6 +1282,8 @@ struct X86CPU { > > int32_t socket_id; > > int32_t core_id; > > int32_t thread_id; > > + > > + bool hv_cpuid_limits_eax; > > }; > > > > static inline X86CPU *x86_env_get_cpu(CPUX86State *env) > > diff --git a/target/i386/kvm.c b/target/i386/kvm.c > > index 6db7783..cf6ef96 100644 > > --- a/target/i386/kvm.c > > +++ b/target/i386/kvm.c > > @@ -751,7 +751,23 @@ int kvm_arch_init_vcpu(CPUState *cs) > > > > c = &cpuid_data.entries[cpuid_i++]; > > c->function = HYPERV_CPUID_IMPLEMENT_LIMITS; > > - c->eax = 0x40; > > + > > + if (!cpu->hv_cpuid_limits_eax) { > > + /* > > + * Starting with Windows Server 2012 and Windows 8, if > > + * CPUID.40000005.EAX contains a value of -1, Windows > > + * assumes specific limit to the number of VPs. In this case, > > + * Windows Server 2012 guest VMs may use more than 64 > VPs, > > + * up to the maximum supported number of processors > > + * applicable to the specific Windows version being used. > > That was a direct quote from a document, so I recommend citing > the specific document you quoted. e.g.: > > /* > * From "Requirements for Implementing the Microsoft > * Hypervisor Interface": > * > https://docs.microsoft.com/en-us/virtualization/hyper-v-on-windows/referenc > e/tlfs > * > * "Starting with Windows Server 2012 and Windows 8, if > * CPUID.40000005.EAX contains a value of -1, Windows assumes > * specific limit to the number of VPs. In this case, Windows > * Server 2012 guest VMs may use more than 64 VPs, up to the > * maximum supported number of processors applicable to the > * specific Windows version being used." > */ > > > > + * > > + * https://docs.microsoft.com/en-us/virtualization/ > > + * hyper-v-on-windows/reference/tlfs > > IMO a long line is preferable to a broken URL. > Make sense to me. Thanks, -Gonglei
On Thu, Sep 07, 2017 at 01:05:33AM +0000, Gonglei (Arei) wrote: > > > > -----Original Message----- > > From: Eduardo Habkost [mailto:ehabkost@redhat.com] > > Sent: Tuesday, September 05, 2017 9:17 PM > > To: Gonglei (Arei) > > Cc: qemu-devel@nongnu.org; mst@redhat.com; pbonzini@redhat.com; > > rth@twiddle.net; mtosatti@redhat.com; vrozenfe@redhat.com; > > Huangweidong (C) > > Subject: Re: [PATCH 2/2] i386/cpu/hyperv: support over 64 vcpus for windows > > guests > > > > On Tue, Sep 05, 2017 at 05:30:05PM +0800, Gonglei wrote: > > > Starting with Windows Server 2012 and Windows 8, if > > > CPUID.40000005.EAX contains a value of -1, Windows assumes specific > > > limit to the number of VPs. In this case, Windows Server 2012 > > > guest VMs may use more than 64 VPs, up to the maximum supported > > > number of processors applicable to the specific Windows > > > version being used. > > > > > > > > https://docs.microsoft.com/en-us/virtualization/hyper-v-on-windows/referenc > > e/tlfs > > > > > > For compatibility, Let's introduce a new property for X86CPU, > > > named "hv-cpuid-limits-eax" as Paolo's suggestion, and set it > > > to "on" before machine 2.10. > > > > > > Signed-off-by: Gonglei <arei.gonglei@huawei.com> > > > --- > > > include/hw/i386/pc.h | 5 +++++ > > > target/i386/cpu.c | 1 + > > > target/i386/cpu.h | 2 ++ > > > target/i386/kvm.c | 18 +++++++++++++++++- > > > 4 files changed, 25 insertions(+), 1 deletion(-) > > > > > > diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h > > > index 8226904..db32e58 100644 > > > --- a/include/hw/i386/pc.h > > > +++ b/include/hw/i386/pc.h > > > @@ -371,6 +371,11 @@ bool e820_get_entry(int, uint32_t, uint64_t *, > > uint64_t *); > > > > > > #define PC_COMPAT_2_10 \ > > > HW_COMPAT_2_10 \ > > > + {\ > > > + .driver = TYPE_X86_CPU,\ > > > + .property = "hv_cpuid_limits_eax",\ > > > > The property name is hv-cpuid-limits-eax. > > > Make sense to me. > > > > + .value = "on",\ > > > + },\ > > > > > > #define PC_COMPAT_2_9 \ > > > HW_COMPAT_2_9 \ > > > diff --git a/target/i386/cpu.c b/target/i386/cpu.c > > > index 69676e1..0d47bdd 100644 > > > --- a/target/i386/cpu.c > > > +++ b/target/i386/cpu.c > > > @@ -4145,6 +4145,7 @@ static Property x86_cpu_properties[] = { > > > false), > > > DEFINE_PROP_BOOL("vmware-cpuid-freq", X86CPU, > > vmware_cpuid_freq, true), > > > DEFINE_PROP_BOOL("tcg-cpuid", X86CPU, expose_tcg, true), > > > + DEFINE_PROP_BOOL("hv-cpuid-limits-eax", X86CPU, > > hv_cpuid_limits_eax, false), > > > > The property name "hv-cpuid-limits-eax" doesn't say anything > > about what it does exactly when set to true. > > > > What about just making it int32? e.g.: > > > > DEFINE_PROP_INT32("x-hv-max-vps", X86CPU, hv_max_vps, -1) > > [...] > > {\ > > .driver = TYPE_X86_CPU,\ > > .property = "x-hv-max-vps",\ > > .value = "0x40",\ > > },\ > > [...] > > c->function = HYPERV_CPUID_IMPLEMENT_LIMITS; > > c->eax = cpu->hv_max_vps; > > > > > > (The "x-" prefix indicates that the property is not supposed to > > be a stable user interface.) > > > I thought about this as well. > but actually we can't assure that users set the x-hv-max-vps an invalid value if > we use this method. Do we really need to expose eax directly? We don't really need to expose eax directly and I'm not against a boolean property, but I think an integer property with the actual CPUID value makes the compat code simpler and the purpose of the entry at PC_COMPAT_* more obvious. Properties prefixed with "x-" are for internal QEMU usage or debugging, if users want to fiddle with it, they do it at their own risk. I don't see a problem with that. > > > > > > DEFINE_PROP_END_OF_LIST() > > > }; > > > > > > diff --git a/target/i386/cpu.h b/target/i386/cpu.h > > > index 525d35d..f8b455a 100644 > > > --- a/target/i386/cpu.h > > > +++ b/target/i386/cpu.h > > > @@ -1282,6 +1282,8 @@ struct X86CPU { > > > int32_t socket_id; > > > int32_t core_id; > > > int32_t thread_id; > > > + > > > + bool hv_cpuid_limits_eax; > > > }; > > > > > > static inline X86CPU *x86_env_get_cpu(CPUX86State *env) > > > diff --git a/target/i386/kvm.c b/target/i386/kvm.c > > > index 6db7783..cf6ef96 100644 > > > --- a/target/i386/kvm.c > > > +++ b/target/i386/kvm.c > > > @@ -751,7 +751,23 @@ int kvm_arch_init_vcpu(CPUState *cs) > > > > > > c = &cpuid_data.entries[cpuid_i++]; > > > c->function = HYPERV_CPUID_IMPLEMENT_LIMITS; > > > - c->eax = 0x40; > > > + > > > + if (!cpu->hv_cpuid_limits_eax) { > > > + /* > > > + * Starting with Windows Server 2012 and Windows 8, if > > > + * CPUID.40000005.EAX contains a value of -1, Windows > > > + * assumes specific limit to the number of VPs. In this case, > > > + * Windows Server 2012 guest VMs may use more than 64 > > VPs, > > > + * up to the maximum supported number of processors > > > + * applicable to the specific Windows version being used. > > > > That was a direct quote from a document, so I recommend citing > > the specific document you quoted. e.g.: > > > > /* > > * From "Requirements for Implementing the Microsoft > > * Hypervisor Interface": > > * > > https://docs.microsoft.com/en-us/virtualization/hyper-v-on-windows/referenc > > e/tlfs > > * > > * "Starting with Windows Server 2012 and Windows 8, if > > * CPUID.40000005.EAX contains a value of -1, Windows assumes > > * specific limit to the number of VPs. In this case, Windows > > * Server 2012 guest VMs may use more than 64 VPs, up to the > > * maximum supported number of processors applicable to the > > * specific Windows version being used." > > */ > > > > > > > + * > > > + * https://docs.microsoft.com/en-us/virtualization/ > > > + * hyper-v-on-windows/reference/tlfs > > > > IMO a long line is preferable to a broken URL. > > > Make sense to me. > > Thanks, > -Gonglei >
> -----Original Message----- > From: Eduardo Habkost [mailto:ehabkost@redhat.com] > Sent: Sunday, September 10, 2017 4:46 AM > To: Gonglei (Arei) > Cc: qemu-devel@nongnu.org; mst@redhat.com; pbonzini@redhat.com; > rth@twiddle.net; mtosatti@redhat.com; vrozenfe@redhat.com; > Huangweidong (C) > Subject: Re: [PATCH 2/2] i386/cpu/hyperv: support over 64 vcpus for windows > guests > > On Thu, Sep 07, 2017 at 01:05:33AM +0000, Gonglei (Arei) wrote: > > > > > > > -----Original Message----- > > > From: Eduardo Habkost [mailto:ehabkost@redhat.com] > > > Sent: Tuesday, September 05, 2017 9:17 PM > > > To: Gonglei (Arei) > > > Cc: qemu-devel@nongnu.org; mst@redhat.com; pbonzini@redhat.com; > > > rth@twiddle.net; mtosatti@redhat.com; vrozenfe@redhat.com; > > > Huangweidong (C) > > > Subject: Re: [PATCH 2/2] i386/cpu/hyperv: support over 64 vcpus for > windows > > > guests > > > > > > On Tue, Sep 05, 2017 at 05:30:05PM +0800, Gonglei wrote: > > > > Starting with Windows Server 2012 and Windows 8, if > > > > CPUID.40000005.EAX contains a value of -1, Windows assumes specific > > > > limit to the number of VPs. In this case, Windows Server 2012 > > > > guest VMs may use more than 64 VPs, up to the maximum supported > > > > number of processors applicable to the specific Windows > > > > version being used. > > > > > > > > > > > > https://docs.microsoft.com/en-us/virtualization/hyper-v-on-windows/referenc > > > e/tlfs > > > > > > > > For compatibility, Let's introduce a new property for X86CPU, > > > > named "hv-cpuid-limits-eax" as Paolo's suggestion, and set it > > > > to "on" before machine 2.10. > > > > > > > > Signed-off-by: Gonglei <arei.gonglei@huawei.com> > > > > --- > > > > include/hw/i386/pc.h | 5 +++++ > > > > target/i386/cpu.c | 1 + > > > > target/i386/cpu.h | 2 ++ > > > > target/i386/kvm.c | 18 +++++++++++++++++- > > > > 4 files changed, 25 insertions(+), 1 deletion(-) > > > > > > > > diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h > > > > index 8226904..db32e58 100644 > > > > --- a/include/hw/i386/pc.h > > > > +++ b/include/hw/i386/pc.h > > > > @@ -371,6 +371,11 @@ bool e820_get_entry(int, uint32_t, uint64_t *, > > > uint64_t *); > > > > > > > > #define PC_COMPAT_2_10 \ > > > > HW_COMPAT_2_10 \ > > > > + {\ > > > > + .driver = TYPE_X86_CPU,\ > > > > + .property = "hv_cpuid_limits_eax",\ > > > > > > The property name is hv-cpuid-limits-eax. > > > > > Make sense to me. > > > > > > + .value = "on",\ > > > > + },\ > > > > > > > > #define PC_COMPAT_2_9 \ > > > > HW_COMPAT_2_9 \ > > > > diff --git a/target/i386/cpu.c b/target/i386/cpu.c > > > > index 69676e1..0d47bdd 100644 > > > > --- a/target/i386/cpu.c > > > > +++ b/target/i386/cpu.c > > > > @@ -4145,6 +4145,7 @@ static Property x86_cpu_properties[] = { > > > > false), > > > > DEFINE_PROP_BOOL("vmware-cpuid-freq", X86CPU, > > > vmware_cpuid_freq, true), > > > > DEFINE_PROP_BOOL("tcg-cpuid", X86CPU, expose_tcg, true), > > > > + DEFINE_PROP_BOOL("hv-cpuid-limits-eax", X86CPU, > > > hv_cpuid_limits_eax, false), > > > > > > The property name "hv-cpuid-limits-eax" doesn't say anything > > > about what it does exactly when set to true. > > > > > > What about just making it int32? e.g.: > > > > > > DEFINE_PROP_INT32("x-hv-max-vps", X86CPU, hv_max_vps, -1) > > > [...] > > > {\ > > > .driver = TYPE_X86_CPU,\ > > > .property = "x-hv-max-vps",\ > > > .value = "0x40",\ > > > },\ > > > [...] > > > c->function = HYPERV_CPUID_IMPLEMENT_LIMITS; > > > c->eax = cpu->hv_max_vps; > > > > > > > > > (The "x-" prefix indicates that the property is not supposed to > > > be a stable user interface.) > > > > > I thought about this as well. > > but actually we can't assure that users set the x-hv-max-vps an invalid value if > > we use this method. Do we really need to expose eax directly? > > We don't really need to expose eax directly and I'm not against a > boolean property, but I think an integer property with the actual > CPUID value makes the compat code simpler and the purpose of the > entry at PC_COMPAT_* more obvious. > > Properties prefixed with "x-" are for internal QEMU usage or > debugging, if users want to fiddle with it, they do it at their > own risk. I don't see a problem with that. > Ok, it's fair. Will do it as your suggestion. Thanks, -Gonglei
diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h index 8226904..db32e58 100644 --- a/include/hw/i386/pc.h +++ b/include/hw/i386/pc.h @@ -371,6 +371,11 @@ bool e820_get_entry(int, uint32_t, uint64_t *, uint64_t *); #define PC_COMPAT_2_10 \ HW_COMPAT_2_10 \ + {\ + .driver = TYPE_X86_CPU,\ + .property = "hv_cpuid_limits_eax",\ + .value = "on",\ + },\ #define PC_COMPAT_2_9 \ HW_COMPAT_2_9 \ diff --git a/target/i386/cpu.c b/target/i386/cpu.c index 69676e1..0d47bdd 100644 --- a/target/i386/cpu.c +++ b/target/i386/cpu.c @@ -4145,6 +4145,7 @@ static Property x86_cpu_properties[] = { false), DEFINE_PROP_BOOL("vmware-cpuid-freq", X86CPU, vmware_cpuid_freq, true), DEFINE_PROP_BOOL("tcg-cpuid", X86CPU, expose_tcg, true), + DEFINE_PROP_BOOL("hv-cpuid-limits-eax", X86CPU, hv_cpuid_limits_eax, false), DEFINE_PROP_END_OF_LIST() }; diff --git a/target/i386/cpu.h b/target/i386/cpu.h index 525d35d..f8b455a 100644 --- a/target/i386/cpu.h +++ b/target/i386/cpu.h @@ -1282,6 +1282,8 @@ struct X86CPU { int32_t socket_id; int32_t core_id; int32_t thread_id; + + bool hv_cpuid_limits_eax; }; static inline X86CPU *x86_env_get_cpu(CPUX86State *env) diff --git a/target/i386/kvm.c b/target/i386/kvm.c index 6db7783..cf6ef96 100644 --- a/target/i386/kvm.c +++ b/target/i386/kvm.c @@ -751,7 +751,23 @@ int kvm_arch_init_vcpu(CPUState *cs) c = &cpuid_data.entries[cpuid_i++]; c->function = HYPERV_CPUID_IMPLEMENT_LIMITS; - c->eax = 0x40; + + if (!cpu->hv_cpuid_limits_eax) { + /* + * Starting with Windows Server 2012 and Windows 8, if + * CPUID.40000005.EAX contains a value of -1, Windows + * assumes specific limit to the number of VPs. In this case, + * Windows Server 2012 guest VMs may use more than 64 VPs, + * up to the maximum supported number of processors + * applicable to the specific Windows version being used. + * + * https://docs.microsoft.com/en-us/virtualization/ + * hyper-v-on-windows/reference/tlfs + */ + c->eax = -1; + } else { + c->eax = 0x40; + } c->ebx = 0x40; kvm_base = KVM_CPUID_SIGNATURE_NEXT;
Starting with Windows Server 2012 and Windows 8, if CPUID.40000005.EAX contains a value of -1, Windows assumes specific limit to the number of VPs. In this case, Windows Server 2012 guest VMs may use more than 64 VPs, up to the maximum supported number of processors applicable to the specific Windows version being used. https://docs.microsoft.com/en-us/virtualization/hyper-v-on-windows/reference/tlfs For compatibility, Let's introduce a new property for X86CPU, named "hv-cpuid-limits-eax" as Paolo's suggestion, and set it to "on" before machine 2.10. Signed-off-by: Gonglei <arei.gonglei@huawei.com> --- include/hw/i386/pc.h | 5 +++++ target/i386/cpu.c | 1 + target/i386/cpu.h | 2 ++ target/i386/kvm.c | 18 +++++++++++++++++- 4 files changed, 25 insertions(+), 1 deletion(-)