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-rw-r--r--results/classifier/016/hypervisor/31349848181
-rw-r--r--results/classifier/016/hypervisor/64571620812
-rw-r--r--results/classifier/016/hypervisor/81775929262
3 files changed, 1255 insertions, 0 deletions
diff --git a/results/classifier/016/hypervisor/31349848 b/results/classifier/016/hypervisor/31349848
new file mode 100644
index 000000000..e6ce2d936
--- /dev/null
+++ b/results/classifier/016/hypervisor/31349848
@@ -0,0 +1,181 @@
+hypervisor: 0.871
+virtual: 0.779
+debug: 0.733
+x86: 0.693
+user-level: 0.414
+TCG: 0.398
+peripherals: 0.296
+register: 0.222
+PID: 0.116
+device: 0.104
+operating system: 0.091
+i386: 0.089
+arm: 0.081
+files: 0.067
+socket: 0.062
+ppc: 0.051
+performance: 0.029
+risc-v: 0.026
+architecture: 0.023
+semantic: 0.022
+boot: 0.020
+VMM: 0.018
+kernel: 0.017
+assembly: 0.017
+alpha: 0.014
+vnc: 0.013
+network: 0.012
+permissions: 0.005
+KVM: 0.005
+graphic: 0.005
+mistranslation: 0.002
+
+[Qemu-devel]  [BUG] qemu stuck when detach host-usb device
+
+Description of problem:
+The guest has a host-usb device(Kingston Technology DataTraveler 100 G3/G4/SE9 
+G2), which is attached
+to xhci controller(on host). Qemu will stuck if I detach it from guest.
+
+How reproducible:
+100%
+
+Steps to Reproduce:
+1.            Use usb stick to copy files in guest , make it busy working.
+2.            virsh detach-device vm_name usb.xml
+
+Then qemu will stuck for 20s, I found this is because libusb_release_interface 
+block for 20s.
+Dmesg prints:
+
+[35442.034861] usb 4-2.1: Disable of device-initiated U1 failed.
+[35447.034993] usb 4-2.1: Disable of device-initiated U2 failed.
+[35452.035131] usb 4-2.1: Set SEL for device-initiated U1 failed.
+[35457.035259] usb 4-2.1: Set SEL for device-initiated U2 failed.
+
+Is this a hardware error or software's bug?
+
+On Tue, Nov 27, 2018 at 01:26:24AM +0000, linzhecheng wrote:
+>
+Description of problem:
+>
+The guest has a host-usb device(Kingston Technology DataTraveler 100
+>
+G3/G4/SE9 G2), which is attached
+>
+to xhci controller(on host). Qemu will stuck if I detach it from guest.
+>
+>
+How reproducible:
+>
+100%
+>
+>
+Steps to Reproduce:
+>
+1.            Use usb stick to copy files in guest , make it busy working.
+>
+2.            virsh detach-device vm_name usb.xml
+>
+>
+Then qemu will stuck for 20s, I found this is because
+>
+libusb_release_interface block for 20s.
+>
+Dmesg prints:
+>
+>
+[35442.034861] usb 4-2.1: Disable of device-initiated U1 failed.
+>
+[35447.034993] usb 4-2.1: Disable of device-initiated U2 failed.
+>
+[35452.035131] usb 4-2.1: Set SEL for device-initiated U1 failed.
+>
+[35457.035259] usb 4-2.1: Set SEL for device-initiated U2 failed.
+>
+>
+Is this a hardware error or software's bug?
+I'd guess software error, could be is libusb or (host) linux kernel.
+Cc'ing libusb-devel.
+
+cheers,
+  Gerd
+
+>
+-----Original Message-----
+>
+From: Gerd Hoffmann [
+mailto:address@hidden
+>
+Sent: Tuesday, November 27, 2018 2:09 PM
+>
+To: linzhecheng <address@hidden>
+>
+Cc: address@hidden; wangxin (U) <address@hidden>;
+>
+Zhoujian (jay) <address@hidden>; address@hidden
+>
+Subject: Re: [Qemu-devel] [BUG] qemu stuck when detach host-usb device
+>
+>
+On Tue, Nov 27, 2018 at 01:26:24AM +0000, linzhecheng wrote:
+>
+> Description of problem:
+>
+> The guest has a host-usb device(Kingston Technology DataTraveler 100
+>
+> G3/G4/SE9 G2), which is attached to xhci controller(on host). Qemu will
+>
+> stuck
+>
+if I detach it from guest.
+>
+>
+>
+> How reproducible:
+>
+> 100%
+>
+>
+>
+> Steps to Reproduce:
+>
+> 1.            Use usb stick to copy files in guest , make it busy working.
+>
+> 2.            virsh detach-device vm_name usb.xml
+>
+>
+>
+> Then qemu will stuck for 20s, I found this is because
+>
+> libusb_release_interface
+>
+block for 20s.
+>
+> Dmesg prints:
+>
+>
+>
+> [35442.034861] usb 4-2.1: Disable of device-initiated U1 failed.
+>
+> [35447.034993] usb 4-2.1: Disable of device-initiated U2 failed.
+>
+> [35452.035131] usb 4-2.1: Set SEL for device-initiated U1 failed.
+>
+> [35457.035259] usb 4-2.1: Set SEL for device-initiated U2 failed.
+>
+>
+>
+> Is this a hardware error or software's bug?
+>
+>
+I'd guess software error, could be is libusb or (host) linux kernel.
+>
+Cc'ing libusb-devel.
+Perhaps it's usb driver's bug. Could you also reproduce it?
+>
+>
+cheers,
+>
+Gerd
+
diff --git a/results/classifier/016/hypervisor/64571620 b/results/classifier/016/hypervisor/64571620
new file mode 100644
index 000000000..29d955013
--- /dev/null
+++ b/results/classifier/016/hypervisor/64571620
@@ -0,0 +1,812 @@
+hypervisor: 0.913
+debug: 0.901
+x86: 0.888
+operating system: 0.737
+kernel: 0.672
+KVM: 0.636
+virtual: 0.626
+TCG: 0.371
+user-level: 0.216
+register: 0.110
+files: 0.107
+socket: 0.102
+PID: 0.097
+performance: 0.063
+device: 0.051
+network: 0.047
+VMM: 0.035
+ppc: 0.032
+permissions: 0.024
+boot: 0.021
+risc-v: 0.020
+vnc: 0.019
+architecture: 0.016
+semantic: 0.014
+alpha: 0.013
+assembly: 0.010
+peripherals: 0.008
+i386: 0.004
+arm: 0.003
+graphic: 0.001
+mistranslation: 0.001
+
+[BUG] Migration hv_time rollback
+
+Hi,
+
+We are experiencing timestamp rollbacks during live-migration of
+Windows 10 guests with the following qemu configuration (linux 5.4.46
+and qemu master):
+```
+$ qemu-system-x86_64 -enable-kvm -cpu host,kvm=off,hv_time [...]
+```
+
+I have tracked the bug to the fact that `kvmclock` is not exposed and
+disabled from qemu PoV but is in fact used by `hv-time` (in KVM).
+
+I think we should enable the `kvmclock` (qemu device) if `hv-time` is
+present and add Hyper-V support for the `kvmclock_current_nsec`
+function.
+
+I'm asking for advice because I am unsure this is the _right_ approach
+and how to keep migration compatibility between qemu versions.
+
+Thank you all,
+
+-- 
+Antoine 'xdbob' Damhet
+signature.asc
+Description:
+PGP signature
+
+cc'ing in Vitaly who knows about the hv stuff.
+
+* Antoine Damhet (antoine.damhet@blade-group.com) wrote:
+>
+Hi,
+>
+>
+We are experiencing timestamp rollbacks during live-migration of
+>
+Windows 10 guests with the following qemu configuration (linux 5.4.46
+>
+and qemu master):
+>
+```
+>
+$ qemu-system-x86_64 -enable-kvm -cpu host,kvm=off,hv_time [...]
+>
+```
+How big a jump are you seeing, and how did you notice it in the guest?
+
+Dave
+
+>
+I have tracked the bug to the fact that `kvmclock` is not exposed and
+>
+disabled from qemu PoV but is in fact used by `hv-time` (in KVM).
+>
+>
+I think we should enable the `kvmclock` (qemu device) if `hv-time` is
+>
+present and add Hyper-V support for the `kvmclock_current_nsec`
+>
+function.
+>
+>
+I'm asking for advice because I am unsure this is the _right_ approach
+>
+and how to keep migration compatibility between qemu versions.
+>
+>
+Thank you all,
+>
+>
+--
+>
+Antoine 'xdbob' Damhet
+-- 
+Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
+
+"Dr. David Alan Gilbert" <dgilbert@redhat.com> writes:
+
+>
+cc'ing in Vitaly who knows about the hv stuff.
+>
+cc'ing Marcelo who knows about clocksources :-)
+
+>
+* Antoine Damhet (antoine.damhet@blade-group.com) wrote:
+>
+> Hi,
+>
+>
+>
+> We are experiencing timestamp rollbacks during live-migration of
+>
+> Windows 10 guests
+Are you migrating to the same hardware (with the same TSC frequency)? Is
+TSC used as the clocksource on the host?
+
+>
+>  with the following qemu configuration (linux 5.4.46
+>
+> and qemu master):
+>
+> ```
+>
+> $ qemu-system-x86_64 -enable-kvm -cpu host,kvm=off,hv_time [...]
+>
+> ```
+Out of pure curiosity, what's the purpose of doing 'kvm=off'? Windows is
+not going to check for KVM identification anyway so we pretend we're
+Hyper-V. 
+
+Also, have you tried adding more Hyper-V enlightenments? 
+
+>
+>
+How big a jump are you seeing, and how did you notice it in the guest?
+>
+>
+Dave
+>
+>
+> I have tracked the bug to the fact that `kvmclock` is not exposed and
+>
+> disabled from qemu PoV but is in fact used by `hv-time` (in KVM).
+>
+>
+>
+> I think we should enable the `kvmclock` (qemu device) if `hv-time` is
+>
+> present and add Hyper-V support for the `kvmclock_current_nsec`
+>
+> function.
+AFAICT kvmclock_current_nsec() checks whether kvmclock was enabled by
+the guest:
+
+   if (!(env->system_time_msr & 1ULL)) {
+        /* KVM clock not active */
+        return 0;
+    }
+
+and this is (and way) always false for Windows guests.
+
+>
+>
+>
+> I'm asking for advice because I am unsure this is the _right_ approach
+>
+> and how to keep migration compatibility between qemu versions.
+>
+>
+>
+> Thank you all,
+>
+>
+>
+> --
+>
+> Antoine 'xdbob' Damhet
+-- 
+Vitaly
+
+On Wed, Sep 16, 2020 at 01:59:43PM +0200, Vitaly Kuznetsov wrote:
+>
+"Dr. David Alan Gilbert" <dgilbert@redhat.com> writes:
+>
+>
+> cc'ing in Vitaly who knows about the hv stuff.
+>
+>
+>
+>
+cc'ing Marcelo who knows about clocksources :-)
+>
+>
+> * Antoine Damhet (antoine.damhet@blade-group.com) wrote:
+>
+>> Hi,
+>
+>>
+>
+>> We are experiencing timestamp rollbacks during live-migration of
+>
+>> Windows 10 guests
+>
+>
+Are you migrating to the same hardware (with the same TSC frequency)? Is
+>
+TSC used as the clocksource on the host?
+Yes we are migrating to the exact same hardware. And yes TSC is used as
+a clocksource in the host (but the bug is still happening with `hpet` as
+a clocksource).
+
+>
+>
+>>  with the following qemu configuration (linux 5.4.46
+>
+>> and qemu master):
+>
+>> ```
+>
+>> $ qemu-system-x86_64 -enable-kvm -cpu host,kvm=off,hv_time [...]
+>
+>> ```
+>
+>
+Out of pure curiosity, what's the purpose of doing 'kvm=off'? Windows is
+>
+not going to check for KVM identification anyway so we pretend we're
+>
+Hyper-V.
+Some softwares explicitly checks for the presence of KVM and then crash
+if they find it in CPUID :/
+
+>
+>
+Also, have you tried adding more Hyper-V enlightenments?
+Yes, I published a stripped-down command-line for a minimal reproducer
+but even `hv-frequencies` and `hv-reenlightenment` don't help.
+
+>
+>
+>
+>
+> How big a jump are you seeing, and how did you notice it in the guest?
+>
+>
+>
+> Dave
+>
+>
+>
+>> I have tracked the bug to the fact that `kvmclock` is not exposed and
+>
+>> disabled from qemu PoV but is in fact used by `hv-time` (in KVM).
+>
+>>
+>
+>> I think we should enable the `kvmclock` (qemu device) if `hv-time` is
+>
+>> present and add Hyper-V support for the `kvmclock_current_nsec`
+>
+>> function.
+>
+>
+AFAICT kvmclock_current_nsec() checks whether kvmclock was enabled by
+>
+the guest:
+>
+>
+if (!(env->system_time_msr & 1ULL)) {
+>
+/* KVM clock not active */
+>
+return 0;
+>
+}
+>
+>
+and this is (and way) always false for Windows guests.
+Hooo, I missed this piece. When is `clock_is_reliable` expected to be
+false ? Because if it is I still think we should be able to query at
+least `HV_X64_MSR_REFERENCE_TSC`
+
+>
+>
+>>
+>
+>> I'm asking for advice because I am unsure this is the _right_ approach
+>
+>> and how to keep migration compatibility between qemu versions.
+>
+>>
+>
+>> Thank you all,
+>
+>>
+>
+>> --
+>
+>> Antoine 'xdbob' Damhet
+>
+>
+--
+>
+Vitaly
+>
+-- 
+Antoine 'xdbob' Damhet
+signature.asc
+Description:
+PGP signature
+
+On Wed, Sep 16, 2020 at 12:29:56PM +0100, Dr. David Alan Gilbert wrote:
+>
+cc'ing in Vitaly who knows about the hv stuff.
+Thanks
+
+>
+>
+* Antoine Damhet (antoine.damhet@blade-group.com) wrote:
+>
+> Hi,
+>
+>
+>
+> We are experiencing timestamp rollbacks during live-migration of
+>
+> Windows 10 guests with the following qemu configuration (linux 5.4.46
+>
+> and qemu master):
+>
+> ```
+>
+> $ qemu-system-x86_64 -enable-kvm -cpu host,kvm=off,hv_time [...]
+>
+> ```
+>
+>
+How big a jump are you seeing, and how did you notice it in the guest?
+I'm seeing jumps of about the guest uptime (indicating a reset of the
+counter). It's expected because we won't call `KVM_SET_CLOCK` to
+restore any value.
+
+We first noticed it because after some migrations `dwm.exe` crashes with
+the "(NTSTATUS) 0x8898009b - QueryPerformanceCounter returned a time in
+the past." error code.
+
+I can also confirm the following hack makes the behavior disappear:
+
+```
+diff --git a/hw/i386/kvm/clock.c b/hw/i386/kvm/clock.c
+index 64283358f9..f334bdf35f 100644
+--- a/hw/i386/kvm/clock.c
++++ b/hw/i386/kvm/clock.c
+@@ -332,11 +332,7 @@ void kvmclock_create(void)
+ {
+     X86CPU *cpu = X86_CPU(first_cpu);
+
+-    if (kvm_enabled() &&
+-        cpu->env.features[FEAT_KVM] & ((1ULL << KVM_FEATURE_CLOCKSOURCE) |
+-                                       (1ULL << KVM_FEATURE_CLOCKSOURCE2))) {
+-        sysbus_create_simple(TYPE_KVM_CLOCK, -1, NULL);
+-    }
++    sysbus_create_simple(TYPE_KVM_CLOCK, -1, NULL);
+ }
+
+ static void kvmclock_register_types(void)
+diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
+index 32b1453e6a..11d980ba85 100644
+--- a/hw/i386/pc_piix.c
++++ b/hw/i386/pc_piix.c
+@@ -158,9 +158,7 @@ static void pc_init1(MachineState *machine,
+
+     x86_cpus_init(x86ms, pcmc->default_cpu_version);
+
+-    if (kvm_enabled() && pcmc->kvmclock_enabled) {
+-        kvmclock_create();
+-    }
++    kvmclock_create();
+
+     if (pcmc->pci_enabled) {
+         pci_memory = g_new(MemoryRegion, 1);
+```
+
+>
+>
+Dave
+>
+>
+> I have tracked the bug to the fact that `kvmclock` is not exposed and
+>
+> disabled from qemu PoV but is in fact used by `hv-time` (in KVM).
+>
+>
+>
+> I think we should enable the `kvmclock` (qemu device) if `hv-time` is
+>
+> present and add Hyper-V support for the `kvmclock_current_nsec`
+>
+> function.
+>
+>
+>
+> I'm asking for advice because I am unsure this is the _right_ approach
+>
+> and how to keep migration compatibility between qemu versions.
+>
+>
+>
+> Thank you all,
+>
+>
+>
+> --
+>
+> Antoine 'xdbob' Damhet
+>
+>
+>
+--
+>
+Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
+>
+-- 
+Antoine 'xdbob' Damhet
+signature.asc
+Description:
+PGP signature
+
+Antoine Damhet <antoine.damhet@blade-group.com> writes:
+
+>
+On Wed, Sep 16, 2020 at 12:29:56PM +0100, Dr. David Alan Gilbert wrote:
+>
+> cc'ing in Vitaly who knows about the hv stuff.
+>
+>
+Thanks
+>
+>
+>
+>
+> * Antoine Damhet (antoine.damhet@blade-group.com) wrote:
+>
+> > Hi,
+>
+> >
+>
+> > We are experiencing timestamp rollbacks during live-migration of
+>
+> > Windows 10 guests with the following qemu configuration (linux 5.4.46
+>
+> > and qemu master):
+>
+> > ```
+>
+> > $ qemu-system-x86_64 -enable-kvm -cpu host,kvm=off,hv_time [...]
+>
+> > ```
+>
+>
+>
+> How big a jump are you seeing, and how did you notice it in the guest?
+>
+>
+I'm seeing jumps of about the guest uptime (indicating a reset of the
+>
+counter). It's expected because we won't call `KVM_SET_CLOCK` to
+>
+restore any value.
+>
+>
+We first noticed it because after some migrations `dwm.exe` crashes with
+>
+the "(NTSTATUS) 0x8898009b - QueryPerformanceCounter returned a time in
+>
+the past." error code.
+>
+>
+I can also confirm the following hack makes the behavior disappear:
+>
+>
+```
+>
+diff --git a/hw/i386/kvm/clock.c b/hw/i386/kvm/clock.c
+>
+index 64283358f9..f334bdf35f 100644
+>
+--- a/hw/i386/kvm/clock.c
+>
++++ b/hw/i386/kvm/clock.c
+>
+@@ -332,11 +332,7 @@ void kvmclock_create(void)
+>
+{
+>
+X86CPU *cpu = X86_CPU(first_cpu);
+>
+>
+-    if (kvm_enabled() &&
+>
+-        cpu->env.features[FEAT_KVM] & ((1ULL << KVM_FEATURE_CLOCKSOURCE) |
+>
+-                                       (1ULL << KVM_FEATURE_CLOCKSOURCE2))) {
+>
+-        sysbus_create_simple(TYPE_KVM_CLOCK, -1, NULL);
+>
+-    }
+>
++    sysbus_create_simple(TYPE_KVM_CLOCK, -1, NULL);
+>
+}
+>
+Oh, I think I see what's going on. When you add 'kvm=off'
+cpu->env.features[FEAT_KVM] is reset (see x86_cpu_expand_features()) so
+kvmclock QEMU device is not created and nobody calls KVM_SET_CLOCK on
+migration.
+
+In case we really want to support 'kvm=off' I think we can add Hyper-V
+features check here along with KVM, this should do the job.
+
+-- 
+Vitaly
+
+Vitaly Kuznetsov <vkuznets@redhat.com> writes:
+
+>
+Antoine Damhet <antoine.damhet@blade-group.com> writes:
+>
+>
+> On Wed, Sep 16, 2020 at 12:29:56PM +0100, Dr. David Alan Gilbert wrote:
+>
+>> cc'ing in Vitaly who knows about the hv stuff.
+>
+>
+>
+> Thanks
+>
+>
+>
+>>
+>
+>> * Antoine Damhet (antoine.damhet@blade-group.com) wrote:
+>
+>> > Hi,
+>
+>> >
+>
+>> > We are experiencing timestamp rollbacks during live-migration of
+>
+>> > Windows 10 guests with the following qemu configuration (linux 5.4.46
+>
+>> > and qemu master):
+>
+>> > ```
+>
+>> > $ qemu-system-x86_64 -enable-kvm -cpu host,kvm=off,hv_time [...]
+>
+>> > ```
+>
+>>
+>
+>> How big a jump are you seeing, and how did you notice it in the guest?
+>
+>
+>
+> I'm seeing jumps of about the guest uptime (indicating a reset of the
+>
+> counter). It's expected because we won't call `KVM_SET_CLOCK` to
+>
+> restore any value.
+>
+>
+>
+> We first noticed it because after some migrations `dwm.exe` crashes with
+>
+> the "(NTSTATUS) 0x8898009b - QueryPerformanceCounter returned a time in
+>
+> the past." error code.
+>
+>
+>
+> I can also confirm the following hack makes the behavior disappear:
+>
+>
+>
+> ```
+>
+> diff --git a/hw/i386/kvm/clock.c b/hw/i386/kvm/clock.c
+>
+> index 64283358f9..f334bdf35f 100644
+>
+> --- a/hw/i386/kvm/clock.c
+>
+> +++ b/hw/i386/kvm/clock.c
+>
+> @@ -332,11 +332,7 @@ void kvmclock_create(void)
+>
+>  {
+>
+>      X86CPU *cpu = X86_CPU(first_cpu);
+>
+>
+>
+> -    if (kvm_enabled() &&
+>
+> -        cpu->env.features[FEAT_KVM] & ((1ULL << KVM_FEATURE_CLOCKSOURCE) |
+>
+> -                                       (1ULL << KVM_FEATURE_CLOCKSOURCE2)))
+>
+> {
+>
+> -        sysbus_create_simple(TYPE_KVM_CLOCK, -1, NULL);
+>
+> -    }
+>
+> +    sysbus_create_simple(TYPE_KVM_CLOCK, -1, NULL);
+>
+>  }
+>
+>
+>
+>
+>
+Oh, I think I see what's going on. When you add 'kvm=off'
+>
+cpu->env.features[FEAT_KVM] is reset (see x86_cpu_expand_features()) so
+>
+kvmclock QEMU device is not created and nobody calls KVM_SET_CLOCK on
+>
+migration.
+>
+>
+In case we really want to support 'kvm=off' I think we can add Hyper-V
+>
+features check here along with KVM, this should do the job.
+Does the untested
+
+diff --git a/hw/i386/kvm/clock.c b/hw/i386/kvm/clock.c
+index 64283358f91d..e03b2ca6d8f6 100644
+--- a/hw/i386/kvm/clock.c
++++ b/hw/i386/kvm/clock.c
+@@ -333,8 +333,9 @@ void kvmclock_create(void)
+     X86CPU *cpu = X86_CPU(first_cpu);
+ 
+     if (kvm_enabled() &&
+-        cpu->env.features[FEAT_KVM] & ((1ULL << KVM_FEATURE_CLOCKSOURCE) |
+-                                       (1ULL << KVM_FEATURE_CLOCKSOURCE2))) {
++        ((cpu->env.features[FEAT_KVM] & ((1ULL << KVM_FEATURE_CLOCKSOURCE) |
++                                         (1ULL << KVM_FEATURE_CLOCKSOURCE2))) 
+||
++         (cpu->env.features[FEAT_HYPERV_EAX] & HV_TIME_REF_COUNT_AVAILABLE))) {
+         sysbus_create_simple(TYPE_KVM_CLOCK, -1, NULL);
+     }
+ }
+
+help?
+
+(I don't think we need to remove all 'if (kvm_enabled())' checks from
+machine types as 'kvm=off' should not be related).
+
+-- 
+Vitaly
+
+On Wed, Sep 16, 2020 at 02:50:56PM +0200, Vitaly Kuznetsov wrote:
+[...]
+
+>
+>>
+>
+>
+>
+>
+>
+> Oh, I think I see what's going on. When you add 'kvm=off'
+>
+> cpu->env.features[FEAT_KVM] is reset (see x86_cpu_expand_features()) so
+>
+> kvmclock QEMU device is not created and nobody calls KVM_SET_CLOCK on
+>
+> migration.
+>
+>
+>
+> In case we really want to support 'kvm=off' I think we can add Hyper-V
+>
+> features check here along with KVM, this should do the job.
+>
+>
+Does the untested
+>
+>
+diff --git a/hw/i386/kvm/clock.c b/hw/i386/kvm/clock.c
+>
+index 64283358f91d..e03b2ca6d8f6 100644
+>
+--- a/hw/i386/kvm/clock.c
+>
++++ b/hw/i386/kvm/clock.c
+>
+@@ -333,8 +333,9 @@ void kvmclock_create(void)
+>
+X86CPU *cpu = X86_CPU(first_cpu);
+>
+>
+if (kvm_enabled() &&
+>
+-        cpu->env.features[FEAT_KVM] & ((1ULL << KVM_FEATURE_CLOCKSOURCE) |
+>
+-                                       (1ULL << KVM_FEATURE_CLOCKSOURCE2))) {
+>
++        ((cpu->env.features[FEAT_KVM] & ((1ULL << KVM_FEATURE_CLOCKSOURCE) |
+>
++                                         (1ULL <<
+>
+KVM_FEATURE_CLOCKSOURCE2))) ||
+>
++         (cpu->env.features[FEAT_HYPERV_EAX] &
+>
+HV_TIME_REF_COUNT_AVAILABLE))) {
+>
+sysbus_create_simple(TYPE_KVM_CLOCK, -1, NULL);
+>
+}
+>
+}
+>
+>
+help?
+It appears to work :)
+
+>
+>
+(I don't think we need to remove all 'if (kvm_enabled())' checks from
+>
+machine types as 'kvm=off' should not be related).
+Indeed (I didn't look at the macro, it was just quick & dirty).
+
+>
+>
+--
+>
+Vitaly
+>
+>
+-- 
+Antoine 'xdbob' Damhet
+signature.asc
+Description:
+PGP signature
+
+On 16/09/20 13:29, Dr. David Alan Gilbert wrote:
+>
+> I have tracked the bug to the fact that `kvmclock` is not exposed and
+>
+> disabled from qemu PoV but is in fact used by `hv-time` (in KVM).
+>
+>
+>
+> I think we should enable the `kvmclock` (qemu device) if `hv-time` is
+>
+> present and add Hyper-V support for the `kvmclock_current_nsec`
+>
+> function.
+Yes, this seems correct.  I would have to check but it may even be
+better to _always_ send kvmclock data in the live migration stream.
+
+Paolo
+
+Paolo Bonzini <pbonzini@redhat.com> writes:
+
+>
+On 16/09/20 13:29, Dr. David Alan Gilbert wrote:
+>
+>> I have tracked the bug to the fact that `kvmclock` is not exposed and
+>
+>> disabled from qemu PoV but is in fact used by `hv-time` (in KVM).
+>
+>>
+>
+>> I think we should enable the `kvmclock` (qemu device) if `hv-time` is
+>
+>> present and add Hyper-V support for the `kvmclock_current_nsec`
+>
+>> function.
+>
+>
+Yes, this seems correct.  I would have to check but it may even be
+>
+better to _always_ send kvmclock data in the live migration stream.
+>
+The question I have is: with 'kvm=off', do we actually restore TSC
+reading on migration? (and I guess the answer is 'no' or Hyper-V TSC
+page would 'just work' I guess). So yea, maybe dropping the
+'cpu->env.features[FEAT_KVM]' check is the right fix.
+
+-- 
+Vitaly
+
diff --git a/results/classifier/016/hypervisor/81775929 b/results/classifier/016/hypervisor/81775929
new file mode 100644
index 000000000..01d16c9e1
--- /dev/null
+++ b/results/classifier/016/hypervisor/81775929
@@ -0,0 +1,262 @@
+hypervisor: 0.832
+debug: 0.680
+risc-v: 0.594
+virtual: 0.452
+x86: 0.349
+register: 0.152
+TCG: 0.150
+files: 0.142
+PID: 0.132
+ppc: 0.127
+i386: 0.101
+vnc: 0.098
+semantic: 0.092
+user-level: 0.082
+VMM: 0.066
+device: 0.062
+operating system: 0.053
+boot: 0.045
+performance: 0.034
+socket: 0.031
+arm: 0.029
+KVM: 0.019
+assembly: 0.018
+network: 0.013
+alpha: 0.012
+kernel: 0.012
+architecture: 0.010
+peripherals: 0.005
+permissions: 0.005
+mistranslation: 0.004
+graphic: 0.004
+
+[Qemu-devel] [BUG] Monitor QMP is broken ?
+
+Hello!
+
+ I have updated my qemu to the recent version and it seems to have lost 
+compatibility with
+libvirt. The error message is:
+--- cut ---
+internal error: unable to execute QEMU command 'qmp_capabilities': QMP input 
+object member
+'id' is unexpected
+--- cut ---
+ What does it mean? Is it intentional or not?
+
+Kind regards,
+Pavel Fedin
+Expert Engineer
+Samsung Electronics Research center Russia
+
+Hello! 
+
+>
+I have updated my qemu to the recent version and it seems to have lost
+>
+compatibility
+with
+>
+libvirt. The error message is:
+>
+--- cut ---
+>
+internal error: unable to execute QEMU command 'qmp_capabilities': QMP input
+>
+object
+>
+member
+>
+'id' is unexpected
+>
+--- cut ---
+>
+What does it mean? Is it intentional or not?
+I have found the problem. It is caused by commit
+65207c59d99f2260c5f1d3b9c491146616a522aa. libvirt does not seem to use the 
+removed
+asynchronous interface but it still feeds in JSONs with 'id' field set to 
+something. So i
+think the related fragment in qmp_check_input_obj() function should be brought 
+back
+
+Kind regards,
+Pavel Fedin
+Expert Engineer
+Samsung Electronics Research center Russia
+
+On Fri, Jun 05, 2015 at 04:58:46PM +0300, Pavel Fedin wrote:
+>
+Hello!
+>
+>
+>  I have updated my qemu to the recent version and it seems to have lost
+>
+> compatibility
+>
+with
+>
+> libvirt. The error message is:
+>
+> --- cut ---
+>
+> internal error: unable to execute QEMU command 'qmp_capabilities': QMP
+>
+> input object
+>
+> member
+>
+> 'id' is unexpected
+>
+> --- cut ---
+>
+>  What does it mean? Is it intentional or not?
+>
+>
+I have found the problem. It is caused by commit
+>
+65207c59d99f2260c5f1d3b9c491146616a522aa. libvirt does not seem to use the
+>
+removed
+>
+asynchronous interface but it still feeds in JSONs with 'id' field set to
+>
+something. So i
+>
+think the related fragment in qmp_check_input_obj() function should be
+>
+brought back
+If QMP is rejecting the 'id' parameter that is a regression bug.
+
+[quote]
+The QMP spec says
+
+2.3 Issuing Commands
+--------------------
+
+The format for command execution is:
+
+{ "execute": json-string, "arguments": json-object, "id": json-value }
+
+ Where,
+
+- The "execute" member identifies the command to be executed by the Server
+- The "arguments" member is used to pass any arguments required for the
+  execution of the command, it is optional when no arguments are
+  required. Each command documents what contents will be considered
+  valid when handling the json-argument
+- The "id" member is a transaction identification associated with the
+  command execution, it is optional and will be part of the response if
+  provided. The "id" member can be any json-value, although most
+  clients merely use a json-number incremented for each successive
+  command
+
+
+2.4 Commands Responses
+----------------------
+
+There are two possible responses which the Server will issue as the result
+of a command execution: success or error.
+
+2.4.1 success
+-------------
+
+The format of a success response is:
+
+{ "return": json-value, "id": json-value }
+
+ Where,
+
+- The "return" member contains the data returned by the command, which
+  is defined on a per-command basis (usually a json-object or
+  json-array of json-objects, but sometimes a json-number, json-string,
+  or json-array of json-strings); it is an empty json-object if the
+  command does not return data
+- The "id" member contains the transaction identification associated
+  with the command execution if issued by the Client
+
+[/quote]
+
+And as such, libvirt chose to /always/ send an 'id' parameter in all
+commands it issues.
+
+We don't however validate the id in the reply, though arguably we
+should have done so.
+
+Regards,
+Daniel
+-- 
+|:
+http://berrange.com
+-o-
+http://www.flickr.com/photos/dberrange/
+:|
+|:
+http://libvirt.org
+-o-
+http://virt-manager.org
+:|
+|:
+http://autobuild.org
+-o-
+http://search.cpan.org/~danberr/
+:|
+|:
+http://entangle-photo.org
+-o-
+http://live.gnome.org/gtk-vnc
+:|
+
+"Daniel P. Berrange" <address@hidden> writes:
+
+>
+On Fri, Jun 05, 2015 at 04:58:46PM +0300, Pavel Fedin wrote:
+>
+>  Hello!
+>
+>
+>
+> >  I have updated my qemu to the recent version and it seems to have
+>
+> > lost compatibility
+>
+> with
+>
+> > libvirt. The error message is:
+>
+> > --- cut ---
+>
+> > internal error: unable to execute QEMU command 'qmp_capabilities':
+>
+> > QMP input object
+>
+> > member
+>
+> > 'id' is unexpected
+>
+> > --- cut ---
+>
+> >  What does it mean? Is it intentional or not?
+>
+>
+>
+>  I have found the problem. It is caused by commit
+>
+> 65207c59d99f2260c5f1d3b9c491146616a522aa. libvirt does not seem to
+>
+> use the removed
+>
+> asynchronous interface but it still feeds in JSONs with 'id' field
+>
+> set to something. So i
+>
+> think the related fragment in qmp_check_input_obj() function should
+>
+> be brought back
+>
+>
+If QMP is rejecting the 'id' parameter that is a regression bug.
+It is definitely a regression, my fault, and I'll get it fixed a.s.a.p.
+
+[...]
+