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[PATCH v1] mc146818rtc: add a way to generate RTC interrupts via QMP

Daniil Tatianin posted 1 patch 1 week, 5 days ago
Patches applied successfully (tree, apply log)
git fetch https://github.com/patchew-project/qemu tags/patchew/20240427075801.491673-1-d-tatianin@yandex-team.ru
Maintainers: "Michael S. Tsirkin" <mst@redhat.com>, Paolo Bonzini <pbonzini@redhat.com>, Eric Blake <eblake@redhat.com>, Markus Armbruster <armbru@redhat.com>
There is a newer version of this series
hw/rtc/mc146818rtc.c         | 20 ++++++++++++++++++++
include/hw/rtc/mc146818rtc.h |  1 +
qapi/misc-target.json        | 16 ++++++++++++++++
3 files changed, 37 insertions(+)
[PATCH v1] mc146818rtc: add a way to generate RTC interrupts via QMP
Posted by Daniil Tatianin 1 week, 5 days ago 
This can be used to force-synchronize the time in guest after a long
stop-cont pause, which can be useful for serverless-type workload.

Also add a comment to highlight the fact that this (and one other QMP
command) only works for the MC146818 RTC controller.

Signed-off-by: Daniil Tatianin <d-tatianin@yandex-team.ru>
---

Changes since v0:
- Rename to rtc-inject-irq to match other similar API
- Add a comment to highlight that this only works for the I386 RTC

---
 hw/rtc/mc146818rtc.c         | 20 ++++++++++++++++++++
 include/hw/rtc/mc146818rtc.h |  1 +
 qapi/misc-target.json        | 16 ++++++++++++++++
 3 files changed, 37 insertions(+)

diff --git a/hw/rtc/mc146818rtc.c b/hw/rtc/mc146818rtc.c
index f4c1869232..8501b55cbd 100644
--- a/hw/rtc/mc146818rtc.c
+++ b/hw/rtc/mc146818rtc.c
@@ -107,6 +107,11 @@ static void rtc_coalesced_timer_update(MC146818RtcState *s)
 static QLIST_HEAD(, MC146818RtcState) rtc_devices =
     QLIST_HEAD_INITIALIZER(rtc_devices);
 
+/*
+ * NOTE:
+ * The two QMP functions below are _only_ implemented for the MC146818.
+ * All other RTC devices ignore this.
+ */
 void qmp_rtc_reset_reinjection(Error **errp)
 {
     MC146818RtcState *s;
@@ -116,6 +121,21 @@ void qmp_rtc_reset_reinjection(Error **errp)
     }
 }
 
+void qmp_rtc_inject_irq(Error **errp)
+{
+    MC146818RtcState *s;
+
+    /*
+     * See:
+     * https://www.kernel.org/doc/Documentation/virtual/kvm/timekeeping.txt
+     */
+    QLIST_FOREACH(s, &rtc_devices, link) {
+        s->cmos_data[RTC_REG_B] |= REG_B_UIE;
+        s->cmos_data[RTC_REG_C] |= REG_C_IRQF | REG_C_UF;
+        qemu_irq_raise(s->irq);
+    }
+}
+
 static bool rtc_policy_slew_deliver_irq(MC146818RtcState *s)
 {
     kvm_reset_irq_delivered();
diff --git a/include/hw/rtc/mc146818rtc.h b/include/hw/rtc/mc146818rtc.h
index 97cec0b3e8..6cd9761d80 100644
--- a/include/hw/rtc/mc146818rtc.h
+++ b/include/hw/rtc/mc146818rtc.h
@@ -56,5 +56,6 @@ MC146818RtcState *mc146818_rtc_init(ISABus *bus, int base_year,
 void mc146818rtc_set_cmos_data(MC146818RtcState *s, int addr, int val);
 int mc146818rtc_get_cmos_data(MC146818RtcState *s, int addr);
 void qmp_rtc_reset_reinjection(Error **errp);
+void qmp_rtc_inject_irq(Error **errp);
 
 #endif /* HW_RTC_MC146818RTC_H */
diff --git a/qapi/misc-target.json b/qapi/misc-target.json
index 4e0a6492a9..d84a5d07a2 100644
--- a/qapi/misc-target.json
+++ b/qapi/misc-target.json
@@ -19,6 +19,22 @@
 { 'command': 'rtc-reset-reinjection',
   'if': 'TARGET_I386' }
 
+##
+# @rtc-inject-irq:
+#
+# Inject an RTC interrupt.
+#
+# Since: 9.1
+#
+# Example:
+#
+#     -> { "execute": "rtc-inject-irq" }
+#     <- { "return": {} }
+#
+##
+{ 'command': 'rtc-inject-irq',
+  'if': 'TARGET_I386' }
+
 ##
 # @SevState:
 #
-- 
2.34.1
Re: [PATCH v1] mc146818rtc: add a way to generate RTC interrupts via QMP
Posted by Markus Armbruster 1 week, 3 days ago 
Daniil Tatianin <d-tatianin@yandex-team.ru> writes:

> This can be used to force-synchronize the time in guest after a long
> stop-cont pause, which can be useful for serverless-type workload.
>
> Also add a comment to highlight the fact that this (and one other QMP
> command) only works for the MC146818 RTC controller.
>
> Signed-off-by: Daniil Tatianin <d-tatianin@yandex-team.ru>
> ---
>
> Changes since v0:
> - Rename to rtc-inject-irq to match other similar API
> - Add a comment to highlight that this only works for the I386 RTC
>
> ---
>  hw/rtc/mc146818rtc.c         | 20 ++++++++++++++++++++
>  include/hw/rtc/mc146818rtc.h |  1 +
>  qapi/misc-target.json        | 16 ++++++++++++++++
>  3 files changed, 37 insertions(+)
>
> diff --git a/hw/rtc/mc146818rtc.c b/hw/rtc/mc146818rtc.c
> index f4c1869232..8501b55cbd 100644
> --- a/hw/rtc/mc146818rtc.c
> +++ b/hw/rtc/mc146818rtc.c
> @@ -107,6 +107,11 @@ static void rtc_coalesced_timer_update(MC146818RtcState *s)
>  static QLIST_HEAD(, MC146818RtcState) rtc_devices =
>      QLIST_HEAD_INITIALIZER(rtc_devices);
>  
> +/*
> + * NOTE:
> + * The two QMP functions below are _only_ implemented for the MC146818.
> + * All other RTC devices ignore this.
> + */
>  void qmp_rtc_reset_reinjection(Error **errp)
>  {
>      MC146818RtcState *s;
> @@ -116,6 +121,21 @@ void qmp_rtc_reset_reinjection(Error **errp)
>      }
>  }
>  
> +void qmp_rtc_inject_irq(Error **errp)
> +{
> +    MC146818RtcState *s;
> +
> +    /*
> +     * See:
> +     * https://www.kernel.org/doc/Documentation/virtual/kvm/timekeeping.txt
> +     */
> +    QLIST_FOREACH(s, &rtc_devices, link) {
> +        s->cmos_data[RTC_REG_B] |= REG_B_UIE;
> +        s->cmos_data[RTC_REG_C] |= REG_C_IRQF | REG_C_UF;
> +        qemu_irq_raise(s->irq);
> +    }
> +}
> +
>  static bool rtc_policy_slew_deliver_irq(MC146818RtcState *s)
>  {
>      kvm_reset_irq_delivered();
> diff --git a/include/hw/rtc/mc146818rtc.h b/include/hw/rtc/mc146818rtc.h
> index 97cec0b3e8..6cd9761d80 100644
> --- a/include/hw/rtc/mc146818rtc.h
> +++ b/include/hw/rtc/mc146818rtc.h
> @@ -56,5 +56,6 @@ MC146818RtcState *mc146818_rtc_init(ISABus *bus, int base_year,
>  void mc146818rtc_set_cmos_data(MC146818RtcState *s, int addr, int val);
>  int mc146818rtc_get_cmos_data(MC146818RtcState *s, int addr);
>  void qmp_rtc_reset_reinjection(Error **errp);
> +void qmp_rtc_inject_irq(Error **errp);
>  
>  #endif /* HW_RTC_MC146818RTC_H */
> diff --git a/qapi/misc-target.json b/qapi/misc-target.json
> index 4e0a6492a9..d84a5d07a2 100644
> --- a/qapi/misc-target.json
> +++ b/qapi/misc-target.json
> @@ -19,6 +19,22 @@
>  { 'command': 'rtc-reset-reinjection',
>    'if': 'TARGET_I386' }
>  
> +##
> +# @rtc-inject-irq:
> +#
> +# Inject an RTC interrupt.

Your cover letter explains what this could be good for.  Would it make
sense to explain it here, too?

> +#
> +# Since: 9.1
> +#
> +# Example:
> +#
> +#     -> { "execute": "rtc-inject-irq" }
> +#     <- { "return": {} }
> +#
> +##
> +{ 'command': 'rtc-inject-irq',
> +  'if': 'TARGET_I386' }
> +
>  ##
>  # @SevState:
>  #
Re: [PATCH v1] mc146818rtc: add a way to generate RTC interrupts via QMP
Posted by Daniil Tatianin 1 week, 3 days ago 
On 4/29/24 11:51 AM, Markus Armbruster wrote:

> Daniil Tatianin <d-tatianin@yandex-team.ru> writes:
>
>> This can be used to force-synchronize the time in guest after a long
>> stop-cont pause, which can be useful for serverless-type workload.
>>
>> Also add a comment to highlight the fact that this (and one other QMP
>> command) only works for the MC146818 RTC controller.
>>
>> Signed-off-by: Daniil Tatianin <d-tatianin@yandex-team.ru>
>> ---
>>
>> Changes since v0:
>> - Rename to rtc-inject-irq to match other similar API
>> - Add a comment to highlight that this only works for the I386 RTC
>>
>> ---
>>   hw/rtc/mc146818rtc.c         | 20 ++++++++++++++++++++
>>   include/hw/rtc/mc146818rtc.h |  1 +
>>   qapi/misc-target.json        | 16 ++++++++++++++++
>>   3 files changed, 37 insertions(+)
>>
>> diff --git a/hw/rtc/mc146818rtc.c b/hw/rtc/mc146818rtc.c
>> index f4c1869232..8501b55cbd 100644
>> --- a/hw/rtc/mc146818rtc.c
>> +++ b/hw/rtc/mc146818rtc.c
>> @@ -107,6 +107,11 @@ static void rtc_coalesced_timer_update(MC146818RtcState *s)
>>   static QLIST_HEAD(, MC146818RtcState) rtc_devices =
>>       QLIST_HEAD_INITIALIZER(rtc_devices);
>>   
>> +/*
>> + * NOTE:
>> + * The two QMP functions below are _only_ implemented for the MC146818.
>> + * All other RTC devices ignore this.
>> + */
>>   void qmp_rtc_reset_reinjection(Error **errp)
>>   {
>>       MC146818RtcState *s;
>> @@ -116,6 +121,21 @@ void qmp_rtc_reset_reinjection(Error **errp)
>>       }
>>   }
>>   
>> +void qmp_rtc_inject_irq(Error **errp)
>> +{
>> +    MC146818RtcState *s;
>> +
>> +    /*
>> +     * See:
>> +     * https://www.kernel.org/doc/Documentation/virtual/kvm/timekeeping.txt
>> +     */
>> +    QLIST_FOREACH(s, &rtc_devices, link) {
>> +        s->cmos_data[RTC_REG_B] |= REG_B_UIE;
>> +        s->cmos_data[RTC_REG_C] |= REG_C_IRQF | REG_C_UF;
>> +        qemu_irq_raise(s->irq);
>> +    }
>> +}
>> +
>>   static bool rtc_policy_slew_deliver_irq(MC146818RtcState *s)
>>   {
>>       kvm_reset_irq_delivered();
>> diff --git a/include/hw/rtc/mc146818rtc.h b/include/hw/rtc/mc146818rtc.h
>> index 97cec0b3e8..6cd9761d80 100644
>> --- a/include/hw/rtc/mc146818rtc.h
>> +++ b/include/hw/rtc/mc146818rtc.h
>> @@ -56,5 +56,6 @@ MC146818RtcState *mc146818_rtc_init(ISABus *bus, int base_year,
>>   void mc146818rtc_set_cmos_data(MC146818RtcState *s, int addr, int val);
>>   int mc146818rtc_get_cmos_data(MC146818RtcState *s, int addr);
>>   void qmp_rtc_reset_reinjection(Error **errp);
>> +void qmp_rtc_inject_irq(Error **errp);
>>   
>>   #endif /* HW_RTC_MC146818RTC_H */
>> diff --git a/qapi/misc-target.json b/qapi/misc-target.json
>> index 4e0a6492a9..d84a5d07a2 100644
>> --- a/qapi/misc-target.json
>> +++ b/qapi/misc-target.json
>> @@ -19,6 +19,22 @@
>>   { 'command': 'rtc-reset-reinjection',
>>     'if': 'TARGET_I386' }
>>   
>> +##
>> +# @rtc-inject-irq:
>> +#
>> +# Inject an RTC interrupt.
> Your cover letter explains what this could be good for.  Would it make
> sense to explain it here, too?

Sure, sounds useful. I'll add a description in the next version.

Thanks

>> +#
>> +# Since: 9.1
>> +#
>> +# Example:
>> +#
>> +#     -> { "execute": "rtc-inject-irq" }
>> +#     <- { "return": {} }
>> +#
>> +##
>> +{ 'command': 'rtc-inject-irq',
>> +  'if': 'TARGET_I386' }
>> +
>>   ##
>>   # @SevState:
>>   #
Re: [PATCH v1] mc146818rtc: add a way to generate RTC interrupts via QMP
Posted by Philippe Mathieu-Daudé 1 week, 3 days ago 
On 29/4/24 11:34, Daniil Tatianin wrote:
> On 4/29/24 11:51 AM, Markus Armbruster wrote:
> 
>> Daniil Tatianin <d-tatianin@yandex-team.ru> writes:
>>
>>> This can be used to force-synchronize the time in guest after a long
>>> stop-cont pause, which can be useful for serverless-type workload.
>>>
>>> Also add a comment to highlight the fact that this (and one other QMP
>>> command) only works for the MC146818 RTC controller.
>>>
>>> Signed-off-by: Daniil Tatianin <d-tatianin@yandex-team.ru>
>>> ---
>>>
>>> Changes since v0:
>>> - Rename to rtc-inject-irq to match other similar API
>>> - Add a comment to highlight that this only works for the I386 RTC
>>>
>>> ---
>>>   hw/rtc/mc146818rtc.c         | 20 ++++++++++++++++++++
>>>   include/hw/rtc/mc146818rtc.h |  1 +
>>>   qapi/misc-target.json        | 16 ++++++++++++++++
>>>   3 files changed, 37 insertions(+)
>>>
>>> diff --git a/hw/rtc/mc146818rtc.c b/hw/rtc/mc146818rtc.c
>>> index f4c1869232..8501b55cbd 100644
>>> --- a/hw/rtc/mc146818rtc.c
>>> +++ b/hw/rtc/mc146818rtc.c
>>> @@ -107,6 +107,11 @@ static void 
>>> rtc_coalesced_timer_update(MC146818RtcState *s)
>>>   static QLIST_HEAD(, MC146818RtcState) rtc_devices =
>>>       QLIST_HEAD_INITIALIZER(rtc_devices);
>>> +/*
>>> + * NOTE:
>>> + * The two QMP functions below are _only_ implemented for the MC146818.
>>> + * All other RTC devices ignore this.
>>> + */
>>>   void qmp_rtc_reset_reinjection(Error **errp)
>>>   {
>>>       MC146818RtcState *s;
>>> @@ -116,6 +121,21 @@ void qmp_rtc_reset_reinjection(Error **errp)
>>>       }
>>>   }
>>> +void qmp_rtc_inject_irq(Error **errp)
>>> +{
>>> +    MC146818RtcState *s;
>>> +
>>> +    /*
>>> +     * See:
>>> +     * 
>>> https://www.kernel.org/doc/Documentation/virtual/kvm/timekeeping.txt
>>> +     */
>>> +    QLIST_FOREACH(s, &rtc_devices, link) {
>>> +        s->cmos_data[RTC_REG_B] |= REG_B_UIE;
>>> +        s->cmos_data[RTC_REG_C] |= REG_C_IRQF | REG_C_UF;
>>> +        qemu_irq_raise(s->irq);
>>> +    }
>>> +}
>>> +
>>>   static bool rtc_policy_slew_deliver_irq(MC146818RtcState *s)
>>>   {
>>>       kvm_reset_irq_delivered();
>>> diff --git a/include/hw/rtc/mc146818rtc.h b/include/hw/rtc/mc146818rtc.h
>>> index 97cec0b3e8..6cd9761d80 100644
>>> --- a/include/hw/rtc/mc146818rtc.h
>>> +++ b/include/hw/rtc/mc146818rtc.h
>>> @@ -56,5 +56,6 @@ MC146818RtcState *mc146818_rtc_init(ISABus *bus, 
>>> int base_year,
>>>   void mc146818rtc_set_cmos_data(MC146818RtcState *s, int addr, int 
>>> val);
>>>   int mc146818rtc_get_cmos_data(MC146818RtcState *s, int addr);
>>>   void qmp_rtc_reset_reinjection(Error **errp);
>>> +void qmp_rtc_inject_irq(Error **errp);
>>>   #endif /* HW_RTC_MC146818RTC_H */
>>> diff --git a/qapi/misc-target.json b/qapi/misc-target.json
>>> index 4e0a6492a9..d84a5d07a2 100644
>>> --- a/qapi/misc-target.json
>>> +++ b/qapi/misc-target.json
>>> @@ -19,6 +19,22 @@
>>>   { 'command': 'rtc-reset-reinjection',
>>>     'if': 'TARGET_I386' }
>>> +##
>>> +# @rtc-inject-irq:
>>> +#
>>> +# Inject an RTC interrupt.
>> Your cover letter explains what this could be good for.  Would it make
>> sense to explain it here, too?
> 
> Sure, sounds useful. I'll add a description in the next version.

Please also see my comments on the previous patch:
https://lore.kernel.org/qemu-devel/11c78645-e87b-4a43-8191-a73540c364a9@linaro.org/
Re: [PATCH v1] mc146818rtc: add a way to generate RTC interrupts via QMP
Posted by Daniil Tatianin 1 week, 3 days ago 
On 4/29/24 12:40 PM, Philippe Mathieu-Daudé wrote:

> On 29/4/24 11:34, Daniil Tatianin wrote:
>> On 4/29/24 11:51 AM, Markus Armbruster wrote:
>>
>>> Daniil Tatianin <d-tatianin@yandex-team.ru> writes:
>>>
>>>> This can be used to force-synchronize the time in guest after a long
>>>> stop-cont pause, which can be useful for serverless-type workload.
>>>>
>>>> Also add a comment to highlight the fact that this (and one other QMP
>>>> command) only works for the MC146818 RTC controller.
>>>>
>>>> Signed-off-by: Daniil Tatianin <d-tatianin@yandex-team.ru>
>>>> ---
>>>>
>>>> Changes since v0:
>>>> - Rename to rtc-inject-irq to match other similar API
>>>> - Add a comment to highlight that this only works for the I386 RTC
>>>>
>>>> ---
>>>>   hw/rtc/mc146818rtc.c         | 20 ++++++++++++++++++++
>>>>   include/hw/rtc/mc146818rtc.h |  1 +
>>>>   qapi/misc-target.json        | 16 ++++++++++++++++
>>>>   3 files changed, 37 insertions(+)
>>>>
>>>> diff --git a/hw/rtc/mc146818rtc.c b/hw/rtc/mc146818rtc.c
>>>> index f4c1869232..8501b55cbd 100644
>>>> --- a/hw/rtc/mc146818rtc.c
>>>> +++ b/hw/rtc/mc146818rtc.c
>>>> @@ -107,6 +107,11 @@ static void 
>>>> rtc_coalesced_timer_update(MC146818RtcState *s)
>>>>   static QLIST_HEAD(, MC146818RtcState) rtc_devices =
>>>>       QLIST_HEAD_INITIALIZER(rtc_devices);
>>>> +/*
>>>> + * NOTE:
>>>> + * The two QMP functions below are _only_ implemented for the 
>>>> MC146818.
>>>> + * All other RTC devices ignore this.
>>>> + */
>>>>   void qmp_rtc_reset_reinjection(Error **errp)
>>>>   {
>>>>       MC146818RtcState *s;
>>>> @@ -116,6 +121,21 @@ void qmp_rtc_reset_reinjection(Error **errp)
>>>>       }
>>>>   }
>>>> +void qmp_rtc_inject_irq(Error **errp)
>>>> +{
>>>> +    MC146818RtcState *s;
>>>> +
>>>> +    /*
>>>> +     * See:
>>>> +     * 
>>>> https://www.kernel.org/doc/Documentation/virtual/kvm/timekeeping.txt
>>>> +     */
>>>> +    QLIST_FOREACH(s, &rtc_devices, link) {
>>>> +        s->cmos_data[RTC_REG_B] |= REG_B_UIE;
>>>> +        s->cmos_data[RTC_REG_C] |= REG_C_IRQF | REG_C_UF;
>>>> +        qemu_irq_raise(s->irq);
>>>> +    }
>>>> +}
>>>> +
>>>>   static bool rtc_policy_slew_deliver_irq(MC146818RtcState *s)
>>>>   {
>>>>       kvm_reset_irq_delivered();
>>>> diff --git a/include/hw/rtc/mc146818rtc.h 
>>>> b/include/hw/rtc/mc146818rtc.h
>>>> index 97cec0b3e8..6cd9761d80 100644
>>>> --- a/include/hw/rtc/mc146818rtc.h
>>>> +++ b/include/hw/rtc/mc146818rtc.h
>>>> @@ -56,5 +56,6 @@ MC146818RtcState *mc146818_rtc_init(ISABus *bus, 
>>>> int base_year,
>>>>   void mc146818rtc_set_cmos_data(MC146818RtcState *s, int addr, int 
>>>> val);
>>>>   int mc146818rtc_get_cmos_data(MC146818RtcState *s, int addr);
>>>>   void qmp_rtc_reset_reinjection(Error **errp);
>>>> +void qmp_rtc_inject_irq(Error **errp);
>>>>   #endif /* HW_RTC_MC146818RTC_H */
>>>> diff --git a/qapi/misc-target.json b/qapi/misc-target.json
>>>> index 4e0a6492a9..d84a5d07a2 100644
>>>> --- a/qapi/misc-target.json
>>>> +++ b/qapi/misc-target.json
>>>> @@ -19,6 +19,22 @@
>>>>   { 'command': 'rtc-reset-reinjection',
>>>>     'if': 'TARGET_I386' }
>>>> +##
>>>> +# @rtc-inject-irq:
>>>> +#
>>>> +# Inject an RTC interrupt.
>>> Your cover letter explains what this could be good for.  Would it make
>>> sense to explain it here, too?
>>
>> Sure, sounds useful. I'll add a description in the next version.
>
> Please also see my comments on the previous patch:
> https://lore.kernel.org/qemu-devel/11c78645-e87b-4a43-8191-a73540c364a9@linaro.org/ 
>
>
I think this makes sense, but there's already a similar command, which 
doesn't do it. Should that one be changed as well then? Or do we only 
change the interface for this one?
Re: [PATCH v1] mc146818rtc: add a way to generate RTC interrupts via QMP
Posted by Philippe Mathieu-Daudé 1 week, 3 days ago 
On 29/4/24 11:43, Daniil Tatianin wrote:
> On 4/29/24 12:40 PM, Philippe Mathieu-Daudé wrote:
> 
>> On 29/4/24 11:34, Daniil Tatianin wrote:
>>> On 4/29/24 11:51 AM, Markus Armbruster wrote:
>>>
>>>> Daniil Tatianin <d-tatianin@yandex-team.ru> writes:
>>>>
>>>>> This can be used to force-synchronize the time in guest after a long
>>>>> stop-cont pause, which can be useful for serverless-type workload.
>>>>>
>>>>> Also add a comment to highlight the fact that this (and one other QMP
>>>>> command) only works for the MC146818 RTC controller.
>>>>>
>>>>> Signed-off-by: Daniil Tatianin <d-tatianin@yandex-team.ru>
>>>>> ---
>>>>>
>>>>> Changes since v0:
>>>>> - Rename to rtc-inject-irq to match other similar API
>>>>> - Add a comment to highlight that this only works for the I386 RTC
>>>>>
>>>>> ---
>>>>>   hw/rtc/mc146818rtc.c         | 20 ++++++++++++++++++++
>>>>>   include/hw/rtc/mc146818rtc.h |  1 +
>>>>>   qapi/misc-target.json        | 16 ++++++++++++++++
>>>>>   3 files changed, 37 insertions(+)
>>>>>
>>>>> diff --git a/hw/rtc/mc146818rtc.c b/hw/rtc/mc146818rtc.c
>>>>> index f4c1869232..8501b55cbd 100644
>>>>> --- a/hw/rtc/mc146818rtc.c
>>>>> +++ b/hw/rtc/mc146818rtc.c
>>>>> @@ -107,6 +107,11 @@ static void 
>>>>> rtc_coalesced_timer_update(MC146818RtcState *s)
>>>>>   static QLIST_HEAD(, MC146818RtcState) rtc_devices =
>>>>>       QLIST_HEAD_INITIALIZER(rtc_devices);
>>>>> +/*
>>>>> + * NOTE:
>>>>> + * The two QMP functions below are _only_ implemented for the 
>>>>> MC146818.
>>>>> + * All other RTC devices ignore this.
>>>>> + */
>>>>>   void qmp_rtc_reset_reinjection(Error **errp)
>>>>>   {
>>>>>       MC146818RtcState *s;
>>>>> @@ -116,6 +121,21 @@ void qmp_rtc_reset_reinjection(Error **errp)
>>>>>       }
>>>>>   }
>>>>> +void qmp_rtc_inject_irq(Error **errp)
>>>>> +{
>>>>> +    MC146818RtcState *s;
>>>>> +
>>>>> +    /*
>>>>> +     * See:
>>>>> +     * 
>>>>> https://www.kernel.org/doc/Documentation/virtual/kvm/timekeeping.txt
>>>>> +     */
>>>>> +    QLIST_FOREACH(s, &rtc_devices, link) {
>>>>> +        s->cmos_data[RTC_REG_B] |= REG_B_UIE;
>>>>> +        s->cmos_data[RTC_REG_C] |= REG_C_IRQF | REG_C_UF;
>>>>> +        qemu_irq_raise(s->irq);
>>>>> +    }
>>>>> +}
>>>>> +
>>>>>   static bool rtc_policy_slew_deliver_irq(MC146818RtcState *s)
>>>>>   {
>>>>>       kvm_reset_irq_delivered();
>>>>> diff --git a/include/hw/rtc/mc146818rtc.h 
>>>>> b/include/hw/rtc/mc146818rtc.h
>>>>> index 97cec0b3e8..6cd9761d80 100644
>>>>> --- a/include/hw/rtc/mc146818rtc.h
>>>>> +++ b/include/hw/rtc/mc146818rtc.h
>>>>> @@ -56,5 +56,6 @@ MC146818RtcState *mc146818_rtc_init(ISABus *bus, 
>>>>> int base_year,
>>>>>   void mc146818rtc_set_cmos_data(MC146818RtcState *s, int addr, int 
>>>>> val);
>>>>>   int mc146818rtc_get_cmos_data(MC146818RtcState *s, int addr);
>>>>>   void qmp_rtc_reset_reinjection(Error **errp);
>>>>> +void qmp_rtc_inject_irq(Error **errp);
>>>>>   #endif /* HW_RTC_MC146818RTC_H */
>>>>> diff --git a/qapi/misc-target.json b/qapi/misc-target.json
>>>>> index 4e0a6492a9..d84a5d07a2 100644
>>>>> --- a/qapi/misc-target.json
>>>>> +++ b/qapi/misc-target.json
>>>>> @@ -19,6 +19,22 @@
>>>>>   { 'command': 'rtc-reset-reinjection',
>>>>>     'if': 'TARGET_I386' }
>>>>> +##
>>>>> +# @rtc-inject-irq:
>>>>> +#
>>>>> +# Inject an RTC interrupt.
>>>> Your cover letter explains what this could be good for.  Would it make
>>>> sense to explain it here, too?
>>>
>>> Sure, sounds useful. I'll add a description in the next version.
>>
>> Please also see my comments on the previous patch:
>> https://lore.kernel.org/qemu-devel/11c78645-e87b-4a43-8191-a73540c364a9@linaro.org/
>>
> I think this makes sense, but there's already a similar command, which 
> doesn't do it. Should that one be changed as well then? Or do we only 
> change the interface for this one?

Better to not follow a short sighted interface. If you can, start
with a correct one. Help fixing broken interface is certainly
welcomed, but that shouldn't block adding your new command.

Regards,

Phil.

Patchew 2.1-devel-0870f84

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