Re: [PATCH for-8.0] hw/rtc/mc146818rtc: Make this rtc device target independent

[Bernhard Beschow]

Am 7. Dezember 2022 15:29:00 UTC schrieb Mark Cave-Ayland 
<mark.cave-ayland@ilande.co.uk>:
>On 06/12/2022 20:06, Thomas Huth wrote:
>
>> The only code that is really, really target dependent is the apic-related
>> code in rtc_policy_slew_deliver_irq(). By moving this code into the hw/i386/
>> folder (renamed to rtc_apic_policy_slew_deliver_irq()) and passing this
>> function as parameter to mc146818_rtc_init(), we can make the RTC completely
>> target-independent.
>> 
>> Signed-off-by: Thomas Huth <thuth@redhat.com>
>> ---
>>   include/hw/rtc/mc146818rtc.h |  7 +++++--
>>   hw/alpha/dp264.c             |  2 +-
>>   hw/hppa/machine.c            |  2 +-
>>   hw/i386/microvm.c            |  3 ++-
>>   hw/i386/pc.c                 | 10 +++++++++-
>>   hw/mips/jazz.c               |  2 +-
>>   hw/ppc/pnv.c                 |  2 +-
>>   hw/rtc/mc146818rtc.c         | 34 +++++++++++-----------------------
>>   hw/rtc/meson.build           |  3 +--
>>   9 files changed, 32 insertions(+), 33 deletions(-)
>> 
>> diff --git a/include/hw/rtc/mc146818rtc.h b/include/hw/rtc/mc146818rtc.h
>> index 1db0fcee92..c687953cc4 100644
>> --- a/include/hw/rtc/mc146818rtc.h
>> +++ b/include/hw/rtc/mc146818rtc.h
>> @@ -46,14 +46,17 @@ struct RTCState {
>>       Notifier clock_reset_notifier;
>>       LostTickPolicy lost_tick_policy;
>>       Notifier suspend_notifier;
>> +    bool (*policy_slew_deliver_irq)(RTCState *s);
>>       QLIST_ENTRY(RTCState) link;
>>   };
>>     #define RTC_ISA_IRQ 8
>>   -ISADevice *mc146818_rtc_init(ISABus *bus, int base_year,
>> -                             qemu_irq intercept_irq);
>> +ISADevice *mc146818_rtc_init(ISABus *bus, int base_year, qemu_irq 
>> intercept_irq,
>> +                             bool (*policy_slew_deliver_irq)(RTCState *s));
>>   void rtc_set_memory(ISADevice *dev, int addr, int val);
>>   int rtc_get_memory(ISADevice *dev, int addr);
>> +bool rtc_apic_policy_slew_deliver_irq(RTCState *s);
>> +void qmp_rtc_reset_reinjection(Error **errp);
>>     #endif /* HW_RTC_MC146818RTC_H */
>> diff --git a/hw/alpha/dp264.c b/hw/alpha/dp264.c
>> index c502c8c62a..8723942b52 100644
>> --- a/hw/alpha/dp264.c
>> +++ b/hw/alpha/dp264.c
>> @@ -118,7 +118,7 @@ static void clipper_init(MachineState *machine)
>>       qdev_connect_gpio_out(i82378_dev, 0, isa_irq);
>>         /* Since we have an SRM-compatible PALcode, use the SRM epoch.  */
>> -    mc146818_rtc_init(isa_bus, 1900, rtc_irq);
>> +    mc146818_rtc_init(isa_bus, 1900, rtc_irq, NULL);
>>         /* VGA setup.  Don't bother loading the bios.  */
>>       pci_vga_init(pci_bus);
>> diff --git a/hw/hppa/machine.c b/hw/hppa/machine.c
>> index de1cc7ab71..311031714a 100644
>> --- a/hw/hppa/machine.c
>> +++ b/hw/hppa/machine.c
>> @@ -232,7 +232,7 @@ static void machine_hppa_init(MachineState *machine)
>>       assert(isa_bus);
>>         /* Realtime clock, used by firmware for PDC_TOD call. */
>> -    mc146818_rtc_init(isa_bus, 2000, NULL);
>> +    mc146818_rtc_init(isa_bus, 2000, NULL, NULL);
>>         /* Serial ports: Lasi and Dino use a 7.272727 MHz clock. */
>>       serial_mm_init(addr_space, LASI_UART_HPA + 0x800, 0,
>> diff --git a/hw/i386/microvm.c b/hw/i386/microvm.c
>> index 170a331e3f..d0ed4dca50 100644
>> --- a/hw/i386/microvm.c
>> +++ b/hw/i386/microvm.c
>> @@ -267,7 +267,8 @@ static void microvm_devices_init(MicrovmMachineState 
>> *mms)
>>         if (mms->rtc == ON_OFF_AUTO_ON ||
>>           (mms->rtc == ON_OFF_AUTO_AUTO && !kvm_enabled())) {
>> -        rtc_state = mc146818_rtc_init(isa_bus, 2000, NULL);
>> +        rtc_state = mc146818_rtc_init(isa_bus, 2000, NULL,
>> +                                      rtc_apic_policy_slew_deliver_irq);
>>           microvm_set_rtc(mms, rtc_state);
>>       }
>>   diff --git a/hw/i386/pc.c b/hw/i386/pc.c
>> index 546b703cb4..650e7bc199 100644
>> --- a/hw/i386/pc.c
>> +++ b/hw/i386/pc.c
>> @@ -1244,6 +1244,13 @@ static void pc_superio_init(ISABus *isa_bus, bool 
>> create_fdctrl,
>>       g_free(a20_line);
>>   }
>>   +bool rtc_apic_policy_slew_deliver_irq(RTCState *s)
>> +{
>> +    apic_reset_irq_delivered();
>> +    qemu_irq_raise(s->irq);
>> +    return apic_get_irq_delivered();
>> +}
>> +
>>   void pc_basic_device_init(struct PCMachineState *pcms,
>>                             ISABus *isa_bus, qemu_irq *gsi,
>>                             ISADevice **rtc_state,
>> @@ -1299,7 +1306,8 @@ void pc_basic_device_init(struct PCMachineState *pcms,
>>           pit_alt_irq = qdev_get_gpio_in(hpet, HPET_LEGACY_PIT_INT);
>>           rtc_irq = qdev_get_gpio_in(hpet, HPET_LEGACY_RTC_INT);
>>       }
>> -    *rtc_state = mc146818_rtc_init(isa_bus, 2000, rtc_irq);
>> +    *rtc_state = mc146818_rtc_init(isa_bus, 2000, rtc_irq,
>> +                                   rtc_apic_policy_slew_deliver_irq);
>>         qemu_register_boot_set(pc_boot_set, *rtc_state);
>>   diff --git a/hw/mips/jazz.c b/hw/mips/jazz.c
>> index 6aefe9a61b..50fbd57b23 100644
>> --- a/hw/mips/jazz.c
>> +++ b/hw/mips/jazz.c
>> @@ -356,7 +356,7 @@ static void mips_jazz_init(MachineState *machine,
>>       fdctrl_init_sysbus(qdev_get_gpio_in(rc4030, 1), 0x80003000, fds);
>>         /* Real time clock */
>> -    mc146818_rtc_init(isa_bus, 1980, NULL);
>> +    mc146818_rtc_init(isa_bus, 1980, NULL, NULL);
>>       memory_region_init_io(rtc, NULL, &rtc_ops, NULL, "rtc", 0x1000);
>>       memory_region_add_subregion(address_space, 0x80004000, rtc);
>>   diff --git a/hw/ppc/pnv.c b/hw/ppc/pnv.c
>> index 3d01e26f84..c5482554b7 100644
>> --- a/hw/ppc/pnv.c
>> +++ b/hw/ppc/pnv.c
>> @@ -992,7 +992,7 @@ static void pnv_init(MachineState *machine)
>>       serial_hds_isa_init(pnv->isa_bus, 0, MAX_ISA_SERIAL_PORTS);
>>         /* Create an RTC ISA device too */
>> -    mc146818_rtc_init(pnv->isa_bus, 2000, NULL);
>> +    mc146818_rtc_init(pnv->isa_bus, 2000, NULL, NULL);
>>         /*
>>        * Create the machine BMC simulator and the IPMI BT device for
>> diff --git a/hw/rtc/mc146818rtc.c b/hw/rtc/mc146818rtc.c
>> index 1ebb412479..9543ae0279 100644
>> --- a/hw/rtc/mc146818rtc.c
>> +++ b/hw/rtc/mc146818rtc.c
>> @@ -44,11 +44,6 @@
>>   #include "qapi/visitor.h"
>>   #include "hw/rtc/mc146818rtc_regs.h"
>>   -#ifdef TARGET_I386
>> -#include "qapi/qapi-commands-misc-target.h"
>> -#include "hw/i386/apic.h"
>> -#endif
>> -
>>   //#define DEBUG_CMOS
>>   //#define DEBUG_COALESCED
>>   @@ -112,7 +107,6 @@ static void rtc_coalesced_timer_update(RTCState *s)
>>   static QLIST_HEAD(, RTCState) rtc_devices =
>>       QLIST_HEAD_INITIALIZER(rtc_devices);
>>   -#ifdef TARGET_I386
>>   void qmp_rtc_reset_reinjection(Error **errp)
>>   {
>>       RTCState *s;
>> @@ -124,9 +118,8 @@ void qmp_rtc_reset_reinjection(Error **errp)
>>     static bool rtc_policy_slew_deliver_irq(RTCState *s)
>>   {
>> -    apic_reset_irq_delivered();
>> -    qemu_irq_raise(s->irq);
>> -    return apic_get_irq_delivered();
>> +    assert(s->policy_slew_deliver_irq);
>> +    return s->policy_slew_deliver_irq(s);
>>   }
>>     static void rtc_coalesced_timer(void *opaque)
>> @@ -145,13 +138,6 @@ static void rtc_coalesced_timer(void *opaque)
>>         rtc_coalesced_timer_update(s);
>>   }
>> -#else
>> -static bool rtc_policy_slew_deliver_irq(RTCState *s)
>> -{
>> -    assert(0);
>> -    return false;
>> -}
>> -#endif
>>     static uint32_t rtc_periodic_clock_ticks(RTCState *s)
>>   {
>> @@ -922,14 +908,14 @@ static void rtc_realizefn(DeviceState *dev, Error 
>> **errp)
>>       rtc_set_date_from_host(isadev);
>>         switch (s->lost_tick_policy) {
>> -#ifdef TARGET_I386
>> -    case LOST_TICK_POLICY_SLEW:
>> -        s->coalesced_timer =
>> -            timer_new_ns(rtc_clock, rtc_coalesced_timer, s);
>> -        break;
>> -#endif
>>       case LOST_TICK_POLICY_DISCARD:
>>           break;
>> +    case LOST_TICK_POLICY_SLEW:
>> +        if (s->policy_slew_deliver_irq) {
>> +            s->coalesced_timer = timer_new_ns(rtc_clock, 
>> rtc_coalesced_timer, s);
>> +            break;
>> +        }
>> +        /* fallthrough */
>>       default:
>>           error_setg(errp, "Invalid lost tick policy.");
>>           return;
>> @@ -960,7 +946,8 @@ static void rtc_realizefn(DeviceState *dev, Error **errp)
>>       QLIST_INSERT_HEAD(&rtc_devices, s, link);
>>   }
>>   -ISADevice *mc146818_rtc_init(ISABus *bus, int base_year, qemu_irq 
>> intercept_irq)
>> +ISADevice *mc146818_rtc_init(ISABus *bus, int base_year, qemu_irq 
>> intercept_irq,
>> +                             bool (*policy_slew_deliver_irq)(RTCState *s))
>>   {
>>       DeviceState *dev;
>>       ISADevice *isadev;
>> @@ -969,6 +956,7 @@ ISADevice *mc146818_rtc_init(ISABus *bus, int base_year, 
>> qemu_irq intercept_irq)
>>       isadev = isa_new(TYPE_MC146818_RTC);
>>       dev = DEVICE(isadev);
>>       s = MC146818_RTC(isadev);
>> +    s->policy_slew_deliver_irq = policy_slew_deliver_irq;
>>       qdev_prop_set_int32(dev, "base_year", base_year);
>>       isa_realize_and_unref(isadev, bus, &error_fatal);
>>       if (intercept_irq) {
>> diff --git a/hw/rtc/meson.build b/hw/rtc/meson.build
>> index dc33973384..34a4d316fa 100644
>> --- a/hw/rtc/meson.build
>> +++ b/hw/rtc/meson.build
>> @@ -13,5 +13,4 @@ softmmu_ss.add(when: 'CONFIG_ASPEED_SOC', if_true: 
>> files('aspeed_rtc.c'))
>>   softmmu_ss.add(when: 'CONFIG_GOLDFISH_RTC', if_true: 
>> files('goldfish_rtc.c'))
>>   softmmu_ss.add(when: 'CONFIG_LS7A_RTC', if_true: files('ls7a_rtc.c'))
>>   softmmu_ss.add(when: 'CONFIG_ALLWINNER_H3', if_true: 
>> files('allwinner-rtc.c'))
>> -
>> -specific_ss.add(when: 'CONFIG_MC146818RTC', if_true: files('mc146818rtc.c'))
>> +softmmu_ss.add(when: 'CONFIG_MC146818RTC', if_true: files('mc146818rtc.c'))
>
>Ouch this is quite a nasty one :/
>
>These days we really should try and avoid setting function pointers outside of 
>_init() and class_init() where possible. If I were looking to model this today 
>I'd probably try an approach like this:
>
>- Move apic_irq_delivered into APICCommonState
>
>- Define apic_reset_irq_delivered() and apic_get_irq_delivered() as function 
>pointers in APICCommonState and assign them to the current implementations in 
>apic_common_initfn() adding an APICCommonState parameter as required
>
>- Grab a reference to APICCommonState in mc146818rtc.c's rtc_realizefn() using 
>either an object property link or object_resolve_path_type("", 
>TYPE_APIC_COMMON, NULL)

AFAICS TYPE_APIC_COMMON is x86-specific which doesn't serve the point of the 
patch well ;)

>- Use "if (s->apic) { .. }" or similar in mc146818rtc.c to guard calling the 
>apic_*() functions

IMO mc146818rtc.c shouldn't make any assumptions outside of its scope, 
especially not about any target specifics like an APIC.

I wonder if we could somehow wire up the APIC handling in the x86 IRQ handler.

Best regards,
Bernhard

>Note that this is a good example as to why legacy global init functions such 
>as mc146818_rtc_init() are a bad idea, since if you add a new optional 
>parameter then you end up having to touch all function callers rather than 
>just the places where you want to make use of the new parameter.
>
>
>ATB,
>
>Mark.
>