Re: [Qemu-devel] [RFC] ppc: qdev-ify CPU creation

[Alexander Graf]

On 24.07.2011, at 21:08, Hervé Poussineau wrote:

> Alexander Graf a écrit :
>> On 21.12.2010, at 21:01, Andreas Färber wrote:
>> 
>>  
>>> From: Hervé Poussineau <address@hidden>
>>> 
>>> v1:
>>> * Coding style fixes.
>>> 
>>> Signed-off-by: Hervé Poussineau <address@hidden>
>>> Cc: Alexander Graf <address@hidden>
>>> Signed-off-by: Andreas Färber <address@hidden>
>>> ---
>>> 
>>> Hello Alex,
>>> 
>>> Seeing the discussions about Leon3, is this the way to go for ppc? Is 
>>> ppc.[hc] right?
>>> 
>>> The unconditional use of 6xx looks suspicious to me, no?
>>> Should we rename cpu_device_irq_request() to cpu_device_irq_request_6xx()?
>>> 
>>> Regards,
>>> Andreas
>>> 
>>> hw/ppc.c            |   75 
>>> +++++++++++++++++++++++++++++++++++++++++++++++++++
>>> hw/ppc.h            |    2 +
>>> target-ppc/cpu.h    |    1 +
>>> target-ppc/helper.c |   21 +++++++++++---
>>> 4 files changed, 94 insertions(+), 5 deletions(-)
>>> 
>>> diff --git a/hw/ppc.c b/hw/ppc.c
>>> index 968aec1..0927326 100644
>>> --- a/hw/ppc.c
>>> +++ b/hw/ppc.c
>>> @@ -30,6 +30,8 @@
>>> #include "loader.h"
>>> #include "kvm.h"
>>> #include "kvm_ppc.h"
>>> +#include "hw/qdev.h"
>>> +#include "hw/sysbus.h"
>>> 
>>> //#define PPC_DEBUG_IRQ
>>> //#define PPC_DEBUG_TB
>>> @@ -1286,3 +1288,76 @@ int PPC_NVRAM_set_params (nvram_t *nvram, uint16_t 
>>> NVRAM_size,
>>> 
>>>    return 0;
>>> }
>>> +
>>> +DeviceState *cpu_ppc_create_simple(const char *cpu_model)
>>> +{
>>> +    DeviceState *dev;
>>> +
>>> +    dev = qdev_create(NULL, "cpu-ppc");
>>> +    if (!dev) {
>>> +        return NULL;
>>> +    }
>>> +    qdev_prop_set_string(dev, "model", qemu_strdup(cpu_model));
>>> +    if (qdev_init(dev) < 0) {
>>> +        return NULL;
>>> +    }
>>> +    return dev;
>>> +}
>>> +
>>> +typedef struct CPUPPC {
>>> +    SysBusDevice busdev;
>>>    
>> 
>> I'm not sure we really want CPUs on the sysbus. They belong to their own CPU 
>> bus. Basically, I think we should try to model our bus topology so that it 
>> reflects the bus topology in the device tree 1:1. Then generating a device 
>> tree from the bug information and some device specific callbacks would be 
>> possible.
>> 
>>  
> CPUs don't need a bus with specific capabilities, so I used the most simple 
> existing one, ie SysBus.

Yeah, that's nice and simple from the implementation POV, but I have this funny 
idea that we might be able to generate a device tree from qemu's bus topology. 
And at that point we'll have to have a separate CPU bus.

>>> +    char *model;
>>> +    CPUPPCState state;
>>> +} CPUPPC;
>>> +
>>> +static void cpu_device_irq_request(void *opaque, int pin, int level)
>>> +{
>>> +    CPUPPC* cpu = opaque;
>>> +    CPUPPCState* env = &cpu->state;
>>> +    ppc6xx_set_irq(env, pin, level);
>>> +}
>>> +
>>> +static int cpu_device_init(SysBusDevice *dev)
>>> +{
>>> +    CPUPPC* cpu = FROM_SYSBUS(CPUPPC, dev);
>>> +    CPUPPCState* env = &cpu->state;
>>> +
>>> +    if (cpu_ppc_init_inplace(env, cpu->model) < 0) {
>>> +        return -1;
>>> +    }
>>> +
>>> +    if (env->flags & POWERPC_FLAG_RTC_CLK) {
>>>    
>> 
>> Where does this flag suddenly come from? Is this related to qdev'ification?
>> 
>>  
> It's not related to qdev'ification. It is already set in CPU definitions 
> since a long time.

Hrm. So where is it usually read out then? Shouldn't that code go away?

> 
>>> +        /* POWER / PowerPC 601 RTC clock frequency is 7.8125 MHz */
>>> +        cpu_ppc_tb_init(env, 7812500UL);
>>> +    } else {
>>> +        /* Set time-base frequency to 100 Mhz */
>>> +        cpu_ppc_tb_init(env, 100UL * 1000UL * 1000UL);
>>>    
>> 
>> Usually we have a TB frequency of 400Mhz in our board/devtrees hardcoded in 
>> the TCG case. How about a qdev property that the creator could just modify 
>> to its needs? We won't need the special 601 flag then either - just move 
>> that into the PREP code.
>> 
>>  
> This code has been extracted from ppc_prep.c ; a qdev property is also fine.

Yes, please :)

>>> +    }
>>> +
>>> +    qdev_init_gpio_in(&dev->qdev, cpu_device_irq_request, PPC6xx_INPUT_NB);
>>> +    return 0;
>>> +}
>>> +
>>> +static void cpu_device_reset(DeviceState *d)
>>> +{
>>> +    CPUPPC *s = FROM_SYSBUS(CPUPPC, sysbus_from_qdev(d));
>>> +    cpu_reset(&s->state);
>>> +}
>>> +
>>> +static SysBusDeviceInfo cpu_device_info = {
>>> +    .qdev.name = "cpu-ppc",
>>> +    .qdev.size = sizeof(CPUPPC),
>>> +    .qdev.reset = cpu_device_reset,
>>> +    .init = cpu_device_init,
>>> +    .qdev.props = (Property[]) {
>>> +        DEFINE_PROP_STRING("model", CPUPPC, model),
>>> +        DEFINE_PROP_END_OF_LIST(),
>>> +    },
>>> +};
>>> +
>>> +static void ppc_register_devices(void)
>>> +{
>>> +    sysbus_register_withprop(&cpu_device_info);
>>> +}
>>> +
>>> +device_init(ppc_register_devices)
>>> diff --git a/hw/ppc.h b/hw/ppc.h
>>> index 34f54cf..ae8dd97 100644
>>> --- a/hw/ppc.h
>>> +++ b/hw/ppc.h
>>> @@ -37,6 +37,8 @@ void ppce500_irq_init (CPUState *env);
>>> void ppc6xx_irq_init (CPUState *env);
>>> void ppc970_irq_init (CPUState *env);
>>> 
>>> +DeviceState *cpu_ppc_create_simple(const char *cpu_model);
>>> +
>>> /* PPC machines for OpenBIOS */
>>> enum {
>>>    ARCH_PREP = 0,
>>> diff --git a/target-ppc/cpu.h b/target-ppc/cpu.h
>>> index deb8d7c..0f56d45 100644
>>> --- a/target-ppc/cpu.h
>>> +++ b/target-ppc/cpu.h
>>> @@ -721,6 +721,7 @@ struct mmu_ctx_t {
>>> 
>>> /*****************************************************************************/
>>> CPUPPCState *cpu_ppc_init (const char *cpu_model);
>>> +int cpu_ppc_init_inplace(CPUPPCState *env, const char *cpu_model);
>>> void ppc_translate_init(void);
>>> int cpu_ppc_exec (CPUPPCState *s);
>>> void cpu_ppc_close (CPUPPCState *s);
>>> diff --git a/target-ppc/helper.c b/target-ppc/helper.c
>>> index 4b49101..99af1f6 100644
>>> --- a/target-ppc/helper.c
>>> +++ b/target-ppc/helper.c
>>> @@ -2794,22 +2794,33 @@ void cpu_reset(CPUPPCState *env)
>>>    tlb_flush(env, 1);
>>> }
>>> 
>>> -CPUPPCState *cpu_ppc_init (const char *cpu_model)
>>> +int cpu_ppc_init_inplace(CPUPPCState *env, const char *cpu_model)
>>> {
>>> -    CPUPPCState *env;
>>>    const ppc_def_t *def;
>>> 
>>>    def = cpu_ppc_find_by_name(cpu_model);
>>> -    if (!def)
>>> -        return NULL;
>>> +    if (!def) {
>>> +        return -1;
>>> +    }
>>> 
>>> -    env = qemu_mallocz(sizeof(CPUPPCState));
>>>    cpu_exec_init(env);
>>>    ppc_translate_init();
>>>    env->cpu_model_str = cpu_model;
>>>    cpu_ppc_register_internal(env, def);
>>> 
>>>    qemu_init_vcpu(env);
>>> +    return 0;
>>> +}
>>> +
>>> +CPUPPCState *cpu_ppc_init(const char *cpu_model)
>>> +{
>>> +    CPUPPCState *env;
>>> +
>>> +    env = qemu_mallocz(sizeof(CPUPPCState));
>>> +    if (cpu_ppc_init_inplace(env, cpu_model) < 0) {
>>>    
>> 
>> Why would we need this function again if the CPUs are qdev'ified?
>>  
> This function is not added ; it is already an existing one (see 25 lines 
> before). I kept it to not put in the same patch the CPU qdev'ification and 
> the change of all the callers.
> Indeed, a second patch may be created to change all callers to use 
> cpu_ppc_create_simple() and to remove this function.

Ah, I see. Please write up a patch set that goes through the bits of fully 
converting it to Qdev :)


Alex