Re: [Qemu-devel] [Qemu-ppc] [PATCH v8 1/6] ppc: spapr: Handle "ibm, nmi-register" and "ibm, nmi-interlock" RTAS calls

[Aravinda Prasad <aravinda@linux.vnet.ibm.com>]

On Friday 10 May 2019 08:03 PM, Greg Kurz wrote:
> On Fri, 10 May 2019 11:06:04 +0200
> Greg Kurz <groug@kaod.org> wrote:
> 
>> On Mon, 22 Apr 2019 12:32:58 +0530
>> Aravinda Prasad <aravinda@linux.vnet.ibm.com> wrote:
>>
>>> This patch adds support in QEMU to handle "ibm,nmi-register"
>>> and "ibm,nmi-interlock" RTAS calls.
>>>
>>> The machine check notification address is saved when the
>>> OS issues "ibm,nmi-register" RTAS call.
>>>
>>> This patch also handles the case when multiple processors
>>> experience machine check at or about the same time by
>>> handling "ibm,nmi-interlock" call. In such cases, as per
>>> PAPR, subsequent processors serialize waiting for the first
>>> processor to issue the "ibm,nmi-interlock" call. The second
>>> processor that also received a machine check error waits
>>> till the first processor is done reading the error log.
>>> The first processor issues "ibm,nmi-interlock" call
>>> when the error log is consumed. This patch implements the
>>> releasing part of the error-log while subsequent patch
>>> (which builds error log) handles the locking part.
>>>
>>> Signed-off-by: Aravinda Prasad <aravinda@linux.vnet.ibm.com>
>>> ---
>>>  hw/ppc/spapr.c         |   18 ++++++++++++++
>>>  hw/ppc/spapr_rtas.c    |   61 ++++++++++++++++++++++++++++++++++++++++++++++++
>>>  include/hw/ppc/spapr.h |    9 ++++++-
>>>  3 files changed, 87 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
>>> index c56939a..6642cb5 100644
>>> --- a/hw/ppc/spapr.c
>>> +++ b/hw/ppc/spapr.c
>>> @@ -1805,6 +1805,11 @@ static void spapr_machine_reset(void)
>>>      first_ppc_cpu->env.gpr[5] = 0;
>>>  
>>>      spapr->cas_reboot = false;
>>> +
>>> +    spapr->guest_machine_check_addr = -1;
>>> +
>>> +    /* Signal all vCPUs waiting on this condition */
>>> +    qemu_cond_broadcast(&spapr->mc_delivery_cond);
>>>  }
>>>  
>>>  static void spapr_create_nvram(SpaprMachineState *spapr)
>>> @@ -2095,6 +2100,16 @@ static const VMStateDescription vmstate_spapr_dtb = {
>>>      },
>>>  };
>>>  
>>> +static const VMStateDescription vmstate_spapr_machine_check = {
>>> +    .name = "spapr_machine_check",
>>> +    .version_id = 1,
>>> +    .minimum_version_id = 1,
>>> +    .fields = (VMStateField[]) {
>>> +        VMSTATE_UINT64(guest_machine_check_addr, SpaprMachineState),
> 
> Also this should use VMSTATE_UINTTL()

sure..

Regards,
Aravinda

> 
>>> +        VMSTATE_END_OF_LIST()
>>> +    },  
>>
>> This VMState descriptor is missing a .needed field because we only want
>> to migrate the subsection if the guest has called NMI register, ie.
>> spapr->guest_machine_check_addr != (target_ulong) -1.
>>
>>> +};
>>> +
>>>  static const VMStateDescription vmstate_spapr = {765cf442a8afe8e5c8c6896b5072066df5129077
>>>      .name = "spapr",
>>>      .version_id = 3,
>>> @@ -2127,6 +2142,7 @@ static const VMStateDescription vmstate_spapr = {
>>>          &vmstate_spapr_dtb,
>>>          &vmstate_spapr_cap_large_decr,
>>>          &vmstate_spapr_cap_ccf_assist,
>>> +        &vmstate_spapr_machine_check,
>>>          NULL
>>>      }
>>>  };
>>> @@ -3068,6 +3084,8 @@ static void spapr_machine_init(MachineState *machine)
>>>  
>>>          kvmppc_spapr_enable_inkernel_multitce();
>>>      }
>>> +
>>> +    qemu_cond_init(&spapr->mc_delivery_cond);
>>>  }
>>>  
>>>  static int spapr_kvm_type(MachineState *machine, const char *vm_type)
>>> diff --git a/hw/ppc/spapr_rtas.c b/hw/ppc/spapr_rtas.c
>>> index ee24212..c2f3991 100644
>>> --- a/hw/ppc/spapr_rtas.c
>>> +++ b/hw/ppc/spapr_rtas.c
>>> @@ -348,6 +348,39 @@ static void rtas_get_power_level(PowerPCCPU *cpu, SpaprMachineState *spapr,
>>>      rtas_st(rets, 1, 100);
>>>  }
>>>  
>>> +static void rtas_ibm_nmi_register(PowerPCCPU *cpu,
>>> +                                  SpaprMachineState *spapr,
>>> +                                  uint32_t token, uint32_t nargs,
>>> +                                  target_ulong args,
>>> +                                  uint32_t nret, target_ulong rets)
>>> +{
>>> +    uint64_t rtas_addr = spapr_get_rtas_addr();
>>> +
>>> +    if (!rtas_addr) {
>>> +        rtas_st(rets, 0, RTAS_OUT_NOT_SUPPORTED);
>>> +        return;
>>> +    }
>>> +
>>> +    spapr->guest_machine_check_addr = rtas_ld(args, 1);
>>> +    rtas_st(rets, 0, RTAS_OUT_SUCCESS);
>>> +}
>>> +
>>> +static void rtas_ibm_nmi_interlock(PowerPCCPU *cpu,
>>> +                                   SpaprMachineState *spapr,
>>> +                                   uint32_t token, uint32_t nargs,
>>> +                                   target_ulong args,
>>> +                                   uint32_t nret, target_ulong rets)
>>> +{
>>> +    if (!spapr->guest_machine_check_addr) {  
>>
>> Hmm... the default value is -1. It looks like the check should rather be:
>>
>>     if (spapr->guest_machine_check_addr == (target_ulong) -1) {
>>
>>
>>> +        /* NMI register not called */
>>> +        rtas_st(rets, 0, RTAS_OUT_PARAM_ERROR);
>>> +    } else {
>>> +        qemu_cond_signal(&spapr->mc_delivery_cond);
>>> +        rtas_st(rets, 0, RTAS_OUT_SUCCESS);
>>> +    }
>>> +}
>>> +
>>> +
>>>  static struct rtas_call {
>>>      const char *name;
>>>      spapr_rtas_fn fn;
>>> @@ -466,6 +499,30 @@ void spapr_load_rtas(SpaprMachineState *spapr, void *fdt, hwaddr addr)
>>>      }
>>>  }
>>>  
>>> +uint64_t spapr_get_rtas_addr(void)  
>>
>> Shouldn't this be hwaddr instead of uint64_t ?
>>
>>> +{
>>> +    SpaprMachineState *spapr = SPAPR_MACHINE(qdev_get_machine());
>>> +    int rtas_node;
>>> +    const struct fdt_property *rtas_addr_prop;
>>> +    void *fdt = spapr->fdt_blob;
>>> +    uint32_t rtas_addr;
>>> +
>>> +    /* fetch rtas addr from fdt */
>>> +    rtas_node = fdt_path_offset(fdt, "/rtas");
>>> +    if (rtas_node == 0) {
>>> +        return 0;
>>> +    }
>>> +
>>> +    rtas_addr_prop = fdt_get_property(fdt, rtas_node, "linux,rtas-base", NULL);
>>> +    if (!rtas_addr_prop) {  
>>
>> Just for curiosity: this is ok for linux, but what about other OSes (eg. AIX) ?
>>
>>> +        return 0;
>>> +    }
>>> +
>>> +    rtas_addr = fdt32_to_cpu(*(uint32_t *)rtas_addr_prop->data);  
>>
>> Also this assumes the OS called RTAS instantiate-rtas, but some other
>> OS might have called RTAS instantiate-rtas-64 instead. I guess it is
>> ok for now because SLOF only provides the 32-bit variant, but a
>> comment would certainly help IMHO.
>>
>>> +    return (uint64_t)rtas_addr;
>>> +}
>>> +
>>> +
>>>  static void core_rtas_register_types(void)
>>>  {
>>>      spapr_rtas_register(RTAS_DISPLAY_CHARACTER, "display-character",
>>> @@ -489,6 +546,10 @@ static void core_rtas_register_types(void)
>>>                          rtas_set_power_level);
>>>      spapr_rtas_register(RTAS_GET_POWER_LEVEL, "get-power-level",
>>>                          rtas_get_power_level);
>>> +    spapr_rtas_register(RTAS_IBM_NMI_REGISTER, "ibm,nmi-register",
>>> +                        rtas_ibm_nmi_register);
>>> +    spapr_rtas_register(RTAS_IBM_NMI_INTERLOCK, "ibm,nmi-interlock",
>>> +                        rtas_ibm_nmi_interlock);
>>>  }
>>>  
>>>  type_init(core_rtas_register_types)
>>> diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
>>> index 7e32f30..ec6f33e 100644
>>> --- a/include/hw/ppc/spapr.h
>>> +++ b/include/hw/ppc/spapr.h
>>> @@ -187,6 +187,10 @@ struct SpaprMachineState {
>>>       * occurs during the unplug process. */
>>>      QTAILQ_HEAD(, SpaprDimmState) pending_dimm_unplugs;
>>>  
>>> +    /* State related to "ibm,nmi-register" and "ibm,nmi-interlock" calls */
>>> +    target_ulong guest_machine_check_addr;
>>> +    QemuCond mc_delivery_cond;
>>> +
>>>      /*< public >*/
>>>      char *kvm_type;
>>>      char *host_model;
>>> @@ -623,8 +627,10 @@ target_ulong spapr_hypercall(PowerPCCPU *cpu, target_ulong opcode,
>>>  #define RTAS_IBM_CREATE_PE_DMA_WINDOW           (RTAS_TOKEN_BASE + 0x27)
>>>  #define RTAS_IBM_REMOVE_PE_DMA_WINDOW           (RTAS_TOKEN_BASE + 0x28)
>>>  #define RTAS_IBM_RESET_PE_DMA_WINDOW            (RTAS_TOKEN_BASE + 0x29)
>>> +#define RTAS_IBM_NMI_REGISTER                   (RTAS_TOKEN_BASE + 0x2A)
>>> +#define RTAS_IBM_NMI_INTERLOCK                  (RTAS_TOKEN_BASE + 0x2B)
>>>  
>>> -#define RTAS_TOKEN_MAX                          (RTAS_TOKEN_BASE + 0x2A)
>>> +#define RTAS_TOKEN_MAX                          (RTAS_TOKEN_BASE + 0x2C)
>>>  
>>>  /* RTAS ibm,get-system-parameter token values */
>>>  #define RTAS_SYSPARM_SPLPAR_CHARACTERISTICS      20
>>> @@ -874,4 +880,5 @@ void spapr_check_pagesize(SpaprMachineState *spapr, hwaddr pagesize,
>>>  #define SPAPR_OV5_XIVE_BOTH     0x80 /* Only to advertise on the platform */
>>>  
>>>  void spapr_set_all_lpcrs(target_ulong value, target_ulong mask);
>>> +uint64_t spapr_get_rtas_addr(void);
>>>  #endif /* HW_SPAPR_H */
>>>
>>>   
>>
>>
> 

-- 
Regards,
Aravinda