Re: [PATCH v20 5/7] ppc: spapr: Handle "ibm,nmi-register" and "ibm,nmi-interlock" RTAS calls

[Ganesh]

On 1/20/20 6:16 AM, David Gibson wrote:
> On Fri, Jan 17, 2020 at 03:08:53PM +0530, Ganesh Goudar wrote:
> > From: Aravinda Prasad <address@hidden>
> >
> > 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.
> >
> > Signed-off-by: Aravinda Prasad <address@hidden>
> > [Register fwnmi RTAS calls in core_rtas_register_types()
> >   where other RTAS calls are registered]
> > Signed-off-by: Ganesh Goudar <address@hidden>
> > ---
> >   hw/ppc/spapr_caps.c    |  7 +++++
> >   hw/ppc/spapr_rtas.c    | 59 ++++++++++++++++++++++++++++++++++++++++++
> >   include/hw/ppc/spapr.h |  4 ++-
> >   3 files changed, 69 insertions(+), 1 deletion(-)
> >
> > diff --git a/hw/ppc/spapr_caps.c b/hw/ppc/spapr_caps.c
> > index 3001098601..c43498da49 100644
> > --- a/hw/ppc/spapr_caps.c
> > +++ b/hw/ppc/spapr_caps.c
> > @@ -502,6 +502,13 @@ static void cap_fwnmi_mce_apply(SpaprMachineState *spapr, 
> > uint8_t val,
> >       if (!val) {
> >           return; /* Disabled by default */
> >       }
> > +
> > +    if (kvm_enabled()) {
> > +        if (kvmppc_set_fwnmi() < 0) {
> > +            error_report("Could not enable fwnmi capability");
> > +            exit(1);
> We have uniform failure handling for the cap_apply functions so you
> shouldn't roll your own.  Simply error_setg() on the supplied errp,
> and the generic caps code will handle exiting out.
>
> Also, I think you should explicitly mention KVM in this message, to
> make it clear that's where the problem is occurring.  From the user's
> point of view they've just *set* the spapr fwnmi capability so this
> won't help them figure out why it isn't working.
sure
> Also, weren't you going to report a (non fatal) warning in the TCG
> case, since TCG FWNMI behaviour doesn't precisely match true FWNMI
> behaviour (though in a way that probably won't matter in practice).
ok
> > +        }
> > +    }
> >   }
> >   
> >   SpaprCapabilityInfo capability_table[SPAPR_CAP_NUM] = {
> > diff --git a/hw/ppc/spapr_rtas.c b/hw/ppc/spapr_rtas.c
> > index 2c066a372d..3f162d82f5 100644
> > --- a/hw/ppc/spapr_rtas.c
> > +++ b/hw/ppc/spapr_rtas.c
> > @@ -400,6 +400,61 @@ 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)
> > +{
> > +    hwaddr rtas_addr;
> > +
> > +    if (spapr_get_cap(spapr, SPAPR_CAP_FWNMI_MCE) == SPAPR_CAP_OFF) {
> > +        rtas_st(rets, 0, RTAS_OUT_NOT_SUPPORTED);
> > +        return;
> > +    }
> > +
> > +    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_get_cap(spapr, SPAPR_CAP_FWNMI_MCE) == SPAPR_CAP_OFF) {
> > +        rtas_st(rets, 0, RTAS_OUT_NOT_SUPPORTED);
> > +        return;
> > +    }
> > +
> > +    if (spapr->guest_machine_check_addr == -1) {
> > +        /* NMI register not called */
> > +        rtas_st(rets, 0, RTAS_OUT_PARAM_ERROR);
> > +        return;
> > +    }
> > +
> > +    if (spapr->mc_status != cpu->vcpu_id) {
> > +        /* The vCPU that hit the NMI should invoke "ibm,nmi-interlock" */
> > +        rtas_st(rets, 0, RTAS_OUT_PARAM_ERROR);
> > +        return;
> > +    }
> > +
> > +    /*
> > +     * vCPU issuing "ibm,nmi-interlock" is done with NMI handling,
> > +     * hence unset mc_status.
> > +     */
> > +    spapr->mc_status = -1;
> > +    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;
> > @@ -528,6 +583,10 @@ 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 652a5514e8..f6f82d88aa 100644
> > --- a/include/hw/ppc/spapr.h
> > +++ b/include/hw/ppc/spapr.h
> > @@ -656,8 +656,10 @@ target_ulong spapr_hypercall(PowerPCCPU *cpu, target_ulong 
> > opcode,
> >   #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_SUSPEND_ME                     (RTAS_TOKEN_BASE + 0x2A)
> > +#define RTAS_IBM_NMI_REGISTER                   (RTAS_TOKEN_BASE + 0x2B)
> > +#define RTAS_IBM_NMI_INTERLOCK                  (RTAS_TOKEN_BASE + 0x2C)
> >   
> > -#define RTAS_TOKEN_MAX                          (RTAS_TOKEN_BASE + 0x2B)
> > +#define RTAS_TOKEN_MAX                          (RTAS_TOKEN_BASE + 0x2D)
> >   
> >   /* RTAS ibm,get-system-parameter token values */
> >   #define RTAS_SYSPARM_SPLPAR_CHARACTERISTICS      20