Re: [Qemu-devel] [PATCH v10 4/6] target/ppc: Build rtas error log upon an MCE

[David Gibson]

On Wed, Jun 12, 2019 at 02:51:21PM +0530, Aravinda Prasad wrote:
> Upon a machine check exception (MCE) in a guest address space,
> KVM causes a guest exit to enable QEMU to build and pass the
> error to the guest in the PAPR defined rtas error log format.
> 
> This patch builds the rtas error log, copies it to the rtas_addr
> and then invokes the guest registered machine check handler. The
> handler in the guest takes suitable action(s) depending on the type
> and criticality of the error. For example, if an error is
> unrecoverable memory corruption in an application inside the
> guest, then the guest kernel sends a SIGBUS to the application.
> For recoverable errors, the guest performs recovery actions and
> logs the error.
> 
> Signed-off-by: Aravinda Prasad <address@hidden>
> ---
>  hw/ppc/spapr.c         |   13 +++
>  hw/ppc/spapr_events.c  |  238 
> ++++++++++++++++++++++++++++++++++++++++++++++++
>  hw/ppc/spapr_rtas.c    |   26 +++++
>  include/hw/ppc/spapr.h |    6 +
>  target/ppc/kvm.c       |    4 +
>  5 files changed, 284 insertions(+), 3 deletions(-)
> 
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index 6cc2c3b..d61905b 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -2908,6 +2908,19 @@ static void spapr_machine_init(MachineState *machine)
>          error_report("Could not get size of LPAR rtas '%s'", filename);
>          exit(1);
>      }
> +
> +    if (spapr_get_cap(spapr, SPAPR_CAP_FWNMI_MCE) == SPAPR_CAP_ON) {
> +        /*
> +         * Ensure that the rtas image size is less than RTAS_ERROR_LOG_OFFSET
> +         * or else the rtas image will be overwritten with the rtas error log
> +         * when a machine check exception is encountered.
> +         */
> +        g_assert(spapr->rtas_size < RTAS_ERROR_LOG_OFFSET);
> +
> +        /* Resize rtas blob to accommodate error log */
> +        spapr->rtas_size = RTAS_ERROR_LOG_MAX;
> +    }
> +
>      spapr->rtas_blob = g_malloc(spapr->rtas_size);
>      if (load_image_size(filename, spapr->rtas_blob, spapr->rtas_size) < 0) {
>          error_report("Could not load LPAR rtas '%s'", filename);
> diff --git a/hw/ppc/spapr_events.c b/hw/ppc/spapr_events.c
> index a0c66d7..51c052e 100644
> --- a/hw/ppc/spapr_events.c
> +++ b/hw/ppc/spapr_events.c
> @@ -212,6 +212,106 @@ struct hp_extended_log {
>      struct rtas_event_log_v6_hp hp;
>  } QEMU_PACKED;
>  
> +struct rtas_event_log_v6_mc {
> +#define RTAS_LOG_V6_SECTION_ID_MC                   0x4D43 /* MC */
> +    struct rtas_event_log_v6_section_header hdr;
> +    uint32_t fru_id;
> +    uint32_t proc_id;
> +    uint8_t error_type;
> +#define RTAS_LOG_V6_MC_TYPE_UE                           0
> +#define RTAS_LOG_V6_MC_TYPE_SLB                          1
> +#define RTAS_LOG_V6_MC_TYPE_ERAT                         2
> +#define RTAS_LOG_V6_MC_TYPE_TLB                          4
> +#define RTAS_LOG_V6_MC_TYPE_D_CACHE                      5
> +#define RTAS_LOG_V6_MC_TYPE_I_CACHE                      7
> +    uint8_t sub_err_type;
> +#define RTAS_LOG_V6_MC_UE_INDETERMINATE                  0
> +#define RTAS_LOG_V6_MC_UE_IFETCH                         1
> +#define RTAS_LOG_V6_MC_UE_PAGE_TABLE_WALK_IFETCH         2
> +#define RTAS_LOG_V6_MC_UE_LOAD_STORE                     3
> +#define RTAS_LOG_V6_MC_UE_PAGE_TABLE_WALK_LOAD_STORE     4
> +#define RTAS_LOG_V6_MC_SLB_PARITY                        0
> +#define RTAS_LOG_V6_MC_SLB_MULTIHIT                      1
> +#define RTAS_LOG_V6_MC_SLB_INDETERMINATE                 2
> +#define RTAS_LOG_V6_MC_ERAT_PARITY                       1
> +#define RTAS_LOG_V6_MC_ERAT_MULTIHIT                     2
> +#define RTAS_LOG_V6_MC_ERAT_INDETERMINATE                3
> +#define RTAS_LOG_V6_MC_TLB_PARITY                        1
> +#define RTAS_LOG_V6_MC_TLB_MULTIHIT                      2
> +#define RTAS_LOG_V6_MC_TLB_INDETERMINATE                 3
> +    uint8_t reserved_1[6];
> +    uint64_t effective_address;
> +    uint64_t logical_address;
> +} QEMU_PACKED;
> +
> +struct mc_extended_log {
> +    struct rtas_event_log_v6 v6hdr;
> +    struct rtas_event_log_v6_mc mc;
> +} QEMU_PACKED;
> +
> +struct MC_ierror_table {
> +    unsigned long srr1_mask;
> +    unsigned long srr1_value;
> +    bool nip_valid; /* nip is a valid indicator of faulting address */
> +    uint8_t error_type;
> +    uint8_t error_subtype;
> +    unsigned int initiator;
> +    unsigned int severity;
> +};
> +
> +static const struct MC_ierror_table mc_ierror_table[] = {
> +{ 0x00000000081c0000, 0x0000000000040000, true,
> +  RTAS_LOG_V6_MC_TYPE_UE, RTAS_LOG_V6_MC_UE_IFETCH,
> +  RTAS_LOG_INITIATOR_CPU, RTAS_LOG_SEVERITY_ERROR_SYNC, },
> +{ 0x00000000081c0000, 0x0000000000080000, true,
> +  RTAS_LOG_V6_MC_TYPE_SLB, RTAS_LOG_V6_MC_SLB_PARITY,
> +  RTAS_LOG_INITIATOR_CPU, RTAS_LOG_SEVERITY_ERROR_SYNC, },
> +{ 0x00000000081c0000, 0x00000000000c0000, true,
> +  RTAS_LOG_V6_MC_TYPE_SLB, RTAS_LOG_V6_MC_SLB_MULTIHIT,
> +  RTAS_LOG_INITIATOR_CPU, RTAS_LOG_SEVERITY_ERROR_SYNC, },
> +{ 0x00000000081c0000, 0x0000000000100000, true,
> +  RTAS_LOG_V6_MC_TYPE_ERAT, RTAS_LOG_V6_MC_ERAT_MULTIHIT,
> +  RTAS_LOG_INITIATOR_CPU, RTAS_LOG_SEVERITY_ERROR_SYNC, },
> +{ 0x00000000081c0000, 0x0000000000140000, true,
> +  RTAS_LOG_V6_MC_TYPE_TLB, RTAS_LOG_V6_MC_TLB_MULTIHIT,
> +  RTAS_LOG_INITIATOR_CPU, RTAS_LOG_SEVERITY_ERROR_SYNC, },
> +{ 0x00000000081c0000, 0x0000000000180000, true,
> +  RTAS_LOG_V6_MC_TYPE_UE, RTAS_LOG_V6_MC_UE_PAGE_TABLE_WALK_IFETCH,
> +  RTAS_LOG_INITIATOR_CPU, RTAS_LOG_SEVERITY_ERROR_SYNC, },
> +{ 0, 0, 0, 0, 0, 0 } };
> +
> +struct MC_derror_table {
> +    unsigned long dsisr_value;
> +    bool dar_valid; /* dar is a valid indicator of faulting address */
> +    uint8_t error_type;
> +    uint8_t error_subtype;
> +    unsigned int initiator;
> +    unsigned int severity;
> +};
> +
> +static const struct MC_derror_table mc_derror_table[] = {
> +{ 0x00008000, false,
> +  RTAS_LOG_V6_MC_TYPE_UE, RTAS_LOG_V6_MC_UE_LOAD_STORE,
> +  RTAS_LOG_INITIATOR_CPU, RTAS_LOG_SEVERITY_ERROR_SYNC, },
> +{ 0x00004000, true,
> +  RTAS_LOG_V6_MC_TYPE_UE, RTAS_LOG_V6_MC_UE_PAGE_TABLE_WALK_LOAD_STORE,
> +  RTAS_LOG_INITIATOR_CPU, RTAS_LOG_SEVERITY_ERROR_SYNC, },
> +{ 0x00000800, true,
> +  RTAS_LOG_V6_MC_TYPE_ERAT, RTAS_LOG_V6_MC_ERAT_MULTIHIT,
> +  RTAS_LOG_INITIATOR_CPU, RTAS_LOG_SEVERITY_ERROR_SYNC, },
> +{ 0x00000400, true,
> +  RTAS_LOG_V6_MC_TYPE_TLB, RTAS_LOG_V6_MC_TLB_MULTIHIT,
> +  RTAS_LOG_INITIATOR_CPU, RTAS_LOG_SEVERITY_ERROR_SYNC, },
> +{ 0x00000080, true,
> +  RTAS_LOG_V6_MC_TYPE_SLB, RTAS_LOG_V6_MC_SLB_MULTIHIT,  /* Before PARITY */
> +  RTAS_LOG_INITIATOR_CPU, RTAS_LOG_SEVERITY_ERROR_SYNC, },
> +{ 0x00000100, true,
> +  RTAS_LOG_V6_MC_TYPE_SLB, RTAS_LOG_V6_MC_SLB_PARITY,
> +  RTAS_LOG_INITIATOR_CPU, RTAS_LOG_SEVERITY_ERROR_SYNC, },
> +{ 0, false, 0, 0, 0, 0 } };
> +
> +#define SRR1_MC_LOADSTORE(srr1) ((srr1) & PPC_BIT(42))
> +
>  typedef enum EventClass {
>      EVENT_CLASS_INTERNAL_ERRORS     = 0,
>      EVENT_CLASS_EPOW                = 1,
> @@ -620,7 +720,141 @@ void 
> spapr_hotplug_req_remove_by_count_indexed(SpaprDrcType drc_type,
>                              RTAS_LOG_V6_HP_ACTION_REMOVE, drc_type, &drc_id);
>  }
>  
> -void spapr_mce_req_event(PowerPCCPU *cpu)
> +static uint32_t spapr_mce_get_elog_type(PowerPCCPU *cpu, bool recovered,
> +                                        struct mc_extended_log *ext_elog)
> +{
> +    int i;
> +    CPUPPCState *env = &cpu->env;
> +    uint32_t summary;
> +    uint64_t dsisr = env->spr[SPR_DSISR];
> +
> +    summary = RTAS_LOG_VERSION_6 | RTAS_LOG_OPTIONAL_PART_PRESENT;
> +    if (recovered) {
> +        summary |= RTAS_LOG_DISPOSITION_FULLY_RECOVERED;
> +    } else {
> +        summary |= RTAS_LOG_DISPOSITION_NOT_RECOVERED;
> +    }
> +
> +    if (SRR1_MC_LOADSTORE(env->spr[SPR_SRR1])) {
> +        for (i = 0; mc_derror_table[i].dsisr_value; i++) {
> +            if (!(dsisr & mc_derror_table[i].dsisr_value)) {
> +                continue;
> +            }
> +
> +            ext_elog->mc.error_type = mc_derror_table[i].error_type;
> +            ext_elog->mc.sub_err_type = mc_derror_table[i].error_subtype;
> +            if (mc_derror_table[i].dar_valid) {
> +                ext_elog->mc.effective_address = 
> cpu_to_be64(env->spr[SPR_DAR]);
> +            }
> +
> +            summary |= mc_derror_table[i].initiator
> +                        | mc_derror_table[i].severity;
> +
> +            return summary;
> +        }
> +    } else {
> +        for (i = 0; mc_ierror_table[i].srr1_mask; i++) {
> +            if ((env->spr[SPR_SRR1] & mc_ierror_table[i].srr1_mask) !=
> +                    mc_ierror_table[i].srr1_value) {
> +                continue;
> +            }
> +
> +            ext_elog->mc.error_type = mc_ierror_table[i].error_type;
> +            ext_elog->mc.sub_err_type = mc_ierror_table[i].error_subtype;
> +            if (mc_ierror_table[i].nip_valid) {
> +                ext_elog->mc.effective_address = cpu_to_be64(env->nip);
> +            }
> +
> +            summary |= mc_ierror_table[i].initiator
> +                        | mc_ierror_table[i].severity;
> +
> +            return summary;
> +        }
> +    }
> +
> +    summary |= RTAS_LOG_INITIATOR_CPU;
> +    return summary;
> +}
> +
> +static void spapr_mce_dispatch_elog(PowerPCCPU *cpu, bool recovered)
> +{
> +    SpaprMachineState *spapr = SPAPR_MACHINE(qdev_get_machine());
> +    CPUState *cs = CPU(cpu);
> +    uint64_t rtas_addr;
> +    CPUPPCState *env = &cpu->env;
> +    PowerPCCPUClass *pcc = POWERPC_CPU_GET_CLASS(cpu);
> +    target_ulong r3, msr = 0;
> +    struct rtas_error_log log;
> +    struct mc_extended_log *ext_elog;
> +    uint32_t summary;
> +
> +    /*
> +     * Properly set bits in MSR before we invoke the handler.
> +     * SRR0/1, DAR and DSISR are properly set by KVM
> +     */
> +    if (!(*pcc->interrupts_big_endian)(cpu)) {
> +        msr |= (1ULL << MSR_LE);
> +    }
> +
> +    if (env->msr & (1ULL << MSR_SF)) {
> +        msr |= (1ULL << MSR_SF);
> +    }
> +
> +    msr |= (1ULL << MSR_ME);
> +
> +    if (spapr->guest_machine_check_addr == -1) {
> +        /*
> +         * This implies that we have hit a machine check between system
> +         * reset and "ibm,nmi-register". Fall back to the old machine
> +         * check behavior in such cases.
> +         */
> +        env->spr[SPR_SRR0] = env->nip;
> +        env->spr[SPR_SRR1] = env->msr;
> +        env->msr = msr;
> +        env->nip = 0x200;
> +        return;

Hm, does this differ from what ppc_cpu_do_system_reset() will do?

> +    }
> +
> +    ext_elog = g_malloc0(sizeof(*ext_elog));
> +    summary = spapr_mce_get_elog_type(cpu, recovered, ext_elog);
> +
> +    log.summary = cpu_to_be32(summary);
> +    log.extended_length = cpu_to_be32(sizeof(*ext_elog));
> +
> +    /* r3 should be in BE always */
> +    r3 = cpu_to_be64(env->gpr[3]);

I don't love bare integer variables being store in a particular
"endianness" because logically they're endianness-free values.  They
only get an endianness when they are placed into byte-ordered memory.

> +    env->msr = msr;
> +
> +    spapr_init_v6hdr(&ext_elog->v6hdr);
> +    ext_elog->mc.hdr.section_id = cpu_to_be16(RTAS_LOG_V6_SECTION_ID_MC);
> +    ext_elog->mc.hdr.section_length =
> +                    cpu_to_be16(sizeof(struct rtas_event_log_v6_mc));
> +    ext_elog->mc.hdr.section_version = 1;
> +
> +    /* get rtas addr from fdt */
> +    rtas_addr = spapr_get_rtas_addr();
> +    if (!rtas_addr) {
> +        /* Unable to fetch rtas_addr. Hence reset the guest */
> +        ppc_cpu_do_system_reset(cs);
> +        g_free(ext_elog);
> +        return;
> +    }
> +
> +    cpu_physical_memory_write(rtas_addr + RTAS_ERROR_LOG_OFFSET, &r3,
> +                              sizeof(r3));

So, I'd prefer to see the endianness coversion done as part of the
memory store.  You can do that using the stl_be_phys() helper.

> +    cpu_physical_memory_write(rtas_addr + RTAS_ERROR_LOG_OFFSET + sizeof(r3),
> +                              &log, sizeof(log));
> +    cpu_physical_memory_write(rtas_addr + RTAS_ERROR_LOG_OFFSET + sizeof(r3) 
> +
> +                              sizeof(log), ext_elog,
> +                              sizeof(*ext_elog));
> +
> +    env->gpr[3] = rtas_addr + RTAS_ERROR_LOG_OFFSET;
> +    env->nip = spapr->guest_machine_check_addr;
> +
> +    g_free(ext_elog);
> +}
> +
> +void spapr_mce_req_event(PowerPCCPU *cpu, bool recovered)
>  {
>      SpaprMachineState *spapr = SPAPR_MACHINE(qdev_get_machine());
>  
> @@ -641,6 +875,8 @@ void spapr_mce_req_event(PowerPCCPU *cpu)
>          }
>      }
>      spapr->mc_status = cpu->vcpu_id;
> +
> +    spapr_mce_dispatch_elog(cpu, recovered);
>  }
>  
>  static void check_exception(PowerPCCPU *cpu, SpaprMachineState *spapr,
> diff --git a/hw/ppc/spapr_rtas.c b/hw/ppc/spapr_rtas.c
> index 5bc1a93..a015a80 100644
> --- a/hw/ppc/spapr_rtas.c
> +++ b/hw/ppc/spapr_rtas.c
> @@ -470,6 +470,32 @@ void spapr_load_rtas(SpaprMachineState *spapr, void 
> *fdt, hwaddr addr)
>      }
>  }
>  
> +hwaddr spapr_get_rtas_addr(void)
> +{
> +    SpaprMachineState *spapr = SPAPR_MACHINE(qdev_get_machine());
> +    int rtas_node;
> +    const fdt32_t *rtas_data;
> +    void *fdt = spapr->fdt_blob;
> +
> +    /* fetch rtas addr from fdt */
> +    rtas_node = fdt_path_offset(fdt, "/rtas");
> +    if (rtas_node < 0) {
> +        return 0;
> +    }
> +
> +    rtas_data = fdt_getprop(fdt, rtas_node, "linux,rtas-base", NULL);
> +    if (!rtas_data) {
> +        return 0;
> +    }
> +
> +    /*
> +     * We assume that the OS called RTAS instantiate-rtas, but some other
> +     * OS might call RTAS instantiate-rtas-64 instead. This fine as of now
> +     * as SLOF only supports 32-bit variant.
> +     */
> +    return (hwaddr)fdt32_to_cpu(*rtas_data);
> +}
> +
>  static void core_rtas_register_types(void)
>  {
>      spapr_rtas_register(RTAS_DISPLAY_CHARACTER, "display-character",
> diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
> index f34c79f..debb57b 100644
> --- a/include/hw/ppc/spapr.h
> +++ b/include/hw/ppc/spapr.h
> @@ -710,6 +710,9 @@ void spapr_load_rtas(SpaprMachineState *spapr, void *fdt, 
> hwaddr addr);
>  
>  #define RTAS_ERROR_LOG_MAX      2048
>  
> +/* Offset from rtas-base where error log is placed */
> +#define RTAS_ERROR_LOG_OFFSET       0x30
> +
>  #define RTAS_EVENT_SCAN_RATE    1
>  
>  /* This helper should be used to encode interrupt specifiers when the related
> @@ -798,7 +801,7 @@ void spapr_clear_pending_events(SpaprMachineState *spapr);
>  int spapr_max_server_number(SpaprMachineState *spapr);
>  void spapr_store_hpte(PowerPCCPU *cpu, hwaddr ptex,
>                        uint64_t pte0, uint64_t pte1);
> -void spapr_mce_req_event(PowerPCCPU *cpu);
> +void spapr_mce_req_event(PowerPCCPU *cpu, bool recovered);
>  
>  /* DRC callbacks. */
>  void spapr_core_release(DeviceState *dev);
> @@ -888,4 +891,5 @@ 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);
> +hwaddr spapr_get_rtas_addr(void);
>  #endif /* HW_SPAPR_H */
> diff --git a/target/ppc/kvm.c b/target/ppc/kvm.c
> index 99f33fe..368ec6e 100644
> --- a/target/ppc/kvm.c
> +++ b/target/ppc/kvm.c
> @@ -2870,9 +2870,11 @@ int kvm_arch_msi_data_to_gsi(uint32_t data)
>  
>  int kvm_handle_nmi(PowerPCCPU *cpu, struct kvm_run *run)
>  {
> +    bool recovered = run->flags & KVM_RUN_PPC_NMI_DISP_FULLY_RECOV;
> +
>      cpu_synchronize_state(CPU(cpu));
>  
> -    spapr_mce_req_event(cpu);
> +    spapr_mce_req_event(cpu, recovered);
>  
>      return 0;
>  }
> 

-- 
David Gibson                    | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au  | minimalist, thank you.  NOT _the_ _other_
                                | _way_ _around_!
http://www.ozlabs.org/~dgibson

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