Re: [Qemu-ppc] [PATCH qemu] ppc/spapr: Receive and store device tree blob from SLOF

[Alexey Kardashevskiy]

On 12/11/2018 05:10, Greg Kurz wrote:
> Hi Alexey,
> 
> Just a few remarks. See below.
> 
> On Thu,  8 Nov 2018 12:44:06 +1100
> Alexey Kardashevskiy <address@hidden> wrote:
> 
>> SLOF receives a device tree and updates it with various properties
>> before switching to the guest kernel and QEMU is not aware of any changes
>> made by SLOF. Since there is no real RTAS (QEMU implements it), it makes
>> sense to pass the SLOF final device tree to QEMU to let it implement
>> RTAS related tasks better, such as PCI host bus adapter hotplug.
>>
>> Specifially, now QEMU can find out the actual XICS phandle (for PHB
>> hotplug) and the RTAS linux,rtas-entry/base properties (for firmware
>> assisted NMI - FWNMI).
>>
>> This stores the initial DT blob in the sPAPR machine and replaces it
>> in the KVMPPC_H_UPDATE_DT (new private hypercall) handler.
>>
>> This adds an @update_dt_enabled machine property to allow backward
>> migration.
>>
>> SLOF already has a hypercall since
>> https://github.com/aik/SLOF/commit/e6fc84652c9c0073f9183
>>
>> Signed-off-by: Alexey Kardashevskiy <address@hidden>
>> ---
>>  include/hw/ppc/spapr.h |  7 ++++++-
>>  hw/ppc/spapr.c         | 29 ++++++++++++++++++++++++++++-
>>  hw/ppc/spapr_hcall.c   | 32 ++++++++++++++++++++++++++++++++
>>  hw/ppc/trace-events    |  2 ++
>>  4 files changed, 68 insertions(+), 2 deletions(-)
>>
>> diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
>> index ad4d7cfd97..f5dcaf44cb 100644
>> --- a/include/hw/ppc/spapr.h
>> +++ b/include/hw/ppc/spapr.h
>> @@ -100,6 +100,7 @@ struct sPAPRMachineClass {
>>  
>>      /*< public >*/
>>      bool dr_lmb_enabled;       /* enable dynamic-reconfig/hotplug of LMBs */
>> +    bool update_dt_enabled;    /* enable KVMPPC_H_UPDATE_DT */
>>      bool use_ohci_by_default;  /* use USB-OHCI instead of XHCI */
>>      bool pre_2_10_has_unused_icps;
>>      bool legacy_irq_allocation;
>> @@ -136,6 +137,9 @@ struct sPAPRMachineState {
>>      int vrma_adjust;
>>      ssize_t rtas_size;
>>      void *rtas_blob;
>> +    uint32_t fdt_size;
>> +    uint32_t fdt_initial_size;
> 
> I don't quite see the purpose of fdt_initial_size... it seems to be only
> used to print a trace.


Ah, lost in rebase. The purpose was to test if the new device tree has
not grown too much.



> 
>> +    void *fdt_blob;
>>      long kernel_size;
>>      bool kernel_le;
>>      uint32_t initrd_base;
>> @@ -462,7 +466,8 @@ struct sPAPRMachineState {
>>  #define KVMPPC_H_LOGICAL_MEMOP  (KVMPPC_HCALL_BASE + 0x1)
>>  /* Client Architecture support */
>>  #define KVMPPC_H_CAS            (KVMPPC_HCALL_BASE + 0x2)
>> -#define KVMPPC_HCALL_MAX        KVMPPC_H_CAS
>> +#define KVMPPC_H_UPDATE_DT      (KVMPPC_HCALL_BASE + 0x3)
>> +#define KVMPPC_HCALL_MAX        KVMPPC_H_UPDATE_DT
>>  
>>  typedef struct sPAPRDeviceTreeUpdateHeader {
>>      uint32_t version_id;
>> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
>> index c08130facb..5e2d4d211c 100644
>> --- a/hw/ppc/spapr.c
>> +++ b/hw/ppc/spapr.c
>> @@ -1633,7 +1633,10 @@ static void spapr_machine_reset(void)
>>      /* Load the fdt */
>>      qemu_fdt_dumpdtb(fdt, fdt_totalsize(fdt));
>>      cpu_physical_memory_write(fdt_addr, fdt, fdt_totalsize(fdt));
>> -    g_free(fdt);
>> +    g_free(spapr->fdt_blob);
>> +    spapr->fdt_size = fdt_totalsize(fdt);
>> +    spapr->fdt_initial_size = spapr->fdt_size;
>> +    spapr->fdt_blob = fdt;
> 
> Hmm... It looks weird to store state in a reset handler. I'd rather zeroe
> both fdt_blob and fdt_size here.


The device tree is built from the reset handler and the idea is that we
want to always have some tree in the machine.



> 
>>  
>>      /* Set up the entry state */
>>      spapr_cpu_set_entry_state(first_ppc_cpu, SPAPR_ENTRY_POINT, fdt_addr);
>> @@ -1887,6 +1890,27 @@ static const VMStateDescription vmstate_spapr_irq_map 
>> = {
>>      },
>>  };
>>  
>> +static bool spapr_dtb_needed(void *opaque)
>> +{
>> +    sPAPRMachineClass *smc = SPAPR_MACHINE_GET_CLASS(opaque);
>> +
>> +    return smc->update_dt_enabled;
> 
> This means we always migrate the fdt, even if migration occurs before
> SLOF could call KVMPPC_H_UPDATE_DT.
> 
> With spapr->fdt_blob set to NULL on reset, a better check would be:
> 
>     sPAPRMachineState *spapr = SPAPR_MACHINE(opaque);
> 
>     return smc->update_dt_enabled && spapr->fdt_blob;
> 
>> +}
>> +
>> +static const VMStateDescription vmstate_spapr_dtb = {
>> +    .name = "spapr_dtb",
>> +    .version_id = 1,
>> +    .minimum_version_id = 1,
>> +    .needed = spapr_dtb_needed,
>> +    .fields = (VMStateField[]) {
>> +        VMSTATE_UINT32(fdt_initial_size, sPAPRMachineState),
>> +        VMSTATE_UINT32(fdt_size, sPAPRMachineState),
>> +        VMSTATE_VBUFFER_ALLOC_UINT32(fdt_blob, sPAPRMachineState, 0, NULL,
>> +                                     fdt_size),
>> +        VMSTATE_END_OF_LIST()
>> +    },
>> +};
>> +
>>  static const VMStateDescription vmstate_spapr = {
>>      .name = "spapr",
>>      .version_id = 3,
>> @@ -1915,6 +1939,7 @@ static const VMStateDescription vmstate_spapr = {
>>          &vmstate_spapr_cap_sbbc,
>>          &vmstate_spapr_cap_ibs,
>>          &vmstate_spapr_irq_map,
>> +        &vmstate_spapr_dtb,
> 
> This needs to be rebased.
> 
> <<<<<<<
>         &vmstate_spapr_cap_nested_kvm_hv,
> =======
>         &vmstate_spapr_dtb,
>>>>>>>>
> 
> 
> I'll try to find some time to respin the PHB hotplug series and I'll happily
> give a try to this patch.


Good :)


> 
>>          NULL
>>      }
>>  };
>> @@ -3849,6 +3874,7 @@ static void spapr_machine_class_init(ObjectClass *oc, 
>> void *data)
>>      hc->unplug = spapr_machine_device_unplug;
>>  
>>      smc->dr_lmb_enabled = true;
>> +    smc->update_dt_enabled = true;
>>      mc->default_cpu_type = POWERPC_CPU_TYPE_NAME("power8_v2.0");
>>      mc->has_hotpluggable_cpus = true;
>>      smc->resize_hpt_default = SPAPR_RESIZE_HPT_ENABLED;
>> @@ -3965,6 +3991,7 @@ static void 
>> spapr_machine_3_0_class_options(MachineClass *mc)
>>  
>>      smc->legacy_irq_allocation = true;
>>      smc->irq = &spapr_irq_xics_legacy;
>> +    smc->update_dt_enabled = false;
>>  }
>>  
>>  DEFINE_SPAPR_MACHINE(3_0, "3.0", false);
>> diff --git a/hw/ppc/spapr_hcall.c b/hw/ppc/spapr_hcall.c
>> index ae913d070f..d5833f3f8d 100644
>> --- a/hw/ppc/spapr_hcall.c
>> +++ b/hw/ppc/spapr_hcall.c
>> @@ -1717,6 +1717,36 @@ static target_ulong 
>> h_get_cpu_characteristics(PowerPCCPU *cpu,
>>  
>>      args[0] = characteristics;
>>      args[1] = behaviour;
>> +    return H_SUCCESS;
>> +}
>> +
>> +static target_ulong h_update_dt(PowerPCCPU *cpu, sPAPRMachineState *spapr,
>> +                                target_ulong opcode, target_ulong *args)
>> +{
>> +    target_ulong dt = ppc64_phys_to_real(args[0]);
>> +    struct fdt_header hdr = { 0 };
>> +    unsigned cb;
>> +    sPAPRMachineClass *smc = SPAPR_MACHINE_GET_CLASS(spapr);
>> +
>> +    cpu_physical_memory_read(dt, &hdr, sizeof(hdr));
>> +    cb = fdt32_to_cpu(hdr.totalsize);
>> +
>> +    if (fdt_check_full(spapr->fdt_blob, cb)) {
>> +        trace_spapr_update_dt_failed(spapr->fdt_initial_size, cb,
>> +            fdt32_to_cpu(hdr.magic));
>> +        return H_PARAMETER;
>> +    }
>> +
>> +    if (!smc->update_dt_enabled) {
>> +        return H_SUCCESS;
>> +    }
>> +
>> +    g_free(spapr->fdt_blob);
>> +    spapr->fdt_size = cb;
>> +    spapr->fdt_blob = g_malloc0(cb);
>> +    cpu_physical_memory_read(dt, spapr->fdt_blob, cb);
>> +
>> +    trace_spapr_update_dt(cb);
>>  
>>      return H_SUCCESS;
>>  }
>> @@ -1822,6 +1852,8 @@ static void hypercall_register_types(void)
>>  
>>      /* ibm,client-architecture-support support */
>>      spapr_register_hypercall(KVMPPC_H_CAS, h_client_architecture_support);
>> +
>> +    spapr_register_hypercall(KVMPPC_H_UPDATE_DT, h_update_dt);
>>  }
>>  
>>  type_init(hypercall_register_types)
>> diff --git a/hw/ppc/trace-events b/hw/ppc/trace-events
>> index dc5e65aee9..4432a5ce74 100644
>> --- a/hw/ppc/trace-events
>> +++ b/hw/ppc/trace-events
>> @@ -22,6 +22,8 @@ spapr_cas_pvr_try(uint32_t pvr) "0x%x"
>>  spapr_cas_pvr(uint32_t cur_pvr, bool explicit_match, uint32_t new_pvr) 
>> "current=0x%x, explicit_match=%u, new=0x%x"
>>  spapr_h_resize_hpt_prepare(uint64_t flags, uint64_t shift) 
>> "flags=0x%"PRIx64", shift=%"PRIu64
>>  spapr_h_resize_hpt_commit(uint64_t flags, uint64_t shift) 
>> "flags=0x%"PRIx64", shift=%"PRIu64
>> +spapr_update_dt(unsigned cb) "New blob %u bytes"
>> +spapr_update_dt_failed(unsigned cbold, unsigned cbnew, unsigned magic) "Old 
>> blob %u bytes, new blob %u bytes, magic 0x%x"
>>  
>>  # hw/ppc/spapr_iommu.c
>>  spapr_iommu_put(uint64_t liobn, uint64_t ioba, uint64_t tce, uint64_t ret) 
>> "liobn=0x%"PRIx64" ioba=0x%"PRIx64" tce=0x%"PRIx64" ret=%"PRId64
> 

-- 
Alexey