Re: [Qemu-ppc] [QEMU-PPC] [PATCH V4 05/11] target/ppc: Add patb_entry to sPAPRMachineState

[David Gibson]

On Fri, Feb 24, 2017 at 12:05:11PM +1100, Suraj Jitindar Singh wrote:
> ISA v3.00 adds the idea of a partition table which is used to store the
> address translation details for all partitions on the system. The partition
> table consists of double word entries indexed by partition id where the second
> double word contains the location of the process table in guest memory. The
> process table is registered by the guest via a h-call.
> 
> We need somewhere to store the address of the process table so we add an entry
> to the sPAPRMachineState struct called patb_entry to represent the second
> doubleword of a single partition table entry corresponding to the current
> guest. We need to store this value so we know if the guest is using radix or
> hash translation and the location of the corresponding process table in guest
> memory. Since we only have a single guest per qemu instance, we only need one
> entry.
> 
> Since the partition table is technically a hypervisor resource we require that
> access to it is abstracted by the virtual hypervisor through the get_patbe()
> call. Currently the value of the entry is never set (and thus
> defaults to 0 indicating hash), but it will be required to both implement
> POWER9 kvm support and tcg radix support.
> 
> We also add this field to be migrated as part of the sPAPRMachineState as we
> will need it on the receiving side as the guest will never tell us this
> information again and we need it to perform translation.
> 
> Signed-off-by: Suraj Jitindar Singh <address@hidden>

Reviewed-by: David Gibson <address@hidden>

It might be possible to get rid of hpt_mask() by folding it into
get_patbe(), but that's a clean up for another day.

> 
> ---
> 
> V2 -> V3:
>  - Only add patbe to migration stream if non-zero
> V3 -> V4:
>  - Remove reference to set_patbe() in commit message
> ---
>  hw/ppc/spapr.c         | 29 +++++++++++++++++++++++++++++
>  include/hw/ppc/spapr.h |  1 +
>  target/ppc/cpu.h       |  1 +
>  3 files changed, 31 insertions(+)
> 
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index c159961..b60b4f5 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -1018,6 +1018,13 @@ static void 
> emulate_spapr_hypercall(PPCVirtualHypervisor *vhyp,
>      }
>  }
>  
> +static uint64_t spapr_get_patbe(PPCVirtualHypervisor *vhyp)
> +{
> +    sPAPRMachineState *spapr = SPAPR_MACHINE(vhyp);
> +
> +    return spapr->patb_entry;
> +}
> +
>  #define HPTE(_table, _i)   (void *)(((uint64_t *)(_table)) + ((_i) * 2))
>  #define HPTE_VALID(_hpte)  (tswap64(*((uint64_t *)(_hpte))) & HPTE64_V_VALID)
>  #define HPTE_DIRTY(_hpte)  (tswap64(*((uint64_t *)(_hpte))) & 
> HPTE64_V_HPTE_DIRTY)
> @@ -1195,6 +1202,8 @@ static void ppc_spapr_reset(void)
>      /* Check for unknown sysbus devices */
>      foreach_dynamic_sysbus_device(find_unknown_sysbus_device, NULL);
>  
> +    spapr->patb_entry = 0;
> +
>      /* Allocate and/or reset the hash page table */
>      spapr_reallocate_hpt(spapr,
>                           spapr_hpt_shift_for_ramsize(machine->maxram_size),
> @@ -1381,6 +1390,24 @@ static const VMStateDescription vmstate_spapr_ov5_cas 
> = {
>      },
>  };
>  
> +static bool spapr_patb_entry_needed(void *opaque)
> +{
> +    sPAPRMachineState *spapr = opaque;
> +
> +    return !!spapr->patb_entry;
> +}
> +
> +static const VMStateDescription vmstate_spapr_patb_entry = {
> +    .name = "spapr_patb_entry",
> +    .version_id = 1,
> +    .minimum_version_id = 1,
> +    .needed = spapr_patb_entry_needed,
> +    .fields = (VMStateField[]) {
> +        VMSTATE_UINT64(patb_entry, sPAPRMachineState),
> +        VMSTATE_END_OF_LIST()
> +    },
> +};
> +
>  static const VMStateDescription vmstate_spapr = {
>      .name = "spapr",
>      .version_id = 3,
> @@ -1398,6 +1425,7 @@ static const VMStateDescription vmstate_spapr = {
>      },
>      .subsections = (const VMStateDescription*[]) {
>          &vmstate_spapr_ov5_cas,
> +        &vmstate_spapr_patb_entry,
>          NULL
>      }
>  };
> @@ -2968,6 +2996,7 @@ static void spapr_machine_class_init(ObjectClass *oc, 
> void *data)
>      vhc->map_hptes = spapr_map_hptes;
>      vhc->unmap_hptes = spapr_unmap_hptes;
>      vhc->store_hpte = spapr_store_hpte;
> +    vhc->get_patbe = spapr_get_patbe;
>  }
>  
>  static const TypeInfo spapr_machine_info = {
> diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
> index f9b17d8..2975967 100644
> --- a/include/hw/ppc/spapr.h
> +++ b/include/hw/ppc/spapr.h
> @@ -63,6 +63,7 @@ struct sPAPRMachineState {
>  
>      void *htab;
>      uint32_t htab_shift;
> +    uint64_t patb_entry; /* Process tbl registed in H_REGISTER_PROCESS_TABLE 
> */
>      hwaddr rma_size;
>      int vrma_adjust;
>      ssize_t rtas_size;
> diff --git a/target/ppc/cpu.h b/target/ppc/cpu.h
> index 09ee374..c720fc0 100644
> --- a/target/ppc/cpu.h
> +++ b/target/ppc/cpu.h
> @@ -1219,6 +1219,7 @@ struct PPCVirtualHypervisorClass {
>                          hwaddr ptex, int n);
>      void (*store_hpte)(PPCVirtualHypervisor *vhyp, hwaddr ptex,
>                         uint64_t pte0, uint64_t pte1);
> +    uint64_t (*get_patbe)(PPCVirtualHypervisor *vhyp);
>  };
>  
>  #define TYPE_PPC_VIRTUAL_HYPERVISOR "ppc-virtual-hypervisor"

-- 
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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