Re: [Qemu-ppc] [PATCH v3 07/12] spapr: Only setup HTP if necessary.

[David Gibson]

On Thu, Mar 02, 2017 at 04:39:02PM +1100, Sam Bobroff wrote:
> If QEMU is using KVM, and KVM is capable of running in radix mode,
> guests can be run in real-mode without allocating a HPT (because KVM
> will use a minimal RPT). So in this case, we avoid creating the HPT
> at reset time and later (during CAS) create it if it is necessary.

Your subject line still has a typo.

> Signed-off-by: Sam Bobroff <address@hidden>
> ---
> Changes in v3:
> * in spapr_setup_hpt_and_vrma() replaced MACHINE(qdev_get_machine()) with 
> MACHINE(spapr).
> 
>  hw/ppc/spapr.c         | 24 +++++++++++++++---------
>  hw/ppc/spapr_hcall.c   | 10 ++++++++++
>  include/hw/ppc/spapr.h |  1 +
>  3 files changed, 26 insertions(+), 9 deletions(-)
> 
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index d154fa2112..0b266e96f1 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -1207,6 +1207,17 @@ static void spapr_reallocate_hpt(sPAPRMachineState 
> *spapr, int shift,
>      }
>  }
>  
> +void spapr_setup_hpt_and_vrma(sPAPRMachineState *spapr)
> +{
> +    spapr_reallocate_hpt(spapr,
> +                     
> spapr_hpt_shift_for_ramsize(MACHINE(spapr)->maxram_size),
> +                     &error_fatal);
> +    if (spapr->vrma_adjust) {
> +        spapr->rma_size = kvmppc_rma_size(spapr_node0_size(),
> +                                          spapr->htab_shift);
> +    }
> +}
> +
>  static void find_unknown_sysbus_device(SysBusDevice *sbdev, void *opaque)
>  {
>      bool matched = false;
> @@ -1237,15 +1248,10 @@ static void ppc_spapr_reset(void)
>  
>      spapr->patb_entry = 0;
>  
> -    /* Allocate and/or reset the hash page table */
> -    spapr_reallocate_hpt(spapr,
> -                         spapr_hpt_shift_for_ramsize(machine->maxram_size),
> -                         &error_fatal);
> -
> -    /* Update the RMA size if necessary */
> -    if (spapr->vrma_adjust) {
> -        spapr->rma_size = kvmppc_rma_size(spapr_node0_size(),
> -                                          spapr->htab_shift);
> +    /* If using KVM with radix mode available, VCPUs can be started
> +     * without a HPT because KVM will start them in radix mode. */
> +    if (!(kvm_enabled() && kvmppc_has_cap_mmu_radix())) {
> +        spapr_setup_hpt_and_vrma(spapr);
>      }
>  
>      qemu_devices_reset();
> diff --git a/hw/ppc/spapr_hcall.c b/hw/ppc/spapr_hcall.c
> index f05a90ed2c..0c1b0326ad 100644
> --- a/hw/ppc/spapr_hcall.c
> +++ b/hw/ppc/spapr_hcall.c
> @@ -999,6 +999,16 @@ static target_ulong 
> h_client_architecture_support(PowerPCCPU *cpu,
>      ov5_updates = spapr_ovec_new();
>      spapr->cas_reboot = spapr_ovec_diff(ov5_updates,
>                                          ov5_cas_old, spapr->ov5_cas);
> +    if (kvm_enabled()) {
> +        if (kvmppc_has_cap_mmu_radix()) {

I'd still like to see this changed so that it is based on whether an
HPT *has* been set up, rather than on whether we expect it would have
been set up.  That will be less fragile against future changes.

> +            /* If the HPT hasn't yet been set up (see
> +             * ppc_spapr_reset()), and it's needed, do it now: */
> +            if (!spapr_ovec_test(ov5_updates, OV5_MMU_RADIX)) {
> +                /* legacy hash or new hash: */
> +                spapr_setup_hpt_and_vrma(spapr);

> +            }
> +        }
> +    }
>  
>      if (!spapr->cas_reboot) {
>          spapr->cas_reboot =
> diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
> index 2975967c07..24da5dc27e 100644
> --- a/include/hw/ppc/spapr.h
> +++ b/include/hw/ppc/spapr.h
> @@ -591,6 +591,7 @@ void spapr_dt_events(sPAPRMachineState *sm, void *fdt);
>  int spapr_h_cas_compose_response(sPAPRMachineState *sm,
>                                   target_ulong addr, target_ulong size,
>                                   sPAPROptionVector *ov5_updates);
> +void spapr_setup_hpt_and_vrma(sPAPRMachineState *spapr);
>  sPAPRTCETable *spapr_tce_new_table(DeviceState *owner, uint32_t liobn);
>  void spapr_tce_table_enable(sPAPRTCETable *tcet,
>                              uint32_t page_shift, uint64_t bus_offset,

-- 
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

signature.asc
Description: PGP signature