Re: [for-5.0 1/4] spapr,ppc: Simplify signature of kvmppc_rma_size()

[Greg Kurz]

On Fri, 29 Nov 2019 12:35:01 +1100
David Gibson <address@hidden> wrote:

> This function calculates the maximum size of the RMA as implied by the
> host's page size of structure of the VRMA (there are a number of other
> constraints on the RMA size which will supersede this one in many
> circumstances).
> 
> The current interface takes the current RMA size estimate, and clamps it
> to the VRMA derived size.  The only current caller passes in an arguably
> wrong value (it will match the current RMA estimate in some but not all
> cases).
> 
> We want to fix that, but for now just keep concerns separated by having the
> KVM helper function just return the VRMA derived limit, and let the caller
> combine it with other constraints.  We call the new function
> kvmppc_vrma_limit() to more clearly indicate its limited responsibility.
> 
> The helper should only ever be called in the KVM enabled case, so replace
> its !CONFIG_KVM stub with an assert() rather than a dummy value.
> 
> Signed-off-by: David Gibson <address@hidden>
> ---

Reviewed-by: Greg Kurz <address@hidden>

>  hw/ppc/spapr.c       | 5 +++--
>  target/ppc/kvm.c     | 5 ++---
>  target/ppc/kvm_ppc.h | 7 +++----
>  3 files changed, 8 insertions(+), 9 deletions(-)
> 
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index d9c9a2bcee..069bd04a8d 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -1635,8 +1635,9 @@ void spapr_setup_hpt_and_vrma(SpaprMachineState *spapr)
>      spapr_reallocate_hpt(spapr, hpt_shift, &error_fatal);
>  
>      if (spapr->vrma_adjust) {
> -        spapr->rma_size = kvmppc_rma_size(spapr_node0_size(MACHINE(spapr)),
> -                                          spapr->htab_shift);
> +        hwaddr vrma_limit = kvmppc_vrma_limit(spapr->htab_shift);
> +
> +        spapr->rma_size = MIN(spapr_node0_size(MACHINE(spapr)), vrma_limit);
>      }
>  }
>  
> diff --git a/target/ppc/kvm.c b/target/ppc/kvm.c
> index c77f9848ec..09b3bd6443 100644
> --- a/target/ppc/kvm.c
> +++ b/target/ppc/kvm.c
> @@ -2101,7 +2101,7 @@ void kvmppc_hint_smt_possible(Error **errp)
>  
>  
>  #ifdef TARGET_PPC64
> -uint64_t kvmppc_rma_size(uint64_t current_size, unsigned int hash_shift)
> +uint64_t kvmppc_vrma_limit(unsigned int hash_shift)
>  {
>      struct kvm_ppc_smmu_info info;
>      long rampagesize, best_page_shift;
> @@ -2128,8 +2128,7 @@ uint64_t kvmppc_rma_size(uint64_t current_size, 
> unsigned int hash_shift)
>          }
>      }
>  
> -    return MIN(current_size,
> -               1ULL << (best_page_shift + hash_shift - 7));
> +    return 1ULL << (best_page_shift + hash_shift - 7));
>  }
>  #endif
>  
> diff --git a/target/ppc/kvm_ppc.h b/target/ppc/kvm_ppc.h
> index 98bd7d5da6..4f0eec4c1b 100644
> --- a/target/ppc/kvm_ppc.h
> +++ b/target/ppc/kvm_ppc.h
> @@ -45,7 +45,7 @@ void *kvmppc_create_spapr_tce(uint32_t liobn, uint32_t 
> page_shift,
>                                int *pfd, bool need_vfio);
>  int kvmppc_remove_spapr_tce(void *table, int pfd, uint32_t window_size);
>  int kvmppc_reset_htab(int shift_hint);
> -uint64_t kvmppc_rma_size(uint64_t current_size, unsigned int hash_shift);
> +uint64_t kvmppc_vrma_limit(unsigned int hash_shift);
>  bool kvmppc_has_cap_spapr_vfio(void);
>  #endif /* !CONFIG_USER_ONLY */
>  bool kvmppc_has_cap_epr(void);
> @@ -241,10 +241,9 @@ static inline int kvmppc_reset_htab(int shift_hint)
>      return 0;
>  }
>  
> -static inline uint64_t kvmppc_rma_size(uint64_t current_size,
> -                                       unsigned int hash_shift)
> +static inline uint64_t kvmppc_vrma_limit(unsigned int hash_shift)
>  {
> -    return ram_size;
> +    g_assert_not_reached();
>  }
>  
>  static inline bool kvmppc_hpt_needs_host_contiguous_pages(void)