Re: [Qemu-devel] [QEMU-PPC] [PATCH 1/2] target/ppc: Move setting of patb_entry on hash table init

[Greg Kurz <groug@kaod.org>]

On Fri, 24 Nov 2017 15:23:24 +1100
Suraj Jitindar Singh <sjitindarsingh@gmail.com> wrote:

> The patb_entry is used to store the location of the process table in
> guest memory. The msb is also used to indicate the mmu mode of the
> guest, that is patb_entry & 1 << 63 ? radix_mode : hash_mode.
> 
> Currently we set this to zero in spapr_setup_hpt_and_vrma() since if
> this function gets called then we know we're hash. However some code
> paths, such as setting up the hpt on incoming migration of a hash guest,
> call spapr_reallocate_hpt() directly bypassing this higher level
> function. Since we assume radix if the host is capable this results in
> the msb in patb_entry being left set so in spapr_post_load() we call
> kvmppc_configure_v3_mmu() and tell the host we're radix which as
> expected means addresses cannot be translated once we actually run the cpu.
> 
> To fix this move the zeroing of patb_entry into spapr_reallocate_hpt().
> 
> Signed-off-by: Suraj Jitindar Singh <sjitindarsingh@gmail.com>
> ---

Reviewed-by: Greg Kurz <groug@kaod.org>

>  hw/ppc/spapr.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index 6841bd294b..e7af47bab0 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -1373,6 +1373,8 @@ void spapr_reallocate_hpt(sPAPRMachineState *spapr, int shift,
>              DIRTY_HPTE(HPTE(spapr->htab, i));
>          }
>      }
> +    /* We're setting up a hash table, so that means we're not radix */
> +    spapr->patb_entry = 0;
>  }
>  
>  void spapr_setup_hpt_and_vrma(sPAPRMachineState *spapr)
> @@ -1392,8 +1394,6 @@ void spapr_setup_hpt_and_vrma(sPAPRMachineState *spapr)
>          spapr->rma_size = kvmppc_rma_size(spapr_node0_size(MACHINE(spapr)),
>                                            spapr->htab_shift);
>      }
> -    /* We're setting up a hash table, so that means we're not radix */
> -    spapr->patb_entry = 0;
>  }
>  
>  static void find_unknown_sysbus_device(SysBusDevice *sbdev, void *opaque)