Re: [Qemu-ppc] [PATCH] spapr: compute interrupt vector address from LPCR

[Greg Kurz]

Hi Cedric,

On Thu, 24 Mar 2016 16:28:53 +0100
Cédric Le Goater <address@hidden> wrote:

> This address is changed by the linux kernel using the H_SET_MODE hcall
> and needs to be migrated in order to restart a spapr VM running in
> TCG. This can be done using the AIL bits from the LPCR register.
> 
> The patch introduces a spapr_h_set_mode_resource_addr() helper to
> share some code with the H_SET_MODE hcall.
> 
> Signed-off-by: Cédric Le Goater <address@hidden>
> ---
>  hw/ppc/spapr.c         |   21 +++++++++++++++++++++
>  hw/ppc/spapr_hcall.c   |   13 ++-----------
>  include/hw/ppc/spapr.h |   14 ++++++++++++++
>  3 files changed, 37 insertions(+), 11 deletions(-)
> 
> Index: qemu-dgibson-for-2.6.git/hw/ppc/spapr.c
> ===================================================================
> --- qemu-dgibson-for-2.6.git.orig/hw/ppc/spapr.c
> +++ qemu-dgibson-for-2.6.git/hw/ppc/spapr.c
> @@ -1244,6 +1244,24 @@ static bool spapr_vga_init(PCIBus *pci_b
>      }
>  }
> 
> +static int load_excp_prefix(void)
> +{
> +    CPUState *cs;
> +
> +    CPU_FOREACH(cs) {
> +        CPUPPCState *env = &POWERPC_CPU(cs)->env;

And how are we sure env contains the migrated register values ?

Actually, this "works" because vmstate_ppc_cpu is registered before 
vmstate_spapr,
and the same ordering happens to be used when sending state over the wire, but 
it
looks wrong.

The excp_prefix should be restored in cpu_post_load(), unless I'm missing
something.

Cheers.

--
Greg

> +        int ail = (env->spr[SPR_LPCR] & LPCR_AIL) >> LPCR_AIL_SHIFT;
> +
> +        env->excp_prefix = spapr_h_set_mode_resource_addr(ail);
> +        if (env->excp_prefix == H_UNSUPPORTED_FLAG) {
> +            error_report("LPCR has an invalid AIL value");
> +            return -EINVAL;
> +        }
> +    }
> +
> +    return 0;
> +}
> +
>  static int spapr_post_load(void *opaque, int version_id)
>  {
>      sPAPRMachineState *spapr = (sPAPRMachineState *)opaque;
> @@ -1257,6 +1275,9 @@ static int spapr_post_load(void *opaque,
>          err = spapr_rtc_import_offset(spapr->rtc, spapr->rtc_offset);
>      }
> 
> +    if (!err) {
> +        err = load_excp_prefix();
> +    }
>      return err;
>  }
> 
> Index: qemu-dgibson-for-2.6.git/include/hw/ppc/spapr.h
> ===================================================================
> --- qemu-dgibson-for-2.6.git.orig/include/hw/ppc/spapr.h
> +++ qemu-dgibson-for-2.6.git/include/hw/ppc/spapr.h
> @@ -561,6 +561,20 @@ struct sPAPREventLogEntry {
>      QTAILQ_ENTRY(sPAPREventLogEntry) next;
>  };
> 
> +static inline target_ulong spapr_h_set_mode_resource_addr(target_ulong 
> mflags)
> +{
> +    switch (mflags) {
> +    case H_SET_MODE_ADDR_TRANS_NONE:
> +        return 0;
> +    case H_SET_MODE_ADDR_TRANS_0001_8000:
> +        return 0x18000;
> +    case H_SET_MODE_ADDR_TRANS_C000_0000_0000_4000:
> +        return 0xC000000000004000ULL;
> +    default:
> +        return H_UNSUPPORTED_FLAG;
> +    }
> +}
> +
>  void spapr_events_init(sPAPRMachineState *sm);
>  void spapr_events_fdt_skel(void *fdt, uint32_t epow_irq);
>  int spapr_h_cas_compose_response(sPAPRMachineState *sm,
> Index: qemu-dgibson-for-2.6.git/hw/ppc/spapr_hcall.c
> ===================================================================
> --- qemu-dgibson-for-2.6.git.orig/hw/ppc/spapr_hcall.c
> +++ qemu-dgibson-for-2.6.git/hw/ppc/spapr_hcall.c
> @@ -835,17 +835,8 @@ static target_ulong h_set_mode_resource_
>          return H_P4;
>      }
> 
> -    switch (mflags) {
> -    case H_SET_MODE_ADDR_TRANS_NONE:
> -        prefix = 0;
> -        break;
> -    case H_SET_MODE_ADDR_TRANS_0001_8000:
> -        prefix = 0x18000;
> -        break;
> -    case H_SET_MODE_ADDR_TRANS_C000_0000_0000_4000:
> -        prefix = 0xC000000000004000ULL;
> -        break;
> -    default:
> +    prefix = spapr_h_set_mode_resource_addr(mflags);
> +    if (prefix == H_UNSUPPORTED_FLAG) {
>          return H_UNSUPPORTED_FLAG;
>      }
> 
> 
>