On 17/05/2017 08:35, David Gibson wrote:
> Guests of the qemu machine type go through a feature negotiation process
> known as "client architecture support" (CAS) during early boot. This does
> a number of things, one of which is finding a CPU compatibility mode which
> can be supported by both guest and host.
>
> In fact the CPU negotiation is probably the single most complex part of the
> CAS process, so this splits it out into a helper function. We've recently
> made some mistakes in maintaining backward compatibility for old machine
> types here. Splitting this out will also make it easier to fix this.
>
> This also adds a possibly useful error message if the negotiation fails
> (i.e. if there is CPU mode that's suitable for both guest and host).
>
> Signed-off-by: David Gibson
> ---
> hw/ppc/spapr_hcall.c | 43 +++
> 1 file changed, 27 insertions(+), 16 deletions(-)
>
> diff --git a/hw/ppc/spapr_hcall.c b/hw/ppc/spapr_hcall.c
> index 0d608d6..007ae8d 100644
> --- a/hw/ppc/spapr_hcall.c
> +++ b/hw/ppc/spapr_hcall.c
> @@ -1047,19 +1047,13 @@ static target_ulong h_signal_sys_reset(PowerPCCPU
> *cpu,
> }
> }
>
> -static target_ulong h_client_architecture_support(PowerPCCPU *cpu,
> - sPAPRMachineState *spapr,
> - target_ulong opcode,
> - target_ulong *args)
> +static uint32_t cas_check_pvr(PowerPCCPU *cpu, target_ulong list,
> + Error **errp)
> {
> -target_ulong list = ppc64_phys_to_real(args[0]);
> -target_ulong ov_table;
> bool explicit_match = false; /* Matched the CPU's real PVR */
> uint32_t max_compat = cpu->max_compat;
> uint32_t best_compat = 0;
> int i;
> -sPAPROptionVector *ov1_guest, *ov5_guest, *ov5_cas_old, *ov5_updates;
> -bool guest_radix;
>
> /*
> * We scan the supplied table of PVRs looking for two things
> @@ -1090,26 +1084,43 @@ static target_ulong
> h_client_architecture_support(PowerPCCPU *cpu,
> /* We couldn't find a suitable compatibility mode, and either
> * the guest doesn't support "raw" mode for this CPU, or raw
> * mode is disabled because a maximum compat mode is set */
> -return H_HARDWARE;
> +error_setg(errp, "Couldn't negotiate a suitable PVR during CAS");
> +return 0;
> }
>
> /* Parsing finished */
> trace_spapr_cas_pvr(cpu->compat_pvr, explicit_match, best_compat);
>
> -/* Update CPUs */
> -if (cpu->compat_pvr != best_compat) {
> -Error *local_err = NULL;
> +return best_compat;
> +}
> +
> +static target_ulong h_client_architecture_support(PowerPCCPU *cpu,
> + sPAPRMachineState *spapr,
> + target_ulong opcode,
> + target_ulong *args)
> +{
> +/* @ov_table points to the first option vector */
> +target_ulong ov_table = ppc64_phys_to_real(args[0]);
> +uint32_t cas_pvr;
> +sPAPROptionVector *ov1_guest, *ov5_guest, *ov5_cas_old, *ov5_updates;
> +bool guest_radix;
> +Error *local_err = NULL;
>
> -ppc_set_compat_all(best_compat, &local_err);
> +cas_pvr = cas_check_pvr(cpu, ov_table, &local_err);
> +if (local_err) {
> +error_report_err(local_err);
> +return H_HARDWARE;
> +}
> +
> +/* Update CPUs */
> +if (cpu->compat_pvr != cas_pvr) {
> +ppc_set_compat_all(cas_pvr, &local_err);
> if (local_err) {
> error_report_err(local_err);
> return H_HARDWARE;
> }
> }
>
> -/* For the future use: here @ov_table points to the first option vector
> */
> -ov_table = list;
> -
I think there is a change here: now ov_table is always
ppc64_phys_to_real(args[0]), as it is not updated by cas_check() as list
was by h_client_architecture_support().
> ov1_guest = spapr_ovec_parse_vector(ov_table, 1);
> ov5_guest = spapr_ovec_parse_vector(ov_table, 5);
> if (spapr_ovec_test(ov5_guest, OV5_MMU_BOTH)) {
Laurent
