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Re: [Qemu-ppc] [PATCH 1/3] pseries: Split CAS PVR negotiation out into a
From: |
Greg Kurz |
Subject: |
Re: [Qemu-ppc] [PATCH 1/3] pseries: Split CAS PVR negotiation out into a separate function |
Date: |
Thu, 18 May 2017 09:59:08 +0200 |
On Thu, 18 May 2017 15:45:20 +1000
David Gibson <address@hidden> 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 isn't a CPU mode that's suitable for both guest and host).
>
> Signed-off-by: David Gibson <address@hidden>
> ---
Reviewed-by: Greg Kurz <address@hidden>
> hw/ppc/spapr_hcall.c | 49 ++++++++++++++++++++++++++++++++-----------------
> 1 file changed, 32 insertions(+), 17 deletions(-)
>
> diff --git a/hw/ppc/spapr_hcall.c b/hw/ppc/spapr_hcall.c
> index 2daace4..77d2d66 100644
> --- a/hw/ppc/spapr_hcall.c
> +++ b/hw/ppc/spapr_hcall.c
> @@ -1044,19 +1044,13 @@ 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 *addr,
> + 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
> @@ -1066,9 +1060,9 @@ static target_ulong
> h_client_architecture_support(PowerPCCPU *cpu,
> for (i = 0; i < 512; ++i) {
> uint32_t pvr, pvr_mask;
>
> - pvr_mask = ldl_be_phys(&address_space_memory, list);
> - pvr = ldl_be_phys(&address_space_memory, list + 4);
> - list += 8;
> + pvr_mask = ldl_be_phys(&address_space_memory, *addr);
> + pvr = ldl_be_phys(&address_space_memory, *addr + 4);
> + *addr += 8;
>
> if (~pvr_mask & pvr) {
> break; /* Terminator record */
> @@ -1087,17 +1081,38 @@ 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;
> +}
>
> - ppc_set_compat_all(best_compat, &local_err);
> +static target_ulong h_client_architecture_support(PowerPCCPU *cpu,
> + sPAPRMachineState *spapr,
> + target_ulong opcode,
> + target_ulong *args)
> +{
> + /* Working address in data buffer */
> + target_ulong addr = ppc64_phys_to_real(args[0]);
> + target_ulong ov_table;
> + uint32_t cas_pvr;
> + sPAPROptionVector *ov1_guest, *ov5_guest, *ov5_cas_old, *ov5_updates;
> + bool guest_radix;
> + Error *local_err = NULL;
> +
> + cas_pvr = cas_check_pvr(cpu, &addr, &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;
> @@ -1105,7 +1120,7 @@ static target_ulong
> h_client_architecture_support(PowerPCCPU *cpu,
> }
>
> /* For the future use: here @ov_table points to the first option vector
> */
> - ov_table = list;
> + ov_table = addr;
>
> ov1_guest = spapr_ovec_parse_vector(ov_table, 1);
> ov5_guest = spapr_ovec_parse_vector(ov_table, 5);
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