On Wed, Oct 12, 2016 at 06:13:51PM -0500, Michael Roth wrote: > In some cases, ibm,client-architecture-support calls can fail. This > could happen in the current code for situations where the modified > device tree segment exceeds the buffer size provided by the guest > via the call parameters. In these cases, QEMU will reset, allowing > an opportunity to regenerate the device tree from scratch via > boot-time handling. There are potentially other scenarios as well, > not currently reachable in the current code, but possible in theory, > such as cases where device-tree properties or nodes need to be removed. > > We currently don't handle either of these properly for option vector > capabilities however. Instead of carrying the negotiated capability > beyond the reset and creating the boot-time device tree accordingly, > we start from scratch, generating the same boot-time device tree as we > did prior to the CAS-generated and the same device tree updates as we > did before. This could (in theory) cause us to get stuck in a reset > loop. This hasn't been observed, but depending on the extensiveness > of CAS-induced device tree updates in the future, could eventually > become an issue. > > Address this by pulling capability-related device tree > updates resulting from CAS calls into a common routine, > spapr_populate_cas_updates(), and adding an sPAPROptionVector* > parameter that allows us to test for newly-negotiated capabilities. > We invoke it as follows: > > 1) When ibm,client-architecture-support gets called, we > call spapr_populate_cas_updates() with the set of capabilities > added since the previous call to ibm,client-architecture-support. > For the initial boot, or a system reset generated by something > other than the CAS call itself, this set will consist of *all* > options supported both the platform and the guest. For calls > to ibm,client-architecture-support immediately after a CAS-induced > reset, we call spapr_populate_cas_updates() with only the set > of capabilities added since the previous call, since the other > capabilities will have already been addressed by the boot-time > device-tree this time around. In the unlikely event that > capabilities are *removed* since the previous CAS, we will > generate a CAS-induced reset. In the unlikely event that we > cannot fit the device-tree updates into the buffer provided > by the guest, well generate a CAS-induced reset. > > 2) When a CAS update results in the need to reset the machine and > include the updates in the boot-time device tree, we call the > spapr_populate_cas_updates() using the full set of negotiated > capabilities as part of the reset path. At initial boot, or after > a reset generated by something other than the CAS call itself, > this set will be empty, resulting in what should be the same > boot-time device-tree as we generated prior to this patch. For > CAS-induced reset, this routine will be called with the full set of > capabilities negotiated by the platform/guest in the previous > CAS call, which should result in CAS updates from previous call > being accounted for in the initial boot-time device tree. > > Signed-off-by: Michael Roth <mdr...@linux.vnet.ibm.com>
Reviewed-by: David Gibson <da...@gibson.dropbear.id.au>
I suspect HPT resizing is also going to need actual CAS reboots
(rather than just adjusting the DT), so it's handy you've implemented
that here.
> ---
> hw/ppc/spapr.c | 43 ++++++++++++++++++++++++++++++++++---------
> hw/ppc/spapr_hcall.c | 22 ++++++++++++++++++----
> include/hw/ppc/spapr.h | 4 +++-
> 3 files changed, 55 insertions(+), 14 deletions(-)
>
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index 934d6b2..460c7a8 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -854,13 +854,28 @@ out:
> return ret;
> }
>
> +static int spapr_populate_cas_updates(sPAPRMachineState *spapr, void *fdt,
> + sPAPROptionVector *ov5_updates)
> +{
> + sPAPRMachineClass *smc = SPAPR_MACHINE_GET_CLASS(spapr);
> + int ret = 0;
> +
> + /* Generate ibm,dynamic-reconfiguration-memory node if required */
> + if (spapr_ovec_test(ov5_updates, OV5_DRCONF_MEMORY)) {
> + g_assert(smc->dr_lmb_enabled);
> + ret = spapr_populate_drconf_memory(spapr, fdt);
> + }
> +
> + return ret;
> +}
> +
> int spapr_h_cas_compose_response(sPAPRMachineState *spapr,
> target_ulong addr, target_ulong size,
> - bool cpu_update)
> + bool cpu_update,
> + sPAPROptionVector *ov5_updates)
> {
> void *fdt, *fdt_skel;
> sPAPRDeviceTreeUpdateHeader hdr = { .version_id = 1 };
> - sPAPRMachineClass *smc = SPAPR_MACHINE_GET_CLASS(qdev_get_machine());
>
> size -= sizeof(hdr);
>
> @@ -879,11 +894,7 @@ int spapr_h_cas_compose_response(sPAPRMachineState
> *spapr,
> _FDT((spapr_fixup_cpu_dt(fdt, spapr)));
> }
>
> - /* Generate ibm,dynamic-reconfiguration-memory node if required */
> - if (spapr_ovec_test(spapr->ov5_cas, OV5_DRCONF_MEMORY)) {
> - g_assert(smc->dr_lmb_enabled);
> - _FDT((spapr_populate_drconf_memory(spapr, fdt)));
> - }
> + spapr_populate_cas_updates(spapr, fdt, ov5_updates);
>
> /* Pack resulting tree */
> _FDT((fdt_pack(fdt)));
> @@ -904,7 +915,8 @@ int spapr_h_cas_compose_response(sPAPRMachineState *spapr,
> static void spapr_finalize_fdt(sPAPRMachineState *spapr,
> hwaddr fdt_addr,
> hwaddr rtas_addr,
> - hwaddr rtas_size)
> + hwaddr rtas_size,
> + sPAPROptionVector *ov5_updates)
> {
> MachineState *machine = MACHINE(qdev_get_machine());
> MachineClass *mc = MACHINE_GET_CLASS(machine);
> @@ -1000,6 +1012,11 @@ static void spapr_finalize_fdt(sPAPRMachineState
> *spapr,
> }
> }
>
> + ret = spapr_populate_cas_updates(spapr, fdt, ov5_updates);
> + if (ret < 0) {
> + error_report("couldn't setup CAS properties fdt");
> + }
> +
> _FDT((fdt_pack(fdt)));
>
> if (fdt_totalsize(fdt) > FDT_MAX_SIZE) {
> @@ -1174,9 +1191,16 @@ static void ppc_spapr_reset(void)
> spapr->rtas_addr = rtas_limit - RTAS_MAX_SIZE;
> spapr->fdt_addr = spapr->rtas_addr - FDT_MAX_SIZE;
>
> + /* if this reset wasn't generated by CAS, we should reset our
> + * negotiated options and start from scratch */
> + if (!spapr->cas_reboot) {
> + spapr_ovec_cleanup(spapr->ov5_cas);
> + spapr->ov5_cas = spapr_ovec_new();
> + }
> +
> /* Load the fdt */
> spapr_finalize_fdt(spapr, spapr->fdt_addr, spapr->rtas_addr,
> - spapr->rtas_size);
> + spapr->rtas_size, spapr->ov5_cas);
>
> /* Copy RTAS over */
> cpu_physical_memory_write(spapr->rtas_addr, spapr->rtas_blob,
> @@ -1189,6 +1213,7 @@ static void ppc_spapr_reset(void)
> first_cpu->halted = 0;
> first_ppc_cpu->env.nip = SPAPR_ENTRY_POINT;
>
> + spapr->cas_reboot = false;
> }
>
> static void spapr_create_nvram(sPAPRMachineState *spapr)
> diff --git a/hw/ppc/spapr_hcall.c b/hw/ppc/spapr_hcall.c
> index f1d081b..d277813 100644
> --- a/hw/ppc/spapr_hcall.c
> +++ b/hw/ppc/spapr_hcall.c
> @@ -950,7 +950,7 @@ static target_ulong
> h_client_architecture_support(PowerPCCPU *cpu_,
> unsigned compat_lvl = 0, cpu_version = 0;
> unsigned max_lvl = get_compat_level(cpu_->max_compat);
> int counter;
> - sPAPROptionVector *ov5_guest;
> + sPAPROptionVector *ov5_guest, *ov5_cas_old, *ov5_updates;
>
> /* Parse PVR list */
> for (counter = 0; counter < 512; ++counter) {
> @@ -1013,13 +1013,27 @@ static target_ulong
> h_client_architecture_support(PowerPCCPU *cpu_,
> * of guest input. To model these properly we'd want some sort of mask,
> * but since they only currently apply to memory migration as defined
> * by LoPAPR 1.1, 14.5.4.8, which QEMU doesn't implement, we don't need
> - * to worry about this.
> + * to worry about this for now.
> */
> + ov5_cas_old = spapr_ovec_clone(spapr->ov5_cas);
> + /* full range of negotiated ov5 capabilities */
> spapr_ovec_intersect(spapr->ov5_cas, spapr->ov5, ov5_guest);
> spapr_ovec_cleanup(ov5_guest);
> + /* capabilities that have been added since CAS-generated guest reset.
> + * if capabilities have since been removed, generate another reset
> + */
> + ov5_updates = spapr_ovec_new();
> + spapr->cas_reboot = spapr_ovec_diff(ov5_updates,
> + ov5_cas_old, spapr->ov5_cas);
> +
> + if (!spapr->cas_reboot) {
> + spapr->cas_reboot =
> + spapr_h_cas_compose_response(spapr, args[1], args[2], cpu_update,
> + ov5_updates);
> + }
> + spapr_ovec_cleanup(ov5_updates);
>
> - if (spapr_h_cas_compose_response(spapr, args[1], args[2],
> - cpu_update)) {
> + if (spapr->cas_reboot) {
> qemu_system_reset_request();
> }
>
> diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
> index 6c20d28..27a3328 100644
> --- a/include/hw/ppc/spapr.h
> +++ b/include/hw/ppc/spapr.h
> @@ -69,6 +69,7 @@ struct sPAPRMachineState {
> bool has_graphics;
> sPAPROptionVector *ov5;
> sPAPROptionVector *ov5_cas;
> + bool cas_reboot;
>
> uint32_t check_exception_irq;
> Notifier epow_notifier;
> @@ -580,7 +581,8 @@ 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,
> target_ulong addr, target_ulong size,
> - bool cpu_update);
> + bool cpu_update,
> + sPAPROptionVector *ov5_updates);
> sPAPRTCETable *spapr_tce_new_table(DeviceState *owner, uint32_t liobn);
> void spapr_tce_table_enable(sPAPRTCETable *tcet,
> uint32_t page_shift, uint64_t bus_offset,
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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