Re: [Qemu-ppc] [PATCHv6 1/5] pseries: Stubs for HPT resizing

[Laurent Vivier]

On 12/05/2017 07:04, David Gibson wrote:
> This introduces stub implementations of the H_RESIZE_HPT_PREPARE and
> H_RESIZE_HPT_COMMIT hypercalls which we hope to add in a PAPR
> extension to allow run time resizing of a guest's hash page table.  It
> also adds a new machine property for controlling whether this new
> facility is available.
> 
> For now we only allow resizing with TCG, allowing it with KVM will require
> kernel changes as well.
> 
> Finally, it adds a new string to the hypertas property in the device
> tree, advertising to the guest the availability of the HPT resizing
> hypercalls.  This is a tentative suggested value, and would need to be
> standardized by PAPR before being merged.
> 
> Signed-off-by: David Gibson <address@hidden>
> Reviewed-by: Suraj Jitindar Singh <address@hidden>

Reviewed-by: Laurent Vivier <address@hidden>

> ---
>  hw/ppc/spapr.c         | 75 
> ++++++++++++++++++++++++++++++++++++++++++++++++++
>  hw/ppc/spapr_hcall.c   | 36 ++++++++++++++++++++++++
>  hw/ppc/trace-events    |  2 ++
>  include/hw/ppc/spapr.h | 11 ++++++++
>  target/ppc/kvm.c       | 12 ++++++++
>  target/ppc/kvm_ppc.h   |  5 ++++
>  6 files changed, 141 insertions(+)
> 
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index 1b7cada..50beee0 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -816,6 +816,11 @@ static void spapr_dt_rtas(sPAPRMachineState *spapr, void 
> *fdt)
>      if (!kvm_enabled() || kvmppc_spapr_use_multitce()) {
>          add_str(hypertas, "hcall-multi-tce");
>      }
> +
> +    if (spapr->resize_hpt != SPAPR_RESIZE_HPT_DISABLED) {
> +        add_str(hypertas, "hcall-hpt-resize");
> +    }
> +
>      _FDT(fdt_setprop(fdt, rtas, "ibm,hypertas-functions",
>                       hypertas->str, hypertas->len));
>      g_string_free(hypertas, TRUE);
> @@ -2046,11 +2051,40 @@ static void ppc_spapr_init(MachineState *machine)
>      hwaddr node0_size = spapr_node0_size();
>      long load_limit, fw_size;
>      char *filename;
> +    Error *resize_hpt_err = NULL;
>  
>      msi_nonbroken = true;
>  
>      QLIST_INIT(&spapr->phbs);
>  
> +    /* Check HPT resizing availability */
> +    kvmppc_check_papr_resize_hpt(&resize_hpt_err);
> +    if (spapr->resize_hpt == SPAPR_RESIZE_HPT_DEFAULT) {
> +        /*
> +         * If the user explicitly requested a mode we should either
> +         * supply it, or fail completely (which we do below).  But if
> +         * it's not set explicitly, we reset our mode to something
> +         * that works
> +         */
> +        if (resize_hpt_err) {
> +            spapr->resize_hpt = SPAPR_RESIZE_HPT_DISABLED;
> +            error_free(resize_hpt_err);
> +            resize_hpt_err = NULL;
> +        } else {
> +            spapr->resize_hpt = smc->resize_hpt_default;
> +        }
> +    }
> +
> +    assert(spapr->resize_hpt != SPAPR_RESIZE_HPT_DEFAULT);
> +
> +    if ((spapr->resize_hpt != SPAPR_RESIZE_HPT_DISABLED) && resize_hpt_err) {
> +        /*
> +         * User requested HPT resize, but this host can't supply it.  Bail 
> out
> +         */
> +        error_report_err(resize_hpt_err);
> +        exit(1);
> +    }
> +
>      /* Allocate RMA if necessary */
>      rma_alloc_size = kvmppc_alloc_rma(&rma);
>  
> @@ -2467,6 +2501,40 @@ static void spapr_set_modern_hotplug_events(Object 
> *obj, bool value,
>      spapr->use_hotplug_event_source = value;
>  }
>  
> +static char *spapr_get_resize_hpt(Object *obj, Error **errp)
> +{
> +    sPAPRMachineState *spapr = SPAPR_MACHINE(obj);
> +
> +    switch (spapr->resize_hpt) {
> +    case SPAPR_RESIZE_HPT_DEFAULT:
> +        return g_strdup("default");
> +    case SPAPR_RESIZE_HPT_DISABLED:
> +        return g_strdup("disabled");
> +    case SPAPR_RESIZE_HPT_ENABLED:
> +        return g_strdup("enabled");
> +    case SPAPR_RESIZE_HPT_REQUIRED:
> +        return g_strdup("required");
> +    }
> +    assert(0);
> +}
> +
> +static void spapr_set_resize_hpt(Object *obj, const char *value, Error 
> **errp)
> +{
> +    sPAPRMachineState *spapr = SPAPR_MACHINE(obj);
> +
> +    if (strcmp(value, "default") == 0) {
> +        spapr->resize_hpt = SPAPR_RESIZE_HPT_DEFAULT;
> +    } else if (strcmp(value, "disabled") == 0) {
> +        spapr->resize_hpt = SPAPR_RESIZE_HPT_DISABLED;
> +    } else if (strcmp(value, "enabled") == 0) {
> +        spapr->resize_hpt = SPAPR_RESIZE_HPT_ENABLED;
> +    } else if (strcmp(value, "required") == 0) {
> +        spapr->resize_hpt = SPAPR_RESIZE_HPT_REQUIRED;
> +    } else {
> +        error_setg(errp, "Bad value for \"resize-hpt\" property");
> +    }
> +}
> +
>  static void spapr_machine_initfn(Object *obj)
>  {
>      sPAPRMachineState *spapr = SPAPR_MACHINE(obj);
> @@ -2487,6 +2555,12 @@ static void spapr_machine_initfn(Object *obj)
>                                      " place of standard EPOW events when 
> possible"
>                                      " (required for memory hot-unplug 
> support)",
>                                      NULL);
> +
> +    object_property_add_str(obj, "resize-hpt",
> +                            spapr_get_resize_hpt, spapr_set_resize_hpt, 
> NULL);
> +    object_property_set_description(obj, "resize-hpt",
> +                                    "Resizing of the Hash Page Table 
> (enabled, disabled, required)",
> +                                    NULL);
>  }
>  
>  static void spapr_machine_finalizefn(Object *obj)
> @@ -3152,6 +3226,7 @@ static void spapr_machine_class_init(ObjectClass *oc, 
> void *data)
>      smc->dr_lmb_enabled = true;
>      smc->tcg_default_cpu = "POWER8";
>      mc->has_hotpluggable_cpus = true;
> +    smc->resize_hpt_default = SPAPR_RESIZE_HPT_DISABLED;
>      fwc->get_dev_path = spapr_get_fw_dev_path;
>      nc->nmi_monitor_handler = spapr_nmi;
>      smc->phb_placement = spapr_phb_placement;
> diff --git a/hw/ppc/spapr_hcall.c b/hw/ppc/spapr_hcall.c
> index 0d608d6..29d549f 100644
> --- a/hw/ppc/spapr_hcall.c
> +++ b/hw/ppc/spapr_hcall.c
> @@ -354,6 +354,38 @@ static target_ulong h_read(PowerPCCPU *cpu, 
> sPAPRMachineState *spapr,
>      return H_SUCCESS;
>  }
>  
> +static target_ulong h_resize_hpt_prepare(PowerPCCPU *cpu,
> +                                         sPAPRMachineState *spapr,
> +                                         target_ulong opcode,
> +                                         target_ulong *args)
> +{
> +    target_ulong flags = args[0];
> +    target_ulong shift = args[1];
> +
> +    if (spapr->resize_hpt == SPAPR_RESIZE_HPT_DISABLED) {
> +        return H_AUTHORITY;
> +    }
> +
> +    trace_spapr_h_resize_hpt_prepare(flags, shift);
> +    return H_HARDWARE;
> +}
> +
> +static target_ulong h_resize_hpt_commit(PowerPCCPU *cpu,
> +                                        sPAPRMachineState *spapr,
> +                                        target_ulong opcode,
> +                                        target_ulong *args)
> +{
> +    target_ulong flags = args[0];
> +    target_ulong shift = args[1];
> +
> +    if (spapr->resize_hpt == SPAPR_RESIZE_HPT_DISABLED) {
> +        return H_AUTHORITY;
> +    }
> +
> +    trace_spapr_h_resize_hpt_commit(flags, shift);
> +    return H_HARDWARE;
> +}
> +
>  static target_ulong h_set_sprg0(PowerPCCPU *cpu, sPAPRMachineState *spapr,
>                                  target_ulong opcode, target_ulong *args)
>  {
> @@ -1233,6 +1265,10 @@ static void hypercall_register_types(void)
>      /* hcall-bulk */
>      spapr_register_hypercall(H_BULK_REMOVE, h_bulk_remove);
>  
> +    /* hcall-hpt-resize */
> +    spapr_register_hypercall(H_RESIZE_HPT_PREPARE, h_resize_hpt_prepare);
> +    spapr_register_hypercall(H_RESIZE_HPT_COMMIT, h_resize_hpt_commit);
> +
>      /* hcall-splpar */
>      spapr_register_hypercall(H_REGISTER_VPA, h_register_vpa);
>      spapr_register_hypercall(H_CEDE, h_cede);
> diff --git a/hw/ppc/trace-events b/hw/ppc/trace-events
> index 43d265f..7c77cc6 100644
> --- a/hw/ppc/trace-events
> +++ b/hw/ppc/trace-events
> @@ -16,6 +16,8 @@ spapr_cas_continue(unsigned long n) "Copy changes to the 
> guest: %ld bytes"
>  # hw/ppc/spapr_hcall.c
>  spapr_cas_pvr_try(uint32_t pvr) "%x"
>  spapr_cas_pvr(uint32_t cur_pvr, bool explicit_match, uint32_t new_pvr) 
> "current=%x, explicit_match=%u, new=%x"
> +spapr_h_resize_hpt_prepare(uint64_t flags, uint64_t shift) 
> "flags=0x%"PRIx64", shift=%"PRIu64
> +spapr_h_resize_hpt_commit(uint64_t flags, uint64_t shift) 
> "flags=0x%"PRIx64", shift=%"PRIu64
>  
>  # hw/ppc/spapr_iommu.c
>  spapr_iommu_put(uint64_t liobn, uint64_t ioba, uint64_t tce, uint64_t ret) 
> "liobn=%"PRIx64" ioba=0x%"PRIx64" tce=0x%"PRIx64" ret=%"PRId64
> diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
> index 5802f88..a1fa801 100644
> --- a/include/hw/ppc/spapr.h
> +++ b/include/hw/ppc/spapr.h
> @@ -42,6 +42,13 @@ typedef struct sPAPRMachineClass sPAPRMachineClass;
>  #define SPAPR_MACHINE_CLASS(klass) \
>      OBJECT_CLASS_CHECK(sPAPRMachineClass, klass, TYPE_SPAPR_MACHINE)
>  
> +typedef enum {
> +    SPAPR_RESIZE_HPT_DEFAULT = 0,
> +    SPAPR_RESIZE_HPT_DISABLED,
> +    SPAPR_RESIZE_HPT_ENABLED,
> +    SPAPR_RESIZE_HPT_REQUIRED,
> +} sPAPRResizeHPT;
> +
>  /**
>   * sPAPRMachineClass:
>   */
> @@ -57,6 +64,7 @@ struct sPAPRMachineClass {
>                            uint64_t *buid, hwaddr *pio, 
>                            hwaddr *mmio32, hwaddr *mmio64,
>                            unsigned n_dma, uint32_t *liobns, Error **errp);
> +    sPAPRResizeHPT resize_hpt_default;
>  };
>  
>  /**
> @@ -72,6 +80,7 @@ struct sPAPRMachineState {
>      ICSState *ics;
>      sPAPRRTCState rtc;
>  
> +    sPAPRResizeHPT resize_hpt;
>      void *htab;
>      uint32_t htab_shift;
>      uint64_t patb_entry; /* Process tbl registed in H_REGISTER_PROCESS_TABLE 
> */
> @@ -361,6 +370,8 @@ struct sPAPRMachineState {
>  #define H_XIRR_X                0x2FC
>  #define H_RANDOM                0x300
>  #define H_SET_MODE              0x31C
> +#define H_RESIZE_HPT_PREPARE    0x36C
> +#define H_RESIZE_HPT_COMMIT     0x370
>  #define H_CLEAN_SLB             0x374
>  #define H_INVALIDATE_PID        0x378
>  #define H_REGISTER_PROC_TBL     0x37C
> diff --git a/target/ppc/kvm.c b/target/ppc/kvm.c
> index 51249ce..7815e01 100644
> --- a/target/ppc/kvm.c
> +++ b/target/ppc/kvm.c
> @@ -22,6 +22,7 @@
>  #include <linux/kvm.h>
>  
>  #include "qemu-common.h"
> +#include "qapi/error.h"
>  #include "qemu/error-report.h"
>  #include "cpu.h"
>  #include "cpu-models.h"
> @@ -2705,3 +2706,14 @@ int kvmppc_enable_hwrng(void)
>  
>      return kvmppc_enable_hcall(kvm_state, H_RANDOM);
>  }
> +
> +void kvmppc_check_papr_resize_hpt(Error **errp)
> +{
> +    if (!kvm_enabled()) {
> +        return;
> +    }
> +
> +    /* TODO: Check for resize-capable KVM implementations */
> +
> +    error_setg(errp, "Hash page table resizing not available with this KVM 
> version");
> +}
> diff --git a/target/ppc/kvm_ppc.h b/target/ppc/kvm_ppc.h
> index f48243d..1054be4 100644
> --- a/target/ppc/kvm_ppc.h
> +++ b/target/ppc/kvm_ppc.h
> @@ -63,6 +63,7 @@ bool kvmppc_has_cap_mmu_hash_v3(void);
>  int kvmppc_enable_hwrng(void);
>  int kvmppc_put_books_sregs(PowerPCCPU *cpu);
>  PowerPCCPUClass *kvm_ppc_get_host_cpu_class(void);
> +void kvmppc_check_papr_resize_hpt(Error **errp);
>  
>  bool kvmppc_is_mem_backend_page_size_ok(char *obj_path);
>  
> @@ -297,6 +298,10 @@ static inline PowerPCCPUClass 
> *kvm_ppc_get_host_cpu_class(void)
>      return NULL;
>  }
>  
> +static inline void kvmppc_check_papr_resize_hpt(Error **errp)
> +{
> +    return;
> +}
>  #endif
>  
>  #ifndef CONFIG_KVM
>