Quoting David Gibson (2016-12-08 20:23:11)
> 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, and logic to check that against availability
> with KVM (only supported with KVM PR for now).
>
> 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 <da...@gibson.dropbear.id.au>
> ---
> hw/ppc/spapr.c | 66
> ++++++++++++++++++++++++++++++++++++++++++++++++++
> hw/ppc/spapr_hcall.c | 36 +++++++++++++++++++++++++++
> hw/ppc/trace-events | 2 ++
> include/hw/ppc/spapr.h | 11 +++++++++
> target-ppc/kvm.c | 26 ++++++++++++++++++++
> target-ppc/kvm_ppc.h | 5 ++++
> 6 files changed, 146 insertions(+)
>
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index 0f25e83..ecb0822 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -760,6 +760,11 @@ 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);
> @@ -1839,11 +1844,31 @@ static void ppc_spapr_init(MachineState *machine)
> long load_limit, fw_size;
> char *filename;
> int smt = kvmppc_smt_threads();
> + 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 (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) {
> + error_report_err(resize_hpt_err);
> + exit(1);
> + }
I'm also a bit confused by this. Aren't semantics that HPT_ENABLED will allow
a fallback to non-resizable HPTs if the feature isn't available (whereas
HPT_REQUIRED won't)? I don't understand how such a fallback can ever be reached
with this check in place.
> +
> /* Allocate RMA if necessary */
> rma_alloc_size = kvmppc_alloc_rma(&rma);
>
> @@ -2236,6 +2261,40 @@ 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);
> @@ -2256,6 +2315,12 @@ 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)
> @@ -2707,6 +2772,7 @@ static void spapr_machine_class_init(ObjectClass *oc,
> void *data)
>
> smc->dr_lmb_enabled = true;
> smc->tcg_default_cpu = "POWER8";
> + smc->resize_hpt_default = SPAPR_RESIZE_HPT_DISABLED;
> mc->query_hotpluggable_cpus = spapr_query_hotpluggable_cpus;
> fwc->get_dev_path = spapr_get_fw_dev_path;
> nc->nmi_monitor_handler = spapr_nmi;
> diff --git a/hw/ppc/spapr_hcall.c b/hw/ppc/spapr_hcall.c
> index fd9f1d4..72a9c4d 100644
> --- a/hw/ppc/spapr_hcall.c
> +++ b/hw/ppc/spapr_hcall.c
> @@ -355,6 +355,38 @@ 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)
> {
> @@ -1134,6 +1166,10 @@ 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 2297ead..bf59a8f 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 cpu_match, uint32_t new_pvr, uint64_t
> pcr) "current=%x, cpu_match=%u, new=%x, compat flags=%"PRIx64
> +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 a2d8964..d2c758b 100644
> --- a/include/hw/ppc/spapr.h
> +++ b/include/hw/ppc/spapr.h
> @@ -31,6 +31,13 @@ typedef struct sPAPRMachineState sPAPRMachineState;
> #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:
> */
> @@ -46,6 +53,7 @@ struct sPAPRMachineClass {
> uint64_t *buid, hwaddr *pio,
> hwaddr *mmio32, hwaddr *mmio64,
> unsigned n_dma, uint32_t *liobns, Error **errp);
> + sPAPRResizeHPT resize_hpt_default;
> };
>
> /**
> @@ -61,6 +69,7 @@ struct sPAPRMachineState {
> XICSState *xics;
> DeviceState *rtc;
>
> + sPAPRResizeHPT resize_hpt;
> void *htab;
> uint32_t htab_shift;
> hwaddr rma_size;
> @@ -347,6 +356,8 @@ 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_SIGNAL_SYS_RESET 0x380
> #define MAX_HCALL_OPCODE H_SIGNAL_SYS_RESET
>
> diff --git a/target-ppc/kvm.c b/target-ppc/kvm.c
> index 15e12f3..dcd8cef 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 "qemu/timer.h"
> @@ -2269,6 +2270,7 @@ int kvmppc_reset_htab(int shift_hint)
> /* Full emulation, tell caller to allocate htab itself */
> return 0;
> }
> +
> if (kvm_check_extension(kvm_state, KVM_CAP_PPC_ALLOC_HTAB)) {
> int ret;
> ret = kvm_vm_ioctl(kvm_state, KVM_PPC_ALLOCATE_HTAB, &shift);
> @@ -2672,3 +2674,27 @@ 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 specific capabilities for HPT resize aware host kernels */
> +
> + /*
> + * It's tempting to try to check directly if the HPT is under our
> + * control or KVM's, which is what's really relevant here.
> + * Unfortunately, in order to correctly size the HPT, we need to
> + * know if we can do resizing, _before_ we attempt to allocate it
> + * with KVM. Before that point, we don't officially know whether
> + * we'll control the HPT or not. So we have to use a fallback
> + * test for PR vs HV KVM to predict that.
> + */
> + if (kvmppc_is_pr(kvm_state)) {
> + return;
> + }
> +
> + 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 841a29b..3e852ba 100644
> --- a/target-ppc/kvm_ppc.h
> +++ b/target-ppc/kvm_ppc.h
> @@ -59,6 +59,7 @@ bool kvmppc_has_cap_htm(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);
>
> #else
>
> @@ -270,6 +271,10 @@ 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
> --
> 2.9.3
>
