Re: [Qemu-ppc] [PATCH v4] Enable kvm emulated watchdog

[Alexander Graf]

On 08.02.2013, at 11:04, Bharat Bhushan wrote:

> Enable the KVM emulated watchdog if KVM supports (use the
> capability enablement in watchdog handler). Also watchdog exit
> (KVM_EXIT_WATCHDOG) handling is added.
> Watchdog state machine is cleared whenever VM state changes to running.
> This is to handle the cases like return from debug halt etc.
> 
> Signed-off-by: Bharat Bhushan <address@hidden>
> ---
> hw/ppc_booke.c       |   43 +++++++++++++++++++++-
> target-ppc/kvm.c     |   99 ++++++++++++++++++++++++++++++++++++++++++++++++++
> target-ppc/kvm_ppc.h |   33 +++++++++++++++++
> 3 files changed, 173 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/ppc_booke.c b/hw/ppc_booke.c
> index 25a4e91..1eb8415 100644
> --- a/hw/ppc_booke.c
> +++ b/hw/ppc_booke.c
> @@ -28,7 +28,7 @@
> #include "nvram.h"
> #include "qemu/log.h"
> #include "loader.h"
> -
> +#include "kvm_ppc.h"
> 
> /* Timer Control Register */
> 
> @@ -211,6 +211,7 @@ void store_booke_tsr(CPUPPCState *env, target_ulong val)
>     PowerPCCPU *cpu = ppc_env_get_cpu(env);
> 
>     env->spr[SPR_BOOKE_TSR] &= ~val;
> +    kvmppc_clear_tsr_bits(cpu, val);
>     booke_update_irq(cpu);
> }
> 
> @@ -222,6 +223,7 @@ void store_booke_tcr(CPUPPCState *env, target_ulong val)
> 
>     tb_env = env->tb_env;
>     env->spr[SPR_BOOKE_TCR] = val;
> +    kvmppc_set_tcr(cpu);
> 
>     booke_update_irq(cpu);
> 
> @@ -234,7 +236,6 @@ void store_booke_tcr(CPUPPCState *env, target_ulong val)
>                              booke_get_wdt_target(env, tb_env),
>                              &booke_timer->wdt_next,
>                              booke_timer->wdt_timer);
> -
> }
> 
> static void ppc_booke_timer_reset_handle(void *opaque)
> @@ -244,14 +245,40 @@ static void ppc_booke_timer_reset_handle(void *opaque)
> 
>     env->spr[SPR_BOOKE_TSR] = 0;
>     env->spr[SPR_BOOKE_TCR] = 0;
> +    kvmppc_sync_set_timer_regs(cpu);

If you replace the direct spr access with

store_booke_tcr(env, 0);
store_booke_tsr(env, -1);

then you should automatically get the kvm updates for free, no? Reset is not 
timing critical, so optimizing this path is useless.

> 
>     booke_update_irq(cpu);
> }
> 
> +/*
> + * This function will be called whenever the CPU state changes.
> + * CPU states are defined "typedef enum RunState".
> + * Regarding timer, When CPU state changes to running after debug halt
> + * or similar cases which takes time then in between final watchdog
> + * expiry happenes. This will cause exit to QEMU and configured watchdog
> + * action will be taken. To avoid this we always clear the watchdog state 
> when
> + * state changes to running.
> + */
> +static void cpu_state_change_handler(void *opaque, int running, RunState 
> state)
> +{
> +    PowerPCCPU *cpu = opaque;
> +    CPUPPCState *env = &cpu->env;
> +
> +    if (!running) {
> +        return;
> +    }
> +
> +    /*
> +     * Clear watchdog interrupt condition by clearing TSR.
> +     */
> +    store_booke_tsr(env, TSR_ENW | TSR_WIS | TSR_WRS_MASK);
> +}
> +
> void ppc_booke_timers_init(PowerPCCPU *cpu, uint32_t freq, uint32_t flags)
> {
>     ppc_tb_t *tb_env;
>     booke_timer_t *booke_timer;
> +    int ret = 0;
> 
>     tb_env      = g_malloc0(sizeof(ppc_tb_t));
>     booke_timer = g_malloc0(sizeof(booke_timer_t));
> @@ -269,5 +296,17 @@ void ppc_booke_timers_init(PowerPCCPU *cpu, uint32_t 
> freq, uint32_t flags)
>     booke_timer->wdt_timer =
>         qemu_new_timer_ns(vm_clock, &booke_wdt_cb, cpu);
> 
> +    ret = kvmppc_booke_watchdog_enable(cpu);
> +
> +    if (ret) {
> +        /* TODO: Start the QEMU emulated watchdog if not running on KVM.
> +         * Also start the QEMU emulated watchdog if KVM does not support
> +         * emulated watchdog or somehow it is not enabled (supported but
> +         * not enabled is though some bug and requires debugging :)).
> +         */
> +    }
> +
> +    qemu_add_vm_change_state_handler(cpu_state_change_handler, cpu);
> +
>     qemu_register_reset(ppc_booke_timer_reset_handle, cpu);
> }
> diff --git a/target-ppc/kvm.c b/target-ppc/kvm.c
> index 2c64c63..d0898f5 100644
> --- a/target-ppc/kvm.c
> +++ b/target-ppc/kvm.c
> @@ -36,6 +36,7 @@
> #include "hw/sysbus.h"
> #include "hw/spapr.h"
> #include "hw/spapr_vio.h"
> +#include "hw/watchdog.h"
> 
> //#define DEBUG_KVM
> 
> @@ -61,6 +62,7 @@ static int cap_ppc_smt;
> static int cap_ppc_rma;
> static int cap_spapr_tce;
> static int cap_hior;
> +static int cap_ppc_watchdog;
> 
> /* XXX We have a race condition where we actually have a level triggered
>  *     interrupt, but the infrastructure can't expose that yet, so the guest
> @@ -90,6 +92,7 @@ int kvm_arch_init(KVMState *s)
>     cap_ppc_rma = kvm_check_extension(s, KVM_CAP_PPC_RMA);
>     cap_spapr_tce = kvm_check_extension(s, KVM_CAP_SPAPR_TCE);
>     cap_hior = kvm_check_extension(s, KVM_CAP_PPC_HIOR);
> +    cap_ppc_watchdog = kvm_check_extension(s, KVM_CAP_PPC_BOOKE_WATCHDOG);
> 
>     if (!cap_interrupt_level) {
>         fprintf(stderr, "KVM: Couldn't find level irq capability. Expect the "
> @@ -856,6 +859,12 @@ int kvm_arch_handle_exit(CPUState *cs, struct kvm_run 
> *run)
>         run->epr.epr = ldl_phys(env->mpic_iack);
>         ret = 0;
>         break;
> +    case KVM_EXIT_WATCHDOG:
> +        dprintf("handle watchdog expiry\n");
> +        watchdog_perform_action();
> +        ret = 0;
> +        break;
> +
>     default:
>         fprintf(stderr, "KVM: unknown exit reason %d\n", run->exit_reason);
>         ret = -1;
> @@ -865,6 +874,96 @@ int kvm_arch_handle_exit(CPUState *cs, struct kvm_run 
> *run)
>     return ret;
> }
> 
> +void kvmppc_sync_get_timer_regs(PowerPCCPU *cpu)
> +{
> +    CPUPPCState *env = &cpu->env;
> +    if (kvm_enabled()) {
> +        cpu_synchronize_state(env);
> +    }
> +}

unused function


Alex

> +
> +int kvmppc_sync_set_timer_regs(PowerPCCPU *cpu)
> +{
> +    CPUPPCState *env = &cpu->env;
> +    CPUState *cs = CPU(cpu);
> +    struct kvm_sregs sregs;
> +
> +    if (!kvm_enabled() || !cap_booke_sregs) {
> +        return -1;
> +    }
> +
> +    sregs.u.e.tsr = env->spr[SPR_BOOKE_TSR];
> +    sregs.u.e.tcr = env->spr[SPR_BOOKE_TCR];
> +    sregs.u.e.update_special = KVM_SREGS_E_BASE | KVM_SREGS_E_UPDATE_TSR;
> +
> +    return kvm_vcpu_ioctl(cs, KVM_SET_SREGS, &sregs);
> +}
> +
> +int kvmppc_or_tsr_bits(PowerPCCPU *cpu, uint32_t tsr_bits)
> +{
> +    CPUState *cs = CPU(cpu);
> +    uint32_t bits = tsr_bits;
> +    struct kvm_one_reg reg = {
> +        .id = KVM_REG_PPC_OR_TSR,
> +        .addr = (uintptr_t) &bits,
> +    };
> +
> +    return kvm_vcpu_ioctl(cs, KVM_SET_ONE_REG, &reg);
> +}
> +
> +int kvmppc_clear_tsr_bits(PowerPCCPU *cpu, uint32_t tsr_bits)
> +{
> +
> +    CPUState *cs = CPU(cpu);
> +    uint32_t bits = tsr_bits;
> +    struct kvm_one_reg reg = {
> +        .id = KVM_REG_PPC_CLEAR_TSR,
> +        .addr = (uintptr_t) &bits,
> +    };
> +
> +    return kvm_vcpu_ioctl(cs, KVM_SET_ONE_REG, &reg);
> +}
> +
> +int kvmppc_set_tcr(PowerPCCPU *cpu)
> +{
> +    CPUState *cs = CPU(cpu);
> +    CPUPPCState *env = &cpu->env;
> +    uint32_t tcr = env->spr[SPR_BOOKE_TCR];
> +
> +    struct kvm_one_reg reg = {
> +        .id = KVM_REG_PPC_SET_TCR,
> +        .addr = (uintptr_t) &tcr,
> +    };
> +
> +    return kvm_vcpu_ioctl(cs, KVM_SET_ONE_REG, &reg);
> +}
> +
> +int kvmppc_booke_watchdog_enable(PowerPCCPU *cpu)
> +{
> +    CPUState *cs = CPU(cpu);
> +    struct kvm_enable_cap encap = {};
> +    int ret;
> +
> +    if (!kvm_enabled()) {
> +        return -1;
> +    }
> +
> +    if (!cap_ppc_watchdog) {
> +        printf("warning: KVM does not support watchdog");
> +        return -1;
> +    }
> +
> +    encap.cap = KVM_CAP_PPC_BOOKE_WATCHDOG;
> +    ret = kvm_vcpu_ioctl(cs, KVM_ENABLE_CAP, &encap);
> +    if (ret < 0) {
> +        fprintf(stderr, "%s: couldn't enable KVM_CAP_PPC_BOOKE_WATCHDOG: 
> %s\n",
> +                __func__, strerror(-ret));
> +        return ret;
> +    }
> +
> +    return ret;
> +}
> +
> static int read_cpuinfo(const char *field, char *value, int len)
> {
>     FILE *f;
> diff --git a/target-ppc/kvm_ppc.h b/target-ppc/kvm_ppc.h
> index c30b006..f0bf95a 100644
> --- a/target-ppc/kvm_ppc.h
> +++ b/target-ppc/kvm_ppc.h
> @@ -27,6 +27,12 @@ int kvmppc_set_interrupt(PowerPCCPU *cpu, int irq, int 
> level);
> void kvmppc_set_papr(PowerPCCPU *cpu);
> void kvmppc_set_mpic_proxy(PowerPCCPU *cpu, int mpic_proxy);
> int kvmppc_smt_threads(void);
> +void kvmppc_sync_get_timer_regs(PowerPCCPU *cpu);
> +int kvmppc_sync_set_timer_regs(PowerPCCPU *cpu);
> +int kvmppc_clear_tsr_bits(PowerPCCPU *cpu, uint32_t tsr_bits);
> +int kvmppc_or_tsr_bits(PowerPCCPU *cpu, uint32_t tsr_bits);
> +int kvmppc_set_tcr(PowerPCCPU *cpu);
> +int kvmppc_booke_watchdog_enable(PowerPCCPU *cpu);
> #ifndef CONFIG_USER_ONLY
> off_t kvmppc_alloc_rma(const char *name, MemoryRegion *sysmem);
> void *kvmppc_create_spapr_tce(uint32_t liobn, uint32_t window_size, int *pfd);
> @@ -90,6 +96,33 @@ static inline int kvmppc_smt_threads(void)
> {
>     return 1;
> }
> +static void kvmppc_sync_get_timer_regs(PowerPCCPU *cpu)
> +{
> +}
> +
> +static int kvmppc_sync_set_timer_regs(PowerPCCPU *cpu)
> +{
> +    return 0;
> +}
> +
> +int kvmppc_or_tsr_bits(PowerPCCPU *cpu, u32 tsr_bits)
> +{
> +    return 0;
> +}
> +int kvmppc_clear_tsr_bits(PowerPCCPU *cpu, u32 tsr_bits)
> +{
> +    return 0;
> +}
> +
> +int kvmppc_set_tcr(PowerPCCPU *cpu)
> +{
> +    return 0;
> +}
> +
> +static inline int kvmppc_booke_watchdog_enable(PowerPCCPU *cpu)
> +{
> +    return -1;
> +}
> 
> #ifndef CONFIG_USER_ONLY
> static inline off_t kvmppc_alloc_rma(const char *name, MemoryRegion *sysmem)
> -- 
> 1.7.0.4
> 
>