diff mbox series

[v9,09/10] target/ppc: PMU Event-Based exception support

Message ID 20211201151734.654994-10-danielhb413@gmail.com
State Changes Requested
Headers show
Series PMU-EBB support for PPC64 TCG | expand

Commit Message

Daniel Henrique Barboza Dec. 1, 2021, 3:17 p.m. UTC
From: Gustavo Romero <gromero@linux.ibm.com>

Following up the rfebb implementation, this patch adds the EBB exception
support that are triggered by Performance Monitor alerts. This exception
occurs when an enabled PMU condition or event happens and both MMCR0_EBE
and BESCR_PME are set.

The supported PM alerts will consist of counter negative conditions of
the PMU counters. This will be achieved by a timer mechanism that will
predict when a counter becomes negative. The PMU timer callback will set
the appropriate bits in MMCR0 and fire a PMC interrupt. The EBB
exception code will then set the appropriate BESCR bits, set the next
instruction pointer to the address pointed by the return register
(SPR_EBBRR), and redirect execution to the handler (pointed by
SPR_EBBHR).

CC: Gustavo Romero <gustavo.romero@linaro.org>
Signed-off-by: Gustavo Romero <gromero@linux.ibm.com>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
---
 target/ppc/cpu.h         |  5 ++++-
 target/ppc/excp_helper.c | 29 +++++++++++++++++++++++++++++
 target/ppc/power8-pmu.c  | 40 ++++++++++++++++++++++++++++++++++++++--
 3 files changed, 71 insertions(+), 3 deletions(-)

Comments

Cédric Le Goater Dec. 3, 2021, 9:27 a.m. UTC | #1
Hello,

On 12/1/21 16:17, Daniel Henrique Barboza wrote:
> From: Gustavo Romero <gromero@linux.ibm.com>
> 
> Following up the rfebb implementation, this patch adds the EBB exception
> support that are triggered by Performance Monitor alerts. This exception
> occurs when an enabled PMU condition or event happens and both MMCR0_EBE
> and BESCR_PME are set.
> 
> The supported PM alerts will consist of counter negative conditions of
> the PMU counters. This will be achieved by a timer mechanism that will
> predict when a counter becomes negative. The PMU timer callback will set
> the appropriate bits in MMCR0 and fire a PMC interrupt. The EBB
> exception code will then set the appropriate BESCR bits, set the next
> instruction pointer to the address pointed by the return register
> (SPR_EBBRR), and redirect execution to the handler (pointed by
> SPR_EBBHR).
> 
> CC: Gustavo Romero <gustavo.romero@linaro.org>
> Signed-off-by: Gustavo Romero <gromero@linux.ibm.com>
> Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
> ---
>   target/ppc/cpu.h         |  5 ++++-
>   target/ppc/excp_helper.c | 29 +++++++++++++++++++++++++++++
>   target/ppc/power8-pmu.c  | 40 ++++++++++++++++++++++++++++++++++++++--
>   3 files changed, 71 insertions(+), 3 deletions(-)
> 
> diff --git a/target/ppc/cpu.h b/target/ppc/cpu.h
> index 741b8baf4c..8e0e6319ee 100644
> --- a/target/ppc/cpu.h
> +++ b/target/ppc/cpu.h
> @@ -129,8 +129,10 @@ enum {
>       /* ISA 3.00 additions */
>       POWERPC_EXCP_HVIRT    = 101,
>       POWERPC_EXCP_SYSCALL_VECTORED = 102, /* scv exception                     */
> +    POWERPC_EXCP_EBB = 103, /* Event-based branch exception                  */
> +
>       /* EOL                                                                   */
> -    POWERPC_EXCP_NB       = 103,
> +    POWERPC_EXCP_NB       = 104,
>       /* QEMU exceptions: special cases we want to stop translation            */
>       POWERPC_EXCP_SYSCALL_USER = 0x203, /* System call in user mode only      */
>   };
> @@ -2452,6 +2454,7 @@ enum {
>       PPC_INTERRUPT_HMI,            /* Hypervisor Maintenance interrupt    */
>       PPC_INTERRUPT_HDOORBELL,      /* Hypervisor Doorbell interrupt        */
>       PPC_INTERRUPT_HVIRT,          /* Hypervisor virtualization interrupt  */
> +    PPC_INTERRUPT_PMC,            /* PMU interrupt  */

This is referred as a Performance Monitor event-based exception in ISA.
PPC_INTERRUPT_PM_EBB would be a better name I think.

We also have :

   Load Monitored event-based exceptions
   External event-based exceptions



>   };
>   
>   /* Processor Compatibility mask (PCR) */
> diff --git a/target/ppc/excp_helper.c b/target/ppc/excp_helper.c
> index 7ead32279c..a26d266fe6 100644
> --- a/target/ppc/excp_helper.c
> +++ b/target/ppc/excp_helper.c
> @@ -799,6 +799,23 @@ static inline void powerpc_excp(PowerPCCPU *cpu, int excp_model, int excp)
>           cpu_abort(cs, "Non maskable external exception "
>                     "is not implemented yet !\n");
>           break;
> +    case POWERPC_EXCP_EBB:       /* Event-based branch exception             */
> +        if ((env->spr[SPR_FSCR] & (1ull << FSCR_EBB)) &&
> +            (env->spr[SPR_BESCR] & BESCR_GE) &&
> +            (env->spr[SPR_BESCR] & BESCR_PME)) {


Shouldn't we check these conditions to gate the EBB before sending it ?
What about the HFSCR_EBB case ?


> +            target_ulong nip;
> +
> +            env->spr[SPR_BESCR] &= ~BESCR_GE;   /* Clear GE */
> +            env->spr[SPR_BESCR] |= BESCR_PMEO;  /* Set PMEO */
> +            env->spr[SPR_EBBRR] = env->nip;     /* Save NIP for rfebb insn */
> +            nip = env->spr[SPR_EBBHR];          /* EBB handler */
> +            powerpc_set_excp_state(cpu, nip, env->msr);
> +        }


I am in favor of not adding anything more under the powerpc_excp() routine.
Can we add a helper to isolate the EBB case ? I have the feeling it could
become big.


> +        /*
> +         * This interrupt is handled by userspace. No need
> +         * to proceed.
> +         */
> +        return;
>       default:
>       excp_invalid:
>           cpu_abort(cs, "Invalid PowerPC exception %d. Aborting\n", excp);
> @@ -1046,6 +1063,18 @@ static void ppc_hw_interrupt(CPUPPCState *env)
>               powerpc_excp(cpu, env->excp_model, POWERPC_EXCP_THERM);
>               return;
>           }
> +        /* PMC -> Event-based branch exception */
> +        if (env->pending_interrupts & (1 << PPC_INTERRUPT_PMC)) {
> +            /*
> +             * Performance Monitor event-based exception can only
> +             * occur in problem state.
> +             */

Yes. is the PM EBB exception gated by EE also ?

Thanks,

C.


> +            if (msr_pr == 1) {
> +                env->pending_interrupts &= ~(1 << PPC_INTERRUPT_PMC);
> +                powerpc_excp(cpu, env->excp_model, POWERPC_EXCP_EBB);
> +                return;
> +            }
> +        }
>       }
>   
>       if (env->resume_as_sreset) {
> diff --git a/target/ppc/power8-pmu.c b/target/ppc/power8-pmu.c
> index 08d1902cd5..279b824c3f 100644
> --- a/target/ppc/power8-pmu.c
> +++ b/target/ppc/power8-pmu.c
> @@ -297,6 +297,20 @@ void helper_store_pmc(CPUPPCState *env, uint32_t sprn, uint64_t value)
>       pmc_update_overflow_timer(env, sprn);
>   }
>   
> +static void pmu_delete_timers(CPUPPCState *env)
> +{
> +    QEMUTimer *pmc_overflow_timer;
> +    int sprn;
> +
> +    for (sprn = SPR_POWER_PMC1; sprn <= SPR_POWER_PMC6; sprn++) {
> +        pmc_overflow_timer = get_cyc_overflow_timer(env, sprn);
> +
> +        if (pmc_overflow_timer) {
> +            timer_del(pmc_overflow_timer);
> +        }
> +    }
> +}
> +
>   static void fire_PMC_interrupt(PowerPCCPU *cpu)
>   {
>       CPUPPCState *env = &cpu->env;
> @@ -305,8 +319,30 @@ static void fire_PMC_interrupt(PowerPCCPU *cpu)
>           return;
>       }
>   
> -    /* PMC interrupt not implemented yet */
> -    return;
> +    pmu_update_cycles(env);
> +
> +    if (env->spr[SPR_POWER_MMCR0] & MMCR0_FCECE) {
> +        env->spr[SPR_POWER_MMCR0] &= ~MMCR0_FCECE;
> +        env->spr[SPR_POWER_MMCR0] |= MMCR0_FC;
> +
> +        /* Changing MMCR0_FC demands a new hflags compute */
> +        hreg_compute_hflags(env);
> +
> +        /*
> +         * Delete all pending timers if we need to freeze
> +         * the PMC. We'll restart them when the PMC starts
> +         * running again.
> +         */
> +        pmu_delete_timers(env);
> +    }
> +
> +    if (env->spr[SPR_POWER_MMCR0] & MMCR0_PMAE) {
> +        env->spr[SPR_POWER_MMCR0] &= ~MMCR0_PMAE;
> +        env->spr[SPR_POWER_MMCR0] |= MMCR0_PMAO;
> +    }
> +
> +    /* Fire the PMC hardware exception */
> +    ppc_set_irq(cpu, PPC_INTERRUPT_PMC, 1);
>   }
>   
>   /* This helper assumes that the PMC is running. */
>
David Gibson Dec. 9, 2021, 1:51 a.m. UTC | #2
On Wed, Dec 01, 2021 at 12:17:33PM -0300, Daniel Henrique Barboza wrote:
> From: Gustavo Romero <gromero@linux.ibm.com>
> 
> Following up the rfebb implementation, this patch adds the EBB exception
> support that are triggered by Performance Monitor alerts. This exception
> occurs when an enabled PMU condition or event happens and both MMCR0_EBE
> and BESCR_PME are set.
> 
> The supported PM alerts will consist of counter negative conditions of
> the PMU counters. This will be achieved by a timer mechanism that will
> predict when a counter becomes negative. The PMU timer callback will set
> the appropriate bits in MMCR0 and fire a PMC interrupt. The EBB
> exception code will then set the appropriate BESCR bits, set the next
> instruction pointer to the address pointed by the return register
> (SPR_EBBRR), and redirect execution to the handler (pointed by
> SPR_EBBHR).
> 
> CC: Gustavo Romero <gustavo.romero@linaro.org>
> Signed-off-by: Gustavo Romero <gromero@linux.ibm.com>
> Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
> ---
>  target/ppc/cpu.h         |  5 ++++-
>  target/ppc/excp_helper.c | 29 +++++++++++++++++++++++++++++
>  target/ppc/power8-pmu.c  | 40 ++++++++++++++++++++++++++++++++++++++--
>  3 files changed, 71 insertions(+), 3 deletions(-)
> 
> diff --git a/target/ppc/cpu.h b/target/ppc/cpu.h
> index 741b8baf4c..8e0e6319ee 100644
> --- a/target/ppc/cpu.h
> +++ b/target/ppc/cpu.h
> @@ -129,8 +129,10 @@ enum {
>      /* ISA 3.00 additions */
>      POWERPC_EXCP_HVIRT    = 101,
>      POWERPC_EXCP_SYSCALL_VECTORED = 102, /* scv exception                     */
> +    POWERPC_EXCP_EBB = 103, /* Event-based branch exception                  */
> +
>      /* EOL                                                                   */
> -    POWERPC_EXCP_NB       = 103,
> +    POWERPC_EXCP_NB       = 104,
>      /* QEMU exceptions: special cases we want to stop translation            */
>      POWERPC_EXCP_SYSCALL_USER = 0x203, /* System call in user mode only      */
>  };
> @@ -2452,6 +2454,7 @@ enum {
>      PPC_INTERRUPT_HMI,            /* Hypervisor Maintenance interrupt    */
>      PPC_INTERRUPT_HDOORBELL,      /* Hypervisor Doorbell interrupt        */
>      PPC_INTERRUPT_HVIRT,          /* Hypervisor virtualization interrupt  */
> +    PPC_INTERRUPT_PMC,            /* PMU interrupt  */
>  };

All this low-level exception stuff is very clunky, but addressing
that is not reasonably in scope for this series.  So,

Reviewed-by: David Gibson <david@gibson.dropbear.id.au>

>  
>  /* Processor Compatibility mask (PCR) */
> diff --git a/target/ppc/excp_helper.c b/target/ppc/excp_helper.c
> index 7ead32279c..a26d266fe6 100644
> --- a/target/ppc/excp_helper.c
> +++ b/target/ppc/excp_helper.c
> @@ -799,6 +799,23 @@ static inline void powerpc_excp(PowerPCCPU *cpu, int excp_model, int excp)
>          cpu_abort(cs, "Non maskable external exception "
>                    "is not implemented yet !\n");
>          break;
> +    case POWERPC_EXCP_EBB:       /* Event-based branch exception             */
> +        if ((env->spr[SPR_FSCR] & (1ull << FSCR_EBB)) &&
> +            (env->spr[SPR_BESCR] & BESCR_GE) &&
> +            (env->spr[SPR_BESCR] & BESCR_PME)) {
> +            target_ulong nip;
> +
> +            env->spr[SPR_BESCR] &= ~BESCR_GE;   /* Clear GE */
> +            env->spr[SPR_BESCR] |= BESCR_PMEO;  /* Set PMEO */
> +            env->spr[SPR_EBBRR] = env->nip;     /* Save NIP for rfebb insn */
> +            nip = env->spr[SPR_EBBHR];          /* EBB handler */
> +            powerpc_set_excp_state(cpu, nip, env->msr);
> +        }
> +        /*
> +         * This interrupt is handled by userspace. No need
> +         * to proceed.
> +         */
> +        return;
>      default:
>      excp_invalid:
>          cpu_abort(cs, "Invalid PowerPC exception %d. Aborting\n", excp);
> @@ -1046,6 +1063,18 @@ static void ppc_hw_interrupt(CPUPPCState *env)
>              powerpc_excp(cpu, env->excp_model, POWERPC_EXCP_THERM);
>              return;
>          }
> +        /* PMC -> Event-based branch exception */
> +        if (env->pending_interrupts & (1 << PPC_INTERRUPT_PMC)) {
> +            /*
> +             * Performance Monitor event-based exception can only
> +             * occur in problem state.
> +             */
> +            if (msr_pr == 1) {
> +                env->pending_interrupts &= ~(1 << PPC_INTERRUPT_PMC);
> +                powerpc_excp(cpu, env->excp_model, POWERPC_EXCP_EBB);
> +                return;
> +            }
> +        }
>      }
>  
>      if (env->resume_as_sreset) {
> diff --git a/target/ppc/power8-pmu.c b/target/ppc/power8-pmu.c
> index 08d1902cd5..279b824c3f 100644
> --- a/target/ppc/power8-pmu.c
> +++ b/target/ppc/power8-pmu.c
> @@ -297,6 +297,20 @@ void helper_store_pmc(CPUPPCState *env, uint32_t sprn, uint64_t value)
>      pmc_update_overflow_timer(env, sprn);
>  }
>  
> +static void pmu_delete_timers(CPUPPCState *env)
> +{
> +    QEMUTimer *pmc_overflow_timer;
> +    int sprn;
> +
> +    for (sprn = SPR_POWER_PMC1; sprn <= SPR_POWER_PMC6; sprn++) {
> +        pmc_overflow_timer = get_cyc_overflow_timer(env, sprn);
> +
> +        if (pmc_overflow_timer) {
> +            timer_del(pmc_overflow_timer);
> +        }
> +    }
> +}
> +
>  static void fire_PMC_interrupt(PowerPCCPU *cpu)
>  {
>      CPUPPCState *env = &cpu->env;
> @@ -305,8 +319,30 @@ static void fire_PMC_interrupt(PowerPCCPU *cpu)
>          return;
>      }
>  
> -    /* PMC interrupt not implemented yet */
> -    return;
> +    pmu_update_cycles(env);
> +
> +    if (env->spr[SPR_POWER_MMCR0] & MMCR0_FCECE) {
> +        env->spr[SPR_POWER_MMCR0] &= ~MMCR0_FCECE;
> +        env->spr[SPR_POWER_MMCR0] |= MMCR0_FC;
> +
> +        /* Changing MMCR0_FC demands a new hflags compute */
> +        hreg_compute_hflags(env);
> +
> +        /*
> +         * Delete all pending timers if we need to freeze
> +         * the PMC. We'll restart them when the PMC starts
> +         * running again.
> +         */
> +        pmu_delete_timers(env);
> +    }
> +
> +    if (env->spr[SPR_POWER_MMCR0] & MMCR0_PMAE) {
> +        env->spr[SPR_POWER_MMCR0] &= ~MMCR0_PMAE;
> +        env->spr[SPR_POWER_MMCR0] |= MMCR0_PMAO;
> +    }
> +
> +    /* Fire the PMC hardware exception */
> +    ppc_set_irq(cpu, PPC_INTERRUPT_PMC, 1);
>  }
>  
>  /* This helper assumes that the PMC is running. */
diff mbox series

Patch

diff --git a/target/ppc/cpu.h b/target/ppc/cpu.h
index 741b8baf4c..8e0e6319ee 100644
--- a/target/ppc/cpu.h
+++ b/target/ppc/cpu.h
@@ -129,8 +129,10 @@  enum {
     /* ISA 3.00 additions */
     POWERPC_EXCP_HVIRT    = 101,
     POWERPC_EXCP_SYSCALL_VECTORED = 102, /* scv exception                     */
+    POWERPC_EXCP_EBB = 103, /* Event-based branch exception                  */
+
     /* EOL                                                                   */
-    POWERPC_EXCP_NB       = 103,
+    POWERPC_EXCP_NB       = 104,
     /* QEMU exceptions: special cases we want to stop translation            */
     POWERPC_EXCP_SYSCALL_USER = 0x203, /* System call in user mode only      */
 };
@@ -2452,6 +2454,7 @@  enum {
     PPC_INTERRUPT_HMI,            /* Hypervisor Maintenance interrupt    */
     PPC_INTERRUPT_HDOORBELL,      /* Hypervisor Doorbell interrupt        */
     PPC_INTERRUPT_HVIRT,          /* Hypervisor virtualization interrupt  */
+    PPC_INTERRUPT_PMC,            /* PMU interrupt  */
 };
 
 /* Processor Compatibility mask (PCR) */
diff --git a/target/ppc/excp_helper.c b/target/ppc/excp_helper.c
index 7ead32279c..a26d266fe6 100644
--- a/target/ppc/excp_helper.c
+++ b/target/ppc/excp_helper.c
@@ -799,6 +799,23 @@  static inline void powerpc_excp(PowerPCCPU *cpu, int excp_model, int excp)
         cpu_abort(cs, "Non maskable external exception "
                   "is not implemented yet !\n");
         break;
+    case POWERPC_EXCP_EBB:       /* Event-based branch exception             */
+        if ((env->spr[SPR_FSCR] & (1ull << FSCR_EBB)) &&
+            (env->spr[SPR_BESCR] & BESCR_GE) &&
+            (env->spr[SPR_BESCR] & BESCR_PME)) {
+            target_ulong nip;
+
+            env->spr[SPR_BESCR] &= ~BESCR_GE;   /* Clear GE */
+            env->spr[SPR_BESCR] |= BESCR_PMEO;  /* Set PMEO */
+            env->spr[SPR_EBBRR] = env->nip;     /* Save NIP for rfebb insn */
+            nip = env->spr[SPR_EBBHR];          /* EBB handler */
+            powerpc_set_excp_state(cpu, nip, env->msr);
+        }
+        /*
+         * This interrupt is handled by userspace. No need
+         * to proceed.
+         */
+        return;
     default:
     excp_invalid:
         cpu_abort(cs, "Invalid PowerPC exception %d. Aborting\n", excp);
@@ -1046,6 +1063,18 @@  static void ppc_hw_interrupt(CPUPPCState *env)
             powerpc_excp(cpu, env->excp_model, POWERPC_EXCP_THERM);
             return;
         }
+        /* PMC -> Event-based branch exception */
+        if (env->pending_interrupts & (1 << PPC_INTERRUPT_PMC)) {
+            /*
+             * Performance Monitor event-based exception can only
+             * occur in problem state.
+             */
+            if (msr_pr == 1) {
+                env->pending_interrupts &= ~(1 << PPC_INTERRUPT_PMC);
+                powerpc_excp(cpu, env->excp_model, POWERPC_EXCP_EBB);
+                return;
+            }
+        }
     }
 
     if (env->resume_as_sreset) {
diff --git a/target/ppc/power8-pmu.c b/target/ppc/power8-pmu.c
index 08d1902cd5..279b824c3f 100644
--- a/target/ppc/power8-pmu.c
+++ b/target/ppc/power8-pmu.c
@@ -297,6 +297,20 @@  void helper_store_pmc(CPUPPCState *env, uint32_t sprn, uint64_t value)
     pmc_update_overflow_timer(env, sprn);
 }
 
+static void pmu_delete_timers(CPUPPCState *env)
+{
+    QEMUTimer *pmc_overflow_timer;
+    int sprn;
+
+    for (sprn = SPR_POWER_PMC1; sprn <= SPR_POWER_PMC6; sprn++) {
+        pmc_overflow_timer = get_cyc_overflow_timer(env, sprn);
+
+        if (pmc_overflow_timer) {
+            timer_del(pmc_overflow_timer);
+        }
+    }
+}
+
 static void fire_PMC_interrupt(PowerPCCPU *cpu)
 {
     CPUPPCState *env = &cpu->env;
@@ -305,8 +319,30 @@  static void fire_PMC_interrupt(PowerPCCPU *cpu)
         return;
     }
 
-    /* PMC interrupt not implemented yet */
-    return;
+    pmu_update_cycles(env);
+
+    if (env->spr[SPR_POWER_MMCR0] & MMCR0_FCECE) {
+        env->spr[SPR_POWER_MMCR0] &= ~MMCR0_FCECE;
+        env->spr[SPR_POWER_MMCR0] |= MMCR0_FC;
+
+        /* Changing MMCR0_FC demands a new hflags compute */
+        hreg_compute_hflags(env);
+
+        /*
+         * Delete all pending timers if we need to freeze
+         * the PMC. We'll restart them when the PMC starts
+         * running again.
+         */
+        pmu_delete_timers(env);
+    }
+
+    if (env->spr[SPR_POWER_MMCR0] & MMCR0_PMAE) {
+        env->spr[SPR_POWER_MMCR0] &= ~MMCR0_PMAE;
+        env->spr[SPR_POWER_MMCR0] |= MMCR0_PMAO;
+    }
+
+    /* Fire the PMC hardware exception */
+    ppc_set_irq(cpu, PPC_INTERRUPT_PMC, 1);
 }
 
 /* This helper assumes that the PMC is running. */