Re: [Qemu-ppc] [PATCH 7/8] spapr: Move PAPR mode cpu setup fully to spapr code

[Cédric Le Goater]

On 05/03/2018 08:21 AM, David Gibson wrote:
> cpu_ppc_set_papr() does several things:
>     1) it sets up the virtual hypervisor interface
>     2) it prevents the cpu from ever entering hypervisor mode
>     3) it tells KVM that we're emulating a cpu in PAPR mode
> and 4) it configures the LPCR and AMOR (hypervisor privileged registers)
>        so that TCG will behave correctly for PAPR guests, without
>        attempting to emulate the cpu in hypervisor mode
> 
> (1) & (2) make sense for any virtual hypervisor (if another one ever
> exists).
> 
> (3) belongs more properly in the machine type specific to a PAPR guest, so
> move it to spapr_cpu_init().  While we're at it, remove an ugly test on
> kvm_enabled() by making kvmppc_set_papr() a safe no-op on non-KVM.
> 
> (4) also belongs more properly in the machine type specific code.  (4) is
> done by mangling the default values of the SPRs, so that they will be set
> correctly at reset time.  Manipulating usually-static parameters of the cpu
> model like this is kind of ugly, especially since the values used really
> have more to do with the platform than the cpu.
> 
> The spapr code already has places for PAPR specific initializations of
> register state in spapr_cpu_reset(), so move this handling there.
> 
> Signed-off-by: David Gibson <address@hidden>

Reviewed-by: Cédric Le Goater <address@hidden>

> ---
>  hw/ppc/spapr_cpu_core.c     | 36 ++++++++++++++++++++++++++++---
>  target/ppc/cpu.h            |  2 +-
>  target/ppc/kvm.c            |  4 ++++
>  target/ppc/translate_init.c | 42 +------------------------------------
>  4 files changed, 39 insertions(+), 45 deletions(-)
> 
> diff --git a/hw/ppc/spapr_cpu_core.c b/hw/ppc/spapr_cpu_core.c
> index a98c7b04c6..a52ddade5e 100644
> --- a/hw/ppc/spapr_cpu_core.c
> +++ b/hw/ppc/spapr_cpu_core.c
> @@ -28,6 +28,7 @@ static void spapr_cpu_reset(void *opaque)
>      CPUState *cs = CPU(cpu);
>      CPUPPCState *env = &cpu->env;
>      PowerPCCPUClass *pcc = POWERPC_CPU_GET_CLASS(cpu);
> +    target_ulong lpcr;
>  
>      cpu_reset(cs);
>  
> @@ -43,13 +44,42 @@ static void spapr_cpu_reset(void *opaque)
>  
>      env->spr[SPR_HIOR] = 0;
>  
> +    lpcr = env->spr[SPR_LPCR];
> +
> +    /* Set emulated LPCR to not send interrupts to hypervisor. Note that
> +     * under KVM, the actual HW LPCR will be set differently by KVM itself,
> +     * the settings below ensure proper operations with TCG in absence of
> +     * a real hypervisor.
> +     *
> +     * Clearing VPM0 will also cause us to use RMOR in mmu-hash64.c for
> +     * real mode accesses, which thankfully defaults to 0 and isn't
> +     * accessible in guest mode.
> +     */
> +    lpcr &= ~(LPCR_VPM0 | LPCR_VPM1 | LPCR_ISL | LPCR_KBV);
> +    lpcr |= LPCR_LPES0 | LPCR_LPES1;
> +
> +    /* Set RMLS to the max (ie, 16G) */
> +    lpcr &= ~LPCR_RMLS;
> +    lpcr |= 1ull << LPCR_RMLS_SHIFT;
> +
> +    /* Only enable Power-saving mode Exit Cause exceptions on the boot
> +     * CPU. The RTAS command start-cpu will enable them on secondaries.
> +     */
> +    if (cs == first_cpu) {
> +        lpcr |= pcc->lpcr_pm;
> +    }
> +
>      /* Disable Power-saving mode Exit Cause exceptions for the CPU.
>       * This can cause issues when rebooting the guest if a secondary
>       * is awaken */
>      if (cs != first_cpu) {
> -        env->spr[SPR_LPCR] &= ~pcc->lpcr_pm;
> +        lpcr &= ~pcc->lpcr_pm;
>      }
>  
> +    ppc_store_lpcr(cpu, lpcr);
> +
> +    /* Set a full AMOR so guest can use the AMR as it sees fit */
> +    env->spr[SPR_AMOR] = 0xffffffffffffffffull;
>  }
>  
>  void spapr_cpu_set_entry_state(PowerPCCPU *cpu, target_ulong nip, 
> target_ulong r3)
> @@ -74,8 +104,8 @@ static void spapr_cpu_init(sPAPRMachineState *spapr, 
> PowerPCCPU *cpu,
>      /* Set time-base frequency to 512 MHz */
>      cpu_ppc_tb_init(env, SPAPR_TIMEBASE_FREQ);
>  
> -    /* Enable PAPR mode in TCG or KVM */
> -    cpu_ppc_set_papr(cpu, PPC_VIRTUAL_HYPERVISOR(spapr));
> +    cpu_ppc_set_vhyp(cpu, PPC_VIRTUAL_HYPERVISOR(spapr));
> +    kvmppc_set_papr(cpu);
>  
>      qemu_register_reset(spapr_cpu_reset, cpu);
>      spapr_cpu_reset(cpu);
> diff --git a/target/ppc/cpu.h b/target/ppc/cpu.h
> index 2f619f39d3..7ccd2f460e 100644
> --- a/target/ppc/cpu.h
> +++ b/target/ppc/cpu.h
> @@ -1332,7 +1332,7 @@ void store_booke_tcr (CPUPPCState *env, target_ulong 
> val);
>  void store_booke_tsr (CPUPPCState *env, target_ulong val);
>  void ppc_tlb_invalidate_all (CPUPPCState *env);
>  void ppc_tlb_invalidate_one (CPUPPCState *env, target_ulong addr);
> -void cpu_ppc_set_papr(PowerPCCPU *cpu, PPCVirtualHypervisor *vhyp);
> +void cpu_ppc_set_vhyp(PowerPCCPU *cpu, PPCVirtualHypervisor *vhyp);
>  #endif
>  #endif
>  
> diff --git a/target/ppc/kvm.c b/target/ppc/kvm.c
> index 6de59c5b21..28311a98e0 100644
> --- a/target/ppc/kvm.c
> +++ b/target/ppc/kvm.c
> @@ -2090,6 +2090,10 @@ void kvmppc_set_papr(PowerPCCPU *cpu)
>      CPUState *cs = CPU(cpu);
>      int ret;
>  
> +    if (!kvm_enabled()) {
> +        return;
> +    }
> +
>      ret = kvm_vcpu_enable_cap(cs, KVM_CAP_PPC_PAPR, 0);
>      if (ret) {
>          error_report("This vCPU type or KVM version does not support PAPR");
> diff --git a/target/ppc/translate_init.c b/target/ppc/translate_init.c
> index d92a84c622..118631efbe 100644
> --- a/target/ppc/translate_init.c
> +++ b/target/ppc/translate_init.c
> @@ -8882,13 +8882,9 @@ POWERPC_FAMILY(POWER9)(ObjectClass *oc, void *data)
>  }
>  
>  #if !defined(CONFIG_USER_ONLY)
> -void cpu_ppc_set_papr(PowerPCCPU *cpu, PPCVirtualHypervisor *vhyp)
> +void cpu_ppc_set_vhyp(PowerPCCPU *cpu, PPCVirtualHypervisor *vhyp)
>  {
> -    PowerPCCPUClass *pcc = POWERPC_CPU_GET_CLASS(cpu);
>      CPUPPCState *env = &cpu->env;
> -    ppc_spr_t *lpcr = &env->spr_cb[SPR_LPCR];
> -    ppc_spr_t *amor = &env->spr_cb[SPR_AMOR];
> -    CPUState *cs = CPU(cpu);
>  
>      cpu->vhyp = vhyp;
>  
> @@ -8897,42 +8893,6 @@ void cpu_ppc_set_papr(PowerPCCPU *cpu, 
> PPCVirtualHypervisor *vhyp)
>       * hypervisor mode itself
>       */
>      env->msr_mask &= ~MSR_HVB;
> -
> -    /* Set emulated LPCR to not send interrupts to hypervisor. Note that
> -     * under KVM, the actual HW LPCR will be set differently by KVM itself,
> -     * the settings below ensure proper operations with TCG in absence of
> -     * a real hypervisor.
> -     *
> -     * Clearing VPM0 will also cause us to use RMOR in mmu-hash64.c for
> -     * real mode accesses, which thankfully defaults to 0 and isn't
> -     * accessible in guest mode.
> -     */
> -    lpcr->default_value &= ~(LPCR_VPM0 | LPCR_VPM1 | LPCR_ISL | LPCR_KBV);
> -    lpcr->default_value |= LPCR_LPES0 | LPCR_LPES1;
> -
> -    /* Set RMLS to the max (ie, 16G) */
> -    lpcr->default_value &= ~LPCR_RMLS;
> -    lpcr->default_value |= 1ull << LPCR_RMLS_SHIFT;
> -
> -    /* Only enable Power-saving mode Exit Cause exceptions on the boot
> -     * CPU. The RTAS command start-cpu will enable them on secondaries.
> -     */
> -    if (cs == first_cpu) {
> -        lpcr->default_value |= pcc->lpcr_pm;
> -    }
> -
> -    /* We should be followed by a CPU reset but update the active value
> -     * just in case...
> -     */
> -    ppc_store_lpcr(cpu, lpcr->default_value);
> -
> -    /* Set a full AMOR so guest can use the AMR as it sees fit */
> -    env->spr[SPR_AMOR] = amor->default_value = 0xffffffffffffffffull;
> -
> -    /* Tell KVM that we're in PAPR mode */
> -    if (kvm_enabled()) {
> -        kvmppc_set_papr(cpu);
> -    }
>  }
>  
>  #endif /* !defined(CONFIG_USER_ONLY) */
>