Re: [PATCH 1/7] target/ppc: Implement the VTB for HV access

[David Gibson <david@gibson.dropbear.id.au>]

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On Thu, Nov 28, 2019 at 02:46:54PM +0100, Cédric Le Goater wrote:
> From: Suraj Jitindar Singh <sjitindarsingh@gmail.com>
> 
> The virtual timebase register (VTB) is a 64-bit register which
> increments at the same rate as the timebase register, present on POWER8
> and later processors.
> 
> The register is able to be read/written by the hypervisor and read by
> the supervisor. All other accesses are illegal.
> 
> Currently the VTB is just an alias for the timebase (TB) register.
> 
> Implement the VTB so that is can be read/written independent of the TB.
> Make use of the existing method for accessing timebase facilities where
> by the compensation is stored and used to compute the value on reads/is
> updated on writes.
> 
> Signed-off-by: Suraj Jitindar Singh <sjitindarsingh@gmail.com>
> [ clg: rebased on current ppc tree ]
> Signed-off-by: Cédric Le Goater <clg@kaod.org>

Don't we need something to make the VTB migrate correctly?  Or do we
not care because it's only used on pnv which isn't migratable yet?

> ---
>  include/hw/ppc/ppc.h            |  1 +
>  target/ppc/cpu.h                |  2 ++
>  target/ppc/helper.h             |  2 ++
>  hw/ppc/ppc.c                    | 16 ++++++++++++++++
>  linux-user/ppc/cpu_loop.c       |  5 +++++
>  target/ppc/timebase_helper.c    | 10 ++++++++++
>  target/ppc/translate_init.inc.c | 19 +++++++++++++++----
>  7 files changed, 51 insertions(+), 4 deletions(-)
> 
> diff --git a/include/hw/ppc/ppc.h b/include/hw/ppc/ppc.h
> index 585be6ab98c5..02481cd27c36 100644
> --- a/include/hw/ppc/ppc.h
> +++ b/include/hw/ppc/ppc.h
> @@ -24,6 +24,7 @@ struct ppc_tb_t {
>      /* Time base management */
>      int64_t  tb_offset;    /* Compensation                    */
>      int64_t  atb_offset;   /* Compensation                    */
> +    int64_t  vtb_offset;
>      uint32_t tb_freq;      /* TB frequency                    */
>      /* Decrementer management */
>      uint64_t decr_next;    /* Tick for next decr interrupt    */
> diff --git a/target/ppc/cpu.h b/target/ppc/cpu.h
> index e3e82327b723..19d6e724bb5a 100644
> --- a/target/ppc/cpu.h
> +++ b/target/ppc/cpu.h
> @@ -1305,6 +1305,8 @@ uint64_t cpu_ppc_load_atbl(CPUPPCState *env);
>  uint32_t cpu_ppc_load_atbu(CPUPPCState *env);
>  void cpu_ppc_store_atbl(CPUPPCState *env, uint32_t value);
>  void cpu_ppc_store_atbu(CPUPPCState *env, uint32_t value);
> +uint64_t cpu_ppc_load_vtb(CPUPPCState *env);
> +void cpu_ppc_store_vtb(CPUPPCState *env, uint64_t value);
>  bool ppc_decr_clear_on_delivery(CPUPPCState *env);
>  target_ulong cpu_ppc_load_decr(CPUPPCState *env);
>  void cpu_ppc_store_decr(CPUPPCState *env, target_ulong value);
> diff --git a/target/ppc/helper.h b/target/ppc/helper.h
> index f843814b8aa8..a5f53bb421a7 100644
> --- a/target/ppc/helper.h
> +++ b/target/ppc/helper.h
> @@ -649,6 +649,7 @@ DEF_HELPER_FLAGS_1(load_tbl, TCG_CALL_NO_RWG, tl, env)
>  DEF_HELPER_FLAGS_1(load_tbu, TCG_CALL_NO_RWG, tl, env)
>  DEF_HELPER_FLAGS_1(load_atbl, TCG_CALL_NO_RWG, tl, env)
>  DEF_HELPER_FLAGS_1(load_atbu, TCG_CALL_NO_RWG, tl, env)
> +DEF_HELPER_FLAGS_1(load_vtb, TCG_CALL_NO_RWG, tl, env)
>  DEF_HELPER_FLAGS_1(load_601_rtcl, TCG_CALL_NO_RWG, tl, env)
>  DEF_HELPER_FLAGS_1(load_601_rtcu, TCG_CALL_NO_RWG, tl, env)
>  #if !defined(CONFIG_USER_ONLY)
> @@ -669,6 +670,7 @@ DEF_HELPER_FLAGS_1(load_decr, TCG_CALL_NO_RWG, tl, env)
>  DEF_HELPER_FLAGS_2(store_decr, TCG_CALL_NO_RWG, void, env, tl)
>  DEF_HELPER_FLAGS_1(load_hdecr, TCG_CALL_NO_RWG, tl, env)
>  DEF_HELPER_FLAGS_2(store_hdecr, TCG_CALL_NO_RWG, void, env, tl)
> +DEF_HELPER_FLAGS_2(store_vtb, TCG_CALL_NO_RWG, void, env, tl)
>  DEF_HELPER_2(store_hid0_601, void, env, tl)
>  DEF_HELPER_3(store_403_pbr, void, env, i32, tl)
>  DEF_HELPER_FLAGS_1(load_40x_pit, TCG_CALL_NO_RWG, tl, env)
> diff --git a/hw/ppc/ppc.c b/hw/ppc/ppc.c
> index 8dd982fc1e40..263922052536 100644
> --- a/hw/ppc/ppc.c
> +++ b/hw/ppc/ppc.c
> @@ -694,6 +694,22 @@ void cpu_ppc_store_atbu (CPUPPCState *env, uint32_t value)
>                       &tb_env->atb_offset, ((uint64_t)value << 32) | tb);
>  }
>  
> +uint64_t cpu_ppc_load_vtb(CPUPPCState *env)
> +{
> +    ppc_tb_t *tb_env = env->tb_env;
> +
> +    return cpu_ppc_get_tb(tb_env, qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL),
> +                          tb_env->vtb_offset);
> +}
> +
> +void cpu_ppc_store_vtb(CPUPPCState *env, uint64_t value)
> +{
> +    ppc_tb_t *tb_env = env->tb_env;
> +
> +    cpu_ppc_store_tb(tb_env, qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL),
> +                     &tb_env->vtb_offset, value);
> +}
> +
>  static void cpu_ppc_tb_stop (CPUPPCState *env)
>  {
>      ppc_tb_t *tb_env = env->tb_env;
> diff --git a/linux-user/ppc/cpu_loop.c b/linux-user/ppc/cpu_loop.c
> index d5704def2902..5b27f8603e33 100644
> --- a/linux-user/ppc/cpu_loop.c
> +++ b/linux-user/ppc/cpu_loop.c
> @@ -47,6 +47,11 @@ uint32_t cpu_ppc_load_atbu(CPUPPCState *env)
>      return cpu_ppc_get_tb(env) >> 32;
>  }
>  
> +uint64_t cpu_ppc_load_vtb(CPUPPCState *env)
> +{
> +    return cpu_ppc_get_tb(env);
> +}
> +
>  uint32_t cpu_ppc601_load_rtcu(CPUPPCState *env)
>  __attribute__ (( alias ("cpu_ppc_load_tbu") ));
>  
> diff --git a/target/ppc/timebase_helper.c b/target/ppc/timebase_helper.c
> index 73363e08ae71..8c3c2fe67c2c 100644
> --- a/target/ppc/timebase_helper.c
> +++ b/target/ppc/timebase_helper.c
> @@ -45,6 +45,11 @@ target_ulong helper_load_atbu(CPUPPCState *env)
>      return cpu_ppc_load_atbu(env);
>  }
>  
> +target_ulong helper_load_vtb(CPUPPCState *env)
> +{
> +    return cpu_ppc_load_vtb(env);
> +}
> +
>  #if defined(TARGET_PPC64) && !defined(CONFIG_USER_ONLY)
>  target_ulong helper_load_purr(CPUPPCState *env)
>  {
> @@ -113,6 +118,11 @@ void helper_store_hdecr(CPUPPCState *env, target_ulong val)
>      cpu_ppc_store_hdecr(env, val);
>  }
>  
> +void helper_store_vtb(CPUPPCState *env, target_ulong val)
> +{
> +    cpu_ppc_store_vtb(env, val);
> +}
> +
>  target_ulong helper_load_40x_pit(CPUPPCState *env)
>  {
>      return load_40x_pit(env);
> diff --git a/target/ppc/translate_init.inc.c b/target/ppc/translate_init.inc.c
> index ba726dec4d00..5a560164d4a4 100644
> --- a/target/ppc/translate_init.inc.c
> +++ b/target/ppc/translate_init.inc.c
> @@ -312,6 +312,16 @@ static void spr_write_hdecr(DisasContext *ctx, int sprn, int gprn)
>      }
>  }
>  
> +static void spr_read_vtb(DisasContext *ctx, int gprn, int sprn)
> +{
> +    gen_helper_load_vtb(cpu_gpr[gprn], cpu_env);
> +}
> +
> +static void spr_write_vtb(DisasContext *ctx, int sprn, int gprn)
> +{
> +    gen_helper_store_vtb(cpu_env, cpu_gpr[gprn]);
> +}
> +
>  #endif
>  #endif
>  
> @@ -8169,10 +8179,11 @@ static void gen_spr_power8_ebb(CPUPPCState *env)
>  /* Virtual Time Base */
>  static void gen_spr_vtb(CPUPPCState *env)
>  {
> -    spr_register_kvm(env, SPR_VTB, "VTB",
> -                 SPR_NOACCESS, SPR_NOACCESS,
> -                 &spr_read_tbl, SPR_NOACCESS,
> -                 KVM_REG_PPC_VTB, 0x00000000);
> +    spr_register_kvm_hv(env, SPR_VTB, "VTB",
> +                        SPR_NOACCESS, SPR_NOACCESS,
> +                        &spr_read_vtb, SPR_NOACCESS,
> +                        &spr_read_vtb, &spr_write_vtb,
> +                        KVM_REG_PPC_VTB, 0x00000000);
>  }
>  
>  static void gen_spr_power8_fscr(CPUPPCState *env)

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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