Re: [PATCH 6/7] target/ppc: add support for Hypervisor Facility Unavailable Exception

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

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On Thu, Nov 28, 2019 at 02:46:59PM +0100, Cédric Le Goater wrote:
> The privileged message send and clear instructions (msgsndp & msgclrp)
> are privileged, but will generate a hypervisor facility unavailable
> exception if not enabled in the HFSCR and executed in privileged
> non-hypervisor state.
> 
> Add checks when accessing the DPDES register and when using the
> msgsndp and msgclrp isntructions.
> 
> Based on previous work from Suraj Jitindar Singh.
> 
> Cc: Suraj Jitindar Singh <sjitindarsingh@gmail.com>
> Signed-off-by: Cédric Le Goater <clg@kaod.org>
> ---
>  target/ppc/cpu.h                |  6 ++++++
>  target/ppc/helper.h             |  1 +
>  target/ppc/excp_helper.c        |  9 +++++++++
>  target/ppc/misc_helper.c        | 24 ++++++++++++++++++++++++
>  target/ppc/translate.c          |  4 ++++
>  target/ppc/translate_init.inc.c | 18 ++++++++++++++++++
>  6 files changed, 62 insertions(+)
> 
> diff --git a/target/ppc/cpu.h b/target/ppc/cpu.h
> index 8ffcfa0ea162..52608dfe6ff4 100644
> --- a/target/ppc/cpu.h
> +++ b/target/ppc/cpu.h
> @@ -397,6 +397,10 @@ typedef struct ppc_v3_pate_t {
>  #define PSSCR_ESL         PPC_BIT(42) /* Enable State Loss */
>  #define PSSCR_EC          PPC_BIT(43) /* Exit Criterion */
>  
> +/* HFSCR bits */
> +#define HFSCR_MSGP     PPC_BIT(53) /* Privileged Message Send Facilities */
> +#define HFSCR_IC_MSGP  0xA
> +
>  #define msr_sf   ((env->msr >> MSR_SF)   & 1)
>  #define msr_isf  ((env->msr >> MSR_ISF)  & 1)
>  #define msr_shv  ((env->msr >> MSR_SHV)  & 1)
> @@ -1333,6 +1337,8 @@ void cpu_ppc_set_vhyp(PowerPCCPU *cpu, PPCVirtualHypervisor *vhyp);
>  #endif
>  
>  void store_fpscr(CPUPPCState *env, uint64_t arg, uint32_t mask);
> +void gen_hfscr_facility_check(DisasContext *ctx, int facility_sprn, int bit,
> +                              int sprn, int cause);
>  
>  static inline uint64_t ppc_dump_gpr(CPUPPCState *env, int gprn)
>  {
> diff --git a/target/ppc/helper.h b/target/ppc/helper.h
> index 76518a1df6f0..14c9a30a45c9 100644
> --- a/target/ppc/helper.h
> +++ b/target/ppc/helper.h
> @@ -643,6 +643,7 @@ DEF_HELPER_3(store_dcr, void, env, tl, tl)
>  
>  DEF_HELPER_2(load_dump_spr, void, env, i32)
>  DEF_HELPER_2(store_dump_spr, void, env, i32)
> +DEF_HELPER_4(hfscr_facility_check, void, env, i32, i32, i32)
>  DEF_HELPER_4(fscr_facility_check, void, env, i32, i32, i32)
>  DEF_HELPER_4(msr_facility_check, void, env, i32, i32, i32)
>  DEF_HELPER_FLAGS_1(load_tbl, TCG_CALL_NO_RWG, tl, env)
> diff --git a/target/ppc/excp_helper.c b/target/ppc/excp_helper.c
> index 5a247945e97f..17dad626b74e 100644
> --- a/target/ppc/excp_helper.c
> +++ b/target/ppc/excp_helper.c
> @@ -469,6 +469,15 @@ static inline void powerpc_excp(PowerPCCPU *cpu, int excp_model, int excp)
>      case POWERPC_EXCP_FU:         /* Facility unavailable exception          */
>  #ifdef TARGET_PPC64
>          env->spr[SPR_FSCR] |= ((target_ulong)env->error_code << 56);
> +#endif
> +        break;
> +    case POWERPC_EXCP_HV_FU:     /* Hypervisor Facility Unavailable Exception */
> +#ifdef TARGET_PPC64
> +        env->spr[SPR_HFSCR] |= ((target_ulong)env->error_code << FSCR_IC_POS);
> +        srr0 = SPR_HSRR0;
> +        srr1 = SPR_HSRR1;
> +        new_msr |= (target_ulong)MSR_HVB;
> +        new_msr |= env->msr & ((target_ulong)1 << MSR_RI);
>  #endif
>          break;
>      case POWERPC_EXCP_PIT:       /* Programmable interval timer interrupt    */
> diff --git a/target/ppc/misc_helper.c b/target/ppc/misc_helper.c
> index a0e7bd9c32d3..0cd44c6edd82 100644
> --- a/target/ppc/misc_helper.c
> +++ b/target/ppc/misc_helper.c
> @@ -41,6 +41,17 @@ void helper_store_dump_spr(CPUPPCState *env, uint32_t sprn)
>  }
>  
>  #ifdef TARGET_PPC64
> +static void raise_hv_fu_exception(CPUPPCState *env, uint32_t bit,
> +                                  uint32_t sprn, uint32_t cause,
> +                                  uintptr_t raddr)
> +{
> +    qemu_log("Facility SPR %d is unavailable (SPR HFSCR:%d)\n", sprn, bit);

That looks overly verbose.  Leftover debugging?

> +    env->spr[SPR_HFSCR] &= ~((target_ulong)FSCR_IC_MASK << FSCR_IC_POS);
> +
> +    raise_exception_err_ra(env, POWERPC_EXCP_HV_FU, cause, raddr);
> +}
> +
>  static void raise_fu_exception(CPUPPCState *env, uint32_t bit,
>                                 uint32_t sprn, uint32_t cause,
>                                 uintptr_t raddr)
> @@ -55,6 +66,17 @@ static void raise_fu_exception(CPUPPCState *env, uint32_t bit,
>  }
>  #endif
>  
> +void helper_hfscr_facility_check(CPUPPCState *env, uint32_t bit,
> +                                 uint32_t sprn, uint32_t cause)
> +{
> +#ifdef TARGET_PPC64
> +    if ((env->msr_mask & MSR_HVB) && !msr_hv &&
> +                                     !(env->spr[SPR_HFSCR] & (1UL << bit))) {
> +        raise_hv_fu_exception(env, bit, sprn, cause, GETPC());
> +    }
> +#endif
> +}
> +
>  void helper_fscr_facility_check(CPUPPCState *env, uint32_t bit,
>                                  uint32_t sprn, uint32_t cause)
>  {
> @@ -108,6 +130,8 @@ void helper_store_pcr(CPUPPCState *env, target_ulong value)
>  
>  target_ulong helper_load_dpdes(CPUPPCState *env)
>  {
> +    helper_hfscr_facility_check(env, HFSCR_MSGP, SPR_DPDES,
> +                                HFSCR_IC_MSGP);
>      if (env->pending_interrupts & (1 << PPC_INTERRUPT_DOORBELL)) {
>          return 1;
>      }
> diff --git a/target/ppc/translate.c b/target/ppc/translate.c
> index ba759ab2bb0f..e9e70ca149fd 100644
> --- a/target/ppc/translate.c
> +++ b/target/ppc/translate.c
> @@ -6652,6 +6652,8 @@ static void gen_msgclrp(DisasContext *ctx)
>      GEN_PRIV;
>  #else
>      CHK_SV;
> +    gen_hfscr_facility_check(ctx, SPR_HFSCR, HFSCR_MSGP, 0,
> +                             HFSCR_IC_MSGP);
>      gen_helper_book3s_msgclrp(cpu_env, cpu_gpr[rB(ctx->opcode)]);

Calling a helper for the facility check, then another helper for the
actual instruction is a bit yucky.  I'd prefer if you either call out
for the facility check within the instruction helper, or generate the
instructions necessary for the HFSCR check

>  #endif /* defined(CONFIG_USER_ONLY) */
>  }
> @@ -6662,6 +6664,8 @@ static void gen_msgsndp(DisasContext *ctx)
>      GEN_PRIV;
>  #else
>      CHK_SV;
> +    gen_hfscr_facility_check(ctx, SPR_HFSCR, HFSCR_MSGP, 0,
> +                             HFSCR_IC_MSGP);
>      gen_helper_book3s_msgsndp(cpu_gpr[rB(ctx->opcode)]);
>  #endif /* defined(CONFIG_USER_ONLY) */
>  }
> diff --git a/target/ppc/translate_init.inc.c b/target/ppc/translate_init.inc.c
> index 7c74a763ba66..154e01451270 100644
> --- a/target/ppc/translate_init.inc.c
> +++ b/target/ppc/translate_init.inc.c
> @@ -468,11 +468,15 @@ static void spr_write_pcr(DisasContext *ctx, int sprn, int gprn)
>  /* DPDES */
>  static void spr_read_dpdes(DisasContext *ctx, int gprn, int sprn)
>  {
> +    gen_hfscr_facility_check(ctx, SPR_HFSCR, HFSCR_MSGP, sprn,
> +                             HFSCR_IC_MSGP);
>      gen_helper_load_dpdes(cpu_gpr[gprn], cpu_env);
>  }
>  
>  static void spr_write_dpdes(DisasContext *ctx, int sprn, int gprn)
>  {
> +    gen_hfscr_facility_check(ctx, SPR_HFSCR, HFSCR_MSGP, sprn,
> +                             HFSCR_IC_MSGP);
>      gen_helper_store_dpdes(cpu_env, cpu_gpr[gprn]);
>  }
>  #endif
> @@ -7523,6 +7527,20 @@ POWERPC_FAMILY(e600)(ObjectClass *oc, void *data)
>  #define POWERPC970_HID5_INIT 0x00000000
>  #endif
>  
> +void gen_hfscr_facility_check(DisasContext *ctx, int facility_sprn, int bit,
> +                              int sprn, int cause)
> +{
> +    TCGv_i32 t1 = tcg_const_i32(bit);
> +    TCGv_i32 t2 = tcg_const_i32(sprn);
> +    TCGv_i32 t3 = tcg_const_i32(cause);
> +
> +    gen_helper_hfscr_facility_check(cpu_env, t1, t2, t3);
> +
> +    tcg_temp_free_i32(t3);
> +    tcg_temp_free_i32(t2);
> +    tcg_temp_free_i32(t1);
> +}
> +
>  static void gen_fscr_facility_check(DisasContext *ctx, int facility_sprn,
>                                      int bit, int sprn, int cause)
>  {

-- 
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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