Re: [Qemu-devel] [PATCH v2 01/10] ppc: Fix rfi/rfid/hrfi/... emulation

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

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On Tue, Jun 21, 2016 at 11:48:46PM +0200, Cédric Le Goater wrote:
> From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> 
> This reworks emulation of the various "rfi" variants. I removed
> some masking bits that I couldn't make sense of, the only bit that
> I am aware we should mask here is POW, the CPU's MSR mask should
> take care of the rest.
> 
> This also fixes some problems when running 32-bit userspace under
> a 64-bit kernel.
> 
> This patch broke 32bit OpenBIOS when run under a 970 cpu. A fix was
> proposed here :
> 
>     https://www.coreboot.org/pipermail/openbios/2016-June/009452.html
> 
> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
> [clg: updated the commit log with the reference of the openbios fix ]
> Signed-off-by: Cédric Le Goater <clg@kaod.org>

I'm not comfortable merging this until the openbios change is pulled
back into the qemu tree (submodule and pre-built binary).

Again - sure you don't want to apply this with rfi still enabled for
64-bit for now, letting the rest of this series go in as well, then
clean up the rfi/64 behaviour later?

> ---
> 
>  target-ppc/excp_helper.c | 51 +++++++++++++++++++-----------------------------
>  target-ppc/translate.c   |  8 ++++++++
>  2 files changed, 28 insertions(+), 31 deletions(-)
> 
> diff --git a/target-ppc/excp_helper.c b/target-ppc/excp_helper.c
> index 30e960e30b63..aa0b63f4b0de 100644
> --- a/target-ppc/excp_helper.c
> +++ b/target-ppc/excp_helper.c
> @@ -922,25 +922,20 @@ void helper_store_msr(CPUPPCState *env, target_ulong val)
>      }
>  }
>  
> -static inline void do_rfi(CPUPPCState *env, target_ulong nip, target_ulong msr,
> -                          target_ulong msrm, int keep_msrh)
> +static inline void do_rfi(CPUPPCState *env, target_ulong nip, target_ulong msr)
>  {
>      CPUState *cs = CPU(ppc_env_get_cpu(env));
>  
> +    /* MSR:POW cannot be set by any form of rfi */
> +    msr &= ~(1ULL << MSR_POW);
> +
>  #if defined(TARGET_PPC64)
> -    if (msr_is_64bit(env, msr)) {
> -        nip = (uint64_t)nip;
> -        msr &= (uint64_t)msrm;
> -    } else {
> +    /* Switching to 32-bit ? Crop the nip */
> +    if (!msr_is_64bit(env, msr)) {
>          nip = (uint32_t)nip;
> -        msr = (uint32_t)(msr & msrm);
> -        if (keep_msrh) {
> -            msr |= env->msr & ~((uint64_t)0xFFFFFFFF);
> -        }
>      }
>  #else
>      nip = (uint32_t)nip;
> -    msr &= (uint32_t)msrm;
>  #endif
>      /* XXX: beware: this is false if VLE is supported */
>      env->nip = nip & ~((target_ulong)0x00000003);
> @@ -959,26 +954,24 @@ static inline void do_rfi(CPUPPCState *env, target_ulong nip, target_ulong msr,
>  
>  void helper_rfi(CPUPPCState *env)
>  {
> -    if (env->excp_model == POWERPC_EXCP_BOOKE) {
> -        do_rfi(env, env->spr[SPR_SRR0], env->spr[SPR_SRR1],
> -               ~((target_ulong)0), 0);
> -    } else {
> -        do_rfi(env, env->spr[SPR_SRR0], env->spr[SPR_SRR1],
> -               ~((target_ulong)0x783F0000), 1);
> -    }
> +    do_rfi(env, env->spr[SPR_SRR0], env->spr[SPR_SRR1] & 0xfffffffful);
>  }
>  
> +#define MSR_BOOK3S_MASK
>  #if defined(TARGET_PPC64)
>  void helper_rfid(CPUPPCState *env)
>  {
> -    do_rfi(env, env->spr[SPR_SRR0], env->spr[SPR_SRR1],
> -           ~((target_ulong)0x783F0000), 0);
> +    /* The architeture defines a number of rules for which bits
> +     * can change but in practice, we handle this in hreg_store_msr()
> +     * which will be called by do_rfi(), so there is no need to filter
> +     * here
> +     */
> +    do_rfi(env, env->spr[SPR_SRR0], env->spr[SPR_SRR1]);
>  }
>  
>  void helper_hrfid(CPUPPCState *env)
>  {
> -    do_rfi(env, env->spr[SPR_HSRR0], env->spr[SPR_HSRR1],
> -           ~((target_ulong)0x783F0000), 0);
> +    do_rfi(env, env->spr[SPR_HSRR0], env->spr[SPR_HSRR1]);
>  }
>  #endif
>  
> @@ -986,28 +979,24 @@ void helper_hrfid(CPUPPCState *env)
>  /* Embedded PowerPC specific helpers */
>  void helper_40x_rfci(CPUPPCState *env)
>  {
> -    do_rfi(env, env->spr[SPR_40x_SRR2], env->spr[SPR_40x_SRR3],
> -           ~((target_ulong)0xFFFF0000), 0);
> +    do_rfi(env, env->spr[SPR_40x_SRR2], env->spr[SPR_40x_SRR3]);
>  }
>  
>  void helper_rfci(CPUPPCState *env)
>  {
> -    do_rfi(env, env->spr[SPR_BOOKE_CSRR0], env->spr[SPR_BOOKE_CSRR1],
> -           ~((target_ulong)0), 0);
> +    do_rfi(env, env->spr[SPR_BOOKE_CSRR0], env->spr[SPR_BOOKE_CSRR1]);
>  }
>  
>  void helper_rfdi(CPUPPCState *env)
>  {
>      /* FIXME: choose CSRR1 or DSRR1 based on cpu type */
> -    do_rfi(env, env->spr[SPR_BOOKE_DSRR0], env->spr[SPR_BOOKE_DSRR1],
> -           ~((target_ulong)0), 0);
> +    do_rfi(env, env->spr[SPR_BOOKE_DSRR0], env->spr[SPR_BOOKE_DSRR1]);
>  }
>  
>  void helper_rfmci(CPUPPCState *env)
>  {
>      /* FIXME: choose CSRR1 or MCSRR1 based on cpu type */
> -    do_rfi(env, env->spr[SPR_BOOKE_MCSRR0], env->spr[SPR_BOOKE_MCSRR1],
> -           ~((target_ulong)0), 0);
> +    do_rfi(env, env->spr[SPR_BOOKE_MCSRR0], env->spr[SPR_BOOKE_MCSRR1]);
>  }
>  #endif
>  
> @@ -1045,7 +1034,7 @@ void helper_td(CPUPPCState *env, target_ulong arg1, target_ulong arg2,
>  
>  void helper_rfsvc(CPUPPCState *env)
>  {
> -    do_rfi(env, env->lr, env->ctr, 0x0000FFFF, 0);
> +    do_rfi(env, env->lr, env->ctr & 0x0000FFFF);
>  }
>  
>  /* Embedded.Processor Control */
> diff --git a/target-ppc/translate.c b/target-ppc/translate.c
> index b6894751e8df..81481955a589 100644
> --- a/target-ppc/translate.c
> +++ b/target-ppc/translate.c
> @@ -4087,6 +4087,14 @@ static void gen_rfi(DisasContext *ctx)
>  #if defined(CONFIG_USER_ONLY)
>      gen_inval_exception(ctx, POWERPC_EXCP_PRIV_OPC);
>  #else
> +    /* This instruction doesn't exist anymore on 64-bit server
> +     * processors compliant with arch 2.x
> +     */
> +    if (ctx->insns_flags & PPC_SEGMENT_64B) {
> +        gen_inval_exception(ctx, POWERPC_EXCP_INVAL_INVAL);
> +        return;
> +    }
> +
>      /* Restore CPU state */
>      if (unlikely(ctx->pr)) {
>          gen_inval_exception(ctx, POWERPC_EXCP_PRIV_OPC);

-- 
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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