Re: [PATCH] target/ppc: Fix test on mmu_model in hreg_compute_hflags_value()

[David Gibson]

On Mon, Jan 24, 2022 at 09:16:09AM +0100, Cédric le Goater wrote:
> POWERPC_MMU_BOOKE is not a mask and should not be tested with a
> bitwise AND operator.
> 
> It went unnoticed because it only impacts the 601 CPU implementation
> for which we don't have a known firmware image.
> 
> Signed-off-by: Cédric Le Goater <clg@kaod.org>

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

The longer term fix, of course, is to entirely get rid of the unholy
mix of enum and bitmask that is mmu_model.

> ---
>  target/ppc/helper_regs.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/target/ppc/helper_regs.c b/target/ppc/helper_regs.c
> index 7dca585dddeb..5b12cb03c961 100644
> --- a/target/ppc/helper_regs.c
> +++ b/target/ppc/helper_regs.c
> @@ -156,7 +156,8 @@ static uint32_t hreg_compute_hflags_value(CPUPPCState 
> *env)
>       */
>      unsigned immu_idx, dmmu_idx;
>      dmmu_idx = msr & (1 << MSR_PR) ? 0 : 1;
> -    if (env->mmu_model & POWERPC_MMU_BOOKE) {
> +    if (env->mmu_model == POWERPC_MMU_BOOKE ||
> +        env->mmu_model == POWERPC_MMU_BOOKE206) {
>          dmmu_idx |= msr & (1 << MSR_GS) ? 4 : 0;
>          immu_idx = dmmu_idx;
>          immu_idx |= msr & (1 << MSR_IS) ? 2 : 0;
> @@ -237,7 +238,8 @@ int hreg_store_msr(CPUPPCState *env, target_ulong value, 
> int alter_hv)
>          ((value >> MSR_DR) & 1) != msr_dr) {
>          cpu_interrupt_exittb(cs);
>      }
> -    if ((env->mmu_model & POWERPC_MMU_BOOKE) &&
> +    if ((env->mmu_model == POWERPC_MMU_BOOKE ||
> +         env->mmu_model == POWERPC_MMU_BOOKE206) &&
>          ((value >> MSR_GS) & 1) != msr_gs) {
>          cpu_interrupt_exittb(cs);
>      }

-- 
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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