Re: [Qemu-devel] [1/3] powerpc: scan_features() updates incorrect bits

[Michael Ellerman]

On Fri, 2016-15-04 at 02:06:13 UTC, Unknown sender due to SPF wrote:
> The real LE feature entry in the ibm_pa_feature struct has the
> wrong number of elements. Instead of checking for byte 5, bit 0,
> we check for byte 0, bit 0, and we also incorrectly update cpu user
> feature bit 5.
> 
> diff --git a/arch/powerpc/kernel/prom.c b/arch/powerpc/kernel/prom.c
> index 7030b03..9a3a7c6 100644
> --- a/arch/powerpc/kernel/prom.c
> +++ b/arch/powerpc/kernel/prom.c
> @@ -158,7 +158,7 @@ static struct ibm_pa_feature {
>       {CPU_FTR_NOEXECUTE, 0, 0,       0, 6, 0},
>       {CPU_FTR_NODSISRALIGN, 0, 0,    1, 1, 1},
>       {0, MMU_FTR_CI_LARGE_PAGE, 0,   1, 2, 0},
> -     {CPU_FTR_REAL_LE, PPC_FEATURE_TRUE_LE, 5, 0, 0},
> +     {CPU_FTR_REAL_LE, PPC_FEATURE_TRUE_LE, 0, 5, 0, 0},

This should be:

> +     {CPU_FTR_REAL_LE, 0, PPC_FEATURE_TRUE_LE, 5, 0, 0},

Because the struct layout is:

static struct ibm_pa_feature {
        unsigned long   cpu_features;   /* CPU_FTR_xxx bit */
        unsigned long   mmu_features;   /* MMU_FTR_xxx bit */
        unsigned int    cpu_user_ftrs;  /* PPC_FEATURE_xxx bit */
        unsigned int    cpu_user_ftrs2; /* PPC_FEATURE2_xxx bit */
        unsigned char   pabyte;         /* byte number in ibm,pa-features */
        unsigned char   pabit;          /* bit number (big-endian) */
        unsigned char   invert;         /* if 1, pa bit set => clear feature */
}


I'll fix it up locally.

cheers