Re: [Xen-devel] [PATCH v2 02/25] x86/cpuid: Introduce struct cpuid_policy

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 09.01.17 at 12:03, <andrew.cooper3@xxxxxxxxxx> wrote:
> @@ -67,6 +80,58 @@ static void __init sanitise_featureset(uint32_t *fs)
>                            (fs[FEATURESET_e1d] & ~CPUID_COMMON_1D_FEATURES));
>  }
>  
> +static void __init calculate_raw_policy(void)
> +{
> +    struct cpuid_policy *p = &raw_policy;
> +    unsigned int i;
> +
> +    cpuid_leaf(0, &p->basic.raw[0]);
> +    for ( i = 1; i < min(ARRAY_SIZE(p->basic.raw),
> +                         p->basic.max_leaf + 1ul); ++i )
> +    {
> +        switch ( i )
> +        {
> +        case 0x2: case 0x4: case 0x7: case 0xd:
> +            /* Multi-invocation leaves.  Deferred. */
> +            continue;
> +        }
> +
> +        cpuid_leaf(i, &p->basic.raw[i]);
> +    }
> +
> +    if ( p->basic.max_leaf >= 7 )
> +    {
> +        cpuid_count_leaf(7, 0, &p->feat.raw[0]);
> +
> +        for ( i = 1; i < min(ARRAY_SIZE(p->feat.raw),
> +                             p->feat.max_subleaf + 1ul); ++i )
> +            cpuid_count_leaf(7, i, &p->feat.raw[i]);
> +    }
> +
> +    if ( p->basic.max_leaf >= 0xd )
> +    {
> +        uint64_t xstates;
> +
> +        cpuid_count_leaf(0xd, 0, &p->xstate.raw[0]);
> +        cpuid_count_leaf(0xd, 1, &p->xstate.raw[1]);
> +
> +        xstates = ((uint64_t)(p->xstate.xcr0_high | p->xstate.xss_high) << 
> 32) |
> +            (p->xstate.xcr0_low | p->xstate.xss_low);
> +
> +        for ( i = 2; i < 63; ++i )

Perhaps better to use ARRAY_SIZE() (or min()) here, too?

> +        {
> +            if ( xstates & (1ul << i) )
> +                cpuid_count_leaf(0xd, i, &p->xstate.raw[i]);
> +        }

Also, overall in this code block I think you should really use
XSTATE_CPUID instead of 0xd.

> +    }
> +
> +    /* Extended leaves. */
> +    cpuid_leaf(0x80000000, &p->extd.raw[0]);
> +    for ( i = 1; i < min(ARRAY_SIZE(p->extd.raw),
> +                         p->extd.max_leaf + 1 - 0x80000000ul); ++i )

Would it be worthwhile to make the code resilient to max_leaf not
having the high bit set?

Once again in any event
Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>

Jan



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