Re: [Xen-devel] [PATCH v2 18/30] x86/cpu: Rework AMD masking MSR setup

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 17/02/16 07:40, Jan Beulich wrote:
>
>> +    if ((rdmsr_amd_safe(msr, &lo, &hi) == 0) &&
>> +        (wrmsr_amd_safe(msr, lo, hi) == 0))
>> +            levelling_caps |= caps;
>> +
>> +    *msr_val = ((uint64_t)hi << 32) | lo;
>> +}
> Why can't this function, currently returning void, simply return the
> value read?

Hmm - it can.  This current layout is an artefact of several changes in
design.

>> +static void __init noinline amd_init_levelling(void)
>>  {
>> -    static unsigned int feat_ecx, feat_edx;
>> -    static unsigned int extfeat_ecx, extfeat_edx;
>> -    static unsigned int l7s0_eax, l7s0_ebx;
>> -    static unsigned int thermal_ecx;
>> -    static bool_t skip_feat, skip_extfeat;
>> -    static bool_t skip_l7s0_eax_ebx, skip_thermal_ecx;
>> -    static enum { not_parsed, no_mask, set_mask } status;
>> -    unsigned int eax, ebx, ecx, edx;
>> -
>> -    if (status == no_mask)
>> -            return;
>> +    const struct cpuidmask *m = NULL;
>>  
>> -    if (status == set_mask)
>> -            goto setmask;
>> +    probe_masking_msrs();
>>  
>> -    ASSERT((status == not_parsed) && (c == &boot_cpu_data));
>> -    status = no_mask;
>> +    if (*opt_famrev != '\0') {
>> +            m = get_cpuidmask(opt_famrev);
>>  
>> -    /* Fam11 doesn't support masking at all. */
>> -    if (c->x86 == 0x11)
>> -            return;
>> +            if (!m)
>> +                    printk("Invalid processor string: %s\n", opt_famrev);
>> +    }
>>  
>> -    if (~(opt_cpuid_mask_ecx & opt_cpuid_mask_edx &
>> -          opt_cpuid_mask_ext_ecx & opt_cpuid_mask_ext_edx &
>> -          opt_cpuid_mask_l7s0_eax & opt_cpuid_mask_l7s0_ebx &
>> -          opt_cpuid_mask_thermal_ecx)) {
>> -            feat_ecx = opt_cpuid_mask_ecx;
>> -            feat_edx = opt_cpuid_mask_edx;
>> -            extfeat_ecx = opt_cpuid_mask_ext_ecx;
>> -            extfeat_edx = opt_cpuid_mask_ext_edx;
>> -            l7s0_eax = opt_cpuid_mask_l7s0_eax;
>> -            l7s0_ebx = opt_cpuid_mask_l7s0_ebx;
>> -            thermal_ecx = opt_cpuid_mask_thermal_ecx;
>> -    } else if (*opt_famrev == '\0') {
>> -            return;
>> -    } else {
>> -            const struct cpuidmask *m = get_cpuidmask(opt_famrev);
>> +    if ((levelling_caps & LCAP_1cd) == LCAP_1cd) {
>> +            uint32_t ecx, edx, tmp;
>>  
>> -            if (!m) {
>> -                    printk("Invalid processor string: %s\n", opt_famrev);
>> -                    printk("CPUID will not be masked\n");
>> -                    return;
>> +            cpuid(0x00000001, &tmp, &tmp, &ecx, &edx);
> Didn't you collect raw CPUID output already?

This is now c_early_init(), which is ahead of populating c->x86_capability

~Andrew

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