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Re: [Xen-devel] [PATCH v2] x86: generic MSRs save/restore



>>> On 16.12.13 at 04:01, "Liu, Jinsong" <jinsong.liu@xxxxxxxxx> wrote:
> Jan Beulich wrote:
>> This patch introduces a generic MSRs save/restore mechanism, so that
>> in the future new MSRs save/restore could be added w/ smaller change
>> than the full blown addition of a new save/restore type.
>> 
>> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
>> 
>> --- a/xen/arch/x86/hvm/hvm.c
>> +++ b/xen/arch/x86/hvm/hvm.c
>> @@ -1127,10 +1127,117 @@ static int hvm_load_cpu_xsave_states(str
>>      return 0;
>>  }
>> 
>> -/* We need variable length data chunk for xsave area, hence
>> customized 
>> - * declaration other than HVM_REGISTER_SAVE_RESTORE.
>> +#define HVM_CPU_MSR_SIZE(cnt) offsetof(struct hvm_msr, msr[cnt])
>> +static unsigned int __read_mostly msr_count_max;
>> +
>> +static int hvm_save_cpu_msrs(struct domain *d, hvm_domain_context_t
>> *h) +{
>> +    struct vcpu *v;
>> +
>> +    for_each_vcpu ( d, v )
>> +    {
>> +        struct hvm_msr *ctxt;
>> +        unsigned int i;
>> +
>> +        if ( _hvm_init_entry(h, CPU_MSR_CODE, v->vcpu_id,
>> +                             HVM_CPU_MSR_SIZE(msr_count_max)) )
>> +            return 1;
>> +        ctxt = (struct hvm_msr *)&h->data[h->cur];
>> +        ctxt->count = 0;
>> +
>> +        if ( hvm_funcs.save_msr )
>> +            hvm_funcs.save_msr(v, ctxt);
>> +
>> +        for ( i = 0; i < ctxt->count; ++i )
>> +            ctxt->msr[i]._rsvd = 0;
>> +
>> +        if ( ctxt->count )
>> +            h->cur += HVM_CPU_MSR_SIZE(ctxt->count);
>> +        else
>> +            h->cur -= sizeof(struct hvm_save_descriptor);
>> +    }
>> +
>> +    return 0;
>> +}
>> +
>> +static int hvm_load_cpu_msrs(struct domain *d, hvm_domain_context_t
>> *h) +{
>> +    unsigned int i, vcpuid = hvm_load_instance(h);
>> +    struct vcpu *v;
>> +    const struct hvm_save_descriptor *desc;
>> +    struct hvm_msr *ctxt;
>> +    int err = 0;
>> +
>> +    if ( vcpuid >= d->max_vcpus || (v = d->vcpu[vcpuid]) == NULL )
>> +    {
>> +        dprintk(XENLOG_G_ERR, "HVM restore: dom%d has no vcpu%u\n",
>> +                d->domain_id, vcpuid);
>> +        return -EINVAL;
>> +    }
>> +
>> +    /* Customized checking for entry since our entry is of variable
>> length */ +    desc = (struct hvm_save_descriptor *)&h->data[h->cur];
>> +    if ( sizeof (*desc) > h->size - h->cur)
>> +    {
>> +        printk(XENLOG_G_WARNING
>> +               "HVM%d.%d restore: not enough data left to read MSR
>> descriptor\n", +               d->domain_id, vcpuid);
>> +        return -ENODATA;
>> +    }
>> +    if ( desc->length + sizeof (*desc) > h->size - h->cur)
>> +    {
>> +        printk(XENLOG_G_WARNING
>> +               "HVM%d.%d restore: not enough data left to read %u
>> MSR bytes\n", +               d->domain_id, vcpuid, desc->length);
>> +        return -ENODATA;
>> +    }
>> +    if ( desc->length < HVM_CPU_MSR_SIZE(1) )
>> +    {
>> +        printk(XENLOG_G_WARNING
>> +               "HVM%d.%d restore mismatch: MSR length %u < %zu\n",
>> +               d->domain_id, vcpuid, desc->length,
>> HVM_CPU_MSR_SIZE(1)); +        return -EINVAL;
>> +    }
>> +
>> +    h->cur += sizeof(*desc);
>> +    ctxt = (struct hvm_msr *)&h->data[h->cur];
>> +    h->cur += desc->length;
>> +
>> +    if ( desc->length != HVM_CPU_MSR_SIZE(ctxt->count) )
>> +    {
>> +        printk(XENLOG_G_WARNING
>> +               "HVM%d.%d restore mismatch: MSR length %u != %zu\n",
>> +               d->domain_id, vcpuid, desc->length,
>> +               HVM_CPU_MSR_SIZE(ctxt->count));
>> +        return -EOPNOTSUPP;
>> +    }
>> +
>> +    for ( i = 0; i < ctxt->count; ++i )
>> +        if ( ctxt->msr[i]._rsvd )
>> +            return -EOPNOTSUPP;
>> +    /* Checking finished */
>> +
>> +    if ( hvm_funcs.load_msr )
>> +        err = hvm_funcs.load_msr(v, ctxt);
>> +
>> +    for ( i = 0; !err && i < ctxt->count; ++i )
>> +    {
>> +        switch ( ctxt->msr[i].index )
>> +        {
>> +        default:
>> +            if ( !ctxt->msr[i]._rsvd )
>> +                err = -ENXIO;
>> +            break;
>> +        }
>> +    }
>> +
>> +    return err;
>> +}
>> +
>> +/* We need variable length data chunks for XSAVE area and MSRs, hence
>> + * a custom declaration rather than HVM_REGISTER_SAVE_RESTORE.
>>   */
>> -static int __init __hvm_register_CPU_XSAVE_save_and_restore(void)
>> +static int __init hvm_register_CPU_save_and_restore(void)
>>  {
>>      hvm_register_savevm(CPU_XSAVE_CODE,
>>                          "CPU_XSAVE",
>> @@ -1139,9 +1246,22 @@ static int __init __hvm_register_CPU_XSA
>>                          HVM_CPU_XSAVE_SIZE(xfeature_mask) +
>>                              sizeof(struct hvm_save_descriptor),
>>                          HVMSR_PER_VCPU);
>> +
>> +    if ( hvm_funcs.init_msr )
>> +        msr_count_max += hvm_funcs.init_msr();
>> +
>> +    if ( msr_count_max )
>> +        hvm_register_savevm(CPU_MSR_CODE,
>> +                            "CPU_MSR",
>> +                            hvm_save_cpu_msrs,
>> +                            hvm_load_cpu_msrs,
>> +                            HVM_CPU_MSR_SIZE(msr_count_max) +
>> +                                sizeof(struct hvm_save_descriptor),
>> +                            HVMSR_PER_VCPU);
>> +
>>      return 0;
>>  }
>> -__initcall(__hvm_register_CPU_XSAVE_save_and_restore);
>> +__initcall(hvm_register_CPU_save_and_restore);
>> 
>>  int hvm_vcpu_initialise(struct vcpu *v)
>>  {
>> --- a/xen/include/asm-x86/hvm/hvm.h
>> +++ b/xen/include/asm-x86/hvm/hvm.h
>> @@ -109,6 +109,10 @@ struct hvm_function_table {
>>      void (*save_cpu_ctxt)(struct vcpu *v, struct hvm_hw_cpu *ctxt);
>>      int (*load_cpu_ctxt)(struct vcpu *v, struct hvm_hw_cpu *ctxt);
>> 
>> +    unsigned int (*init_msr)(void);
>> +    void (*save_msr)(struct vcpu *, struct hvm_msr *);
>> +    int (*load_msr)(struct vcpu *, struct hvm_msr *);
>> +
>>      /* Examine specifics of the guest state. */
>>      unsigned int (*get_interrupt_shadow)(struct vcpu *v);
>>      void (*set_interrupt_shadow)(struct vcpu *v, unsigned int
>> intr_shadow); --- a/xen/include/public/arch-x86/hvm/save.h
>> +++ b/xen/include/public/arch-x86/hvm/save.h
>> @@ -592,9 +592,21 @@ struct hvm_tsc_adjust {
>> 
>>  DECLARE_HVM_SAVE_TYPE(TSC_ADJUST, 19, struct hvm_tsc_adjust);
>> 
>> +
>> +struct hvm_msr {
>> +    uint32_t count;
>> +    struct hvm_one_msr {
>> +        uint32_t index;
>> +        uint32_t _rsvd;
>> +        uint64_t val;
>> +    } msr[1 /* variable size */];
>> +};
>> +
>> +#define CPU_MSR_CODE  20
>> +
> 
> +DECLARE_HVM_SAVE_TYPE(CPU_MSR, CPU_MSR_CODE, struct hvm_msr);
> +msr dump patch at tools/misc/xen-hvmctx.c

Sorry, I don't follow what this is to mean. If that other patch of
yours needs adjustment, then this surely doesn't belong here.

Jan

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