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



Jan Beulich wrote:
>>>> 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.
> 

OK, I will adjust tools side msr dump patch.

DECLARE_HVM_SAVE_TYPE(CPU_MSR, CPU_MSR_CODE, struct hvm_msr) is for msr dump 
tools side patch, so if you don't add it here I can use a distinct patch to add 
it.

Thanks,
Jinsong


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