Re: [Xen-devel] [PATCH v4 4/4] xen: rework paging_log_dirty_op to work with hvm guests

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

El 07/05/15 a les 17.48, Jan Beulich ha escrit:
>>>> On 07.05.15 at 16:29, <roger.pau@xxxxxxxxxx> wrote:
>> --- a/xen/arch/x86/mm/paging.c
>> +++ b/xen/arch/x86/mm/paging.c
>> @@ -408,6 +408,51 @@ int paging_mfn_is_dirty(struct domain *d, mfn_t gmfn)
>>      return rv;
>>  }
>>  
>> +static inline void *map_dirty_bitmap(XEN_GUEST_HANDLE_64(uint8) 
>> dirty_bitmap,
>> +                                     unsigned long pages,
>> +                                     struct page_info **page)
>> +{
>> +    uint32_t pfec = PFEC_page_present | PFEC_write_access;
>> +    unsigned long gfn;
>> +    p2m_type_t p2mt;
>> +
>> +    gfn = paging_gva_to_gfn(current,
>> +                            (paddr_t)(dirty_bitmap.p + (pages >> 3)),
> 
> Why paddr_t?

Without it I get:

paging.c:421:29: error: passing argument 2 of 'paging_gva_to_gfn' makes
integer from pointer without a cast [-Werror]

>> @@ -455,6 +511,7 @@ static int paging_log_dirty_op(struct domain *d,
>>                   d->arch.paging.log_dirty.fault_count,
>>                   d->arch.paging.log_dirty.dirty_count);
>>  
>> +again:
> 
> Labels indented by at least one space please.
>
>> @@ -472,18 +529,18 @@ static int paging_log_dirty_op(struct domain *d,
>>      l4 = paging_map_log_dirty_bitmap(d);
>>      i4 = d->arch.paging.preempt.log_dirty.i4;
>>      i3 = d->arch.paging.preempt.log_dirty.i3;
>> +    i2 = d->arch.paging.preempt.log_dirty.i2;
> 
> I don't see why this needs to be stored in struct domain - upon being
> preempted you never seem to leave this non-zero.
> 
>> @@ -492,15 +549,34 @@ static int paging_log_dirty_op(struct domain *d,
>>                      bytes = (unsigned int)((sc->pages - pages + 7) >> 3);
>>                  if ( likely(peek) )
>>                  {
>> -                    if ( (l1 ? copy_to_guest_offset(sc->dirty_bitmap,
>> -                                                    pages >> 3, (uint8_t 
>> *)l1,
>> -                                                    bytes)
>> -                             : clear_guest_offset(sc->dirty_bitmap,
>> -                                                  pages >> 3, bytes)) != 0 )
>> +                    if ( pages >> (3 + PAGE_SHIFT) !=
>> +                         index_mapped >> (3 + PAGE_SHIFT) )
>>                      {
>> -                        rv = -EFAULT;
>> -                        goto out;
>> +                        /* We need to map next page */
>> +                        paging_unlock(d);
>> +                        unmap_dirty_bitmap(dirty_bitmap, page);
>> +                        index_mapped = pages;
>> +                        dirty_bitmap = map_dirty_bitmap(sc->dirty_bitmap, 
>> pages,
>> +                                                        &page);
>> +                        paging_lock(d);
>> +                        if ( dirty_bitmap == NULL )
>> +                        {
>> +                            rv = -EFAULT;
>> +                            goto out;
>> +                        }
>> +                        d->arch.paging.preempt.log_dirty.i4 = i4;
>> +                        d->arch.paging.preempt.log_dirty.i3 = i3;
>> +                        d->arch.paging.preempt.log_dirty.i2 = i2;
>> +                        d->arch.paging.preempt.log_dirty.done = pages;
>> +                        goto again;
> 
> I think you need to update the state before dropping the paging lock.
> And that would then actually seem to make the new i2 field necessary.

I've moved it so the fields are set before dropping the paging lock.

Roger.


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