On 16.07.2018 14:02, David Hildenbrand wrote:
> On 13.07.2018 15:20, Janosch Frank wrote:
>> To do dirty loging with huge pages, we protect huge pmds in the
>> gmap. When they are written to, we unprotect them and mark them dirty.
>>
>> We introduce the function gmap_test_and_clear_dirty_segment which
>> handles dirty sync for huge pages.
>>
>> Signed-off-by: Janosch Frank <frankja@xxxxxxxxxxxxx>
>> ---
>>
>> So, that's a shot from the hip, I'll have to review this on Monday,
>> but here's what David wanted.
>
> Looks cleaner to me!
>> BUG_ON(gmap_is_shadow(gmap));
>> @@ -598,12 +603,19 @@ int __gmap_link(struct gmap *gmap, unsigned long gaddr, unsigned long vmaddr)
>> vmaddr >> PMD_SHIFT, table);
>> if (!rc) {
>> if (pmd_large(*pmd)) {
>> - *table = pmd_val(*pmd) &
>> - _SEGMENT_ENTRY_HARDWARE_BITS_LARGE;
>> + *table = (pmd_val(*pmd) &
>> + _SEGMENT_ENTRY_HARDWARE_BITS_LARGE)
>> + | _SEGMENT_ENTRY_GMAP_UC;
>> } else
>> *table = pmd_val(*pmd) &
>> _SEGMENT_ENTRY_HARDWARE_BITS;
>> }
>> + } else if (*table & _SEGMENT_ENTRY_PROTECT &&
>> + !(pmd_val(*pmd) & _SEGMENT_ENTRY_PROTECT)) {
>> + unprot = *table & _SEGMENT_ENTRY_HARDWARE_BITS_LARGE;
>
> As I said, this looks somewhat dangerous. It is okay to clear notifiers
> (has to be done) but if we ever add another bit, this will silently get
> erased here. Not sure how this could be done better. My take would be to
> always let gmap_pmdp_xchg() clear the notifier bits in the new value and
> not remove any bit except protection at this point.
Alright, this will also solve, that we do not remove notifiers on
gmap_protect_pmd right now...
For split and VSIE I will add definitions for status and notifier bits,
for easier masking, something like:
#define _SEGMENT_ENTRY_NOTIFY_BITS (_SEGMENT_ENTRY_GMAP_IN |
_SEGMENT_ENTRY_GMAP_VSIE)
#define _SEGMENT_ENTRY_STATUS_BITS (_SEGMENT_ENTRY_GMAP_UC |
_SEGMENT_ENTRY_SPLIT)
I applied all of your other changes, except for the find_first_bit
stuff, I'll worry about that later.
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