* mm_pages_next() question
@ 2009-03-29 12:24 Avi Kivity
2009-03-31 16:18 ` Marcelo Tosatti
0 siblings, 1 reply; 4+ messages in thread
From: Avi Kivity @ 2009-03-29 12:24 UTC (permalink / raw)
To: Marcelo Tosatti; +Cc: KVM list
> static int mmu_pages_next(struct kvm_mmu_pages *pvec,
> struct mmu_page_path *parents,
> int i)
> {
> int n;
>
> for (n = i+1; n < pvec->nr; n++) {
> struct kvm_mmu_page *sp = pvec->page[n].sp;
>
> if (sp->role.level == PT_PAGE_TABLE_LEVEL) {
> parents->idx[0] = pvec->page[n].idx;
> return n;
> }
>
> parents->parent[sp->role.level-2] = sp;
> parents->idx[sp->role.level-1] = pvec->page[n].idx;
> }
>
> return n;
> }
Do we need to break out of the loop if we switch parents during the loop
(since that will give us a different mmu_page_path)? Or are callers
careful to only pass pvecs which belong to the same shadow page?
--
error compiling committee.c: too many arguments to function
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: mm_pages_next() question
2009-03-29 12:24 mm_pages_next() question Avi Kivity
@ 2009-03-31 16:18 ` Marcelo Tosatti
2009-04-01 8:40 ` Avi Kivity
0 siblings, 1 reply; 4+ messages in thread
From: Marcelo Tosatti @ 2009-03-31 16:18 UTC (permalink / raw)
To: Avi Kivity; +Cc: KVM list
On Sun, Mar 29, 2009 at 03:24:08PM +0300, Avi Kivity wrote:
>> static int mmu_pages_next(struct kvm_mmu_pages *pvec,
>> struct mmu_page_path *parents,
>> int i)
>> {
>> int n;
>>
>> for (n = i+1; n < pvec->nr; n++) {
>> struct kvm_mmu_page *sp = pvec->page[n].sp;
>>
>> if (sp->role.level == PT_PAGE_TABLE_LEVEL) {
>> parents->idx[0] = pvec->page[n].idx;
>> return n;
>> }
>>
>> parents->parent[sp->role.level-2] = sp;
>> parents->idx[sp->role.level-1] = pvec->page[n].idx;
>> }
>>
>> return n;
>> }
>
> Do we need to break out of the loop if we switch parents during the loop
> (since that will give us a different mmu_page_path)? Or are callers
> careful to only pass pvecs which belong to the same shadow page?
This function builds mmu_page_path for a number of pagetable (leaf)
pages. Whenever the path changes, mmu_page_path will be rebuilt.
The pages in the pvec must be organized as follows:
level4, level3, level2, level1, level1, level1, ...., level3, level2,
level1, level1, ...
So you don't have to repeat higher levels for a number of leaf pages.
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: mm_pages_next() question
2009-03-31 16:18 ` Marcelo Tosatti
@ 2009-04-01 8:40 ` Avi Kivity
2009-04-01 17:15 ` Marcelo Tosatti
0 siblings, 1 reply; 4+ messages in thread
From: Avi Kivity @ 2009-04-01 8:40 UTC (permalink / raw)
To: Marcelo Tosatti; +Cc: KVM list
Marcelo Tosatti wrote:
> On Sun, Mar 29, 2009 at 03:24:08PM +0300, Avi Kivity wrote:
>
>>> static int mmu_pages_next(struct kvm_mmu_pages *pvec,
>>> struct mmu_page_path *parents,
>>> int i)
>>> {
>>> int n;
>>>
>>> for (n = i+1; n < pvec->nr; n++) {
>>> struct kvm_mmu_page *sp = pvec->page[n].sp;
>>>
>>> if (sp->role.level == PT_PAGE_TABLE_LEVEL) {
>>> parents->idx[0] = pvec->page[n].idx;
>>> return n;
>>> }
>>>
>>> parents->parent[sp->role.level-2] = sp;
>>> parents->idx[sp->role.level-1] = pvec->page[n].idx;
>>> }
>>>
>>> return n;
>>> }
>>>
>> Do we need to break out of the loop if we switch parents during the loop
>> (since that will give us a different mmu_page_path)? Or are callers
>> careful to only pass pvecs which belong to the same shadow page?
>>
>
> This function builds mmu_page_path for a number of pagetable (leaf)
> pages. Whenever the path changes, mmu_page_path will be rebuilt.
>
> The pages in the pvec must be organized as follows:
>
> level4, level3, level2, level1, level1, level1, ...., level3, level2,
> level1, level1, ...
>
> So you don't have to repeat higher levels for a number of leaf pages.
>
I'm still missing something. That if () tests for level ==
PT_PAGE_TABLE_LEVEL. So it looks like we'll have batch sizes of 4, 1,
1, 1, ... 3, 1, 1, 1, ...?
--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: mm_pages_next() question
2009-04-01 8:40 ` Avi Kivity
@ 2009-04-01 17:15 ` Marcelo Tosatti
0 siblings, 0 replies; 4+ messages in thread
From: Marcelo Tosatti @ 2009-04-01 17:15 UTC (permalink / raw)
To: Avi Kivity; +Cc: KVM list
On Wed, Apr 01, 2009 at 11:40:30AM +0300, Avi Kivity wrote:
> Marcelo Tosatti wrote:
>> On Sun, Mar 29, 2009 at 03:24:08PM +0300, Avi Kivity wrote:
>>
>>>> static int mmu_pages_next(struct kvm_mmu_pages *pvec,
>>>> struct mmu_page_path *parents,
>>>> int i)
>>>> {
>>>> int n;
>>>>
>>>> for (n = i+1; n < pvec->nr; n++) {
>>>> struct kvm_mmu_page *sp = pvec->page[n].sp;
>>>>
>>>> if (sp->role.level == PT_PAGE_TABLE_LEVEL) {
>>>> parents->idx[0] = pvec->page[n].idx;
>>>> return n;
>>>> }
>>>>
>>>> parents->parent[sp->role.level-2] = sp;
>>>> parents->idx[sp->role.level-1] = pvec->page[n].idx;
>>>> }
>>>>
>>>> return n;
>>>> }
>>>>
>>> Do we need to break out of the loop if we switch parents during the
>>> loop (since that will give us a different mmu_page_path)? Or are
>>> callers careful to only pass pvecs which belong to the same shadow
>>> page?
>>>
>>
>> This function builds mmu_page_path for a number of pagetable (leaf)
>> pages. Whenever the path changes, mmu_page_path will be rebuilt.
>>
>> The pages in the pvec must be organized as follows:
>>
>> level4, level3, level2, level1, level1, level1, ...., level3, level2,
>> level1, level1, ...
>>
>> So you don't have to repeat higher levels for a number of leaf pages.
>>
>
> I'm still missing something. That if () tests for level ==
> PT_PAGE_TABLE_LEVEL. So it looks like we'll have batch sizes of 4, 1,
> 1, 1, ... 3, 1, 1, 1, ...?
The input is the pvec array, organized as follows: 4, 3, 2, 1, 1, 1,
2, 1, 1, 3, 2, 1.
The output will be:
1 (pvec position 4), 1 (pos 5), 1 (pos 6). All of them with the same
path.
Then 1 (pos 8), 1 (pos 9). With the same path as before but level 2
being the page in position 7.
So the if() tests for level == PT_PAGE_TABLE_LEVEL because these are the
pages we're interested in walking (the ones that can be unsync). If
we're not PT_PAGE_TABLE_LEVEL, we walk the pvec building mmu_page_path.
^ permalink raw reply [flat|nested] 4+ messages in thread
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2009-03-29 12:24 mm_pages_next() question Avi Kivity
2009-03-31 16:18 ` Marcelo Tosatti
2009-04-01 8:40 ` Avi Kivity
2009-04-01 17:15 ` Marcelo Tosatti
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