On 12/04/16 13:14, Christoffer Dall wrote:
On Mon, Apr 11, 2016 at 03:33:45PM +0100, Suzuki K Poulose wrote:
On 08/04/16 16:05, Christoffer Dall wrote:
On Mon, Apr 04, 2016 at 05:26:15PM +0100, Suzuki K Poulose wrote:
-#if PGDIR_SHIFT > KVM_PHYS_SHIFT
-#define PTRS_PER_S2_PGD_SHIFT 0
-#else
-#define PTRS_PER_S2_PGD_SHIFT (KVM_PHYS_SHIFT - PGDIR_SHIFT)
-#endif
-#define PTRS_PER_S2_PGD (1 << PTRS_PER_S2_PGD_SHIFT)
+#define STAGE2_PGTABLE_LEVELS ARM64_HW_PGTABLE_LEVELS(KVM_PHYS_SHIFT - 4)
/*
- * If we are concatenating first level stage-2 page tables, we would have less
- * than or equal to 16 pointers in the fake PGD, because that's what the
- * architecture allows. In this case, (4 - CONFIG_PGTABLE_LEVELS)
- * represents the first level for the host, and we add 1 to go to the next
- * level (which uses contatenation) for the stage-2 tables.
just noticed: s/contatenation/concatenation/
Thanks for catching that. Will fix it.
which case this should be reworded to just state the assumptions and why
this is a good assumption.
(If my assumptions are wrong here, then there are also weird cases where
the host does huge pages at the PMD level and we don't. Not sure I can
see the full ramifications of that.)
I am sorry, I didn't get your point about the PMD level.
Right, I expressed that terribly, and I may have gotten myself confused
when writing that.
My concern is this: if the number of levels between the host and stage-2
are different, and the host uses huge pmd mappings (either THP or huge
tlb fs), then do we always do the right thing for stage-2 tables, even
if we support the case with more levels in Stage-2 than on the host?
Yes. We are safe with PMD (level 2). In the worst case we will have a 2level
page table at host and say 4 at stage2. In either case, we have a PMD level
(which in host is folded to PGD) and both will use section mapping at level 2
for huge pmd. Also pmd_huge() doesn't care if the PMD is folded or not. So,
we are fine with that. I hope that answers your question.
Thanks for trying to parse my crytptic and potentially nonsensical
questions.
No no, they make absolute sense. I had gone through these questions myself initially
when I wrote the series, so its good to share them :-).
Btw, I have rebased my series to kvmarm and have addressed the comments. I will post
them after a round of testing.
Cheers
Suzuki
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