On 2017年01月23日 10:54, Peter Xu wrote:
+ trace_vtd_page_walk_skip_read(iova, iova_next);
+ skipped_local++;
+ goto next;
+ }
+
+ if (vtd_slpte_nonzero_rsvd(slpte, level)) {
+ trace_vtd_page_walk_skip_reserve(iova, iova_next);
+ skipped_local++;
+ goto next;
+ }
+
+ /* Permissions are stacked with parents' */
+ read_cur = read && (slpte & VTD_SL_R);
+ write_cur = write && (slpte & VTD_SL_W);
+
+ /*
+ * As long as we have either read/write permission, this is
+ * a valid entry. The rule works for both page or page tables.
+ */
+ entry_valid = read_cur | write_cur;
+
+ if (vtd_is_last_slpte(slpte, level)) {
+ entry.target_as = &address_space_memory;
+ entry.iova = iova & subpage_mask;
+ /*
+ * This might be meaningless addr if (!read_cur &&
+ * !write_cur), but after all this field will be
+ * meaningless in that case, so let's share the code to
+ * generate the IOTLBs no matter it's an MAP or UNMAP
+ */
+ entry.translated_addr = vtd_get_slpte_addr(slpte);
+ entry.addr_mask = ~subpage_mask;
+ entry.perm = IOMMU_ACCESS_FLAG(read_cur, write_cur);
+ if (!entry_valid && !notify_unmap) {
+ trace_vtd_page_walk_skip_perm(iova, iova_next);
+ skipped_local++;
+ goto next;
+ }
Under which case should we care about unmap here (better with a comment I
think)?
When PSIs are for invalidation, rather than newly mapped entries. In
that case, notify_unmap will be true, and here we need to notify
IOMMU_NONE to do the cache flush or unmap.
(this page walk is not only for replaying, it is for cache flushing as
well)
Do you have suggestion on the comments?
I think then we'd better move this to patch 18 which will use notify_unmap.
Do you mean to add some more comment on patch 18?
I mean move the unmap_nofity and its comment to patch 18 (real user).
But if you want to keep it in the patch, I'm also fine.
Thanks
