[xen master] VT-d: replace all-contiguous page tables by superpage mappings

[patchbot@xxxxxxx]

commit 3eb5c23542fabeeaff3c20a1fb1f6dddc2874890
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Mon Jul 25 15:41:48 2022 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Mon Jul 25 15:41:48 2022 +0200

    VT-d: replace all-contiguous page tables by superpage mappings
    
    When a page table ends up with all contiguous entries (including all
    identical attributes), it can be replaced by a superpage entry at the
    next higher level. The page table itself can then be scheduled for
    freeing.
    
    The adjustment to LEVEL_MASK is merely to avoid leaving a latent trap
    for whenever we (and obviously hardware) start supporting 512G mappings.
    
    Note that cache sync-ing is likely more strict than necessary. This is
    both to be on the safe side as well as to maintain the pattern of all
    updates of (potentially) live tables being accompanied by a flush (if so
    needed).
    
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>
    Reviewed-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
    Reviewed-by: Paul Durrant <paul@xxxxxxx>
---
 xen/drivers/passthrough/vtd/iommu.c | 35 ++++++++++++++++++++++++++++-------
 xen/drivers/passthrough/vtd/iommu.h |  2 +-
 2 files changed, 29 insertions(+), 8 deletions(-)

diff --git a/xen/drivers/passthrough/vtd/iommu.c 
b/xen/drivers/passthrough/vtd/iommu.c
index 745c7bae0d..35545bfaef 100644
--- a/xen/drivers/passthrough/vtd/iommu.c
+++ b/xen/drivers/passthrough/vtd/iommu.c
@@ -2211,14 +2211,35 @@ static int __must_check cf_check intel_iommu_map_page(
      * While the (ab)use of PTE_kind_table here allows to save some work in
      * the function, the main motivation for it is that it avoids a so far
      * unexplained hang during boot (while preparing Dom0) on a Westmere
-     * based laptop.
+     * based laptop.  This also has the intended effect of terminating the
+     * loop when super pages aren't supported anymore at the next level.
      */
-    pt_update_contig_markers(&page->val,
-                             address_level_offset(dfn_to_daddr(dfn), level),
-                             level,
-                             (hd->platform_ops->page_sizes &
-                              (1UL << level_to_offset_bits(level + 1))
-                              ? PTE_kind_leaf : PTE_kind_table));
+    while ( pt_update_contig_markers(&page->val,
+                                     address_level_offset(dfn_to_daddr(dfn), 
level),
+                                     level,
+                                     (hd->platform_ops->page_sizes &
+                                      (1UL << level_to_offset_bits(level + 1))
+                                       ? PTE_kind_leaf : PTE_kind_table)) )
+    {
+        struct page_info *pg = maddr_to_page(pg_maddr);
+
+        unmap_vtd_domain_page(page);
+
+        new.val &= ~(LEVEL_MASK << level_to_offset_bits(level));
+        dma_set_pte_superpage(new);
+
+        pg_maddr = addr_to_dma_page_maddr(d, dfn_to_daddr(dfn), ++level,
+                                          flush_flags, false);
+        BUG_ON(pg_maddr < PAGE_SIZE);
+
+        page = map_vtd_domain_page(pg_maddr);
+        pte = &page[address_level_offset(dfn_to_daddr(dfn), level)];
+        *pte = new;
+        iommu_sync_cache(pte, sizeof(*pte));
+
+        *flush_flags |= IOMMU_FLUSHF_modified | IOMMU_FLUSHF_all;
+        iommu_queue_free_pgtable(hd, pg);
+    }
 
     spin_unlock(&hd->arch.mapping_lock);
     unmap_vtd_domain_page(page);
diff --git a/xen/drivers/passthrough/vtd/iommu.h 
b/xen/drivers/passthrough/vtd/iommu.h
index 7c3fe40150..78aa8a96f5 100644
--- a/xen/drivers/passthrough/vtd/iommu.h
+++ b/xen/drivers/passthrough/vtd/iommu.h
@@ -232,7 +232,7 @@ struct context_entry {
 
 /* page table handling */
 #define LEVEL_STRIDE       (9)
-#define LEVEL_MASK         ((1 << LEVEL_STRIDE) - 1)
+#define LEVEL_MASK         (PTE_NUM - 1UL)
 #define PTE_NUM            (1 << LEVEL_STRIDE)
 #define level_to_agaw(val) ((val) - 2)
 #define agaw_to_level(val) ((val) + 2)
--
generated by git-patchbot for /home/xen/git/xen.git#master