[xen staging] AMD/IOMMU: replace all-contiguous page tables by superpage mappings

[patchbot@xxxxxxx]

commit 0f91f75eb7ec589700c2c651b03d606bb19471dc
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Mon Jul 25 15:41:12 2022 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Mon Jul 25 15:41:12 2022 +0200

    AMD/IOMMU: 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.
    
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
    Reviewed-by: Paul Durrant <paul@xxxxxxx>
---
 xen/drivers/passthrough/amd/iommu_map.c | 34 ++++++++++++++++++++++++++++-----
 1 file changed, 29 insertions(+), 5 deletions(-)

diff --git a/xen/drivers/passthrough/amd/iommu_map.c 
b/xen/drivers/passthrough/amd/iommu_map.c
index a50a6b79ab..85d3a85fbb 100644
--- a/xen/drivers/passthrough/amd/iommu_map.c
+++ b/xen/drivers/passthrough/amd/iommu_map.c
@@ -81,7 +81,8 @@ static union amd_iommu_pte set_iommu_pte_present(unsigned 
long pt_mfn,
                                                  unsigned long dfn,
                                                  unsigned long next_mfn,
                                                  unsigned int level,
-                                                 bool iw, bool ir)
+                                                 bool iw, bool ir,
+                                                 bool *contig)
 {
     union amd_iommu_pte *table, *pde, old;
 
@@ -94,11 +95,15 @@ static union amd_iommu_pte set_iommu_pte_present(unsigned 
long pt_mfn,
          old.iw != iw || old.ir != ir )
     {
         set_iommu_pde_present(pde, next_mfn, 0, iw, ir);
-        pt_update_contig_markers(&table->raw, pfn_to_pde_idx(dfn, level),
-                                 level, PTE_kind_leaf);
+        *contig = pt_update_contig_markers(&table->raw,
+                                           pfn_to_pde_idx(dfn, level),
+                                           level, PTE_kind_leaf);
     }
     else
+    {
         old.pr = false; /* signal "no change" to the caller */
+        *contig = false;
+    }
 
     unmap_domain_page(table);
 
@@ -409,6 +414,7 @@ int cf_check amd_iommu_map_page(
 {
     struct domain_iommu *hd = dom_iommu(d);
     unsigned int level = (IOMMUF_order(flags) / PTE_PER_TABLE_SHIFT) + 1;
+    bool contig;
     int rc;
     unsigned long pt_mfn = 0;
     union amd_iommu_pte old;
@@ -452,8 +458,26 @@ int cf_check amd_iommu_map_page(
 
     /* Install mapping */
     old = set_iommu_pte_present(pt_mfn, dfn_x(dfn), mfn_x(mfn), level,
-                                (flags & IOMMUF_writable),
-                                (flags & IOMMUF_readable));
+                                flags & IOMMUF_writable,
+                                flags & IOMMUF_readable, &contig);
+
+    while ( unlikely(contig) && ++level < hd->arch.amd.paging_mode )
+    {
+        struct page_info *pg = mfn_to_page(_mfn(pt_mfn));
+        unsigned long next_mfn;
+
+        if ( iommu_pde_from_dfn(d, dfn_x(dfn), level, &pt_mfn, flush_flags,
+                                false) )
+            BUG();
+        BUG_ON(!pt_mfn);
+
+        next_mfn = mfn_x(mfn) & (~0UL << (PTE_PER_TABLE_SHIFT * (level - 1)));
+        set_iommu_pte_present(pt_mfn, dfn_x(dfn), next_mfn, level,
+                              flags & IOMMUF_writable,
+                              flags & IOMMUF_readable, &contig);
+        *flush_flags |= IOMMU_FLUSHF_modified | IOMMU_FLUSHF_all;
+        iommu_queue_free_pgtable(hd, pg);
+    }
 
     spin_unlock(&hd->arch.mapping_lock);
 
--
generated by git-patchbot for /home/xen/git/xen.git#staging