[Xen-devel] [PATCH v7 2/7] iommu: track reserved ranges using a rangeset

[Paul Durrant <paul.durrant@xxxxxxxxxx>]

Ranges that should be considered reserved in the IOMMU are not necessarily
limited to RMRRs. Any frame number that is not RAM but is present in the
initial domain map should be considered as reserved in the IOMMU.
This patch adds a rangeset to the domain_iommu structure that is then used
to track all reserved ranges. This will be needed by a subsequent patch
to test whether it is safe to modify a particular IOMMU entry.

Signed-off-by: Paul Durrant <paul.durrant@xxxxxxxxxx>
---
Cc: George Dunlap <george.dunlap@xxxxxxxxxx>
Cc: Wei Liu <wei.liu2@xxxxxxxxxx>
Cc: Jan Beulich <jbeulich@xxxxxxxx>
Cc: Kevin Tian <kevin.tian@xxxxxxxxx>

v7:
 - Re-base.
 - NULL the rangeset pointer after freeing.
 - As well as RMRRs, include all non-RAM mapped PFNs in the rangeset
   rather than just E820 reserved.
 - Dropping George's and Wei's R-b due to non-trivial changes.

v6:
 - Re-base.

v2:
 - New in v2.
---
 xen/drivers/passthrough/iommu.c     | 11 ++++++++++-
 xen/drivers/passthrough/vtd/iommu.c | 20 +++++++++++++-------
 xen/drivers/passthrough/x86/iommu.c |  4 ++++
 xen/include/xen/iommu.h             |  6 ++++++
 4 files changed, 33 insertions(+), 8 deletions(-)

diff --git a/xen/drivers/passthrough/iommu.c b/xen/drivers/passthrough/iommu.c
index 8b438ae4bc..9f07112367 100644
--- a/xen/drivers/passthrough/iommu.c
+++ b/xen/drivers/passthrough/iommu.c
@@ -180,6 +180,10 @@ int iommu_domain_init(struct domain *d)
     if ( !iommu_enabled )
         return 0;
 
+    hd->reserved_ranges = rangeset_new(d, NULL, 0);
+    if ( !hd->reserved_ranges )
+        return -ENOMEM;
+
     hd->platform_ops = iommu_get_ops();
     return hd->platform_ops->init(d);
 }
@@ -296,12 +300,17 @@ int iommu_construct(struct domain *d)
 
 void iommu_domain_destroy(struct domain *d)
 {
-    if ( !iommu_enabled || !dom_iommu(d)->platform_ops )
+    struct domain_iommu *hd = dom_iommu(d);
+
+    if ( !iommu_enabled || !hd->platform_ops )
         return;
 
     iommu_teardown(d);
 
     arch_iommu_domain_destroy(d);
+
+    rangeset_destroy(hd->reserved_ranges);
+    hd->reserved_ranges = NULL;
 }
 
 int iommu_map_page(struct domain *d, dfn_t dfn, mfn_t mfn,
diff --git a/xen/drivers/passthrough/vtd/iommu.c 
b/xen/drivers/passthrough/vtd/iommu.c
index 4d1ff10817..d8873167e1 100644
--- a/xen/drivers/passthrough/vtd/iommu.c
+++ b/xen/drivers/passthrough/vtd/iommu.c
@@ -1963,6 +1963,7 @@ static int rmrr_identity_mapping(struct domain *d, bool_t 
map,
     unsigned long end_pfn = PAGE_ALIGN_4K(rmrr->end_address) >> PAGE_SHIFT_4K;
     struct mapped_rmrr *mrmrr;
     struct domain_iommu *hd = dom_iommu(d);
+    int err = 0;
 
     ASSERT(pcidevs_locked());
     ASSERT(rmrr->base_address < rmrr->end_address);
@@ -1976,8 +1977,6 @@ static int rmrr_identity_mapping(struct domain *d, bool_t 
map,
         if ( mrmrr->base == rmrr->base_address &&
              mrmrr->end == rmrr->end_address )
         {
-            int ret = 0;
-
             if ( map )
             {
                 ++mrmrr->count;
@@ -1987,28 +1986,35 @@ static int rmrr_identity_mapping(struct domain *d, 
bool_t map,
             if ( --mrmrr->count )
                 return 0;
 
-            while ( base_pfn < end_pfn )
+            err = rangeset_remove_range(hd->reserved_ranges,
+                                        base_pfn, end_pfn);
+            while ( !err && base_pfn < end_pfn )
             {
                 if ( clear_identity_p2m_entry(d, base_pfn) )
-                    ret = -ENXIO;
+                    err = -ENXIO;
+
                 base_pfn++;
             }
 
             list_del(&mrmrr->list);
             xfree(mrmrr);
-            return ret;
+            return err;
         }
     }
 
     if ( !map )
         return -ENOENT;
 
+    err = rangeset_add_range(hd->reserved_ranges, base_pfn, end_pfn);
+    if ( err )
+        return err;
+
     while ( base_pfn < end_pfn )
     {
-        int err = set_identity_p2m_entry(d, base_pfn, p2m_access_rw, flag);
-
+        err = set_identity_p2m_entry(d, base_pfn, p2m_access_rw, flag);
         if ( err )
             return err;
+
         base_pfn++;
     }
 
diff --git a/xen/drivers/passthrough/x86/iommu.c 
b/xen/drivers/passthrough/x86/iommu.c
index b20bad17de..e661dc0b45 100644
--- a/xen/drivers/passthrough/x86/iommu.c
+++ b/xen/drivers/passthrough/x86/iommu.c
@@ -241,6 +241,10 @@ void __hwdom_init arch_iommu_hwdom_init(struct domain *d)
         else
             rc = iommu_map_page(d, _dfn(pfn), _mfn(pfn),
                                 IOMMUF_readable | IOMMUF_writable);
+
+        if ( !rc && !page_is_ram_type(pfn, RAM_TYPE_CONVENTIONAL) )
+            rc = rangeset_add_singleton(dom_iommu(d)->reserved_ranges, pfn);
+
         if ( rc )
             printk(XENLOG_WARNING " d%d: IOMMU mapping failed: %d\n",
                    d->domain_id, rc);
diff --git a/xen/include/xen/iommu.h b/xen/include/xen/iommu.h
index c75333c077..9113f37b85 100644
--- a/xen/include/xen/iommu.h
+++ b/xen/include/xen/iommu.h
@@ -133,6 +133,12 @@ struct domain_iommu {
      * include/xen/mm.h).
      */
     bool need_sync;
+
+    /*
+     * DFN ranges that are reserved in the domain IOMMU mappings and
+     * must not be modified after initialization.
+     */
+    struct rangeset *reserved_ranges;
 };
 
 #define dom_iommu(d)              (&(d)->iommu)
-- 
2.11.0


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