[Xen-devel] [PATCH v3 4/4] x86/mm/p2m: stop checking for IOMMU shared page tables in mmio_order()

[Paul Durrant <paul.durrant@xxxxxxxxxx>]

Now that the iommu_map() and iommu_unmap() operations take an order
parameter and elide flushing there's no strong reason why modifying MMIO
ranges in the p2m should be restricted to a 4k granularity simply because
the IOMMU is enabled but shared page tables are not in operation.

Signed-off-by: Paul Durrant <paul.durrant@xxxxxxxxxx>
Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
---
Cc: George Dunlap <george.dunlap@xxxxxxxxxxxxx>
Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Cc: Wei Liu <wei.liu2@xxxxxxxxxx>
Cc: "Roger Pau Monné" <roger.pau@xxxxxxxxxx>

v2:
 - New in v2. (Adapted from a previously independent patch).
---
 xen/arch/x86/mm/p2m.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/xen/arch/x86/mm/p2m.c b/xen/arch/x86/mm/p2m.c
index ed76e96d33..a9cfd1b2e4 100644
--- a/xen/arch/x86/mm/p2m.c
+++ b/xen/arch/x86/mm/p2m.c
@@ -2059,13 +2059,12 @@ static unsigned int mmio_order(const struct domain *d,
                                unsigned long start_fn, unsigned long nr)
 {
     /*
-     * Note that the !iommu_use_hap_pt() here has three effects:
-     * - cover iommu_{,un}map_page() not having an "order" input yet,
+     * Note that the !hap_enabled() here has two effects:
      * - exclude shadow mode (which doesn't support large MMIO mappings),
      * - exclude PV guests, should execution reach this code for such.
      * So be careful when altering this.
      */
-    if ( !iommu_use_hap_pt(d) ||
+    if ( !hap_enabled(d) ||
          (start_fn & ((1UL << PAGE_ORDER_2M) - 1)) || !(nr >> PAGE_ORDER_2M) )
         return PAGE_ORDER_4K;
 
-- 
2.11.0


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