#include <linux/export.h>
#include <linux/highmem.h>
+#include <xen/xen.h>
#include <drm/drm_cache.h>
#endif
}
EXPORT_SYMBOL(drm_clflush_virt_range);
+
+bool drm_need_swiotlb(int dma_bits)
+{
+ struct resource *tmp;
+ resource_size_t max_iomem = 0;
+
+ /*
+ * Xen paravirtual hosts require swiotlb regardless of requested dma
+ * transfer size.
+ *
+ * NOTE: Really, what it requires is use of the dma_alloc_coherent
+ * allocator used in ttm_dma_populate() instead of
+ * ttm_populate_and_map_pages(), which bounce buffers so much in
+ * Xen it leads to swiotlb buffer exhaustion.
+ */
+ if (xen_pv_domain())
+ return true;
+
+ /*
+ * Enforce dma_alloc_coherent when memory encryption is active as well
+ * for the same reasons as for Xen paravirtual hosts.
+ */
+ if (mem_encrypt_active())
+ return true;
+
+ for (tmp = iomem_resource.child; tmp; tmp = tmp->sibling)
+ max_iomem = max(max_iomem, tmp->end);
+
+ return max_iomem > ((u64)1 << dma_bits);
+}
+EXPORT_SYMBOL(drm_need_swiotlb);