[Qemu-devel] [PATCH 15/30] memory: add address_space_valid

[Paolo Bonzini <pbonzini@redhat.com>]

The old-style IOMMU lets you check whether an access is valid in a
given DMAContext.  There is no equivalent for AddressSpace in the
memory API, implement it with a lookup of the dispatch tree.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 dma-helpers.c         |  5 +++++
 exec.c                | 25 +++++++++++++++++++++++++
 include/exec/memory.h | 14 ++++++++++++++
 include/sysemu/dma.h  |  3 ++-
 4 files changed, 46 insertions(+), 1 deletion(-)

diff --git a/dma-helpers.c b/dma-helpers.c
index 272632f..2962b69 100644
--- a/dma-helpers.c
+++ b/dma-helpers.c
@@ -298,6 +298,11 @@ bool iommu_dma_memory_valid(DMAContext *dma, dma_addr_t addr, dma_addr_t len,
             plen = len;
         }
 
+        if (!address_space_valid(dma->as, paddr, len,
+                                 dir == DMA_DIRECTION_FROM_DEVICE)) {
+            return false;
+        }
+
         len -= plen;
         addr += plen;
     }
diff --git a/exec.c b/exec.c
index 8d91221..8f1b507 100644
--- a/exec.c
+++ b/exec.c
@@ -2079,6 +2079,31 @@ static void cpu_notify_map_clients(void)
     }
 }
 
+bool address_space_valid(AddressSpace *as, hwaddr addr, int len, bool is_write)
+{
+    AddressSpaceDispatch *d = as->dispatch;
+    MemoryRegionSection *section;
+    int l;
+    hwaddr page;
+
+    while (len > 0) {
+        page = addr & TARGET_PAGE_MASK;
+        l = (page + TARGET_PAGE_SIZE) - addr;
+        if (l > len) {
+            l = len;
+        }
+        section = phys_page_find(d, addr >> TARGET_PAGE_BITS);
+        if (section->mr == &io_mem_unassigned ||
+            (is_write && section->mr->readonly)) {
+            return false;
+        }
+
+        len -= l;
+        addr += l;
+    }
+    return true;
+}
+
 /* Map a physical memory region into a host virtual address.
  * May map a subset of the requested range, given by and returned in *plen.
  * May return NULL if resources needed to perform the mapping are exhausted.
diff --git a/include/exec/memory.h b/include/exec/memory.h
index 6ed593c..2e5fd11 100644
--- a/include/exec/memory.h
+++ b/include/exec/memory.h
@@ -860,6 +860,20 @@ void address_space_write(AddressSpace *as, hwaddr addr,
  */
 void address_space_read(AddressSpace *as, hwaddr addr, uint8_t *buf, int len);
 
+/* address_space_valid: check for validity of an address space range
+ *
+ * Check whether memory is assigned to the given address space range.
+ *
+ * For now, addr and len should be aligned to a page size.  This limitation
+ * will be lifted in the future.
+ *
+ * @as: #AddressSpace to be accessed
+ * @addr: address within that address space
+ * @len: length of the area to be checked
+ * @is_write: indicates the transfer direction
+ */
+bool address_space_valid(AddressSpace *as, hwaddr addr, int len, bool is_write);
+
 /* address_space_map: map a physical memory region into a host virtual address
  *
  * May map a subset of the requested range, given by and returned in @plen.
diff --git a/include/sysemu/dma.h b/include/sysemu/dma.h
index a52c93a..2e239dc 100644
--- a/include/sysemu/dma.h
+++ b/include/sysemu/dma.h
@@ -113,7 +113,8 @@ static inline bool dma_memory_valid(DMAContext *dma,
                                     DMADirection dir)
 {
     if (!dma_has_iommu(dma)) {
-        return true;
+        return address_space_valid(dma->as, addr, len,
+                                   dir == DMA_DIRECTION_FROM_DEVICE);
     } else {
         return iommu_dma_memory_valid(dma, addr, len, dir);
     }
-- 
1.8.1.4