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Re: [Xen-devel] [RFC][v3][PATCH 2/6] xen:x86: introduce a new hypercall to get RMRR mappings



On 2014/8/15 17:46, Andrew Cooper wrote:
On 15/08/14 09:27, Tiejun Chen wrote:
We need this new hypercall to get RMRR mapping for VM.

Signed-off-by: Tiejun Chen <tiejun.chen@xxxxxxxxx>
---
  xen/arch/x86/x86_64/compat/mm.c |  9 +++++++++
  xen/include/public/memory.h     | 14 +++++++++++++-
  2 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/xen/arch/x86/x86_64/compat/mm.c b/xen/arch/x86/x86_64/compat/mm.c
index 69c6195..ff16f17 100644
--- a/xen/arch/x86/x86_64/compat/mm.c
+++ b/xen/arch/x86/x86_64/compat/mm.c
@@ -132,6 +132,15 @@ int compat_arch_memory_op(unsigned long cmd, 
XEN_GUEST_HANDLE_PARAM(void) arg)
          break;
      }

+    case XENMEM_reserved_device_memory_map:
+    {
+        /* Currently we just need to cover RMRR. */
+        if ( copy_to_guest(arg, &rmrr_maps, 1) )
+            return -EFAULT;

This will trivially clobber the hypercaller's stack/heap.

You are not even using the correct indirection of
xen_rmrr_memory_map_t.buffer

You *must* start by copying xen_rmrr_memory_map_t from the guest.

Okay, I will try to do this.

Thanks
Tiejun


~Andrew

+
+        return 0;
+    }
+
      case XENMEM_machphys_mapping:
      {
          struct domain *d = current->domain;
diff --git a/xen/include/public/memory.h b/xen/include/public/memory.h
index 2c57aa0..13e539f 100644
--- a/xen/include/public/memory.h
+++ b/xen/include/public/memory.h
@@ -523,7 +523,19 @@ DEFINE_XEN_GUEST_HANDLE(xen_mem_sharing_op_t);

  #endif /* defined(__XEN__) || defined(__XEN_TOOLS__) */

-/* Next available subop number is 26 */
+/*
+ * Some devices may reserve some range.
+ *
+ * Currently we just have RMRR
+ * - Reserved memory Region Reporting Structure,
+ * So returns the RMRR memory map as it was when the domain
+ * was started.
+ */
+#define XENMEM_reserved_device_memory_map   26
+typedef struct xen_memory_map xen_rmrr_memory_map_t;
+DEFINE_XEN_GUEST_HANDLE(xen_rmrr_memory_map_t);
+
+/* Next available subop number is 27 */

  #endif /* __XEN_PUBLIC_MEMORY_H__ */



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