[Xen-devel] [PATCH for 4.7] Remove HVMMEM_mmio_write_dm from the public interface.

[Yu Zhang <yu.c.zhang@xxxxxxxxxxxxxxx>]

HVMMEM_mmio_write_dm is removed for new xen interface versions, and
is replaced with type HVMMEM_unused. Attempts to set a page to this
type will return -EINVAL in xen after 4.7.0. And there will be no
pages with type p2m_mmio_write_dm, therefore HVMOP_get_mem_type will
never get the old type - HVMMEM_mmio_write_dm.

New approaches to write protect guest ram pages will be provided in
future patches.

Signed-off-by: Yu Zhang <yu.c.zhang@xxxxxxxxxxxxxxx>
---
Cc: Jan Beulich <jbeulich@xxxxxxxx>
Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Cc: George Dunlap <george.dunlap@xxxxxxxxxxxxx>
Cc: Paul Durrant <paul.durrant@xxxxxxxxxx>
Cc: Wei Liu <wei.liu2@xxxxxxxxxx>
---
 xen/arch/x86/hvm/hvm.c          | 7 +++----
 xen/include/public/hvm/hvm_op.h | 5 +++++
 2 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index 8cb6e9e..82e2ed1 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -5497,8 +5497,6 @@ long do_hvm_op(unsigned long op, 
XEN_GUEST_HANDLE_PARAM(void) arg)
             get_gfn_query_unlocked(d, a.pfn, &t);
             if ( p2m_is_mmio(t) )
                 a.mem_type =  HVMMEM_mmio_dm;
-            else if ( t == p2m_mmio_write_dm )
-                a.mem_type = HVMMEM_mmio_write_dm;
             else if ( p2m_is_readonly(t) )
                 a.mem_type =  HVMMEM_ram_ro;
             else if ( p2m_is_ram(t) )
@@ -5529,7 +5527,7 @@ long do_hvm_op(unsigned long op, 
XEN_GUEST_HANDLE_PARAM(void) arg)
             [HVMMEM_ram_rw]  = p2m_ram_rw,
             [HVMMEM_ram_ro]  = p2m_ram_ro,
             [HVMMEM_mmio_dm] = p2m_mmio_dm,
-            [HVMMEM_mmio_write_dm] = p2m_mmio_write_dm
+            [HVMMEM_unused] = p2m_invalid
         };
 
         if ( copy_from_guest(&a, arg, 1) )
@@ -5553,7 +5551,8 @@ long do_hvm_op(unsigned long op, 
XEN_GUEST_HANDLE_PARAM(void) arg)
              ((a.first_pfn + a.nr - 1) > domain_get_maximum_gpfn(d)) )
             goto setmemtype_fail;
             
-        if ( a.hvmmem_type >= ARRAY_SIZE(memtype) )
+        if ( a.hvmmem_type >= ARRAY_SIZE(memtype) ||
+             unlikely(a.hvmmem_type == HVMMEM_unused) )
             goto setmemtype_fail;
 
         while ( a.nr > start_iter )
diff --git a/xen/include/public/hvm/hvm_op.h b/xen/include/public/hvm/hvm_op.h
index 1606185..ebb907a 100644
--- a/xen/include/public/hvm/hvm_op.h
+++ b/xen/include/public/hvm/hvm_op.h
@@ -83,7 +83,12 @@ typedef enum {
     HVMMEM_ram_rw,             /* Normal read/write guest RAM */
     HVMMEM_ram_ro,             /* Read-only; writes are discarded */
     HVMMEM_mmio_dm,            /* Reads and write go to the device model */
+#if __XEN_INTERFACE_VERSION__ < 0x00040700
     HVMMEM_mmio_write_dm       /* Read-only; writes go to the device model */
+#else
+    HVMMEM_unused              /* Placeholder; setting memory to this type
+                                  will fail for code after 4.7.0 */
+#endif
 } hvmmem_type_t;
 
 /* Following tools-only interfaces may change in future. */
-- 
1.9.1


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