The internal Xen x86 emulator is fixed to handle shared/sharable pages corretly.

If pages cannot be unshared immediately (due to lack of free memory required to
create private copies) the VCPU under emulation is paused, and the emulator
returns X86EMUL_RETRY, which will get resolved after some memory is freed back
to Xen (possibly through host paging).

Signed-off-by: Grzegorz Milos <Grzegorz.Milos@citrix.com>

1 files changed, 12 insertions, 4 deletions

diff --git a/xen/arch/x86/hvm/io.c b/xen/arch/x86/hvm/io.c
index 29079f296d..3c31a6d2e4 100644
--- a/xen/arch/x86/hvm/io.c
+++ b/xen/arch/x86/hvm/io.c
@@ -263,8 +263,11 @@ static int dpci_ioport_read(uint32_t mport, ioreq_t *p)
 
         if ( p->data_is_ptr )
         {
-            if ( hvm_copy_to_guest_phys(p->data + (sign * i * p->size), &data,
-                                        p->size) ==  HVMCOPY_gfn_paged_out )
+            int ret;
+            ret = hvm_copy_to_guest_phys(p->data + (sign * i * p->size), &data,
+                                         p->size);
+            if ( (ret == HVMCOPY_gfn_paged_out) ||
+                 (ret == HVMCOPY_gfn_shared) )
                 return X86EMUL_RETRY;
         }
         else
@@ -284,8 +287,13 @@ static int dpci_ioport_write(uint32_t mport, ioreq_t *p)
         data = p->data;
         if ( p->data_is_ptr )
         {
-            if ( hvm_copy_from_guest_phys(&data, p->data + (sign * i * p->size),
-                                          p->size) ==  HVMCOPY_gfn_paged_out )
+            int ret;
+            
+            ret = hvm_copy_from_guest_phys(&data, 
+                                           p->data + (sign * i * p->size),
+                                           p->size);
+            if ( (ret == HVMCOPY_gfn_paged_out) &&
+                 (ret == HVMCOPY_gfn_shared) )
                 return X86EMUL_RETRY;
         }