No need split mmio read region into 8-bits pieces since we do it in
emulator_read_write_onepage

Changelog:
  Add a WARN_ON to check read-cache overflow

Acked-by: Marcelo Tosatti <mtosa...@redhat.com>
Signed-off-by: Xiao Guangrong <xiaoguangr...@linux.vnet.ibm.com>
---
 arch/x86/kvm/emulate.c |   31 ++++++++++++++-----------------
 1 files changed, 14 insertions(+), 17 deletions(-)

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 97d9a99..e33eb02 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -1166,24 +1166,21 @@ static int read_emulated(struct x86_emulate_ctxt *ctxt,
        int rc;
        struct read_cache *mc = &ctxt->mem_read;

-       while (size) {
-               int n = min(size, 8u);
-               size -= n;
-               if (mc->pos < mc->end)
-                       goto read_cached;
-
-               rc = ctxt->ops->read_emulated(ctxt, addr, mc->data + mc->end, n,
-                                             &ctxt->exception);
-               if (rc != X86EMUL_CONTINUE)
-                       return rc;
-               mc->end += n;
+       if (mc->pos < mc->end)
+               goto read_cached;

-       read_cached:
-               memcpy(dest, mc->data + mc->pos, n);
-               mc->pos += n;
-               dest += n;
-               addr += n;
-       }
+       WARN_ON((mc->end + size) >= sizeof(mc->data));
+
+       rc = ctxt->ops->read_emulated(ctxt, addr, mc->data + mc->end, size,
+                                     &ctxt->exception);
+       if (rc != X86EMUL_CONTINUE)
+               return rc;
+
+       mc->end += size;
+
+read_cached:
+       memcpy(dest, mc->data + mc->pos, size);
+       mc->pos += size;
        return X86EMUL_CONTINUE;
 }

-- 
1.7.7.6

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