From: Keir Fraser <keir.fraser@citrix.com>
Date: Mon, 26 Nov 2007 16:57:57 +0000 (+0000)
Subject: x86 emulate: Emulate atomic read-modify-write instructions as a
X-Git-Tag: archive/raspbian/4.8.0-1+rpi1~1^2~14684^2~20
X-Git-Url: https://dgit.raspbian.org/%22http://www.example.com/cgi/%22/%22http:/www.example.com/cgi/%22?a=commitdiff_plain;h=a209260781bec2fa050c0ed9f38171373e8d81a2;p=xen.git

x86 emulate: Emulate atomic read-modify-write instructions as a
straightforward write. Hopefully multiprocessor synchronisation is not
relied upon in real mode!
Signed-off-by: Keir Fraser <keir.fraser@citrix.com>
---

diff --git a/xen/arch/x86/hvm/vmx/realmode.c b/xen/arch/x86/hvm/vmx/realmode.c
index 2f31d8fbcd..d26725ba00 100644
--- a/xen/arch/x86/hvm/vmx/realmode.c
+++ b/xen/arch/x86/hvm/vmx/realmode.c
@@ -237,7 +237,8 @@ realmode_emulate_cmpxchg(
     unsigned int bytes,
     struct x86_emulate_ctxt *ctxt)
 {
-    return X86EMUL_UNHANDLEABLE;
+    /* Fix this in case the guest is really relying on r-m-w atomicity. */
+    return realmode_emulate_write(seg, offset, new, bytes, ctxt);
 }
 
 static int