[Xen-changelog] [xen-3.4-testing] x86 ept: ignore guest writes to read only memory regions or memory

["Xen patchbot-3.4-testing" <patchbot-3.4-testing@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User Keir Fraser <keir.fraser@xxxxxxxxxx>
# Date 1256290441 -3600
# Node ID 2a5604621e21435c9421ffca2419151566e49014
# Parent  156dde712ec083b37e09415a704b37e510f13764
x86 ept: ignore guest writes to read only memory regions or memory
holes in EPT.

This patch prevents domain crash when running memtest86 with EPT.

Signed-off-by: Xin Li <xin.li@xxxxxxxxx>
xen-unstable changeset:   20364:e36ffdd9e8cf
xen-unstable date:        Fri Oct 23 10:13:52 2009 +0100
---
 xen/arch/x86/hvm/vmx/vmx.c |   11 +++++++++++
 1 files changed, 11 insertions(+)

diff -r 156dde712ec0 -r 2a5604621e21 xen/arch/x86/hvm/vmx/vmx.c
--- a/xen/arch/x86/hvm/vmx/vmx.c        Fri Oct 23 10:32:00 2009 +0100
+++ b/xen/arch/x86/hvm/vmx/vmx.c        Fri Oct 23 10:34:01 2009 +0100
@@ -2154,6 +2154,17 @@ static void ept_handle_violation(unsigne
         return;
     }
 
+    /* Ignore writes to:
+     *     1. read only memory regions;
+     *     2. memory holes. */
+    if ( (qualification & EPT_WRITE_VIOLATION)
+         && (((gla_validity == EPT_GLA_VALIDITY_MATCH) && (t == p2m_ram_ro))
+             || (mfn_x(mfn) == INVALID_MFN)) ) {
+        int inst_len = __get_instruction_length();
+        __update_guest_eip(inst_len);
+        return;
+    }
+
     /* Everything else is an error. */
     gla = __vmread(GUEST_LINEAR_ADDRESS);
     gdprintk(XENLOG_ERR, "EPT violation %#lx (%c%c%c/%c%c%c), "

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