[Xen-devel] [PATCH] ignore guest writes to read only memory regions or memory holes in EPT

["Li, Xin" <xin.li@xxxxxxxxx>]

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>

diff -r 37829fd7c1e3 xen/arch/x86/hvm/vmx/vmx.c
--- a/xen/arch/x86/hvm/vmx/vmx.c        Wed Oct 21 16:08:28 2009 +0100
+++ b/xen/arch/x86/hvm/vmx/vmx.c        Fri Oct 23 23:21:27 2009 +0800
@@ -2184,6 +2184,17 @@
         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), "

fix-ept-memtest86.patch
Description: fix-ept-memtest86.patch

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