[Xen-changelog] [xen master] pvh: do not allow PVH guests to change paging modes

[patchbot@xxxxxxx]

commit 9001eb540b815110302505cfd799f1356f40e47f
Author:     Mukesh Rathor <mukesh.rathor@xxxxxxxxxx>
AuthorDate: Wed Nov 13 09:35:58 2013 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Wed Nov 13 09:35:58 2013 +0100

    pvh: do not allow PVH guests to change paging modes
    
    Signed-off-by: Mukesh Rathor <mukesh.rathor@xxxxxxxxxx>
    Signed-off-by: George Dunlap <george.dunlap@xxxxxxxxxxxxx>
    Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
    Acked-by: Tim Deegan <tim@xxxxxxx>
    Acked-by: Keir Fraser <keir@xxxxxxx>
    Acked-by: Eddie Dong <eddie.dong@xxxxxxxxx>
---
 xen/arch/x86/hvm/hvm.c |    9 +++++++++
 1 files changed, 9 insertions(+), 0 deletions(-)

diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index 484319f..4df46be 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -1818,6 +1818,15 @@ int hvm_set_cr0(unsigned long value)
          (value & (X86_CR0_PE | X86_CR0_PG)) == X86_CR0_PG )
         goto gpf;
 
+    /* A pvh is not expected to change to real mode. */
+    if ( is_pvh_vcpu(v)
+         && (value & (X86_CR0_PE | X86_CR0_PG)) != (X86_CR0_PG | X86_CR0_PE) )
+    {
+        printk(XENLOG_G_WARNING
+               "PVH attempting to turn off PE/PG. CR0:%lx\n", value);
+        goto gpf;
+    }
+
     if ( (value & X86_CR0_PG) && !(old_value & X86_CR0_PG) )
     {
         if ( v->arch.hvm_vcpu.guest_efer & EFER_LME )
--
generated by git-patchbot for /home/xen/git/xen.git#master

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