[Xen-changelog] [xen stable-4.8] x86/p2m: missing adjustments after 1486caf8a0cf

[patchbot@xxxxxxx]

commit a260e93db794f560502e89859aaf111d178e80e4
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Tue Dec 3 14:41:57 2019 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Tue Dec 3 14:41:57 2019 +0100

    x86/p2m: missing adjustments after 1486caf8a0cf
    
    There was a piece of code missing in the backport of 183f354e1430
    ("x86/vvmx: Fix livelock with XSA-304 fix"), which ought to have been
    taken from 0cafb89ae632 ("x86/vtx: Allow runtime modification of the
    exec-sp setting").
    
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
---
 xen/arch/x86/mm/p2m.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/xen/arch/x86/mm/p2m.c b/xen/arch/x86/mm/p2m.c
index 9c1849bf52..5d5af7aa55 100644
--- a/xen/arch/x86/mm/p2m.c
+++ b/xen/arch/x86/mm/p2m.c
@@ -265,17 +265,22 @@ int p2m_is_logdirty_range(struct p2m_domain *p2m, 
unsigned long start,
     return 0;
 }
 
+/*
+ * May be called with ot = nt = p2m_ram_rw for its side effect of
+ * recalculating all PTEs in the p2m.
+ */
 void p2m_change_entry_type_global(struct domain *d,
                                   p2m_type_t ot, p2m_type_t nt)
 {
     struct p2m_domain *p2m = p2m_get_hostp2m(d);
 
-    ASSERT(ot != nt);
     ASSERT(p2m_is_changeable(ot) && p2m_is_changeable(nt));
 
     p2m_lock(p2m);
     p2m->change_entry_type_global(p2m, ot, nt);
-    p2m->global_logdirty = (nt == p2m_ram_logdirty);
+    /* Don't allow 'recalculate' operations to change the logdirty state. */
+    if ( ot != nt )
+        p2m->global_logdirty = (nt == p2m_ram_logdirty);
     p2m_unlock(p2m);
 }
 
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.8

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