[Xen-devel] [PATCH] xen/ept: Correct double unmap_domain_page() on error path

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

c/s 3d90d6e6 "x86/EPT: split super pages upon mismatching memory types"
accidentally introduced an error path where the epte domain page would be
unmapped twice if splitting the superpage failed.

Only unmap the page if the loop is to be continued.  When breaking from the
loop, the page will be unmapped by the subsequent code.

Coverity-ID: 1203047
Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
CC: Keir Fraser <keir@xxxxxxx>
CC: Jan Beulich <JBeulich@xxxxxxxx>
CC: Tim Deegan <tim@xxxxxxx>
---
 xen/arch/x86/mm/p2m-ept.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/xen/arch/x86/mm/p2m-ept.c b/xen/arch/x86/mm/p2m-ept.c
index eeb95bb..f064f0b 100644
--- a/xen/arch/x86/mm/p2m-ept.c
+++ b/xen/arch/x86/mm/p2m-ept.c
@@ -350,9 +350,9 @@ bool_t ept_handle_misconfig(uint64_t gpa)
                                              e.sa_p2mt == p2m_mmio_direct);
                 if ( unlikely(emt < 0) )
                 {
-                    unmap_domain_page(epte);
                     if ( ept_split_super_page(p2m, &e, level, level - 1) )
                     {
+                        unmap_domain_page(epte);
                         mfn = e.mfn;
                         continue;
                     }
-- 
1.7.10.4


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