[Xen-changelog] [xen master] x86emul: in_longmode() should not ignore ->read_msr() errors

[patchbot@xxxxxxx]

commit 122dd9575c7a3b503e8f4aec64d16e8986a0bb91
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Wed Nov 23 15:27:47 2016 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Wed Nov 23 15:27:47 2016 +0100

    x86emul: in_longmode() should not ignore ->read_msr() errors
    
    All present hook implementations succeed for EFER, but we shouldn't
    really build on this being the case.
    
    Suggested-by: George Dunlap <george.dunlap@xxxxxxxxxx>
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Release-acked-by: Wei Liu <wei.liu2@xxxxxxxxxx>
---
 xen/arch/x86/x86_emulate/x86_emulate.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/xen/arch/x86/x86_emulate/x86_emulate.c 
b/xen/arch/x86/x86_emulate/x86_emulate.c
index a85f45e..04f0dac 100644
--- a/xen/arch/x86/x86_emulate/x86_emulate.c
+++ b/xen/arch/x86/x86_emulate/x86_emulate.c
@@ -1296,10 +1296,10 @@ in_longmode(
 {
     uint64_t efer;
 
-    if (ops->read_msr == NULL)
+    if ( !ops->read_msr ||
+         unlikely(ops->read_msr(MSR_EFER, &efer, ctxt) != X86EMUL_OKAY) )
         return -1;
 
-    ops->read_msr(MSR_EFER, &efer, ctxt);
     return !!(efer & EFER_LMA);
 }
 
--
generated by git-patchbot for /home/xen/git/xen.git#master

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