[Xen-changelog] [xen stable-4.1] x86/MCA: suppress bank clearing for certain injected events

[patchbot@xxxxxxx]

commit cf7ec303a920cfead31ebd4373ecd365b527e680
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Tue Apr 2 12:26:22 2013 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Tue Apr 2 12:26:22 2013 +0200

    x86/MCA: suppress bank clearing for certain injected events
    
    As the bits indicating validity of the ADDR and MISC bank MSRs may be
    injected in a way that isn't consistent with what the underlying
    hardware implements (while the bank must be valid for injection to
    work, the auxiliary MSRs may not be implemented - and hence cause #GP
    upon access - if the hardware never sets the corresponding valid bits.
    
    Consequently we need to do the clearing writes only if no value was
    interposed for the respective MSR (which also makes sense the other way
    around: there's no point in clearing a hardware register when all data
    read came from software). Of course this all requires the injection
    tool to do things in a consistent way (but that had been a requirement
    before already).
    
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Tested-by: Ren Yongjie <yongjie.ren@xxxxxxxxx>
    Acked-by: Liu Jinsong <jinsong.liu@xxxxxxxxx>
    master changeset: b0583c0e64cc8bb6229c95c3304fdac2051f79b3
    master date: 2013-03-12 15:53:30 +0100
---
 xen/arch/x86/cpu/mcheck/mce.c |   12 +++++++-----
 xen/arch/x86/cpu/mcheck/mce.h |    8 ++++----
 2 files changed, 11 insertions(+), 9 deletions(-)

diff --git a/xen/arch/x86/cpu/mcheck/mce.c b/xen/arch/x86/cpu/mcheck/mce.c
index 8a1c19c..1842e52 100644
--- a/xen/arch/x86/cpu/mcheck/mce.c
+++ b/xen/arch/x86/cpu/mcheck/mce.c
@@ -1117,13 +1117,15 @@ static void intpose_add(unsigned int cpu_nr, uint64_t 
msr, uint64_t val)
     printk("intpose_add: interpose array full - request dropped\n");
 }
 
-void intpose_inval(unsigned int cpu_nr, uint64_t msr)
+bool_t intpose_inval(unsigned int cpu_nr, uint64_t msr)
 {
-    struct intpose_ent *ent;
+    struct intpose_ent *ent = intpose_lookup(cpu_nr, msr, NULL);
 
-    if ((ent = intpose_lookup(cpu_nr, msr, NULL)) != NULL) {
-        ent->cpu_nr = -1;
-    }
+    if ( !ent )
+        return 0;
+
+    ent->cpu_nr = -1;
+    return 1;
 }
 
 #define IS_MCA_BANKREG(r) \
diff --git a/xen/arch/x86/cpu/mcheck/mce.h b/xen/arch/x86/cpu/mcheck/mce.h
index f87fd08..2428f3a 100644
--- a/xen/arch/x86/cpu/mcheck/mce.h
+++ b/xen/arch/x86/cpu/mcheck/mce.h
@@ -83,7 +83,7 @@ extern void mce_recoverable_register(mce_recoverable_t);
 /* Read an MSR, checking for an interposed value first */
 extern struct intpose_ent *intpose_lookup(unsigned int, uint64_t,
     uint64_t *);
-extern void intpose_inval(unsigned int, uint64_t);
+extern bool_t intpose_inval(unsigned int, uint64_t);
 
 static inline uint64_t mca_rdmsr(unsigned int msr)
 {
@@ -95,9 +95,9 @@ static inline uint64_t mca_rdmsr(unsigned int msr)
 
 /* Write an MSR, invalidating any interposed value */
 #define mca_wrmsr(msr, val) do { \
-       intpose_inval(smp_processor_id(), msr); \
-       wrmsrl(msr, val); \
-} while (0)
+    if ( !intpose_inval(smp_processor_id(), msr) ) \
+        wrmsrl(msr, val); \
+} while ( 0 )
 
 
 /* Utility function to "logout" all architectural MCA telemetry from the MCA
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.1

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