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@suse.com>
Tested-by: Ren Yongjie <yongjie.ren@intel.com>
Acked-by: Liu Jinsong <jinsong.liu@intel.com>

diff --git a/xen/arch/x86/cpu/mcheck/mce.c b/xen/arch/x86/cpu/mcheck/mce.c
index ced1a89f4ffdf23479af959b6de545b139eb7a59..fa879821fe3305e14eefcb2066fc82f7a82ad047 100644 (file)
--- a/xen/arch/x86/cpu/mcheck/mce.c
+++ b/xen/arch/x86/cpu/mcheck/mce.c
@@ -1065,13 +1065,15 @@ 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 6006fb4b7ed27c02c2dc3fa155d8bdfe4e3167d1..cbd123d555e49a04ffad466b05d46a1fe945477b 100644 (file)
--- a/xen/arch/x86/cpu/mcheck/mce.h
+++ b/xen/arch/x86/cpu/mcheck/mce.h
@@ -77,7 +77,7 @@ 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)
 {
@@ -89,9 +89,9 @@ 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