Re: [Xen-devel] [PATCH 1/2] Xen/MCA: bugfix for mca bank clear

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 28.02.13 at 09:05, "Jan Beulich" <JBeulich@xxxxxxxx> wrote:
> And then I don't see why you would do physical MSR accesses in
> the injection case at all. It should really be mca_wrmsr() to take
> care of this, it just needs to have a way to know it got called in
> the context of an injection. One fundamental question here is
> why the invalidation of the interposed data is being done
> before the MSR write rather than after. One thing we surely
> don't care much about in the injection logic is interference with
> a real #MC.

Like this (RFC only, untested so far), based on having gone through
all call sites of mca_wrmsr():

--- 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
     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) \
--- 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
 /* 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(unsigne
 
 /* 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



_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel