[PATCH v2] x86/HVM: drop stale check from hvm_load_cpu_msrs()

[PATCH v2] x86/HVM: drop stale check from hvm_load_cpu_msrs()

[Jan Beulich]

Up until f61685a66903 ("x86: remove defunct init/load/save_msr()
hvm_funcs") the check of the _rsvd field served as an error check for
the earlier hvm_funcs.save_msr() invocation. With that invocation gone
the check makes no sense anymore: It is effectively dead code due to the
checking of the field in the earlier loop.

While dropping the conditional also eliminate the "err" local variable
(using a non-standard name anyway), replaced by suitable new/adjusted
"return" statements.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
---
v2: Remove "err". Amend description.

--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -1428,7 +1428,6 @@ static int cf_check hvm_load_cpu_msrs(st
     struct vcpu *v;
     const struct hvm_save_descriptor *desc;
     struct hvm_msr *ctxt;
-    int err = 0;
 
     if ( vcpuid >= d->max_vcpus || (v = d->vcpu[vcpuid]) == NULL )
     {
@@ -1479,7 +1478,7 @@ static int cf_check hvm_load_cpu_msrs(st
             return -EOPNOTSUPP;
     /* Checking finished */
 
-    for ( i = 0; !err && i < ctxt->count; ++i )
+    for ( i = 0; i < ctxt->count; ++i )
     {
         switch ( ctxt->msr[i].index )
         {
@@ -1495,17 +1494,15 @@ static int cf_check hvm_load_cpu_msrs(st
             rc = guest_wrmsr(v, ctxt->msr[i].index, ctxt->msr[i].val);
 
             if ( rc != X86EMUL_OKAY )
-                err = -ENXIO;
+                return -ENXIO;
             break;
 
         default:
-            if ( !ctxt->msr[i]._rsvd )
-                err = -ENXIO;
-            break;
+            return -ENXIO;
         }
     }
 
-    return err;
+    return 0;
 }
 
 /* We need variable length data chunks for XSAVE area and MSRs, hence

Re: [PATCH v2] x86/HVM: drop stale check from hvm_load_cpu_msrs()

[Andrew Cooper]

On 06/12/2022 13:00, Jan Beulich wrote:
> Up until f61685a66903 ("x86: remove defunct init/load/save_msr()
> hvm_funcs") the check of the _rsvd field served as an error check for
> the earlier hvm_funcs.save_msr() invocation. With that invocation gone
> the check makes no sense anymore: It is effectively dead code due to the
> checking of the field in the earlier loop.
>
> While dropping the conditional also eliminate the "err" local variable
> (using a non-standard name anyway), replaced by suitable new/adjusted
> "return" statements.
>
> Signed-off-by: Jan Beulich <jbeulich@suse.com>

Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>