[Xen-devel] [PATCH] x86/HVM: don't give the wrong impression of WRMSR succeeding

["Jan Beulich" <JBeulich@xxxxxxxx>]

... for unknown MSRs: wrmsr_hypervisor_regs()'s comment clearly says
that the function returns 0 for unrecognized MSRs, so
{svm,vmx}_msr_write_intercept() should not convert this into success.

At the time it went in, commit 013e34f5a6 ("x86: handle paged gfn in
wrmsr_hypervisor_regs") was probably okay, since prior to that the
return value wasn't checked at all. But that's not how we want things
to be handled nowadays.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

--- a/xen/arch/x86/hvm/svm/svm.c
+++ b/xen/arch/x86/hvm/svm/svm.c
@@ -2124,7 +2124,6 @@ static int svm_msr_write_intercept(unsig
         case -ERESTART:
             result = X86EMUL_RETRY;
             break;
-        case 0:
         case 1:
             break;
         default:
--- a/xen/arch/x86/hvm/vmx/vmx.c
+++ b/xen/arch/x86/hvm/vmx/vmx.c
@@ -3160,7 +3160,6 @@ static int vmx_msr_write_intercept(unsig
                 {
                 case -ERESTART:
                     return X86EMUL_RETRY;
-                case 0:
                 case 1:
                     break;
                 default:




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