x86, amd, xen: Avoid NULL pointer paravirt references

Stub out MSR methods that aren't actually needed.  This fixes a crash
as Xen Dom0 on AMD Trinity systems.  A bigger patch should be added to
remove the paravirt machinery completely for the methods which
apparently have no users!

Reported-by: Andre Przywara <andre.przywara@amd.com>
Link: http://lkml.kernel.org/r/20120530222356.GA28417@andromeda.dapyr.net
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Cc: <stable@vger.kernel.org>

diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 75f33b2..e74df95 100644 (file)
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -1116,7 +1116,10 @@ static const struct pv_cpu_ops xen_cpu_ops __initconst = {
        .wbinvd = native_wbinvd,
 
        .read_msr = native_read_msr_safe,
+       .rdmsr_regs = native_rdmsr_safe_regs,
        .write_msr = xen_write_msr_safe,
+       .wrmsr_regs = native_wrmsr_safe_regs,
+
        .read_tsc = native_read_tsc,
        .read_pmc = native_read_pmc,