[PATCH] xen: suppress known wrmsrs

Jeremy Fitzhardinge
2008-07-24T20:49:33Z

In general, Xen doesn't support wrmsr from an unprivileged domain; it
just ends up ignoring the instruction and printing a message on the
console.

Given that there are sets of MSRs we know the kernel will try to write
to, but we don't care, just eat them in xen_write_msr to cut down on
console noise.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
---
arch/x86/xen/enlighten.c | 13 +++++++++++++
1 file changed, 13 insertions(+)

===================================================================
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -803,6 +803,19 @@
ret = -EFAULT;
break;
#endif
+
+ case MSR_STAR:
+ case MSR_CSTAR:
+ case MSR_LSTAR:
+ case MSR_SYSCALL_MASK:
+ case MSR_IA32_SYSENTER_CS:
+ case MSR_IA32_SYSENTER_ESP:
+ case MSR_IA32_SYSENTER_EIP:
+ /* Fast syscall setup is all done in hypercalls, so
+ these are all ignored. Stub them out here to stop
+ Xen console noise. */
+ break;
+
default:
ret = native_write_msr_safe(msr, low, high);
}