[PATCH 1 of 2] traps: AMD PM RDMSRs (MSR_K8_PSTATE_CTRL, etc)

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

# HG changeset patch
# User Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
# Date 1330065828 18000
# Node ID a34b652afb0ca484b7416008c95fd36ffbbea334
# Parent  a4d93d0e0df2fafe5b3e2dab3e34799498a875e2
traps: AMD PM RDMSRs (MSR_K8_PSTATE_CTRL, etc)

The restriction to read and write the AMD power management MSRs is gated if the
domain 0 is the PM domain (so FREQCTL_dom0_kernel is set). But we can
relax this restriction and allow the privileged domain to read the MSRs
(but not write). This allows the priviliged domain to harvest the power
management information (ACPI _PSS states) and send it to the hypervisor.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

diff -r a4d93d0e0df2 -r a34b652afb0c xen/arch/x86/traps.c
--- a/xen/arch/x86/traps.c	Wed Feb 22 14:33:24 2012 +0000
+++ b/xen/arch/x86/traps.c	Fri Feb 24 01:43:48 2012 -0500
@@ -2610,7 +2610,7 @@ static int emulate_privileged_op(struct 
         case MSR_K8_PSTATE7:
             if ( boot_cpu_data.x86_vendor != X86_VENDOR_AMD )
                 goto fail;
-            if ( !is_cpufreq_controller(v->domain) )
+            if ( !is_cpufreq_controller(v->domain) && !IS_PRIV(v->domain) )
             {
                 regs->eax = regs->edx = 0;
                 break;