x86/msr: handle IA32_THERM_STATUS

x86/msr: handle IA32_THERM_STATUS

Windows 8 will attempt to read MSR_IA32_THERM_STATUS and panic if a
#GP fault is injected as a result:

vmx.c:3035:d8v0 RDMSR 0x0000019c unimplemented
d8v0 VIRIDIAN CRASH: 3b c0000096 fffff8061de31651 fffff4088a613720 0

So handle the MSR and return 0 instead.

Note that this is done on the generic MSR handler, and PV guest will
also get 0 back when trying to read the MSR. There doesn't seem to be
much value in handling the MSR for HVM guests only.

Fixes: 84e848fd7a1 ('x86/hvm: disallow access to unknown MSRs')
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>