[PATCH] x86: Add MMIO Stale Data arch_caps to hardware domain

[Jason Andryuk <jandryuk@xxxxxxxxx>]

Let the hardware domain know about the hardware it is running on.  This
allows a linux Dom0 to know that it has the appropriate microcode via
FB_CLEAR.  /sys/devices/system/cpu/vulnerabilities/mmio_stale_data
changes from:
"Vulnerable: Clear CPU buffers attempted, no microcode; SMT Host state
unknown"
to:
"Mitigation: Clear CPU buffers; SMT Host state unknown"

Signed-off-by: Jason Andryuk <jandryuk@xxxxxxxxx>
---
Should calculate_host_policy()'s arch_caps mask also be updated?  They
are not identical today, but I'm don't know this code to understand why
they differ.

 xen/arch/x86/msr.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/xen/arch/x86/msr.c b/xen/arch/x86/msr.c
index c2c0025e3a..f1c36d423f 100644
--- a/xen/arch/x86/msr.c
+++ b/xen/arch/x86/msr.c
@@ -163,7 +163,9 @@ int init_domain_msr_policy(struct domain *d)
 
         mp->arch_caps.raw = val &
             (ARCH_CAPS_RDCL_NO | ARCH_CAPS_IBRS_ALL | ARCH_CAPS_RSBA |
-             ARCH_CAPS_SSB_NO | ARCH_CAPS_MDS_NO | ARCH_CAPS_TAA_NO);
+             ARCH_CAPS_SSB_NO | ARCH_CAPS_MDS_NO | ARCH_CAPS_TAA_NO |
+             ARCH_CAPS_SBDR_SSDP_NO | ARCH_CAPS_FBSDP_NO | ARCH_CAPS_PSDP_NO |
+             ARCH_CAPS_FB_CLEAR);
     }
 
     d->arch.msr = mp;
-- 
2.36.1