public/x86: add TSC defines for cpuid leaf 4

Cpuid leaf 4 contains information about how the state of the tsc, its
mode, and some additional information.  A commit that is queued for
linux would like to use this to determine whether the tsc mode has been
set to 'no emulation' in order to make some decisions about which
clocksource is more reliable.

Expose this information in the public API headers so that they can
subsequently be imported into linux and used there.

Link: https://lore.kernel.org/xen-devel/eda8d9f2-3013-1b68-0df8-64d7f13ee35e@suse.com/
Link: https://lore.kernel.org/xen-devel/0835453d-9617-48d5-b2dc-77a2ac298bad@oracle.com/
Signed-off-by: Krister Johansen <kjlx@templeofstupid.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>

diff --git a/xen/include/public/arch-x86/cpuid.h b/xen/include/public/arch-x86/cpuid.h
index 7ecd16ae05fd13aec508331e98b549360a427528..3bb0dd249ff988515eb6465b22ea5f07606ebdf9 100644 (file)
--- a/xen/include/public/arch-x86/cpuid.h
+++ b/xen/include/public/arch-x86/cpuid.h
@@ -72,6 +72,15 @@
  * Sub-leaf 2: EAX: host tsc frequency in kHz
  */
 
+#define XEN_CPUID_TSC_EMULATED               (1u << 0)
+#define XEN_CPUID_HOST_TSC_RELIABLE          (1u << 1)
+#define XEN_CPUID_RDTSCP_INSTR_AVAIL         (1u << 2)
+
+#define XEN_CPUID_TSC_MODE_DEFAULT           (0)
+#define XEN_CPUID_TSC_MODE_ALWAYS_EMULATE    (1u)
+#define XEN_CPUID_TSC_MODE_NEVER_EMULATE     (2u)
+#define XEN_CPUID_TSC_MODE_PVRDTSCP          (3u)
+
 /*
  * Leaf 5 (0x40000x04)
  * HVM-specific features