[PATCH v2] xen/x86: public: add TSC defines for cpuid leaf 4

[Krister Johansen <kjlx@xxxxxxxxxxxxxxxxxx>]

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@xxxxxxxx/
Link: 
https://lore.kernel.org/xen-devel/0835453d-9617-48d5-b2dc-77a2ac298bad@xxxxxxxxxx/
Signed-off-by: Krister Johansen <kjlx@xxxxxxxxxxxxxxxxxx>
---
v2:
  - Fix whitespace between comment and #defines (feedback from Jan Beulich)
  - Add tsc mode 3: no emulate TSC_AUX (feedback from Jan Beulich)
---
 xen/include/public/arch-x86/cpuid.h | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/xen/include/public/arch-x86/cpuid.h 
b/xen/include/public/arch-x86/cpuid.h
index 7ecd16ae05..090f7f0034 100644
--- a/xen/include/public/arch-x86/cpuid.h
+++ b/xen/include/public/arch-x86/cpuid.h
@@ -72,6 +72,14 @@
  * 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_EMULATE           (1u)
+#define XEN_CPUID_TSC_MODE_NOEMULATE         (2u)
+#define XEN_CPUID_TSC_MODE_NOEMULATE_TSC_AUX (3u)
+
 /*
  * Leaf 5 (0x40000x04)
  * HVM-specific features
-- 
2.25.1