x86/hyperv: detect if Linux is the root partition

For now we can use the privilege flag to check. Stash the value to be
used later.

Put in a bunch of defines for future use when we want to have more
fine-grained detection.

Signed-off-by: Wei Liu <wei.liu@kernel.org>
Reviewed-by: Pavel Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/20210203150435.27941-3-wei.liu@kernel.org

1 files changed, 10 insertions, 0 deletions

diff --git a/arch/x86/include/asm/hyperv-tlfs.h b/arch/x86/include/asm/hyperv-tlfs.h
index 6aed936e5e96..e3a6a723d661 100644
--- a/arch/x86/include/asm/hyperv-tlfs.h
+++ b/arch/x86/include/asm/hyperv-tlfs.h
@@ -21,6 +21,7 @@
 #define HYPERV_CPUID_FEATURES			0x40000003
 #define HYPERV_CPUID_ENLIGHTMENT_INFO		0x40000004
 #define HYPERV_CPUID_IMPLEMENT_LIMITS		0x40000005
+#define HYPERV_CPUID_CPU_MANAGEMENT_FEATURES	0x40000007
 #define HYPERV_CPUID_NESTED_FEATURES		0x4000000A
 #define HYPERV_CPUID_ISOLATION_CONFIG		0x4000000C
 
@@ -112,6 +113,15 @@
 #define HV_X64_ENLIGHTENED_VMCS_RECOMMENDED		BIT(14)
 
 /*
+ * CPU management features identification.
+ * These are HYPERV_CPUID_CPU_MANAGEMENT_FEATURES.EAX bits.
+ */
+#define HV_X64_START_LOGICAL_PROCESSOR			BIT(0)
+#define HV_X64_CREATE_ROOT_VIRTUAL_PROCESSOR		BIT(1)
+#define HV_X64_PERFORMANCE_COUNTER_SYNC			BIT(2)
+#define HV_X64_RESERVED_IDENTITY_BIT			BIT(31)
+
+/*
  * Virtual processor will never share a physical core with another virtual
  * processor, except for virtual processors that are reported as sibling SMT
  * threads.