[PATCH v2 14/15] asm-generic: hyperv: Use mshv headers conditionally. Add asm-generic/hyperv-defs.h

[Nuno Das Neves]

Add hyperv-defs.h to replace some inclusions of hyperv-tlfs.h.

It includes hyperv-tlfs.h or hvhdk.h depending on a compile-time constant
HV_HYPERV_DEFS which will be defined in the mshv driver.

This is needed to keep unstable Hyper-V interfaces independent of
hyperv-tlfs.h. This ensures hvhdk.h replaces hyperv-tlfs.h in the mshv driver,
even via indirect includes.

Signed-off-by: Nuno Das Neves <nunodasneves@xxxxxxxxxxxxxxxxxxx>
---
 arch/arm64/include/asm/mshyperv.h |  2 +-
 arch/x86/include/asm/mshyperv.h   |  3 +--
 drivers/hv/hyperv_vmbus.h         |  1 -
 include/asm-generic/hyperv-defs.h | 26 ++++++++++++++++++++++++++
 include/asm-generic/mshyperv.h    |  2 +-
 include/linux/hyperv.h            |  2 +-
 6 files changed, 30 insertions(+), 6 deletions(-)
 create mode 100644 include/asm-generic/hyperv-defs.h

diff --git a/arch/arm64/include/asm/mshyperv.h b/arch/arm64/include/asm/mshyperv.h
index 20070a847304..8ec14caf3d4f 100644
--- a/arch/arm64/include/asm/mshyperv.h
+++ b/arch/arm64/include/asm/mshyperv.h
@@ -20,7 +20,7 @@
 
 #include <linux/types.h>
 #include <linux/arm-smccc.h>
-#include <asm/hyperv-tlfs.h>
+#include <asm-generic/hyperv-defs.h>
 
 /*
  * Declare calls to get and set Hyper-V VP register values on ARM64, which
diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
index 79ffc7913016..c009e9c71445 100644
--- a/arch/x86/include/asm/mshyperv.h
+++ b/arch/x86/include/asm/mshyperv.h
@@ -6,10 +6,9 @@
 #include <linux/nmi.h>
 #include <linux/msi.h>
 #include <asm/io.h>
-#include <asm/hyperv-tlfs.h>
 #include <asm/nospec-branch.h>
 #include <asm/paravirt.h>
-#include <asm/mshyperv.h>
+#include <asm-generic/hyperv-defs.h>
 
 /*
  * Hyper-V always provides a single IO-APIC at this MMIO address.
diff --git a/drivers/hv/hyperv_vmbus.h b/drivers/hv/hyperv_vmbus.h
index 85f3c08bb42b..49529f0b8b99 100644
--- a/drivers/hv/hyperv_vmbus.h
+++ b/drivers/hv/hyperv_vmbus.h
@@ -15,7 +15,6 @@
 #include <linux/list.h>
 #include <linux/bitops.h>
 #include <asm/sync_bitops.h>
-#include <asm/hyperv-tlfs.h>
 #include <linux/atomic.h>
 #include <linux/hyperv.h>
 #include <linux/interrupt.h>
diff --git a/include/asm-generic/hyperv-defs.h b/include/asm-generic/hyperv-defs.h
new file mode 100644
index 000000000000..ac6fcba35c8c
--- /dev/null
+++ b/include/asm-generic/hyperv-defs.h
@@ -0,0 +1,26 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_GENERIC_HYPERV_DEFS_H
+#define _ASM_GENERIC_HYPERV_DEFS_H
+
+/*
+ * There are cases where Microsoft Hypervisor ABIs are needed which may not be
+ * stable or present in the Hyper-V TLFS document. E.g. the mshv_root driver.
+ *
+ * As these interfaces are unstable and may differ from hyperv-tlfs.h, they
+ * must be kept separate and independent.
+ *
+ * However, code from files that depend on hyperv-tlfs.h (such as mshyperv.h)
+ * is still needed, so work around the issue by conditionally including the
+ * correct definitions.
+ *
+ * Note: Since they are independent of each other, there are many definitions
+ * duplicated in both hyperv-tlfs.h and uapi/hyperv/hv*.h files.
+ */
+#ifdef HV_HYPERV_DEFS
+#include <uapi/hyperv/hvhdk.h>
+#else
+#include <asm/hyperv-tlfs.h>
+#endif
+
+#endif /* _ASM_GENERIC_HYPERV_DEFS_H */
+
diff --git a/include/asm-generic/mshyperv.h b/include/asm-generic/mshyperv.h
index 2b20994d809e..e86b6f51fb64 100644
--- a/include/asm-generic/mshyperv.h
+++ b/include/asm-generic/mshyperv.h
@@ -25,7 +25,7 @@
 #include <linux/cpumask.h>
 #include <linux/nmi.h>
 #include <asm/ptrace.h>
-#include <asm/hyperv-tlfs.h>
+#include <asm-generic/hyperv-defs.h>
 
 #define VTPM_BASE_ADDRESS 0xfed40000
 
diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
index f90de5abcd50..66ed8b3e5d89 100644
--- a/include/linux/hyperv.h
+++ b/include/linux/hyperv.h
@@ -24,7 +24,7 @@
 #include <linux/mod_devicetable.h>
 #include <linux/interrupt.h>
 #include <linux/reciprocal_div.h>
-#include <asm/hyperv-tlfs.h>
+#include <asm-generic/hyperv-defs.h>
 
 #define MAX_PAGE_BUFFER_COUNT				32
 #define MAX_MULTIPAGE_BUFFER_COUNT			32 /* 128K */
-- 
2.25.1