[RFC PATCH 3/3] arch/x86/acrn: add hypercall for acrn_hypervisor

[Zhao Yakui <yakui.zhao@intel.com>]

When acrn_hypervisor is detected, the other module may communicate with
the hypervisor to query/config some settings. For example: it can be used
to query the resources in hypervisor and manage the CPU/memory/device/
interrupt for Guest system.

So the hypercall is added so that the kernel can communicate with the
low-level acrn-hypervisor. On x86 it is implemented by using vmacll when
the acrn hypervisor is enabled.

Signed-off-by: Jason Chen CJ <jason.cj.chen@intel.com>
Signed-off-by: Zhao Yakui <yakui.zhao@intel.com>
---
 arch/x86/include/asm/acrn_hypercall.h | 85 +++++++++++++++++++++++++++++++++++
 1 file changed, 85 insertions(+)
 create mode 100644 arch/x86/include/asm/acrn_hypercall.h

diff --git a/arch/x86/include/asm/acrn_hypercall.h b/arch/x86/include/asm/acrn_hypercall.h
new file mode 100644
index 0000000..7ffa759
--- /dev/null
+++ b/arch/x86/include/asm/acrn_hypercall.h
@@ -0,0 +1,85 @@
+/* SPDX-License-Identifier: GPL-2.0+ OR BSD-3-Clause */
+/*
+ * acrn_hypercall.h : acrn hypervisor call API
+ */
+
+#ifndef __ACRN_HYPERCALL_H__
+#define __ACRN_HYPERCALL_H__
+
+#include <linux/errno.h>
+
+#ifdef CONFIG_ACRN
+
+static inline long acrn_hypercall0(unsigned long hcall_id)
+{
+
+	/* x86-64 System V ABI register usage */
+	register signed long    result asm("rax");
+	register unsigned long  r8 asm("r8")  = hcall_id;
+
+	/* Execute vmcall */
+	asm volatile(".byte 0x0F,0x01,0xC1\n"
+			: "=r"(result)
+			:  "r"(r8));
+
+	/* Return result to caller */
+	return result;
+}
+
+static inline long acrn_hypercall1(unsigned long hcall_id,
+				   unsigned long param1)
+{
+
+	/* x86-64 System V ABI register usage */
+	register signed long    result asm("rax");
+	register unsigned long  r8 asm("r8")  = hcall_id;
+
+	/* Execute vmcall */
+	asm volatile(".byte 0x0F,0x01,0xC1\n"
+			: "=r"(result)
+			: "D"(param1), "r"(r8));
+
+	/* Return result to caller */
+	return result;
+}
+
+static inline long acrn_hypercall2(unsigned long hcall_id,
+				   unsigned long param1,
+				   unsigned long param2)
+{
+
+	/* x86-64 System V ABI register usage */
+	register signed long    result asm("rax");
+	register unsigned long  r8 asm("r8")  = hcall_id;
+
+	/* Execute vmcall */
+	asm volatile(".byte 0x0F,0x01,0xC1\n"
+			: "=r"(result)
+			: "D"(param1), "S"(param2), "r"(r8));
+
+	/* Return result to caller */
+	return result;
+}
+
+#else
+
+static inline long acrn_hypercall0(unsigned long hcall_id)
+{
+	return -ENOTSUPP;
+}
+
+static inline long acrn_hypercall1(unsigned long hcall_id,
+				   unsigned long param1)
+{
+	return -ENOTSUPP;
+}
+
+static inline long acrn_hypercall2(unsigned long hcall_id,
+				   unsigned long param1,
+				   unsigned long param2)
+{
+	return -ENOTSUPP;
+}
+#endif
+
+#endif /* __ACRN_HYPERCALL_H__ */
-- 
2.7.4