[RFC,v15,04/30] virt: gunyah: Add hypercalls to identify Gunyah

diff --git a/arch/arm64/Kbuild b/arch/arm64/Kbuild
index 5bfbf7d79c99..e4847ba0e3c9 100644
--- a/arch/arm64/Kbuild
+++ b/arch/arm64/Kbuild
@@ -3,6 +3,7 @@  obj-y			+= kernel/ mm/ net/
 obj-$(CONFIG_KVM)	+= kvm/
 obj-$(CONFIG_XEN)	+= xen/
 obj-$(subst m,y,$(CONFIG_HYPERV))	+= hyperv/
+obj-$(CONFIG_GUNYAH)	+= gunyah/
 obj-$(CONFIG_CRYPTO)	+= crypto/
 
 # for cleaning
diff --git a/arch/arm64/gunyah/Makefile b/arch/arm64/gunyah/Makefile
new file mode 100644
index 000000000000..84f1e38cafb1
--- /dev/null
+++ b/arch/arm64/gunyah/Makefile
@@ -0,0 +1,3 @@ 
+# SPDX-License-Identifier: GPL-2.0
+
+obj-$(CONFIG_GUNYAH) += gunyah_hypercall.o
diff --git a/arch/arm64/gunyah/gunyah_hypercall.c b/arch/arm64/gunyah/gunyah_hypercall.c
new file mode 100644
index 000000000000..739d7f9cef9f
--- /dev/null
+++ b/arch/arm64/gunyah/gunyah_hypercall.c
@@ -0,0 +1,62 @@ 
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2022-2023 Qualcomm Innovation Center, Inc. All rights reserved.
+ */
+
+#include <linux/arm-smccc.h>
+#include <linux/module.h>
+#include <linux/gunyah.h>
+#include <linux/uuid.h>
+
+/* {c1d58fcd-a453-5fdb-9265-ce36673d5f14} */
+static const uuid_t GUNYAH_UUID = UUID_INIT(0xc1d58fcd, 0xa453, 0x5fdb, 0x92,
+					    0x65, 0xce, 0x36, 0x67, 0x3d, 0x5f,
+					    0x14);
+
+bool arch_is_gunyah_guest(void)
+{
+	struct arm_smccc_res res;
+	uuid_t uuid;
+	u32 *up;
+
+	arm_smccc_1_1_hvc(ARM_SMCCC_VENDOR_HYP_CALL_UID_FUNC_ID, &res);
+
+	up = (u32 *)&uuid.b[0];
+	up[0] = lower_32_bits(res.a0);
+	up[1] = lower_32_bits(res.a1);
+	up[2] = lower_32_bits(res.a2);
+	up[3] = lower_32_bits(res.a3);
+
+	return uuid_equal(&uuid, &GUNYAH_UUID);
+}
+EXPORT_SYMBOL_GPL(arch_is_gunyah_guest);
+
+#define GUNYAH_HYPERCALL(fn)                                      \
+	ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, ARM_SMCCC_SMC_64, \
+			   ARM_SMCCC_OWNER_VENDOR_HYP, fn)
+
+/* clang-format off */
+#define GUNYAH_HYPERCALL_HYP_IDENTIFY		GUNYAH_HYPERCALL(0x8000)
+/* clang-format on */
+
+/**
+ * gunyah_hypercall_hyp_identify() - Returns build information and feature flags
+ *                               supported by Gunyah.
+ * @hyp_identity: filled by the hypercall with the API info and feature flags.
+ */
+void gunyah_hypercall_hyp_identify(
+	struct gunyah_hypercall_hyp_identify_resp *hyp_identity)
+{
+	struct arm_smccc_res res;
+
+	arm_smccc_1_1_hvc(GUNYAH_HYPERCALL_HYP_IDENTIFY, &res);
+
+	hyp_identity->api_info = res.a0;
+	hyp_identity->flags[0] = res.a1;
+	hyp_identity->flags[1] = res.a2;
+	hyp_identity->flags[2] = res.a3;
+}
+EXPORT_SYMBOL_GPL(gunyah_hypercall_hyp_identify);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Gunyah Hypervisor Hypercalls");
diff --git a/drivers/virt/Kconfig b/drivers/virt/Kconfig
index 40129b6f0eca..172a6a12073c 100644
--- a/drivers/virt/Kconfig
+++ b/drivers/virt/Kconfig
@@ -50,4 +50,6 @@  source "drivers/virt/acrn/Kconfig"
 
 source "drivers/virt/coco/Kconfig"
 
+source "drivers/virt/gunyah/Kconfig"
+
 endif
diff --git a/drivers/virt/gunyah/Kconfig b/drivers/virt/gunyah/Kconfig
new file mode 100644
index 000000000000..6f4c85db80b5
--- /dev/null
+++ b/drivers/virt/gunyah/Kconfig
@@ -0,0 +1,12 @@ 
+# SPDX-License-Identifier: GPL-2.0-only
+
+config GUNYAH
+	tristate "Gunyah Virtualization drivers"
+	depends on ARM64
+	help
+	  The Gunyah drivers are the helper interfaces that run in a guest VM
+	  such as basic inter-VM IPC and signaling mechanisms, and higher level
+	  services such as memory/device sharing, IRQ sharing, and so on.
+
+	  Say Y/M here to enable the drivers needed to interact in a Gunyah
+	  virtual environment.
diff --git a/include/linux/gunyah.h b/include/linux/gunyah.h
index e1a716d802ee..8cdeaba34aa9 100644
--- a/include/linux/gunyah.h
+++ b/include/linux/gunyah.h
@@ -6,9 +6,11 @@ 
 #ifndef _LINUX_GUNYAH_H
 #define _LINUX_GUNYAH_H
 
+#include <linux/bitfield.h>
 #include <linux/errno.h>
 #include <linux/interrupt.h>
 #include <linux/limits.h>
+#include <linux/types.h>
 
 /* Matches resource manager's resource types for VM_GET_HYP_RESOURCES RPC */
 enum gunyah_resource_type {
@@ -103,4 +105,40 @@  static inline int gunyah_error_remap(enum gunyah_error gunyah_error)
 	}
 }
 
+enum gunyah_api_feature {
+	/* clang-format off */
+	GUNYAH_FEATURE_DOORBELL		= 1,
+	GUNYAH_FEATURE_MSGQUEUE		= 2,
+	GUNYAH_FEATURE_VCPU		= 5,
+	GUNYAH_FEATURE_MEMEXTENT	= 6,
+	/* clang-format on */
+};
+
+bool arch_is_gunyah_guest(void);
+
+#define GUNYAH_API_V1 1
+
+/* Other bits reserved for future use and will be zero */
+/* clang-format off */
+#define GUNYAH_API_INFO_API_VERSION_MASK	GENMASK_ULL(13, 0)
+#define GUNYAH_API_INFO_BIG_ENDIAN		BIT_ULL(14)
+#define GUNYAH_API_INFO_IS_64BIT		BIT_ULL(15)
+#define GUNYAH_API_INFO_VARIANT_MASK 		GENMASK_ULL(63, 56)
+/* clang-format on */
+
+struct gunyah_hypercall_hyp_identify_resp {
+	u64 api_info;
+	u64 flags[3];
+};
+
+static inline u16
+gunyah_api_version(const struct gunyah_hypercall_hyp_identify_resp *gunyah_api)
+{
+	return FIELD_GET(GUNYAH_API_INFO_API_VERSION_MASK,
+			 gunyah_api->api_info);
+}
+
+void gunyah_hypercall_hyp_identify(
+	struct gunyah_hypercall_hyp_identify_resp *hyp_identity);
+
 #endif