[PATCH v14 04/25] virt: gunyah: Add hypercalls to identify Gunyah

[Elliot Berman <quic_eberman@quicinc.com>]

Add hypercalls to identify when Linux is running a virtual machine under
Gunyah.

There are two calls to help identify Gunyah:

1. gh_hypercall_get_uid() returns a UID when running under a Gunyah
   hypervisor.
2. gh_hypercall_hyp_identify() returns build information and a set of
   feature flags that are supported by Gunyah.

Reviewed-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Reviewed-by: Alex Elder <elder@linaro.org>
Signed-off-by: Elliot Berman <quic_eberman@quicinc.com>
---
 arch/arm64/Kbuild                    |  1 +
 arch/arm64/gunyah/Makefile           |  3 ++
 arch/arm64/gunyah/gunyah_hypercall.c | 58 ++++++++++++++++++++++++++++
 drivers/virt/Kconfig                 |  2 +
 drivers/virt/gunyah/Kconfig          | 13 +++++++
 include/linux/gunyah.h               | 31 +++++++++++++++
 6 files changed, 108 insertions(+)
 create mode 100644 arch/arm64/gunyah/Makefile
 create mode 100644 arch/arm64/gunyah/gunyah_hypercall.c
 create mode 100644 drivers/virt/gunyah/Kconfig

diff --git a/arch/arm64/Kbuild b/arch/arm64/Kbuild
index 5bfbf7d79c99b..e4847ba0e3c95 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 0000000000000..84f1e38cafb1e
--- /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 0000000000000..ef48e0b8b5448
--- /dev/null
+++ b/arch/arm64/gunyah/gunyah_hypercall.c
@@ -0,0 +1,58 @@
+// 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_gh_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_gh_guest);
+
+#define GH_HYPERCALL(fn)	ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, ARM_SMCCC_SMC_64, \
+						   ARM_SMCCC_OWNER_VENDOR_HYP, \
+						   fn)
+
+#define GH_HYPERCALL_HYP_IDENTIFY		GH_HYPERCALL(0x8000)
+
+/**
+ * gh_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 gh_hypercall_hyp_identify(struct gh_hypercall_hyp_identify_resp *hyp_identity)
+{
+	struct arm_smccc_res res;
+
+	arm_smccc_1_1_hvc(GH_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(gh_hypercall_hyp_identify);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Gunyah Hypervisor Hypercalls");
diff --git a/drivers/virt/Kconfig b/drivers/virt/Kconfig
index f79ab13a5c28b..85bd6626ffc90 100644
--- a/drivers/virt/Kconfig
+++ b/drivers/virt/Kconfig
@@ -54,4 +54,6 @@ source "drivers/virt/coco/sev-guest/Kconfig"
 
 source "drivers/virt/coco/tdx-guest/Kconfig"
 
+source "drivers/virt/gunyah/Kconfig"
+
 endif
diff --git a/drivers/virt/gunyah/Kconfig b/drivers/virt/gunyah/Kconfig
new file mode 100644
index 0000000000000..1a737694c333d
--- /dev/null
+++ b/drivers/virt/gunyah/Kconfig
@@ -0,0 +1,13 @@
+# SPDX-License-Identifier: GPL-2.0-only
+
+config GUNYAH
+	tristate "Gunyah Virtualization drivers"
+	depends on ARM64
+	depends on MAILBOX
+	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 a4e8ec91961d1..6b36cf4787efb 100644
--- a/include/linux/gunyah.h
+++ b/include/linux/gunyah.h
@@ -6,8 +6,10 @@
 #ifndef _LINUX_GUNYAH_H
 #define _LINUX_GUNYAH_H
 
+#include <linux/bitfield.h>
 #include <linux/errno.h>
 #include <linux/limits.h>
+#include <linux/types.h>
 
 /******************************************************************************/
 /* Common arch-independent definitions for Gunyah hypercalls                  */
@@ -80,4 +82,33 @@ static inline int gh_error_remap(enum gh_error gh_error)
 	}
 }
 
+enum gh_api_feature {
+	GH_FEATURE_DOORBELL 	= 1,
+	GH_FEATURE_MSGQUEUE 	= 2,
+	GH_FEATURE_VCPU 	= 5,
+	GH_FEATURE_MEMEXTENT 	= 6,
+};
+
+bool arch_is_gh_guest(void);
+
+#define GH_API_V1			1
+
+/* Other bits reserved for future use and will be zero */
+#define GH_API_INFO_API_VERSION_MASK	GENMASK_ULL(13, 0)
+#define GH_API_INFO_BIG_ENDIAN		BIT_ULL(14)
+#define GH_API_INFO_IS_64BIT		BIT_ULL(15)
+#define GH_API_INFO_VARIANT_MASK	GENMASK_ULL(63, 56)
+
+struct gh_hypercall_hyp_identify_resp {
+	u64 api_info;
+	u64 flags[3];
+};
+
+static inline u16 gh_api_version(const struct gh_hypercall_hyp_identify_resp *gh_api)
+{
+	return FIELD_GET(GH_API_INFO_API_VERSION_MASK, gh_api->api_info);
+}
+
+void gh_hypercall_hyp_identify(struct gh_hypercall_hyp_identify_resp *hyp_identity);
+
 #endif
-- 
2.40.0