Re: [PATCH v5 05/13] virt: gunyah: Add hypercalls to identify Gunyah

From: Dmitry Baryshkov
Date: Wed Oct 12 2022 - 17:31:44 EST

On 11/10/2022 03:08, Elliot Berman wrote:
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.

Signed-off-by: Elliot Berman <quic_eberman@xxxxxxxxxxx>
---
MAINTAINERS | 2 +
arch/arm64/Kbuild | 1 +
arch/arm64/gunyah/Makefile | 2 +
arch/arm64/gunyah/hypercall.c | 71 +++++++++++++++++++++++++++++++++++
drivers/virt/Kconfig | 1 +
drivers/virt/gunyah/Kconfig | 13 +++++++
include/asm-generic/gunyah.h | 36 ++++++++++++++++++
7 files changed, 126 insertions(+)
create mode 100644 arch/arm64/gunyah/Makefile
create mode 100644 arch/arm64/gunyah/hypercall.c
create mode 100644 drivers/virt/gunyah/Kconfig

diff --git a/MAINTAINERS b/MAINTAINERS
index 4fe8cec61551..ed2bc98c3818 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -8886,6 +8886,8 @@ L: linux-arm-msm@xxxxxxxxxxxxxxx
S: Supported
F: Documentation/devicetree/bindings/firmware/gunyah-hypervisor.yaml
F: Documentation/virt/gunyah/
+F: arch/arm64/gunyah/
+F: drivers/virt/gunyah/
F: include/asm-generic/gunyah.h
HABANALABS PCI DRIVER
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..f71a9533c266
--- /dev/null
+++ b/arch/arm64/gunyah/Makefile
@@ -0,0 +1,2 @@
+obj-$(CONFIG_GUNYAH) += gunyah_hypercall.o
+gunyah_hypercall-y += hypercall.o

You don't have to do this. Just rename your source file to gunyah_hypercall.c

diff --git a/arch/arm64/gunyah/hypercall.c b/arch/arm64/gunyah/hypercall.c
new file mode 100644
index 000000000000..5b08c9d80de0
--- /dev/null
+++ b/arch/arm64/gunyah/hypercall.c
@@ -0,0 +1,71 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2022 Qualcomm Innovation Center, Inc. All rights reserved.
+ */
+
+#include <linux/arm-smccc.h>
+#include <linux/module.h>
+#include <asm-generic/gunyah.h>
+
+#define GH_CALL_TYPE_PLATFORM_CALL 0
+#define GH_CALL_TYPE_HYPERCALL 2
+#define GH_CALL_TYPE_SERVICE 3
+#define GH_CALL_TYPE_SHIFT 14
+#define GH_CALL_FUNCTION_NUM_MASK 0x3fff
+
+#define GH_SERVICE(fn) ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, ARM_SMCCC_SMC_32, \
+ ARM_SMCCC_OWNER_VENDOR_HYP, \
+ (GH_CALL_TYPE_SERVICE << GH_CALL_TYPE_SHIFT) \
+ | ((fn) & GH_CALL_FUNCTION_NUM_MASK))

Add a #define for (GH_CALL_TYPE_SERVICE << GH_CALL_TYPE_SHIFT) | ((fn) & GH_CALL_FUNCTION_NUM_MASK)), then use it here and below.

+
+#define GH_HYPERCALL_CALL_UID GH_SERVICE(0x3f01)
+
+#define GH_HYPERCALL(fn) ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, ARM_SMCCC_SMC_64, \
+ ARM_SMCCC_OWNER_VENDOR_HYP, \
+ (GH_CALL_TYPE_HYPERCALL << GH_CALL_TYPE_SHIFT) \
+ | ((fn) & GH_CALL_FUNCTION_NUM_MASK))
+
+#define GH_HYPERCALL_HYP_IDENTIFY GH_HYPERCALL(0x0000)
+
+/**
+ * gh_hypercall_get_uid() - Returns a UID when running under a Gunyah hypervisor.
+ * @uid: An array of 4 u32's (u32 uid[4];)
+ *
+ * The UID will be either QC_HYP_UID or GUNYAH_UID defined in include/asm-generic/gunyah.h.
+ * QC_HYP_UID is returned on platforms using Qualcomm's version of Gunyah.
+ * GUNYAH_UID is returned on platforms using open source version of Gunyah.
+ * If the uid is not one of the above two UIDs, then it is assumed that the hypervisor or firmware
+ * is not Gunyah.
+ */
+void gh_hypercall_get_uid(u32 *uid)
+{
+ struct arm_smccc_res res;
+
+ arm_smccc_1_1_hvc(GH_HYPERCALL_CALL_UID, &res);
+
+ uid[0] = res.a0;
+ uid[1] = res.a1;
+ uid[2] = res.a2;
+ uid[3] = res.a3;
+}
+EXPORT_SYMBOL_GPL(gh_hypercall_get_uid);
+
+/**
+ * gh_hypercall_hyp_identify() - Returns build information and feature flags supported by Gunyah.
+ * @hyp_identify: 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 87ef258cec64..259dc2be6cad 100644
--- a/drivers/virt/Kconfig
+++ b/drivers/virt/Kconfig
@@ -52,4 +52,5 @@ source "drivers/virt/coco/efi_secret/Kconfig"
source "drivers/virt/coco/sev-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 000000000000..7ac917e0aa3f
--- /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
+ select AUXILIARY_BUS
+ help
+ The Gunyah drivers are the helper interfaces that runs 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/asm-generic/gunyah.h b/include/asm-generic/gunyah.h
index 64a02dd3b5ad..86eb59e203ef 100644
--- a/include/asm-generic/gunyah.h
+++ b/include/asm-generic/gunyah.h
@@ -71,4 +71,40 @@ static inline int gh_remap_error(int gh_error)
}
}
+#define QC_HYP_UID0 0x19bd54bd
+#define QC_HYP_UID1 0x0b37571b
+#define QC_HYP_UID2 0x946f609b
+#define QC_HYP_UID3 0x54539de6
+
+#define GUNYAH_UID0 0x673d5f14
+#define GUNYAH_UID1 0x9265ce36
+#define GUNYAH_UID2 0xa4535fdb
+#define GUNYAH_UID3 0xc1d58fcd

It would be better to define them as arrays

+
+#define gh_uid_matches(prefix, uid) \
+ ((uid)[0] == prefix ## _UID0 && (uid)[1] == prefix ## _UID1 && \
+ (uid)[2] == prefix ## _UID2 && (uid)[3] == prefix ## _UID3)

... then you could do memcmp() here.

+
+#define GH_API_INFO_API_VERSION(x) (((x) >> 0) & 0x3fff)

No need to >> 0. And also you can use FIELD_GET to ease review.

+#define GH_API_INFO_BIG_ENDIAN(x) (((x) >> 14) & 1)
+#define GH_API_INFO_IS_64BIT(x) (((x) >> 15) & 1)
+#define GH_API_INFO_VARIANT(x) (((x) >> 56) & 0xff)

Use FIELD_GET here.

+
+#define GH_IDENTIFY_PARTITION_CSPACE(flags) (((flags)[0] >> 0) & 1)
+#define GH_IDENTIFY_DOORBELL(flags) (((flags)[0] >> 1) & 1)
+#define GH_IDENTIFY_MSGQUEUE(flags) (((flags)[0] >> 2) & 1)
+#define GH_IDENTIFY_VIC(flags) (((flags)[0] >> 3) & 1)
+#define GH_IDENTIFY_VPM(flags) (((flags)[0] >> 4) & 1)
+#define GH_IDENTIFY_VCPU(flags) (((flags)[0] >> 5) & 1)
+#define GH_IDENTIFY_MEMEXTENT(flags) (((flags)[0] >> 6) & 1)
+#define GH_IDENTIFY_TRACE_CTRL(flags) (((flags)[0] >> 7) & 1)

Ugh. #define GH_IDENTIFY_DOORBELLflags) (flags & BIT(1)), etc.

+
+struct gh_hypercall_hyp_identify_resp {
+ u64 api_info;
+ u64 flags[3];
+};
+
+void gh_hypercall_get_uid(u32 *uid);
+void gh_hypercall_hyp_identify(struct gh_hypercall_hyp_identify_resp *hyp_identity);
+
#endif

--
With best wishes
Dmitry