On 12/19/22 4:58 PM, 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.
The first is a "service", while the second is a "hypercall".
Can you explain the distinction? The sentence at the top
refers to both as "hypercalls".
Signed-off-by: Elliot Berman <quic_eberman@xxxxxxxxxxx>
---
MAINTAINERS | 2 +
arch/arm64/Kbuild | 1 +
arch/arm64/gunyah/Makefile | 1 +
arch/arm64/gunyah/gunyah_hypercall.c | 69 ++++++++++++++++++++++++++++
drivers/virt/Kconfig | 1 +
drivers/virt/gunyah/Kconfig | 12 +++++
include/linux/gunyah.h | 25 ++++++++++
7 files changed, 111 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/MAINTAINERS b/MAINTAINERS
index 74e76e0ab14d..36698df6b0e5 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -8941,6 +8941,8 @@ 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/linux/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..9fbc720b6fb6
--- /dev/null
+++ b/arch/arm64/gunyah/Makefile
@@ -0,0 +1 @@
+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..0beb3123d650
--- /dev/null
+++ b/arch/arm64/gunyah/gunyah_hypercall.c
@@ -0,0 +1,69 @@
+// 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 <linux/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
A FN_ID is a 32-bit value. Are all 18 high-order bits considered
part of the call type? It might be good to specify that explicitly
by defining a mask for it.
+
+#define GH_FN_ID(type, num) ((type) << GH_CALL_TYPE_SHIFT | ((num) & GH_CALL_FUNCTION_NUM_MASK))
+
Is there any need for the endianness of these values to be specified?
Does Gunyah operate with a well-defined endianness? Is there any
chance a VM can run with an endianness different from Gunyah? I
see that the arm_smcc_* structures are defined without endianness.
(Sorry if these are dumb questions.)
+#define GH_SERVICE(fn) ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, ARM_SMCCC_SMC_32, \
+ ARM_SMCCC_OWNER_VENDOR_HYP, \
+ GH_FN_ID(GH_CALL_TYPE_SERVICE, fn))
+
+#define GH_HYPERCALL_CALL_UID GH_SERVICE(0x3f01)
Perhaps 0x3f01 could be defined symbolically.
However if this is the only place it's ever used, doing so
doesn't add much value (meaning, just do it the way you did).
+
+#define GH_HYPERCALL(fn) ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, ARM_SMCCC_SMC_64, \
+ ARM_SMCCC_OWNER_VENDOR_HYP, \
+ GH_FN_ID(GH_CALL_TYPE_HYPERCALL, fn))
+
+#define GH_HYPERCALL_HYP_IDENTIFY GH_HYPERCALL(0x0000)
Will there be a growing set of well-known hypervisor call functions?
Perhaps 0x0000 should be defined symbolically. (Or not if it's only
used here.)
+
+/**
+ * gh_hypercall_get_uid() - Returns a UID when running under a Gunyah hypervisor
+ * @uid: An array of 4 u32's (u32 uid[4];)
+ *
+ * Caller should compare the resulting UID to a list of known Gunyah UIDs to
+ * confirm that Linux is running as a guest of Gunyah.
I presume that, if the returned UID isn't well-known, then no other
Gunyah-related calls are meaningful. Is that correct?
+ */
+void gh_hypercall_get_uid(u32 uid[4])
+{
+ 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;
I see in the definition of struct arm_smccc_res that the four
fields are unsigned long values. That differs from the u32
array passed as argument. Are the resource IDs guaranteed to
be four 32-bit values? I personally prefer being explicit
about the upper 32-bits being discarded (though some don't
agree with that convention).
+}
+EXPORT_SYMBOL_GPL(gh_hypercall_get_uid);
+
+/**
+ * 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 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..127156a678a6
--- /dev/null
+++ b/drivers/virt/gunyah/Kconfig
@@ -0,0 +1,12 @@
+# SPDX-License-Identifier: GPL-2.0-only
+
+config GUNYAH
Maybe config QCOM_GUNYAH? Will this ever run on hardware
other than Qualcomm's?
+ tristate "Gunyah Virtualization drivers"
+ depends on ARM64
+ help
+ The Gunyah drivers are the helper interfaces that runs in a guest VM
s/runs/run/
+ 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 824e20a11d27..2765d2b40198 100644
--- a/include/linux/gunyah.h
+++ b/include/linux/gunyah.h
@@ -6,6 +6,7 @@
#ifndef _GUNYAH_H
#define _GUNYAH_H
+#include <linux/bitfield.h>
#include <linux/types.h>
#include <linux/errno.h>
@@ -71,4 +72,28 @@ static inline int gh_remap_error(int gh_error)
}
}
+#define GUNYAH_API_V1 1
+
+#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)
+
How are the GH_IDENTIFY bits below used? Are they encoded
in the three 64-bit flags fields in the response structure?
Does that mean only the first of those three is (currently)
used?
+#define GH_IDENTIFY_PARTITION_CSPACE BIT_ULL(0)
+#define GH_IDENTIFY_DOORBELL BIT_ULL(1)
+#define GH_IDENTIFY_MSGQUEUE BIT_ULL(2)
+#define GH_IDENTIFY_VIC BIT_ULL(3)
+#define GH_IDENTIFY_VPM BIT_ULL(4)
+#define GH_IDENTIFY_VCPU BIT_ULL(5)
+#define GH_IDENTIFY_MEMEXTENT BIT_ULL(6)
+#define GH_IDENTIFY_TRACE_CTRL BIT_ULL(7)
+
+struct gh_hypercall_hyp_identify_resp {
+ u64 api_info;
+ u64 flags[3];
+};
Again I'll ask about endianness. This is a response coming *from*
Gunyah. Is it guaranteed to use the same byte order convention as
the running operating system (Linux) guest?
-Alex
+
+void gh_hypercall_get_uid(u32 uid[4]);
+void gh_hypercall_hyp_identify(struct gh_hypercall_hyp_identify_resp *hyp_identity);
+
#endif
