arm64: hyperv: Add Hyper-V hypercall and register access utilities
authorMichael Kelley <mikelley@microsoft.com>
Wed, 4 Aug 2021 15:52:35 +0000 (08:52 -0700)
committerWei Liu <wei.liu@kernel.org>
Wed, 4 Aug 2021 16:54:36 +0000 (16:54 +0000)
hyperv-tlfs.h defines Hyper-V interfaces from the Hyper-V Top Level
Functional Spec (TLFS), and #includes the architecture-independent
part of hyperv-tlfs.h in include/asm-generic.  The published TLFS
is distinctly oriented to x86/x64, so the ARM64-specific
hyperv-tlfs.h includes information for ARM64 that is not yet formally
published. The TLFS is available here:

  docs.microsoft.com/en-us/virtualization/hyper-v-on-windows/reference/tlfs

mshyperv.h defines Linux-specific structures and routines for
interacting with Hyper-V on ARM64, and #includes the architecture-
independent part of mshyperv.h in include/asm-generic.

Use these definitions to provide utility functions to make
Hyper-V hypercalls and to get and set Hyper-V provided
registers associated with a virtual processor.

Signed-off-by: Michael Kelley <mikelley@microsoft.com>
Reviewed-by: Sunil Muthuswamy <sunilmut@microsoft.com>
Acked-by: Marc Zyngier <maz@kernel.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/1628092359-61351-2-git-send-email-mikelley@microsoft.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
MAINTAINERS
arch/arm64/Kbuild
arch/arm64/hyperv/Makefile [new file with mode: 0644]
arch/arm64/hyperv/hv_core.c [new file with mode: 0644]
arch/arm64/include/asm/hyperv-tlfs.h [new file with mode: 0644]
arch/arm64/include/asm/mshyperv.h [new file with mode: 0644]

index a61f4f3..4f84a86 100644 (file)
@@ -8594,6 +8594,9 @@ T:        git git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux.git
 F:     Documentation/ABI/stable/sysfs-bus-vmbus
 F:     Documentation/ABI/testing/debugfs-hyperv
 F:     Documentation/networking/device_drivers/ethernet/microsoft/netvsc.rst
+F:     arch/arm64/hyperv
+F:     arch/arm64/include/asm/hyperv-tlfs.h
+F:     arch/arm64/include/asm/mshyperv.h
 F:     arch/x86/hyperv
 F:     arch/x86/include/asm/hyperv-tlfs.h
 F:     arch/x86/include/asm/mshyperv.h
index 7b393cf..ea7ab4c 100644 (file)
@@ -2,4 +2,5 @@
 obj-y                  += kernel/ mm/ net/
 obj-$(CONFIG_KVM)      += kvm/
 obj-$(CONFIG_XEN)      += xen/
+obj-$(subst m,y,$(CONFIG_HYPERV))      += hyperv/
 obj-$(CONFIG_CRYPTO)   += crypto/
diff --git a/arch/arm64/hyperv/Makefile b/arch/arm64/hyperv/Makefile
new file mode 100644 (file)
index 0000000..1697d30
--- /dev/null
@@ -0,0 +1,2 @@
+# SPDX-License-Identifier: GPL-2.0
+obj-y          := hv_core.o
diff --git a/arch/arm64/hyperv/hv_core.c b/arch/arm64/hyperv/hv_core.c
new file mode 100644 (file)
index 0000000..4c5dc0f
--- /dev/null
@@ -0,0 +1,129 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * Low level utility routines for interacting with Hyper-V.
+ *
+ * Copyright (C) 2021, Microsoft, Inc.
+ *
+ * Author : Michael Kelley <mikelley@microsoft.com>
+ */
+
+#include <linux/types.h>
+#include <linux/export.h>
+#include <linux/mm.h>
+#include <linux/hyperv.h>
+#include <linux/arm-smccc.h>
+#include <linux/module.h>
+#include <asm-generic/bug.h>
+#include <asm/hyperv-tlfs.h>
+#include <asm/mshyperv.h>
+
+/*
+ * hv_do_hypercall- Invoke the specified hypercall
+ */
+u64 hv_do_hypercall(u64 control, void *input, void *output)
+{
+       struct arm_smccc_res    res;
+       u64                     input_address;
+       u64                     output_address;
+
+       input_address = input ? virt_to_phys(input) : 0;
+       output_address = output ? virt_to_phys(output) : 0;
+
+       arm_smccc_1_1_hvc(HV_FUNC_ID, control,
+                         input_address, output_address, &res);
+       return res.a0;
+}
+EXPORT_SYMBOL_GPL(hv_do_hypercall);
+
+/*
+ * hv_do_fast_hypercall8 -- Invoke the specified hypercall
+ * with arguments in registers instead of physical memory.
+ * Avoids the overhead of virt_to_phys for simple hypercalls.
+ */
+
+u64 hv_do_fast_hypercall8(u16 code, u64 input)
+{
+       struct arm_smccc_res    res;
+       u64                     control;
+
+       control = (u64)code | HV_HYPERCALL_FAST_BIT;
+
+       arm_smccc_1_1_hvc(HV_FUNC_ID, control, input, &res);
+       return res.a0;
+}
+EXPORT_SYMBOL_GPL(hv_do_fast_hypercall8);
+
+/*
+ * Set a single VP register to a 64-bit value.
+ */
+void hv_set_vpreg(u32 msr, u64 value)
+{
+       struct arm_smccc_res res;
+
+       arm_smccc_1_1_hvc(HV_FUNC_ID,
+               HVCALL_SET_VP_REGISTERS | HV_HYPERCALL_FAST_BIT |
+                       HV_HYPERCALL_REP_COMP_1,
+               HV_PARTITION_ID_SELF,
+               HV_VP_INDEX_SELF,
+               msr,
+               0,
+               value,
+               0,
+               &res);
+
+       /*
+        * Something is fundamentally broken in the hypervisor if
+        * setting a VP register fails. There's really no way to
+        * continue as a guest VM, so panic.
+        */
+       BUG_ON(!hv_result_success(res.a0));
+}
+EXPORT_SYMBOL_GPL(hv_set_vpreg);
+
+/*
+ * Get the value of a single VP register.  One version
+ * returns just 64 bits and another returns the full 128 bits.
+ * The two versions are separate to avoid complicating the
+ * calling sequence for the more frequently used 64 bit version.
+ */
+
+void hv_get_vpreg_128(u32 msr, struct hv_get_vp_registers_output *result)
+{
+       struct arm_smccc_1_2_regs args;
+       struct arm_smccc_1_2_regs res;
+
+       args.a0 = HV_FUNC_ID;
+       args.a1 = HVCALL_GET_VP_REGISTERS | HV_HYPERCALL_FAST_BIT |
+                       HV_HYPERCALL_REP_COMP_1;
+       args.a2 = HV_PARTITION_ID_SELF;
+       args.a3 = HV_VP_INDEX_SELF;
+       args.a4 = msr;
+
+       /*
+        * Use the SMCCC 1.2 interface because the results are in registers
+        * beyond X0-X3.
+        */
+       arm_smccc_1_2_hvc(&args, &res);
+
+       /*
+        * Something is fundamentally broken in the hypervisor if
+        * getting a VP register fails. There's really no way to
+        * continue as a guest VM, so panic.
+        */
+       BUG_ON(!hv_result_success(res.a0));
+
+       result->as64.low = res.a6;
+       result->as64.high = res.a7;
+}
+EXPORT_SYMBOL_GPL(hv_get_vpreg_128);
+
+u64 hv_get_vpreg(u32 msr)
+{
+       struct hv_get_vp_registers_output output;
+
+       hv_get_vpreg_128(msr, &output);
+
+       return output.as64.low;
+}
+EXPORT_SYMBOL_GPL(hv_get_vpreg);
diff --git a/arch/arm64/include/asm/hyperv-tlfs.h b/arch/arm64/include/asm/hyperv-tlfs.h
new file mode 100644 (file)
index 0000000..4d964a7
--- /dev/null
@@ -0,0 +1,69 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+/*
+ * This file contains definitions from the Hyper-V Hypervisor Top-Level
+ * Functional Specification (TLFS):
+ * https://docs.microsoft.com/en-us/virtualization/hyper-v-on-windows/reference/tlfs
+ *
+ * Copyright (C) 2021, Microsoft, Inc.
+ *
+ * Author : Michael Kelley <mikelley@microsoft.com>
+ */
+
+#ifndef _ASM_HYPERV_TLFS_H
+#define _ASM_HYPERV_TLFS_H
+
+#include <linux/types.h>
+
+/*
+ * All data structures defined in the TLFS that are shared between Hyper-V
+ * and a guest VM use Little Endian byte ordering.  This matches the default
+ * byte ordering of Linux running on ARM64, so no special handling is required.
+ */
+
+/*
+ * These Hyper-V registers provide information equivalent to the CPUID
+ * instruction on x86/x64.
+ */
+#define HV_REGISTER_HYPERVISOR_VERSION         0x00000100 /*CPUID 0x40000002 */
+#define HV_REGISTER_FEATURES                   0x00000200 /*CPUID 0x40000003 */
+#define HV_REGISTER_ENLIGHTENMENTS             0x00000201 /*CPUID 0x40000004 */
+
+/*
+ * Group C Features. See the asm-generic version of hyperv-tlfs.h
+ * for a description of Feature Groups.
+ */
+
+/* Crash MSRs available */
+#define HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE   BIT(8)
+
+/* STIMER direct mode is available */
+#define HV_STIMER_DIRECT_MODE_AVAILABLE                BIT(13)
+
+/*
+ * Synthetic register definitions equivalent to MSRs on x86/x64
+ */
+#define HV_REGISTER_CRASH_P0           0x00000210
+#define HV_REGISTER_CRASH_P1           0x00000211
+#define HV_REGISTER_CRASH_P2           0x00000212
+#define HV_REGISTER_CRASH_P3           0x00000213
+#define HV_REGISTER_CRASH_P4           0x00000214
+#define HV_REGISTER_CRASH_CTL          0x00000215
+
+#define HV_REGISTER_GUEST_OSID         0x00090002
+#define HV_REGISTER_VP_INDEX           0x00090003
+#define HV_REGISTER_TIME_REF_COUNT     0x00090004
+#define HV_REGISTER_REFERENCE_TSC      0x00090017
+
+#define HV_REGISTER_SINT0              0x000A0000
+#define HV_REGISTER_SCONTROL           0x000A0010
+#define HV_REGISTER_SIEFP              0x000A0012
+#define HV_REGISTER_SIMP               0x000A0013
+#define HV_REGISTER_EOM                        0x000A0014
+
+#define HV_REGISTER_STIMER0_CONFIG     0x000B0000
+#define HV_REGISTER_STIMER0_COUNT      0x000B0001
+
+#include <asm-generic/hyperv-tlfs.h>
+
+#endif
diff --git a/arch/arm64/include/asm/mshyperv.h b/arch/arm64/include/asm/mshyperv.h
new file mode 100644 (file)
index 0000000..20070a8
--- /dev/null
@@ -0,0 +1,54 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+/*
+ * Linux-specific definitions for managing interactions with Microsoft's
+ * Hyper-V hypervisor. The definitions in this file are specific to
+ * the ARM64 architecture.  See include/asm-generic/mshyperv.h for
+ * definitions are that architecture independent.
+ *
+ * Definitions that are specified in the Hyper-V Top Level Functional
+ * Spec (TLFS) should not go in this file, but should instead go in
+ * hyperv-tlfs.h.
+ *
+ * Copyright (C) 2021, Microsoft, Inc.
+ *
+ * Author : Michael Kelley <mikelley@microsoft.com>
+ */
+
+#ifndef _ASM_MSHYPERV_H
+#define _ASM_MSHYPERV_H
+
+#include <linux/types.h>
+#include <linux/arm-smccc.h>
+#include <asm/hyperv-tlfs.h>
+
+/*
+ * Declare calls to get and set Hyper-V VP register values on ARM64, which
+ * requires a hypercall.
+ */
+
+void hv_set_vpreg(u32 reg, u64 value);
+u64 hv_get_vpreg(u32 reg);
+void hv_get_vpreg_128(u32 reg, struct hv_get_vp_registers_output *result);
+
+static inline void hv_set_register(unsigned int reg, u64 value)
+{
+       hv_set_vpreg(reg, value);
+}
+
+static inline u64 hv_get_register(unsigned int reg)
+{
+       return hv_get_vpreg(reg);
+}
+
+/* SMCCC hypercall parameters */
+#define HV_SMCCC_FUNC_NUMBER   1
+#define HV_FUNC_ID     ARM_SMCCC_CALL_VAL(                     \
+                               ARM_SMCCC_STD_CALL,             \
+                               ARM_SMCCC_SMC_64,               \
+                               ARM_SMCCC_OWNER_VENDOR_HYP,     \
+                               HV_SMCCC_FUNC_NUMBER)
+
+#include <asm-generic/mshyperv.h>
+
+#endif