1 | // SPDX-License-Identifier: GPL-2.0 |
2 | |
3 | /* |
4 | * Low level utility routines for interacting with Hyper-V. |
5 | * |
6 | * Copyright (C) 2021, Microsoft, Inc. |
7 | * |
8 | * Author : Michael Kelley <mikelley@microsoft.com> |
9 | */ |
10 | |
11 | #include <linux/types.h> |
12 | #include <linux/export.h> |
13 | #include <linux/mm.h> |
14 | #include <linux/hyperv.h> |
15 | #include <linux/arm-smccc.h> |
16 | #include <linux/module.h> |
17 | #include <asm-generic/bug.h> |
18 | #include <asm/hyperv-tlfs.h> |
19 | #include <asm/mshyperv.h> |
20 | |
21 | /* |
22 | * hv_do_hypercall- Invoke the specified hypercall |
23 | */ |
24 | u64 hv_do_hypercall(u64 control, void *input, void *output) |
25 | { |
26 | struct arm_smccc_res res; |
27 | u64 input_address; |
28 | u64 output_address; |
29 | |
30 | input_address = input ? virt_to_phys(address: input) : 0; |
31 | output_address = output ? virt_to_phys(address: output) : 0; |
32 | |
33 | arm_smccc_1_1_hvc(HV_FUNC_ID, control, |
34 | input_address, output_address, &res); |
35 | return res.a0; |
36 | } |
37 | EXPORT_SYMBOL_GPL(hv_do_hypercall); |
38 | |
39 | /* |
40 | * hv_do_fast_hypercall8 -- Invoke the specified hypercall |
41 | * with arguments in registers instead of physical memory. |
42 | * Avoids the overhead of virt_to_phys for simple hypercalls. |
43 | */ |
44 | |
45 | u64 hv_do_fast_hypercall8(u16 code, u64 input) |
46 | { |
47 | struct arm_smccc_res res; |
48 | u64 control; |
49 | |
50 | control = (u64)code | HV_HYPERCALL_FAST_BIT; |
51 | |
52 | arm_smccc_1_1_hvc(HV_FUNC_ID, control, input, &res); |
53 | return res.a0; |
54 | } |
55 | EXPORT_SYMBOL_GPL(hv_do_fast_hypercall8); |
56 | |
57 | /* |
58 | * Set a single VP register to a 64-bit value. |
59 | */ |
60 | void hv_set_vpreg(u32 msr, u64 value) |
61 | { |
62 | struct arm_smccc_res res; |
63 | |
64 | arm_smccc_1_1_hvc(HV_FUNC_ID, |
65 | HVCALL_SET_VP_REGISTERS | HV_HYPERCALL_FAST_BIT | |
66 | HV_HYPERCALL_REP_COMP_1, |
67 | HV_PARTITION_ID_SELF, |
68 | HV_VP_INDEX_SELF, |
69 | msr, |
70 | 0, |
71 | value, |
72 | 0, |
73 | &res); |
74 | |
75 | /* |
76 | * Something is fundamentally broken in the hypervisor if |
77 | * setting a VP register fails. There's really no way to |
78 | * continue as a guest VM, so panic. |
79 | */ |
80 | BUG_ON(!hv_result_success(res.a0)); |
81 | } |
82 | EXPORT_SYMBOL_GPL(hv_set_vpreg); |
83 | |
84 | /* |
85 | * Get the value of a single VP register. One version |
86 | * returns just 64 bits and another returns the full 128 bits. |
87 | * The two versions are separate to avoid complicating the |
88 | * calling sequence for the more frequently used 64 bit version. |
89 | */ |
90 | |
91 | void hv_get_vpreg_128(u32 msr, struct hv_get_vp_registers_output *result) |
92 | { |
93 | struct arm_smccc_1_2_regs args; |
94 | struct arm_smccc_1_2_regs res; |
95 | |
96 | args.a0 = HV_FUNC_ID; |
97 | args.a1 = HVCALL_GET_VP_REGISTERS | HV_HYPERCALL_FAST_BIT | |
98 | HV_HYPERCALL_REP_COMP_1; |
99 | args.a2 = HV_PARTITION_ID_SELF; |
100 | args.a3 = HV_VP_INDEX_SELF; |
101 | args.a4 = msr; |
102 | |
103 | /* |
104 | * Use the SMCCC 1.2 interface because the results are in registers |
105 | * beyond X0-X3. |
106 | */ |
107 | arm_smccc_1_2_hvc(&args, &res); |
108 | |
109 | /* |
110 | * Something is fundamentally broken in the hypervisor if |
111 | * getting a VP register fails. There's really no way to |
112 | * continue as a guest VM, so panic. |
113 | */ |
114 | BUG_ON(!hv_result_success(res.a0)); |
115 | |
116 | result->as64.low = res.a6; |
117 | result->as64.high = res.a7; |
118 | } |
119 | EXPORT_SYMBOL_GPL(hv_get_vpreg_128); |
120 | |
121 | u64 hv_get_vpreg(u32 msr) |
122 | { |
123 | struct hv_get_vp_registers_output output; |
124 | |
125 | hv_get_vpreg_128(msr, &output); |
126 | |
127 | return output.as64.low; |
128 | } |
129 | EXPORT_SYMBOL_GPL(hv_get_vpreg); |
130 | |
131 | /* |
132 | * hyperv_report_panic - report a panic to Hyper-V. This function uses |
133 | * the older version of the Hyper-V interface that admittedly doesn't |
134 | * pass enough information to be useful beyond just recording the |
135 | * occurrence of a panic. The parallel hv_kmsg_dump() uses the |
136 | * new interface that allows reporting 4 Kbytes of data, which is much |
137 | * more useful. Hyper-V on ARM64 always supports the newer interface, but |
138 | * we retain support for the older version because the sysadmin is allowed |
139 | * to disable the newer version via sysctl in case of information security |
140 | * concerns about the more verbose version. |
141 | */ |
142 | void hyperv_report_panic(struct pt_regs *regs, long err, bool in_die) |
143 | { |
144 | static bool panic_reported; |
145 | u64 guest_id; |
146 | |
147 | /* Don't report a panic to Hyper-V if we're not going to panic */ |
148 | if (in_die && !panic_on_oops) |
149 | return; |
150 | |
151 | /* |
152 | * We prefer to report panic on 'die' chain as we have proper |
153 | * registers to report, but if we miss it (e.g. on BUG()) we need |
154 | * to report it on 'panic'. |
155 | * |
156 | * Calling code in the 'die' and 'panic' paths ensures that only |
157 | * one CPU is running this code, so no atomicity is needed. |
158 | */ |
159 | if (panic_reported) |
160 | return; |
161 | panic_reported = true; |
162 | |
163 | guest_id = hv_get_vpreg(HV_REGISTER_GUEST_OS_ID); |
164 | |
165 | /* |
166 | * Hyper-V provides the ability to store only 5 values. |
167 | * Pick the passed in error value, the guest_id, the PC, |
168 | * and the SP. |
169 | */ |
170 | hv_set_vpreg(HV_REGISTER_GUEST_CRASH_P0, err); |
171 | hv_set_vpreg(HV_REGISTER_GUEST_CRASH_P1, guest_id); |
172 | hv_set_vpreg(HV_REGISTER_GUEST_CRASH_P2, regs->pc); |
173 | hv_set_vpreg(HV_REGISTER_GUEST_CRASH_P3, regs->sp); |
174 | hv_set_vpreg(HV_REGISTER_GUEST_CRASH_P4, 0); |
175 | |
176 | /* |
177 | * Let Hyper-V know there is crash data available |
178 | */ |
179 | hv_set_vpreg(HV_REGISTER_GUEST_CRASH_CTL, HV_CRASH_CTL_CRASH_NOTIFY); |
180 | } |
181 | EXPORT_SYMBOL_GPL(hyperv_report_panic); |
182 | |