summaryrefslogtreecommitdiff
path: root/arch/arm64/kernel/hyp-stub.S
blob: 43d212618834dd849bfa7adc1e1a810254928b93 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
/* SPDX-License-Identifier: GPL-2.0-only */
/*
 * Hypervisor stub
 *
 * Copyright (C) 2012 ARM Ltd.
 * Author:	Marc Zyngier <marc.zyngier@arm.com>
 */

#include <linux/init.h>
#include <linux/linkage.h>

#include <asm/assembler.h>
#include <asm/el2_setup.h>
#include <asm/kvm_arm.h>
#include <asm/kvm_asm.h>
#include <asm/ptrace.h>
#include <asm/virt.h>

	.text
	.pushsection	.hyp.text, "ax"

	.align 11

SYM_CODE_START(__hyp_stub_vectors)
	ventry	el2_sync_invalid		// Synchronous EL2t
	ventry	el2_irq_invalid			// IRQ EL2t
	ventry	el2_fiq_invalid			// FIQ EL2t
	ventry	el2_error_invalid		// Error EL2t

	ventry	elx_sync			// Synchronous EL2h
	ventry	el2_irq_invalid			// IRQ EL2h
	ventry	el2_fiq_invalid			// FIQ EL2h
	ventry	el2_error_invalid		// Error EL2h

	ventry	elx_sync			// Synchronous 64-bit EL1
	ventry	el1_irq_invalid			// IRQ 64-bit EL1
	ventry	el1_fiq_invalid			// FIQ 64-bit EL1
	ventry	el1_error_invalid		// Error 64-bit EL1

	ventry	el1_sync_invalid		// Synchronous 32-bit EL1
	ventry	el1_irq_invalid			// IRQ 32-bit EL1
	ventry	el1_fiq_invalid			// FIQ 32-bit EL1
	ventry	el1_error_invalid		// Error 32-bit EL1
SYM_CODE_END(__hyp_stub_vectors)

	.align 11

SYM_CODE_START_LOCAL(elx_sync)
	cmp	x0, #HVC_SET_VECTORS
	b.ne	1f
	msr	vbar_el2, x1
	b	9f

1:	cmp	x0, #HVC_VHE_RESTART
	b.eq	mutate_to_vhe

2:	cmp	x0, #HVC_SOFT_RESTART
	b.ne	3f
	mov	x0, x2
	mov	x2, x4
	mov	x4, x1
	mov	x1, x3
	br	x4				// no return

3:	cmp	x0, #HVC_RESET_VECTORS
	beq	9f				// Nothing to reset!

	/* Someone called kvm_call_hyp() against the hyp-stub... */
	mov_q	x0, HVC_STUB_ERR
	eret

9:	mov	x0, xzr
	eret
SYM_CODE_END(elx_sync)

// nVHE? No way! Give me the real thing!
SYM_CODE_START_LOCAL(mutate_to_vhe)
	// Sanity check: MMU *must* be off
	mrs	x1, sctlr_el2
	tbnz	x1, #0, 1f

	// Needs to be VHE capable, obviously
	mrs	x1, id_aa64mmfr1_el1
	ubfx	x1, x1, #ID_AA64MMFR1_VHE_SHIFT, #4
	cbz	x1, 1f

	// Check whether VHE is disabled from the command line
	adr_l	x1, id_aa64mmfr1_override
	ldr	x2, [x1, FTR_OVR_VAL_OFFSET]
	ldr	x1, [x1, FTR_OVR_MASK_OFFSET]
	ubfx	x2, x2, #ID_AA64MMFR1_VHE_SHIFT, #4
	ubfx	x1, x1, #ID_AA64MMFR1_VHE_SHIFT, #4
	cmp	x1, xzr
	and	x2, x2, x1
	csinv	x2, x2, xzr, ne
	cbnz	x2, 2f

1:	mov_q	x0, HVC_STUB_ERR
	eret
2:
	// Engage the VHE magic!
	mov_q	x0, HCR_HOST_VHE_FLAGS
	msr	hcr_el2, x0
	isb

	// Use the EL1 allocated stack, per-cpu offset
	mrs	x0, sp_el1
	mov	sp, x0
	mrs	x0, tpidr_el1
	msr	tpidr_el2, x0

	// FP configuration, vectors
	mrs_s	x0, SYS_CPACR_EL12
	msr	cpacr_el1, x0
	mrs_s	x0, SYS_VBAR_EL12
	msr	vbar_el1, x0

	// Use EL2 translations for SPE & TRBE and disable access from EL1
	mrs	x0, mdcr_el2
	bic	x0, x0, #(MDCR_EL2_E2PB_MASK << MDCR_EL2_E2PB_SHIFT)
	bic	x0, x0, #(MDCR_EL2_E2TB_MASK << MDCR_EL2_E2TB_SHIFT)
	msr	mdcr_el2, x0

	// Transfer the MM state from EL1 to EL2
	mrs_s	x0, SYS_TCR_EL12
	msr	tcr_el1, x0
	mrs_s	x0, SYS_TTBR0_EL12
	msr	ttbr0_el1, x0
	mrs_s	x0, SYS_TTBR1_EL12
	msr	ttbr1_el1, x0
	mrs_s	x0, SYS_MAIR_EL12
	msr	mair_el1, x0
	isb

	// Hack the exception return to stay at EL2
	mrs	x0, spsr_el1
	and	x0, x0, #~PSR_MODE_MASK
	mov	x1, #PSR_MODE_EL2h
	orr	x0, x0, x1
	msr	spsr_el1, x0

	b	enter_vhe
SYM_CODE_END(mutate_to_vhe)

	// At the point where we reach enter_vhe(), we run with
	// the MMU off (which is enforced by mutate_to_vhe()).
	// We thus need to be in the idmap, or everything will
	// explode when enabling the MMU.

	.pushsection	.idmap.text, "ax"

SYM_CODE_START_LOCAL(enter_vhe)
	// Invalidate TLBs before enabling the MMU
	tlbi	vmalle1
	dsb	nsh
	isb

	// Enable the EL2 S1 MMU, as set up from EL1
	mrs_s	x0, SYS_SCTLR_EL12
	set_sctlr_el1	x0

	// Disable the EL1 S1 MMU for a good measure
	mov_q	x0, INIT_SCTLR_EL1_MMU_OFF
	msr_s	SYS_SCTLR_EL12, x0

	mov	x0, xzr

	eret
SYM_CODE_END(enter_vhe)

	.popsection

.macro invalid_vector	label
SYM_CODE_START_LOCAL(\label)
	b \label
SYM_CODE_END(\label)
.endm

	invalid_vector	el2_sync_invalid
	invalid_vector	el2_irq_invalid
	invalid_vector	el2_fiq_invalid
	invalid_vector	el2_error_invalid
	invalid_vector	el1_sync_invalid
	invalid_vector	el1_irq_invalid
	invalid_vector	el1_fiq_invalid
	invalid_vector	el1_error_invalid

	.popsection

/*
 * __hyp_set_vectors: Call this after boot to set the initial hypervisor
 * vectors as part of hypervisor installation.  On an SMP system, this should
 * be called on each CPU.
 *
 * x0 must be the physical address of the new vector table, and must be
 * 2KB aligned.
 *
 * Before calling this, you must check that the stub hypervisor is installed
 * everywhere, by waiting for any secondary CPUs to be brought up and then
 * checking that is_hyp_mode_available() is true.
 *
 * If not, there is a pre-existing hypervisor, some CPUs failed to boot, or
 * something else went wrong... in such cases, trying to install a new
 * hypervisor is unlikely to work as desired.
 *
 * When you call into your shiny new hypervisor, sp_el2 will contain junk,
 * so you will need to set that to something sensible at the new hypervisor's
 * initialisation entry point.
 */

SYM_FUNC_START(__hyp_set_vectors)
	mov	x1, x0
	mov	x0, #HVC_SET_VECTORS
	hvc	#0
	ret
SYM_FUNC_END(__hyp_set_vectors)

SYM_FUNC_START(__hyp_reset_vectors)
	mov	x0, #HVC_RESET_VECTORS
	hvc	#0
	ret
SYM_FUNC_END(__hyp_reset_vectors)

/*
 * Entry point to switch to VHE if deemed capable
 */
SYM_FUNC_START(switch_to_vhe)
	// Need to have booted at EL2
	adr_l	x1, __boot_cpu_mode
	ldr	w0, [x1]
	cmp	w0, #BOOT_CPU_MODE_EL2
	b.ne	1f

	// and still be at EL1
	mrs	x0, CurrentEL
	cmp	x0, #CurrentEL_EL1
	b.ne	1f

	// Turn the world upside down
	mov	x0, #HVC_VHE_RESTART
	hvc	#0
1:
	ret
SYM_FUNC_END(switch_to_vhe)