summaryrefslogtreecommitdiffstats
path: root/arch/arm/kvm/hyp/hyp-entry.S
blob: 95a2faefc070f5c4b172c65dfdb5dd85b8b3df89 (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
/*
 * Copyright (C) 2012 - Virtual Open Systems and Columbia University
 * Author: Christoffer Dall <c.dall@virtualopensystems.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License, version 2, as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 */

#include <linux/linkage.h>
#include <asm/kvm_arm.h>
#include <asm/kvm_asm.h>

	.arch_extension     virt

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

.macro load_vcpu	reg
	mrc	p15, 4, \reg, c13, c0, 2	@ HTPIDR
.endm

/********************************************************************
 * Hypervisor exception vector and handlers
 *
 *
 * The KVM/ARM Hypervisor ABI is defined as follows:
 *
 * Entry to Hyp mode from the host kernel will happen _only_ when an HVC
 * instruction is issued since all traps are disabled when running the host
 * kernel as per the Hyp-mode initialization at boot time.
 *
 * HVC instructions cause a trap to the vector page + offset 0x14 (see hyp_hvc
 * below) when the HVC instruction is called from SVC mode (i.e. a guest or the
 * host kernel) and they cause a trap to the vector page + offset 0x8 when HVC
 * instructions are called from within Hyp-mode.
 *
 * Hyp-ABI: Calling HYP-mode functions from host (in SVC mode):
 *    Switching to Hyp mode is done through a simple HVC #0 instruction. The
 *    exception vector code will check that the HVC comes from VMID==0.
 *    - r0 contains a pointer to a HYP function
 *    - r1, r2, and r3 contain arguments to the above function.
 *    - The HYP function will be called with its arguments in r0, r1 and r2.
 *    On HYP function return, we return directly to SVC.
 *
 * Note that the above is used to execute code in Hyp-mode from a host-kernel
 * point of view, and is a different concept from performing a world-switch and
 * executing guest code SVC mode (with a VMID != 0).
 */

	.align 5
__kvm_hyp_vector:
	.global __kvm_hyp_vector

	@ Hyp-mode exception vector
	W(b)	hyp_reset
	W(b)	hyp_undef
	W(b)	hyp_svc
	W(b)	hyp_pabt
	W(b)	hyp_dabt
	W(b)	hyp_hvc
	W(b)	hyp_irq
	W(b)	hyp_fiq

.macro invalid_vector label, cause
	.align
\label:	mov	r0, #\cause
	b	__hyp_panic
.endm

	invalid_vector	hyp_reset	ARM_EXCEPTION_RESET
	invalid_vector	hyp_undef	ARM_EXCEPTION_UNDEFINED
	invalid_vector	hyp_svc		ARM_EXCEPTION_SOFTWARE
	invalid_vector	hyp_pabt	ARM_EXCEPTION_PREF_ABORT
	invalid_vector	hyp_fiq		ARM_EXCEPTION_FIQ

ENTRY(__hyp_do_panic)
	mrs	lr, cpsr
	bic	lr, lr, #MODE_MASK
	orr	lr, lr, #SVC_MODE
THUMB(	orr	lr, lr, #PSR_T_BIT	)
	msr	spsr_cxsf, lr
	ldr	lr, =panic
	msr	ELR_hyp, lr
	ldr	lr, =kvm_call_hyp
	clrex
	eret
ENDPROC(__hyp_do_panic)

hyp_hvc:
	/*
	 * Getting here is either because of a trap from a guest,
	 * or from executing HVC from the host kernel, which means
	 * "do something in Hyp mode".
	 */
	push	{r0, r1, r2}

	@ Check syndrome register
	mrc	p15, 4, r1, c5, c2, 0	@ HSR
	lsr	r0, r1, #HSR_EC_SHIFT
	cmp	r0, #HSR_EC_HVC
	bne	guest_trap		@ Not HVC instr.

	/*
	 * Let's check if the HVC came from VMID 0 and allow simple
	 * switch to Hyp mode
	 */
	mrrc    p15, 6, r0, r2, c2
	lsr     r2, r2, #16
	and     r2, r2, #0xff
	cmp     r2, #0
	bne	guest_trap		@ Guest called HVC

	/*
	 * Getting here means host called HVC, we shift parameters and branch
	 * to Hyp function.
	 */
	pop	{r0, r1, r2}

	/*
	 * Check if we have a kernel function, which is guaranteed to be
	 * bigger than the maximum hyp stub hypercall
	 */
	cmp	r0, #HVC_STUB_HCALL_NR
	bhs	1f

	/*
	 * Not a kernel function, treat it as a stub hypercall.
	 * Compute the physical address for __kvm_handle_stub_hvc
	 * (as the code lives in the idmaped page) and branch there.
	 * We hijack ip (r12) as a tmp register.
	 */
	push	{r1}
	ldr	r1, =kimage_voffset
	ldr	r1, [r1]
	ldr	ip, =__kvm_handle_stub_hvc
	sub	ip, ip, r1
	pop	{r1}

	bx	ip

1:
	push	{lr}

	mov	lr, r0
	mov	r0, r1
	mov	r1, r2
	mov	r2, r3

THUMB(	orr	lr, #1)
	blx	lr			@ Call the HYP function

	pop	{lr}
	eret

guest_trap:
	load_vcpu r0			@ Load VCPU pointer to r0

#ifdef CONFIG_VFPv3
	@ Check for a VFP access
	lsr	r1, r1, #HSR_EC_SHIFT
	cmp	r1, #HSR_EC_CP_0_13
	beq	__vfp_guest_restore
#endif

	mov	r1, #ARM_EXCEPTION_HVC
	b	__guest_exit

hyp_irq:
	push	{r0, r1, r2}
	mov	r1, #ARM_EXCEPTION_IRQ
	load_vcpu r0			@ Load VCPU pointer to r0
	b	__guest_exit

hyp_dabt:
	push	{r0, r1}
	mrs	r0, ELR_hyp
	ldr	r1, =abort_guest_exit_start
THUMB(	add	r1, r1, #1)
	cmp	r0, r1
	ldrne	r1, =abort_guest_exit_end
THUMB(	addne	r1, r1, #1)
	cmpne	r0, r1
	pop	{r0, r1}
	bne	__hyp_panic

	orr	r0, r0, #(1 << ARM_EXIT_WITH_ABORT_BIT)
	eret

	.ltorg

	.popsection