summaryrefslogtreecommitdiffstats
path: root/arch/arm/kvm/interrupts.S
blob: 01dcb0e752d9f04cbb1492378cc6382397c9c8e8 (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
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
/*
 * 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 <linux/const.h>
#include <asm/unified.h>
#include <asm/page.h>
#include <asm/ptrace.h>
#include <asm/asm-offsets.h>
#include <asm/kvm_asm.h>
#include <asm/kvm_arm.h>
#include <asm/vfpmacros.h>
#include "interrupts_head.S"

	.text

__kvm_hyp_code_start:
	.globl __kvm_hyp_code_start

/********************************************************************
 * Flush per-VMID TLBs
 *
 * void __kvm_tlb_flush_vmid_ipa(struct kvm *kvm, phys_addr_t ipa);
 *
 * We rely on the hardware to broadcast the TLB invalidation to all CPUs
 * inside the inner-shareable domain (which is the case for all v7
 * implementations).  If we come across a non-IS SMP implementation, we'll
 * have to use an IPI based mechanism. Until then, we stick to the simple
 * hardware assisted version.
 *
 * As v7 does not support flushing per IPA, just nuke the whole TLB
 * instead, ignoring the ipa value.
 */
ENTRY(__kvm_tlb_flush_vmid_ipa)
	push	{r2, r3}

	dsb	ishst
	add	r0, r0, #KVM_VTTBR
	ldrd	r2, r3, [r0]
	mcrr	p15, 6, rr_lo_hi(r2, r3), c2	@ Write VTTBR
	isb
	mcr     p15, 0, r0, c8, c3, 0	@ TLBIALLIS (rt ignored)
	dsb	ish
	isb
	mov	r2, #0
	mov	r3, #0
	mcrr	p15, 6, r2, r3, c2	@ Back to VMID #0
	isb				@ Not necessary if followed by eret

	pop	{r2, r3}
	bx	lr
ENDPROC(__kvm_tlb_flush_vmid_ipa)

/********************************************************************
 * Flush TLBs and instruction caches of all CPUs inside the inner-shareable
 * domain, for all VMIDs
 *
 * void __kvm_flush_vm_context(void);
 */
ENTRY(__kvm_flush_vm_context)
	mov	r0, #0			@ rn parameter for c15 flushes is SBZ

	/* Invalidate NS Non-Hyp TLB Inner Shareable (TLBIALLNSNHIS) */
	mcr     p15, 4, r0, c8, c3, 4
	/* Invalidate instruction caches Inner Shareable (ICIALLUIS) */
	mcr     p15, 0, r0, c7, c1, 0
	dsb	ish
	isb				@ Not necessary if followed by eret

	bx	lr
ENDPROC(__kvm_flush_vm_context)


/********************************************************************
 *  Hypervisor world-switch code
 *
 *
 * int __kvm_vcpu_run(struct kvm_vcpu *vcpu)
 */
ENTRY(__kvm_vcpu_run)
	@ Save the vcpu pointer
	mcr	p15, 4, vcpu, c13, c0, 2	@ HTPIDR

	save_host_regs

	restore_vgic_state
	restore_timer_state

	@ Store hardware CP15 state and load guest state
	read_cp15_state store_to_vcpu = 0
	write_cp15_state read_from_vcpu = 1

	@ If the host kernel has not been configured with VFPv3 support,
	@ then it is safer if we deny guests from using it as well.
#ifdef CONFIG_VFPv3
	@ Set FPEXC_EN so the guest doesn't trap floating point instructions
	VFPFMRX r2, FPEXC		@ VMRS
	push	{r2}
	orr	r2, r2, #FPEXC_EN
	VFPFMXR FPEXC, r2		@ VMSR
#endif

	@ Configure Hyp-role
	configure_hyp_role vmentry

	@ Trap coprocessor CRx accesses
	set_hstr vmentry
	set_hcptr vmentry, (HCPTR_TTA | HCPTR_TCP(10) | HCPTR_TCP(11))
	set_hdcr vmentry

	@ Write configured ID register into MIDR alias
	ldr	r1, [vcpu, #VCPU_MIDR]
	mcr	p15, 4, r1, c0, c0, 0

	@ Write guest view of MPIDR into VMPIDR
	ldr	r1, [vcpu, #CP15_OFFSET(c0_MPIDR)]
	mcr	p15, 4, r1, c0, c0, 5

	@ Set up guest memory translation
	ldr	r1, [vcpu, #VCPU_KVM]
	add	r1, r1, #KVM_VTTBR
	ldrd	r2, r3, [r1]
	mcrr	p15, 6, rr_lo_hi(r2, r3), c2	@ Write VTTBR

	@ We're all done, just restore the GPRs and go to the guest
	restore_guest_regs
	clrex				@ Clear exclusive monitor
	eret

__kvm_vcpu_return:
	/*
	 * return convention:
	 * guest r0, r1, r2 saved on the stack
	 * r0: vcpu pointer
	 * r1: exception code
	 */
	save_guest_regs

	@ Set VMID == 0
	mov	r2, #0
	mov	r3, #0
	mcrr	p15, 6, r2, r3, c2	@ Write VTTBR

	@ Don't trap coprocessor accesses for host kernel
	set_hstr vmexit
	set_hdcr vmexit
	set_hcptr vmexit, (HCPTR_TTA | HCPTR_TCP(10) | HCPTR_TCP(11))

#ifdef CONFIG_VFPv3
	@ Save floating point registers we if let guest use them.
	tst	r2, #(HCPTR_TCP(10) | HCPTR_TCP(11))
	bne	after_vfp_restore

	@ Switch VFP/NEON hardware state to the host's
	add	r7, vcpu, #VCPU_VFP_GUEST
	store_vfp_state r7
	add	r7, vcpu, #VCPU_VFP_HOST
	ldr	r7, [r7]
	restore_vfp_state r7

after_vfp_restore:
	@ Restore FPEXC_EN which we clobbered on entry
	pop	{r2}
	VFPFMXR FPEXC, r2
#endif

	@ Reset Hyp-role
	configure_hyp_role vmexit

	@ Let host read hardware MIDR
	mrc	p15, 0, r2, c0, c0, 0
	mcr	p15, 4, r2, c0, c0, 0

	@ Back to hardware MPIDR
	mrc	p15, 0, r2, c0, c0, 5
	mcr	p15, 4, r2, c0, c0, 5

	@ Store guest CP15 state and restore host state
	read_cp15_state store_to_vcpu = 1
	write_cp15_state read_from_vcpu = 0

	save_timer_state
	save_vgic_state

	restore_host_regs
	clrex				@ Clear exclusive monitor
#ifndef CONFIG_CPU_ENDIAN_BE8
	mov	r0, r1			@ Return the return code
	mov	r1, #0			@ Clear upper bits in return value
#else
	@ r1 already has return code
	mov	r0, #0			@ Clear upper bits in return value
#endif /* CONFIG_CPU_ENDIAN_BE8 */
	bx	lr			@ return to IOCTL

/********************************************************************
 *  Call function in Hyp mode
 *
 *
 * u64 kvm_call_hyp(void *hypfn, ...);
 *
 * This is not really a variadic function in the classic C-way and care must
 * be taken when calling this to ensure parameters are passed in registers
 * only, since the stack will change between the caller and the callee.
 *
 * Call the function with the first argument containing a pointer to the
 * function you wish to call in Hyp mode, and subsequent arguments will be
 * passed as r0, r1, and r2 (a maximum of 3 arguments in addition to the
 * function pointer can be passed).  The function being called must be mapped
 * in Hyp mode (see init_hyp_mode in arch/arm/kvm/arm.c).  Return values are
 * passed in r0 and r1.
 *
 * A function pointer with a value of 0xffffffff has a special meaning,
 * and is used to implement __hyp_get_vectors in the same way as in
 * arch/arm/kernel/hyp_stub.S.
 *
 * The calling convention follows the standard AAPCS:
 *   r0 - r3: caller save
 *   r12:     caller save
 *   rest:    callee save
 */
ENTRY(kvm_call_hyp)
	hvc	#0
	bx	lr

/********************************************************************
 * 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 and if
 *    so will push the necessary state (SPSR, lr_usr) on the Hyp stack.
 *    - 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).
 */

/* Handle undef, svc, pabt, or dabt by crashing with a user notice */
.macro bad_exception exception_code, panic_str
	push	{r0-r2}
	mrrc	p15, 6, r0, r1, c2	@ Read VTTBR
	lsr	r1, r1, #16
	ands	r1, r1, #0xff
	beq	99f

	load_vcpu			@ Load VCPU pointer
	.if \exception_code == ARM_EXCEPTION_DATA_ABORT
	mrc	p15, 4, r2, c5, c2, 0	@ HSR
	mrc	p15, 4, r1, c6, c0, 0	@ HDFAR
	str	r2, [vcpu, #VCPU_HSR]
	str	r1, [vcpu, #VCPU_HxFAR]
	.endif
	.if \exception_code == ARM_EXCEPTION_PREF_ABORT
	mrc	p15, 4, r2, c5, c2, 0	@ HSR
	mrc	p15, 4, r1, c6, c0, 2	@ HIFAR
	str	r2, [vcpu, #VCPU_HSR]
	str	r1, [vcpu, #VCPU_HxFAR]
	.endif
	mov	r1, #\exception_code
	b	__kvm_vcpu_return

	@ We were in the host already. Let's craft a panic-ing return to SVC.
99:	mrs	r2, cpsr
	bic	r2, r2, #MODE_MASK
	orr	r2, r2, #SVC_MODE
THUMB(	orr	r2, r2, #PSR_T_BIT	)
	msr	spsr_cxsf, r2
	mrs	r1, ELR_hyp
	ldr	r2, =BSYM(panic)
	msr	ELR_hyp, r2
	ldr	r0, =\panic_str
	clrex				@ Clear exclusive monitor
	eret
.endm

	.text

	.align 5
__kvm_hyp_vector:
	.globl __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

	.align
hyp_reset:
	b	hyp_reset

	.align
hyp_undef:
	bad_exception ARM_EXCEPTION_UNDEFINED, und_die_str

	.align
hyp_svc:
	bad_exception ARM_EXCEPTION_HVC, svc_die_str

	.align
hyp_pabt:
	bad_exception ARM_EXCEPTION_PREF_ABORT, pabt_die_str

	.align
hyp_dabt:
	bad_exception ARM_EXCEPTION_DATA_ABORT, dabt_die_str

	.align
hyp_hvc:
	/*
	 * Getting here is either becuase of a trap from a guest or from calling
	 * HVC from the host kernel, which means "switch to Hyp mode".
	 */
	push	{r0, r1, r2}

	@ Check syndrome register
	mrc	p15, 4, r1, c5, c2, 0	@ HSR
	lsr	r0, r1, #HSR_EC_SHIFT
#ifdef CONFIG_VFPv3
	cmp	r0, #HSR_EC_CP_0_13
	beq	switch_to_guest_vfp
#endif
	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

host_switch_to_hyp:
	pop	{r0, r1, r2}

	/* Check for __hyp_get_vectors */
	cmp	r0, #-1
	mrceq	p15, 4, r0, c12, c0, 0	@ get HVBAR
	beq	1f

	push	{lr}
	mrs	lr, SPSR
	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}
	msr	SPSR_csxf, lr
	pop	{lr}
1:	eret

guest_trap:
	load_vcpu			@ Load VCPU pointer to r0
	str	r1, [vcpu, #VCPU_HSR]

	@ Check if we need the fault information
	lsr	r1, r1, #HSR_EC_SHIFT
	cmp	r1, #HSR_EC_IABT
	mrceq	p15, 4, r2, c6, c0, 2	@ HIFAR
	beq	2f
	cmp	r1, #HSR_EC_DABT
	bne	1f
	mrc	p15, 4, r2, c6, c0, 0	@ HDFAR

2:	str	r2, [vcpu, #VCPU_HxFAR]

	/*
	 * B3.13.5 Reporting exceptions taken to the Non-secure PL2 mode:
	 *
	 * Abort on the stage 2 translation for a memory access from a
	 * Non-secure PL1 or PL0 mode:
	 *
	 * For any Access flag fault or Translation fault, and also for any
	 * Permission fault on the stage 2 translation of a memory access
	 * made as part of a translation table walk for a stage 1 translation,
	 * the HPFAR holds the IPA that caused the fault. Otherwise, the HPFAR
	 * is UNKNOWN.
	 */

	/* Check for permission fault, and S1PTW */
	mrc	p15, 4, r1, c5, c2, 0	@ HSR
	and	r0, r1, #HSR_FSC_TYPE
	cmp	r0, #FSC_PERM
	tsteq	r1, #(1 << 7)		@ S1PTW
	mrcne	p15, 4, r2, c6, c0, 4	@ HPFAR
	bne	3f

	/* Preserve PAR */
	mrrc	p15, 0, r0, r1, c7	@ PAR
	push	{r0, r1}

	/* Resolve IPA using the xFAR */
	mcr	p15, 0, r2, c7, c8, 0	@ ATS1CPR
	isb
	mrrc	p15, 0, r0, r1, c7	@ PAR
	tst	r0, #1
	bne	4f			@ Failed translation
	ubfx	r2, r0, #12, #20
	lsl	r2, r2, #4
	orr	r2, r2, r1, lsl #24

	/* Restore PAR */
	pop	{r0, r1}
	mcrr	p15, 0, r0, r1, c7	@ PAR

3:	load_vcpu			@ Load VCPU pointer to r0
	str	r2, [r0, #VCPU_HPFAR]

1:	mov	r1, #ARM_EXCEPTION_HVC
	b	__kvm_vcpu_return

4:	pop	{r0, r1}		@ Failed translation, return to guest
	mcrr	p15, 0, r0, r1, c7	@ PAR
	clrex
	pop	{r0, r1, r2}
	eret

/*
 * If VFPv3 support is not available, then we will not switch the VFP
 * registers; however cp10 and cp11 accesses will still trap and fallback
 * to the regular coprocessor emulation code, which currently will
 * inject an undefined exception to the guest.
 */
#ifdef CONFIG_VFPv3
switch_to_guest_vfp:
	load_vcpu			@ Load VCPU pointer to r0
	push	{r3-r7}

	@ NEON/VFP used.  Turn on VFP access.
	set_hcptr vmexit, (HCPTR_TCP(10) | HCPTR_TCP(11))

	@ Switch VFP/NEON hardware state to the guest's
	add	r7, r0, #VCPU_VFP_HOST
	ldr	r7, [r7]
	store_vfp_state r7
	add	r7, r0, #VCPU_VFP_GUEST
	restore_vfp_state r7

	pop	{r3-r7}
	pop	{r0-r2}
	clrex
	eret
#endif

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

	.align
hyp_fiq:
	b	hyp_fiq

	.ltorg

__kvm_hyp_code_end:
	.globl	__kvm_hyp_code_end

	.section ".rodata"

und_die_str:
	.ascii	"unexpected undefined exception in Hyp mode at: %#08x\n"
pabt_die_str:
	.ascii	"unexpected prefetch abort in Hyp mode at: %#08x\n"
dabt_die_str:
	.ascii	"unexpected data abort in Hyp mode at: %#08x\n"
svc_die_str:
	.ascii	"unexpected HVC/SVC trap in Hyp mode at: %#08x\n"