xref: /openbmc/linux/arch/arm64/kvm/hyp/nvhe/host.S (revision bfad37c5) 
1/* SPDX-License-Identifier: GPL-2.0-only */
2/*
3 * Copyright (C) 2020 - Google Inc
4 * Author: Andrew Scull <ascull@google.com>
5 */
6
7#include <linux/linkage.h>
8
9#include <asm/assembler.h>
10#include <asm/kvm_arm.h>
11#include <asm/kvm_asm.h>
12#include <asm/kvm_mmu.h>
13
14	.text
15
16SYM_FUNC_START(__host_exit)
17	get_host_ctxt	x0, x1
18
19	/* Store the host regs x2 and x3 */
20	stp	x2, x3,   [x0, #CPU_XREG_OFFSET(2)]
21
22	/* Retrieve the host regs x0-x1 from the stack */
23	ldp	x2, x3, [sp], #16	// x0, x1
24
25	/* Store the host regs x0-x1 and x4-x17 */
26	stp	x2, x3,   [x0, #CPU_XREG_OFFSET(0)]
27	stp	x4, x5,   [x0, #CPU_XREG_OFFSET(4)]
28	stp	x6, x7,   [x0, #CPU_XREG_OFFSET(6)]
29	stp	x8, x9,   [x0, #CPU_XREG_OFFSET(8)]
30	stp	x10, x11, [x0, #CPU_XREG_OFFSET(10)]
31	stp	x12, x13, [x0, #CPU_XREG_OFFSET(12)]
32	stp	x14, x15, [x0, #CPU_XREG_OFFSET(14)]
33	stp	x16, x17, [x0, #CPU_XREG_OFFSET(16)]
34
35	/* Store the host regs x18-x29, lr */
36	save_callee_saved_regs x0
37
38	/* Save the host context pointer in x29 across the function call */
39	mov	x29, x0
40	bl	handle_trap
41
42	/* Restore host regs x0-x17 */
43__host_enter_restore_full:
44	ldp	x0, x1,   [x29, #CPU_XREG_OFFSET(0)]
45	ldp	x2, x3,   [x29, #CPU_XREG_OFFSET(2)]
46	ldp	x4, x5,   [x29, #CPU_XREG_OFFSET(4)]
47	ldp	x6, x7,   [x29, #CPU_XREG_OFFSET(6)]
48
49	/* x0-7 are use for panic arguments */
50__host_enter_for_panic:
51	ldp	x8, x9,   [x29, #CPU_XREG_OFFSET(8)]
52	ldp	x10, x11, [x29, #CPU_XREG_OFFSET(10)]
53	ldp	x12, x13, [x29, #CPU_XREG_OFFSET(12)]
54	ldp	x14, x15, [x29, #CPU_XREG_OFFSET(14)]
55	ldp	x16, x17, [x29, #CPU_XREG_OFFSET(16)]
56
57	/* Restore host regs x18-x29, lr */
58	restore_callee_saved_regs x29
59
60	/* Do not touch any register after this! */
61__host_enter_without_restoring:
62	eret
63	sb
64SYM_FUNC_END(__host_exit)
65
66/*
67 * void __noreturn __host_enter(struct kvm_cpu_context *host_ctxt);
68 */
69SYM_FUNC_START(__host_enter)
70	mov	x29, x0
71	b	__host_enter_restore_full
72SYM_FUNC_END(__host_enter)
73
74/*
75 * void __noreturn __hyp_do_panic(struct kvm_cpu_context *host_ctxt, u64 spsr,
76 * 				  u64 elr, u64 par);
77 */
78SYM_FUNC_START(__hyp_do_panic)
79	/* Prepare and exit to the host's panic funciton. */
80	mov	lr, #(PSR_F_BIT | PSR_I_BIT | PSR_A_BIT | PSR_D_BIT |\
81		      PSR_MODE_EL1h)
82	msr	spsr_el2, lr
83	ldr	lr, =nvhe_hyp_panic_handler
84	hyp_kimg_va lr, x6
85	msr	elr_el2, lr
86
87	mov	x29, x0
88
89#ifdef CONFIG_NVHE_EL2_DEBUG
90	/* Ensure host stage-2 is disabled */
91	mrs	x0, hcr_el2
92	bic	x0, x0, #HCR_VM
93	msr	hcr_el2, x0
94	isb
95	tlbi	vmalls12e1
96	dsb	nsh
97#endif
98
99	/* Load the panic arguments into x0-7 */
100	mrs	x0, esr_el2
101	mov	x4, x3
102	mov	x3, x2
103	hyp_pa	x3, x6
104	get_vcpu_ptr x5, x6
105	mrs	x6, far_el2
106	mrs	x7, hpfar_el2
107
108	/* Enter the host, conditionally restoring the host context. */
109	cbz	x29, __host_enter_without_restoring
110	b	__host_enter_for_panic
111SYM_FUNC_END(__hyp_do_panic)
112
113.macro host_el1_sync_vect
114	.align 7
115.L__vect_start\@:
116	stp	x0, x1, [sp, #-16]!
117	mrs	x0, esr_el2
118	lsr	x0, x0, #ESR_ELx_EC_SHIFT
119	cmp	x0, #ESR_ELx_EC_HVC64
120	b.ne	__host_exit
121
122	ldp	x0, x1, [sp]		// Don't fixup the stack yet
123
124	/* Check for a stub HVC call */
125	cmp	x0, #HVC_STUB_HCALL_NR
126	b.hs	__host_exit
127
128	add	sp, sp, #16
129	/*
130	 * Compute the idmap address of __kvm_handle_stub_hvc and
131	 * jump there. Since we use kimage_voffset, do not use the
132	 * HYP VA for __kvm_handle_stub_hvc, but the kernel VA instead
133	 * (by loading it from the constant pool).
134	 *
135	 * Preserve x0-x4, which may contain stub parameters.
136	 */
137	ldr	x5, =__kvm_handle_stub_hvc
138	hyp_pa	x5, x6
139	br	x5
140.L__vect_end\@:
141.if ((.L__vect_end\@ - .L__vect_start\@) > 0x80)
142	.error "host_el1_sync_vect larger than vector entry"
143.endif
144.endm
145
146.macro invalid_host_el2_vect
147	.align 7
148	/* If a guest is loaded, panic out of it. */
149	stp	x0, x1, [sp, #-16]!
150	get_loaded_vcpu x0, x1
151	cbnz	x0, __guest_exit_panic
152	add	sp, sp, #16
153
154	/*
155	 * The panic may not be clean if the exception is taken before the host
156	 * context has been saved by __host_exit or after the hyp context has
157	 * been partially clobbered by __host_enter.
158	 */
159	b	hyp_panic
160.endm
161
162.macro invalid_host_el1_vect
163	.align 7
164	mov	x0, xzr		/* restore_host = false */
165	mrs	x1, spsr_el2
166	mrs	x2, elr_el2
167	mrs	x3, par_el1
168	b	__hyp_do_panic
169.endm
170
171/*
172 * The host vector does not use an ESB instruction in order to avoid consuming
173 * SErrors that should only be consumed by the host. Guest entry is deferred by
174 * __guest_enter if there are any pending asynchronous exceptions so hyp will
175 * always return to the host without having consumerd host SErrors.
176 *
177 * CONFIG_KVM_INDIRECT_VECTORS is not applied to the host vectors because the
178 * host knows about the EL2 vectors already, and there is no point in hiding
179 * them.
180 */
181	.align 11
182SYM_CODE_START(__kvm_hyp_host_vector)
183	invalid_host_el2_vect			// Synchronous EL2t
184	invalid_host_el2_vect			// IRQ EL2t
185	invalid_host_el2_vect			// FIQ EL2t
186	invalid_host_el2_vect			// Error EL2t
187
188	invalid_host_el2_vect			// Synchronous EL2h
189	invalid_host_el2_vect			// IRQ EL2h
190	invalid_host_el2_vect			// FIQ EL2h
191	invalid_host_el2_vect			// Error EL2h
192
193	host_el1_sync_vect			// Synchronous 64-bit EL1
194	invalid_host_el1_vect			// IRQ 64-bit EL1
195	invalid_host_el1_vect			// FIQ 64-bit EL1
196	invalid_host_el1_vect			// Error 64-bit EL1
197
198	invalid_host_el1_vect			// Synchronous 32-bit EL1
199	invalid_host_el1_vect			// IRQ 32-bit EL1
200	invalid_host_el1_vect			// FIQ 32-bit EL1
201	invalid_host_el1_vect			// Error 32-bit EL1
202SYM_CODE_END(__kvm_hyp_host_vector)
203
204/*
205 * Forward SMC with arguments in struct kvm_cpu_context, and
206 * store the result into the same struct. Assumes SMCCC 1.2 or older.
207 *
208 * x0: struct kvm_cpu_context*
209 */
210SYM_CODE_START(__kvm_hyp_host_forward_smc)
211	/*
212	 * Use x18 to keep the pointer to the host context because
213	 * x18 is callee-saved in SMCCC but not in AAPCS64.
214	 */
215	mov	x18, x0
216
217	ldp	x0, x1,   [x18, #CPU_XREG_OFFSET(0)]
218	ldp	x2, x3,   [x18, #CPU_XREG_OFFSET(2)]
219	ldp	x4, x5,   [x18, #CPU_XREG_OFFSET(4)]
220	ldp	x6, x7,   [x18, #CPU_XREG_OFFSET(6)]
221	ldp	x8, x9,   [x18, #CPU_XREG_OFFSET(8)]
222	ldp	x10, x11, [x18, #CPU_XREG_OFFSET(10)]
223	ldp	x12, x13, [x18, #CPU_XREG_OFFSET(12)]
224	ldp	x14, x15, [x18, #CPU_XREG_OFFSET(14)]
225	ldp	x16, x17, [x18, #CPU_XREG_OFFSET(16)]
226
227	smc	#0
228
229	stp	x0, x1,   [x18, #CPU_XREG_OFFSET(0)]
230	stp	x2, x3,   [x18, #CPU_XREG_OFFSET(2)]
231	stp	x4, x5,   [x18, #CPU_XREG_OFFSET(4)]
232	stp	x6, x7,   [x18, #CPU_XREG_OFFSET(6)]
233	stp	x8, x9,   [x18, #CPU_XREG_OFFSET(8)]
234	stp	x10, x11, [x18, #CPU_XREG_OFFSET(10)]
235	stp	x12, x13, [x18, #CPU_XREG_OFFSET(12)]
236	stp	x14, x15, [x18, #CPU_XREG_OFFSET(14)]
237	stp	x16, x17, [x18, #CPU_XREG_OFFSET(16)]
238
239	ret
240SYM_CODE_END(__kvm_hyp_host_forward_smc)
241