xref: /openbmc/linux/arch/arm64/kvm/hyp/nvhe/host.S (revision 31e67366) 
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_asm.h>
11#include <asm/kvm_mmu.h>
12
13	.text
14
15SYM_FUNC_START(__host_exit)
16	get_host_ctxt	x0, x1
17
18	/* Store the host regs x2 and x3 */
19	stp	x2, x3,   [x0, #CPU_XREG_OFFSET(2)]
20
21	/* Retrieve the host regs x0-x1 from the stack */
22	ldp	x2, x3, [sp], #16	// x0, x1
23
24	/* Store the host regs x0-x1 and x4-x17 */
25	stp	x2, x3,   [x0, #CPU_XREG_OFFSET(0)]
26	stp	x4, x5,   [x0, #CPU_XREG_OFFSET(4)]
27	stp	x6, x7,   [x0, #CPU_XREG_OFFSET(6)]
28	stp	x8, x9,   [x0, #CPU_XREG_OFFSET(8)]
29	stp	x10, x11, [x0, #CPU_XREG_OFFSET(10)]
30	stp	x12, x13, [x0, #CPU_XREG_OFFSET(12)]
31	stp	x14, x15, [x0, #CPU_XREG_OFFSET(14)]
32	stp	x16, x17, [x0, #CPU_XREG_OFFSET(16)]
33
34	/* Store the host regs x18-x29, lr */
35	save_callee_saved_regs x0
36
37	/* Save the host context pointer in x29 across the function call */
38	mov	x29, x0
39	bl	handle_trap
40
41	/* Restore host regs x0-x17 */
42__host_enter_restore_full:
43	ldp	x0, x1,   [x29, #CPU_XREG_OFFSET(0)]
44	ldp	x2, x3,   [x29, #CPU_XREG_OFFSET(2)]
45	ldp	x4, x5,   [x29, #CPU_XREG_OFFSET(4)]
46	ldp	x6, x7,   [x29, #CPU_XREG_OFFSET(6)]
47
48	/* x0-7 are use for panic arguments */
49__host_enter_for_panic:
50	ldp	x8, x9,   [x29, #CPU_XREG_OFFSET(8)]
51	ldp	x10, x11, [x29, #CPU_XREG_OFFSET(10)]
52	ldp	x12, x13, [x29, #CPU_XREG_OFFSET(12)]
53	ldp	x14, x15, [x29, #CPU_XREG_OFFSET(14)]
54	ldp	x16, x17, [x29, #CPU_XREG_OFFSET(16)]
55
56	/* Restore host regs x18-x29, lr */
57	restore_callee_saved_regs x29
58
59	/* Do not touch any register after this! */
60__host_enter_without_restoring:
61	eret
62	sb
63SYM_FUNC_END(__host_exit)
64
65/*
66 * void __noreturn __host_enter(struct kvm_cpu_context *host_ctxt);
67 */
68SYM_FUNC_START(__host_enter)
69	mov	x29, x0
70	b	__host_enter_restore_full
71SYM_FUNC_END(__host_enter)
72
73/*
74 * void __noreturn __hyp_do_panic(bool restore_host, u64 spsr, u64 elr, u64 par);
75 */
76SYM_FUNC_START(__hyp_do_panic)
77	/* Prepare and exit to the host's panic funciton. */
78	mov	lr, #(PSR_F_BIT | PSR_I_BIT | PSR_A_BIT | PSR_D_BIT |\
79		      PSR_MODE_EL1h)
80	msr	spsr_el2, lr
81	ldr	lr, =panic
82	hyp_kimg_va lr, x6
83	msr	elr_el2, lr
84
85	/* Set the panic format string. Use the, now free, LR as scratch. */
86	ldr	lr, =__hyp_panic_string
87	hyp_kimg_va lr, x6
88
89	/* Load the format arguments into x1-7. */
90	mov	x6, x3
91	get_vcpu_ptr x7, x3
92	mrs	x3, esr_el2
93	mrs	x4, far_el2
94	mrs	x5, hpfar_el2
95
96	/* Enter the host, conditionally restoring the host context. */
97	cmp	x0, xzr
98	mov	x0, lr
99	b.eq	__host_enter_without_restoring
100	b	__host_enter_for_panic
101SYM_FUNC_END(__hyp_do_panic)
102
103.macro host_el1_sync_vect
104	.align 7
105.L__vect_start\@:
106	stp	x0, x1, [sp, #-16]!
107	mrs	x0, esr_el2
108	lsr	x0, x0, #ESR_ELx_EC_SHIFT
109	cmp	x0, #ESR_ELx_EC_HVC64
110	b.ne	__host_exit
111
112	ldp	x0, x1, [sp]		// Don't fixup the stack yet
113
114	/* Check for a stub HVC call */
115	cmp	x0, #HVC_STUB_HCALL_NR
116	b.hs	__host_exit
117
118	add	sp, sp, #16
119	/*
120	 * Compute the idmap address of __kvm_handle_stub_hvc and
121	 * jump there. Since we use kimage_voffset, do not use the
122	 * HYP VA for __kvm_handle_stub_hvc, but the kernel VA instead
123	 * (by loading it from the constant pool).
124	 *
125	 * Preserve x0-x4, which may contain stub parameters.
126	 */
127	ldr	x5, =__kvm_handle_stub_hvc
128	hyp_pa	x5, x6
129	br	x5
130.L__vect_end\@:
131.if ((.L__vect_end\@ - .L__vect_start\@) > 0x80)
132	.error "host_el1_sync_vect larger than vector entry"
133.endif
134.endm
135
136.macro invalid_host_el2_vect
137	.align 7
138	/* If a guest is loaded, panic out of it. */
139	stp	x0, x1, [sp, #-16]!
140	get_loaded_vcpu x0, x1
141	cbnz	x0, __guest_exit_panic
142	add	sp, sp, #16
143
144	/*
145	 * The panic may not be clean if the exception is taken before the host
146	 * context has been saved by __host_exit or after the hyp context has
147	 * been partially clobbered by __host_enter.
148	 */
149	b	hyp_panic
150.endm
151
152.macro invalid_host_el1_vect
153	.align 7
154	mov	x0, xzr		/* restore_host = false */
155	mrs	x1, spsr_el2
156	mrs	x2, elr_el2
157	mrs	x3, par_el1
158	b	__hyp_do_panic
159.endm
160
161/*
162 * The host vector does not use an ESB instruction in order to avoid consuming
163 * SErrors that should only be consumed by the host. Guest entry is deferred by
164 * __guest_enter if there are any pending asynchronous exceptions so hyp will
165 * always return to the host without having consumerd host SErrors.
166 *
167 * CONFIG_KVM_INDIRECT_VECTORS is not applied to the host vectors because the
168 * host knows about the EL2 vectors already, and there is no point in hiding
169 * them.
170 */
171	.align 11
172SYM_CODE_START(__kvm_hyp_host_vector)
173	invalid_host_el2_vect			// Synchronous EL2t
174	invalid_host_el2_vect			// IRQ EL2t
175	invalid_host_el2_vect			// FIQ EL2t
176	invalid_host_el2_vect			// Error EL2t
177
178	invalid_host_el2_vect			// Synchronous EL2h
179	invalid_host_el2_vect			// IRQ EL2h
180	invalid_host_el2_vect			// FIQ EL2h
181	invalid_host_el2_vect			// Error EL2h
182
183	host_el1_sync_vect			// Synchronous 64-bit EL1
184	invalid_host_el1_vect			// IRQ 64-bit EL1
185	invalid_host_el1_vect			// FIQ 64-bit EL1
186	invalid_host_el1_vect			// Error 64-bit EL1
187
188	invalid_host_el1_vect			// Synchronous 32-bit EL1
189	invalid_host_el1_vect			// IRQ 32-bit EL1
190	invalid_host_el1_vect			// FIQ 32-bit EL1
191	invalid_host_el1_vect			// Error 32-bit EL1
192SYM_CODE_END(__kvm_hyp_host_vector)
193
194/*
195 * Forward SMC with arguments in struct kvm_cpu_context, and
196 * store the result into the same struct. Assumes SMCCC 1.2 or older.
197 *
198 * x0: struct kvm_cpu_context*
199 */
200SYM_CODE_START(__kvm_hyp_host_forward_smc)
201	/*
202	 * Use x18 to keep the pointer to the host context because
203	 * x18 is callee-saved in SMCCC but not in AAPCS64.
204	 */
205	mov	x18, x0
206
207	ldp	x0, x1,   [x18, #CPU_XREG_OFFSET(0)]
208	ldp	x2, x3,   [x18, #CPU_XREG_OFFSET(2)]
209	ldp	x4, x5,   [x18, #CPU_XREG_OFFSET(4)]
210	ldp	x6, x7,   [x18, #CPU_XREG_OFFSET(6)]
211	ldp	x8, x9,   [x18, #CPU_XREG_OFFSET(8)]
212	ldp	x10, x11, [x18, #CPU_XREG_OFFSET(10)]
213	ldp	x12, x13, [x18, #CPU_XREG_OFFSET(12)]
214	ldp	x14, x15, [x18, #CPU_XREG_OFFSET(14)]
215	ldp	x16, x17, [x18, #CPU_XREG_OFFSET(16)]
216
217	smc	#0
218
219	stp	x0, x1,   [x18, #CPU_XREG_OFFSET(0)]
220	stp	x2, x3,   [x18, #CPU_XREG_OFFSET(2)]
221	stp	x4, x5,   [x18, #CPU_XREG_OFFSET(4)]
222	stp	x6, x7,   [x18, #CPU_XREG_OFFSET(6)]
223	stp	x8, x9,   [x18, #CPU_XREG_OFFSET(8)]
224	stp	x10, x11, [x18, #CPU_XREG_OFFSET(10)]
225	stp	x12, x13, [x18, #CPU_XREG_OFFSET(12)]
226	stp	x14, x15, [x18, #CPU_XREG_OFFSET(14)]
227	stp	x16, x17, [x18, #CPU_XREG_OFFSET(16)]
228
229	ret
230SYM_CODE_END(__kvm_hyp_host_forward_smc)
231