hyp-stub.S (5628B)
1/* SPDX-License-Identifier: GPL-2.0-only */ 2/* 3 * Hypervisor stub 4 * 5 * Copyright (C) 2012 ARM Ltd. 6 * Author: Marc Zyngier <marc.zyngier@arm.com> 7 */ 8 9#include <linux/init.h> 10#include <linux/linkage.h> 11 12#include <asm/assembler.h> 13#include <asm/el2_setup.h> 14#include <asm/kvm_arm.h> 15#include <asm/kvm_asm.h> 16#include <asm/ptrace.h> 17#include <asm/virt.h> 18 19 .text 20 .pushsection .hyp.text, "ax" 21 22 .align 11 23 24SYM_CODE_START(__hyp_stub_vectors) 25 ventry el2_sync_invalid // Synchronous EL2t 26 ventry el2_irq_invalid // IRQ EL2t 27 ventry el2_fiq_invalid // FIQ EL2t 28 ventry el2_error_invalid // Error EL2t 29 30 ventry elx_sync // Synchronous EL2h 31 ventry el2_irq_invalid // IRQ EL2h 32 ventry el2_fiq_invalid // FIQ EL2h 33 ventry el2_error_invalid // Error EL2h 34 35 ventry elx_sync // Synchronous 64-bit EL1 36 ventry el1_irq_invalid // IRQ 64-bit EL1 37 ventry el1_fiq_invalid // FIQ 64-bit EL1 38 ventry el1_error_invalid // Error 64-bit EL1 39 40 ventry el1_sync_invalid // Synchronous 32-bit EL1 41 ventry el1_irq_invalid // IRQ 32-bit EL1 42 ventry el1_fiq_invalid // FIQ 32-bit EL1 43 ventry el1_error_invalid // Error 32-bit EL1 44SYM_CODE_END(__hyp_stub_vectors) 45 46 .align 11 47 48SYM_CODE_START_LOCAL(elx_sync) 49 cmp x0, #HVC_SET_VECTORS 50 b.ne 1f 51 msr vbar_el2, x1 52 b 9f 53 541: cmp x0, #HVC_VHE_RESTART 55 b.eq mutate_to_vhe 56 572: cmp x0, #HVC_SOFT_RESTART 58 b.ne 3f 59 mov x0, x2 60 mov x2, x4 61 mov x4, x1 62 mov x1, x3 63 br x4 // no return 64 653: cmp x0, #HVC_RESET_VECTORS 66 beq 9f // Nothing to reset! 67 68 /* Someone called kvm_call_hyp() against the hyp-stub... */ 69 mov_q x0, HVC_STUB_ERR 70 eret 71 729: mov x0, xzr 73 eret 74SYM_CODE_END(elx_sync) 75 76// nVHE? No way! Give me the real thing! 77SYM_CODE_START_LOCAL(mutate_to_vhe) 78 // Sanity check: MMU *must* be off 79 mrs x1, sctlr_el2 80 tbnz x1, #0, 1f 81 82 // Needs to be VHE capable, obviously 83 mrs x1, id_aa64mmfr1_el1 84 ubfx x1, x1, #ID_AA64MMFR1_VHE_SHIFT, #4 85 cbz x1, 1f 86 87 // Check whether VHE is disabled from the command line 88 adr_l x1, id_aa64mmfr1_override 89 ldr x2, [x1, FTR_OVR_VAL_OFFSET] 90 ldr x1, [x1, FTR_OVR_MASK_OFFSET] 91 ubfx x2, x2, #ID_AA64MMFR1_VHE_SHIFT, #4 92 ubfx x1, x1, #ID_AA64MMFR1_VHE_SHIFT, #4 93 cmp x1, xzr 94 and x2, x2, x1 95 csinv x2, x2, xzr, ne 96 cbnz x2, 2f 97 981: mov_q x0, HVC_STUB_ERR 99 eret 1002: 101 // Engage the VHE magic! 102 mov_q x0, HCR_HOST_VHE_FLAGS 103 msr hcr_el2, x0 104 isb 105 106 // Use the EL1 allocated stack, per-cpu offset 107 mrs x0, sp_el1 108 mov sp, x0 109 mrs x0, tpidr_el1 110 msr tpidr_el2, x0 111 112 // FP configuration, vectors 113 mrs_s x0, SYS_CPACR_EL12 114 msr cpacr_el1, x0 115 mrs_s x0, SYS_VBAR_EL12 116 msr vbar_el1, x0 117 118 // Use EL2 translations for SPE & TRBE and disable access from EL1 119 mrs x0, mdcr_el2 120 bic x0, x0, #(MDCR_EL2_E2PB_MASK << MDCR_EL2_E2PB_SHIFT) 121 bic x0, x0, #(MDCR_EL2_E2TB_MASK << MDCR_EL2_E2TB_SHIFT) 122 msr mdcr_el2, x0 123 124 // Transfer the MM state from EL1 to EL2 125 mrs_s x0, SYS_TCR_EL12 126 msr tcr_el1, x0 127 mrs_s x0, SYS_TTBR0_EL12 128 msr ttbr0_el1, x0 129 mrs_s x0, SYS_TTBR1_EL12 130 msr ttbr1_el1, x0 131 mrs_s x0, SYS_MAIR_EL12 132 msr mair_el1, x0 133 isb 134 135 // Hack the exception return to stay at EL2 136 mrs x0, spsr_el1 137 and x0, x0, #~PSR_MODE_MASK 138 mov x1, #PSR_MODE_EL2h 139 orr x0, x0, x1 140 msr spsr_el1, x0 141 142 b enter_vhe 143SYM_CODE_END(mutate_to_vhe) 144 145 // At the point where we reach enter_vhe(), we run with 146 // the MMU off (which is enforced by mutate_to_vhe()). 147 // We thus need to be in the idmap, or everything will 148 // explode when enabling the MMU. 149 150 .pushsection .idmap.text, "ax" 151 152SYM_CODE_START_LOCAL(enter_vhe) 153 // Invalidate TLBs before enabling the MMU 154 tlbi vmalle1 155 dsb nsh 156 isb 157 158 // Enable the EL2 S1 MMU, as set up from EL1 159 mrs_s x0, SYS_SCTLR_EL12 160 set_sctlr_el1 x0 161 162 // Disable the EL1 S1 MMU for a good measure 163 mov_q x0, INIT_SCTLR_EL1_MMU_OFF 164 msr_s SYS_SCTLR_EL12, x0 165 166 mov x0, xzr 167 168 eret 169SYM_CODE_END(enter_vhe) 170 171 .popsection 172 173.macro invalid_vector label 174SYM_CODE_START_LOCAL(\label) 175 b \label 176SYM_CODE_END(\label) 177.endm 178 179 invalid_vector el2_sync_invalid 180 invalid_vector el2_irq_invalid 181 invalid_vector el2_fiq_invalid 182 invalid_vector el2_error_invalid 183 invalid_vector el1_sync_invalid 184 invalid_vector el1_irq_invalid 185 invalid_vector el1_fiq_invalid 186 invalid_vector el1_error_invalid 187 188 .popsection 189 190/* 191 * __hyp_set_vectors: Call this after boot to set the initial hypervisor 192 * vectors as part of hypervisor installation. On an SMP system, this should 193 * be called on each CPU. 194 * 195 * x0 must be the physical address of the new vector table, and must be 196 * 2KB aligned. 197 * 198 * Before calling this, you must check that the stub hypervisor is installed 199 * everywhere, by waiting for any secondary CPUs to be brought up and then 200 * checking that is_hyp_mode_available() is true. 201 * 202 * If not, there is a pre-existing hypervisor, some CPUs failed to boot, or 203 * something else went wrong... in such cases, trying to install a new 204 * hypervisor is unlikely to work as desired. 205 * 206 * When you call into your shiny new hypervisor, sp_el2 will contain junk, 207 * so you will need to set that to something sensible at the new hypervisor's 208 * initialisation entry point. 209 */ 210 211SYM_FUNC_START(__hyp_set_vectors) 212 mov x1, x0 213 mov x0, #HVC_SET_VECTORS 214 hvc #0 215 ret 216SYM_FUNC_END(__hyp_set_vectors) 217 218SYM_FUNC_START(__hyp_reset_vectors) 219 mov x0, #HVC_RESET_VECTORS 220 hvc #0 221 ret 222SYM_FUNC_END(__hyp_reset_vectors) 223 224/* 225 * Entry point to switch to VHE if deemed capable 226 */ 227SYM_FUNC_START(switch_to_vhe) 228 // Need to have booted at EL2 229 adr_l x1, __boot_cpu_mode 230 ldr w0, [x1] 231 cmp w0, #BOOT_CPU_MODE_EL2 232 b.ne 1f 233 234 // and still be at EL1 235 mrs x0, CurrentEL 236 cmp x0, #CurrentEL_EL1 237 b.ne 1f 238 239 // Turn the world upside down 240 mov x0, #HVC_VHE_RESTART 241 hvc #0 2421: 243 ret 244SYM_FUNC_END(switch_to_vhe)