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/* SPDX-License-Identifier: GPL-2.0-only */
/*
* Hypervisor stub
*
* Copyright (C) 2012 ARM Ltd.
* Author: Marc Zyngier <marc.zyngier@arm.com>
*/
#include <linux/init.h>
#include <linux/linkage.h>
#include <asm/assembler.h>
#include <asm/el2_setup.h>
#include <asm/kvm_arm.h>
#include <asm/kvm_asm.h>
#include <asm/ptrace.h>
#include <asm/virt.h>
.text
.pushsection .hyp.text, "ax"
.align 11
SYM_CODE_START(__hyp_stub_vectors)
ventry el2_sync_invalid // Synchronous EL2t
ventry el2_irq_invalid // IRQ EL2t
ventry el2_fiq_invalid // FIQ EL2t
ventry el2_error_invalid // Error EL2t
ventry elx_sync // Synchronous EL2h
ventry el2_irq_invalid // IRQ EL2h
ventry el2_fiq_invalid // FIQ EL2h
ventry el2_error_invalid // Error EL2h
ventry elx_sync // Synchronous 64-bit EL1
ventry el1_irq_invalid // IRQ 64-bit EL1
ventry el1_fiq_invalid // FIQ 64-bit EL1
ventry el1_error_invalid // Error 64-bit EL1
ventry el1_sync_invalid // Synchronous 32-bit EL1
ventry el1_irq_invalid // IRQ 32-bit EL1
ventry el1_fiq_invalid // FIQ 32-bit EL1
ventry el1_error_invalid // Error 32-bit EL1
SYM_CODE_END(__hyp_stub_vectors)
.align 11
SYM_CODE_START_LOCAL(elx_sync)
cmp x0, #HVC_SET_VECTORS
b.ne 1f
msr vbar_el2, x1
b 9f
1: cmp x0, #HVC_VHE_RESTART
b.eq mutate_to_vhe
2: cmp x0, #HVC_SOFT_RESTART
b.ne 3f
mov x0, x2
mov x2, x4
mov x4, x1
mov x1, x3
br x4 // no return
3: cmp x0, #HVC_RESET_VECTORS
beq 9f // Nothing to reset!
/* Someone called kvm_call_hyp() against the hyp-stub... */
mov_q x0, HVC_STUB_ERR
eret
9: mov x0, xzr
eret
SYM_CODE_END(elx_sync)
// nVHE? No way! Give me the real thing!
SYM_CODE_START_LOCAL(mutate_to_vhe)
// Sanity check: MMU *must* be off
mrs x1, sctlr_el2
tbnz x1, #0, 1f
// Needs to be VHE capable, obviously
mrs x1, id_aa64mmfr1_el1
ubfx x1, x1, #ID_AA64MMFR1_VHE_SHIFT, #4
cbz x1, 1f
// Check whether VHE is disabled from the command line
adr_l x1, id_aa64mmfr1_override
ldr x2, [x1, FTR_OVR_VAL_OFFSET]
ldr x1, [x1, FTR_OVR_MASK_OFFSET]
ubfx x2, x2, #ID_AA64MMFR1_VHE_SHIFT, #4
ubfx x1, x1, #ID_AA64MMFR1_VHE_SHIFT, #4
cmp x1, xzr
and x2, x2, x1
csinv x2, x2, xzr, ne
cbnz x2, 2f
1: mov_q x0, HVC_STUB_ERR
eret
2:
// Engage the VHE magic!
mov_q x0, HCR_HOST_VHE_FLAGS
msr hcr_el2, x0
isb
// Use the EL1 allocated stack, per-cpu offset
mrs x0, sp_el1
mov sp, x0
mrs x0, tpidr_el1
msr tpidr_el2, x0
// FP configuration, vectors
mrs_s x0, SYS_CPACR_EL12
msr cpacr_el1, x0
mrs_s x0, SYS_VBAR_EL12
msr vbar_el1, x0
// Use EL2 translations for SPE & TRBE and disable access from EL1
mrs x0, mdcr_el2
bic x0, x0, #(MDCR_EL2_E2PB_MASK << MDCR_EL2_E2PB_SHIFT)
bic x0, x0, #(MDCR_EL2_E2TB_MASK << MDCR_EL2_E2TB_SHIFT)
msr mdcr_el2, x0
// Transfer the MM state from EL1 to EL2
mrs_s x0, SYS_TCR_EL12
msr tcr_el1, x0
mrs_s x0, SYS_TTBR0_EL12
msr ttbr0_el1, x0
mrs_s x0, SYS_TTBR1_EL12
msr ttbr1_el1, x0
mrs_s x0, SYS_MAIR_EL12
msr mair_el1, x0
isb
// Hack the exception return to stay at EL2
mrs x0, spsr_el1
and x0, x0, #~PSR_MODE_MASK
mov x1, #PSR_MODE_EL2h
orr x0, x0, x1
msr spsr_el1, x0
b enter_vhe
SYM_CODE_END(mutate_to_vhe)
// At the point where we reach enter_vhe(), we run with
// the MMU off (which is enforced by mutate_to_vhe()).
// We thus need to be in the idmap, or everything will
// explode when enabling the MMU.
.pushsection .idmap.text, "ax"
SYM_CODE_START_LOCAL(enter_vhe)
// Invalidate TLBs before enabling the MMU
tlbi vmalle1
dsb nsh
isb
// Enable the EL2 S1 MMU, as set up from EL1
mrs_s x0, SYS_SCTLR_EL12
set_sctlr_el1 x0
// Disable the EL1 S1 MMU for a good measure
mov_q x0, INIT_SCTLR_EL1_MMU_OFF
msr_s SYS_SCTLR_EL12, x0
mov x0, xzr
eret
SYM_CODE_END(enter_vhe)
.popsection
.macro invalid_vector label
SYM_CODE_START_LOCAL(\label)
b \label
SYM_CODE_END(\label)
.endm
invalid_vector el2_sync_invalid
invalid_vector el2_irq_invalid
invalid_vector el2_fiq_invalid
invalid_vector el2_error_invalid
invalid_vector el1_sync_invalid
invalid_vector el1_irq_invalid
invalid_vector el1_fiq_invalid
invalid_vector el1_error_invalid
.popsection
/*
* __hyp_set_vectors: Call this after boot to set the initial hypervisor
* vectors as part of hypervisor installation. On an SMP system, this should
* be called on each CPU.
*
* x0 must be the physical address of the new vector table, and must be
* 2KB aligned.
*
* Before calling this, you must check that the stub hypervisor is installed
* everywhere, by waiting for any secondary CPUs to be brought up and then
* checking that is_hyp_mode_available() is true.
*
* If not, there is a pre-existing hypervisor, some CPUs failed to boot, or
* something else went wrong... in such cases, trying to install a new
* hypervisor is unlikely to work as desired.
*
* When you call into your shiny new hypervisor, sp_el2 will contain junk,
* so you will need to set that to something sensible at the new hypervisor's
* initialisation entry point.
*/
SYM_FUNC_START(__hyp_set_vectors)
mov x1, x0
mov x0, #HVC_SET_VECTORS
hvc #0
ret
SYM_FUNC_END(__hyp_set_vectors)
SYM_FUNC_START(__hyp_reset_vectors)
mov x0, #HVC_RESET_VECTORS
hvc #0
ret
SYM_FUNC_END(__hyp_reset_vectors)
/*
* Entry point to switch to VHE if deemed capable
*/
SYM_FUNC_START(switch_to_vhe)
// Need to have booted at EL2
adr_l x1, __boot_cpu_mode
ldr w0, [x1]
cmp w0, #BOOT_CPU_MODE_EL2
b.ne 1f
// and still be at EL1
mrs x0, CurrentEL
cmp x0, #CurrentEL_EL1
b.ne 1f
// Turn the world upside down
mov x0, #HVC_VHE_RESTART
hvc #0
1:
ret
SYM_FUNC_END(switch_to_vhe)
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