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/*
* 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 <asm/kvm_arm.h>
#include <asm/kvm_asm.h>
.arch_extension virt
.text
.pushsection .hyp.text, "ax"
.macro load_vcpu reg
mrc p15, 4, \reg, c13, c0, 2 @ HTPIDR
.endm
/********************************************************************
* 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.
* - 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).
*/
.align 5
__hyp_vector:
.global __hyp_vector
__kvm_hyp_vector:
.weak __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
.macro invalid_vector label, cause
.align
\label: b .
.endm
invalid_vector hyp_reset
invalid_vector hyp_undef
invalid_vector hyp_svc
invalid_vector hyp_pabt
invalid_vector hyp_dabt
invalid_vector hyp_fiq
hyp_hvc:
/*
* Getting here is either because of a trap from a guest,
* or from executing HVC from the host kernel, which means
* "do something in Hyp mode".
*/
push {r0, r1, r2}
@ Check syndrome register
mrc p15, 4, r1, c5, c2, 0 @ HSR
lsr r0, r1, #HSR_EC_SHIFT
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
/*
* Getting here means host called HVC, we shift parameters and branch
* to Hyp function.
*/
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}
mov lr, r0
mov r0, r1
mov r1, r2
mov r2, r3
THUMB( orr lr, #1)
blx lr @ Call the HYP function
pop {lr}
1: eret
guest_trap:
load_vcpu r0 @ Load VCPU pointer to r0
#ifdef CONFIG_VFPv3
@ Check for a VFP access
lsr r1, r1, #HSR_EC_SHIFT
cmp r1, #HSR_EC_CP_0_13
beq __vfp_guest_restore
#endif
mov r1, #ARM_EXCEPTION_HVC
b __guest_exit
hyp_irq:
push {r0, r1, r2}
mov r1, #ARM_EXCEPTION_IRQ
load_vcpu r0 @ Load VCPU pointer to r0
b __guest_exit
.ltorg
.popsection
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