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ARM: KVM: Add guest entry code 

Add the very minimal piece of code that is now required to jump
into the guest (and return from it). This code is only concerned
with save/restoring the USR registers (r0-r12+lr for the guest,
r4-r12+lr for the host), as everything else is dealt with in C
(VFP is another matter though).

Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
hifive-unleashed-5.1
Marc Zyngier 2016-01-05 18:40:51 +00:00
parent 33280b4cd1
commit 89ef2b21ed
3 changed files with 73 additions and 0 deletions
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1
arch/arm/kvm/hyp/Makefile
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@ -8,3 +8,4 @@ obj-$(CONFIG_KVM_ARM_HOST) += timer-sr.o
obj-$(CONFIG_KVM_ARM_HOST) += vgic-v2-sr.o
obj-$(CONFIG_KVM_ARM_HOST) += vfp.o
obj-$(CONFIG_KVM_ARM_HOST) += banked-sr.o
obj-$(CONFIG_KVM_ARM_HOST) += entry.o

70
arch/arm/kvm/hyp/entry.S 100644
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@ -0,0 +1,70 @@
/*
* Copyright (C) 2016 - ARM Ltd
* Author: Marc Zyngier <marc.zyngier@arm.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, see <http://www.gnu.org/licenses/>.
*/
#include <linux/linkage.h>
#include <asm/asm-offsets.h>
#include <asm/kvm_arm.h>
.arch_extension virt
.text
.pushsection .hyp.text, "ax"
#define USR_REGS_OFFSET (CPU_CTXT_GP_REGS + GP_REGS_USR)
/* int __guest_enter(struct kvm_vcpu *vcpu, struct kvm_cpu_context *host) */
ENTRY(__guest_enter)
@ Save host registers
add r1, r1, #(USR_REGS_OFFSET + S_R4)
stm r1!, {r4-r12}
str lr, [r1, #4] @ Skip SP_usr (already saved)
@ Restore guest registers
add r0, r0, #(VCPU_GUEST_CTXT + USR_REGS_OFFSET + S_R0)
ldr lr, [r0, #S_LR]
ldm r0, {r0-r12}
clrex
eret
ENDPROC(__guest_enter)
ENTRY(__guest_exit)
/*
* return convention:
* guest r0, r1, r2 saved on the stack
* r0: vcpu pointer
* r1: exception code
*/
add r2, r0, #(VCPU_GUEST_CTXT + USR_REGS_OFFSET + S_R3)
stm r2!, {r3-r12}
str lr, [r2, #4]
add r2, r0, #(VCPU_GUEST_CTXT + USR_REGS_OFFSET + S_R0)
pop {r3, r4, r5} @ r0, r1, r2
stm r2, {r3-r5}
ldr r0, [r0, #VCPU_HOST_CTXT]
add r0, r0, #(USR_REGS_OFFSET + S_R4)
ldm r0!, {r4-r12}
ldr lr, [r0, #4]
mov r0, r1
bx lr
ENDPROC(__guest_exit)
.popsection

2
arch/arm/kvm/hyp/hyp.h
View File

@ -110,4 +110,6 @@ static inline bool __vfp_enabled(void)
void __hyp_text __banked_save_state(struct kvm_cpu_context *ctxt);
void __hyp_text __banked_restore_state(struct kvm_cpu_context *ctxt);
int asmlinkage __guest_enter(struct kvm_vcpu *vcpu,
struct kvm_cpu_context *host);
#endif /* __ARM_KVM_HYP_H__ */