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linux/arch/arm/kvm/emulate.c

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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/mm.h>
#include <linux/kvm_host.h>
#include <asm/kvm_arm.h>
#include <asm/kvm_emulate.h>
#include <asm/opcodes.h>
#include <trace/events/kvm.h>
#include "trace.h"
#define VCPU_NR_MODES 6
#define VCPU_REG_OFFSET_USR 0
#define VCPU_REG_OFFSET_FIQ 1
#define VCPU_REG_OFFSET_IRQ 2
#define VCPU_REG_OFFSET_SVC 3
#define VCPU_REG_OFFSET_ABT 4
#define VCPU_REG_OFFSET_UND 5
#define REG_OFFSET(_reg) \
(offsetof(struct kvm_regs, _reg) / sizeof(u32))
#define USR_REG_OFFSET(_num) REG_OFFSET(usr_regs.uregs[_num])
static const unsigned long vcpu_reg_offsets[VCPU_NR_MODES][15] = {
/* USR/SYS Registers */
[VCPU_REG_OFFSET_USR] = {
USR_REG_OFFSET(0), USR_REG_OFFSET(1), USR_REG_OFFSET(2),
USR_REG_OFFSET(3), USR_REG_OFFSET(4), USR_REG_OFFSET(5),
USR_REG_OFFSET(6), USR_REG_OFFSET(7), USR_REG_OFFSET(8),
USR_REG_OFFSET(9), USR_REG_OFFSET(10), USR_REG_OFFSET(11),
USR_REG_OFFSET(12), USR_REG_OFFSET(13), USR_REG_OFFSET(14),
},
/* FIQ Registers */
[VCPU_REG_OFFSET_FIQ] = {
USR_REG_OFFSET(0), USR_REG_OFFSET(1), USR_REG_OFFSET(2),
USR_REG_OFFSET(3), USR_REG_OFFSET(4), USR_REG_OFFSET(5),
USR_REG_OFFSET(6), USR_REG_OFFSET(7),
REG_OFFSET(fiq_regs[0]), /* r8 */
REG_OFFSET(fiq_regs[1]), /* r9 */
REG_OFFSET(fiq_regs[2]), /* r10 */
REG_OFFSET(fiq_regs[3]), /* r11 */
REG_OFFSET(fiq_regs[4]), /* r12 */
REG_OFFSET(fiq_regs[5]), /* r13 */
REG_OFFSET(fiq_regs[6]), /* r14 */
},
/* IRQ Registers */
[VCPU_REG_OFFSET_IRQ] = {
USR_REG_OFFSET(0), USR_REG_OFFSET(1), USR_REG_OFFSET(2),
USR_REG_OFFSET(3), USR_REG_OFFSET(4), USR_REG_OFFSET(5),
USR_REG_OFFSET(6), USR_REG_OFFSET(7), USR_REG_OFFSET(8),
USR_REG_OFFSET(9), USR_REG_OFFSET(10), USR_REG_OFFSET(11),
USR_REG_OFFSET(12),
REG_OFFSET(irq_regs[0]), /* r13 */
REG_OFFSET(irq_regs[1]), /* r14 */
},
/* SVC Registers */
[VCPU_REG_OFFSET_SVC] = {
USR_REG_OFFSET(0), USR_REG_OFFSET(1), USR_REG_OFFSET(2),
USR_REG_OFFSET(3), USR_REG_OFFSET(4), USR_REG_OFFSET(5),
USR_REG_OFFSET(6), USR_REG_OFFSET(7), USR_REG_OFFSET(8),
USR_REG_OFFSET(9), USR_REG_OFFSET(10), USR_REG_OFFSET(11),
USR_REG_OFFSET(12),
REG_OFFSET(svc_regs[0]), /* r13 */
REG_OFFSET(svc_regs[1]), /* r14 */
},
/* ABT Registers */
[VCPU_REG_OFFSET_ABT] = {
USR_REG_OFFSET(0), USR_REG_OFFSET(1), USR_REG_OFFSET(2),
USR_REG_OFFSET(3), USR_REG_OFFSET(4), USR_REG_OFFSET(5),
USR_REG_OFFSET(6), USR_REG_OFFSET(7), USR_REG_OFFSET(8),
USR_REG_OFFSET(9), USR_REG_OFFSET(10), USR_REG_OFFSET(11),
USR_REG_OFFSET(12),
REG_OFFSET(abt_regs[0]), /* r13 */
REG_OFFSET(abt_regs[1]), /* r14 */
},
/* UND Registers */
[VCPU_REG_OFFSET_UND] = {
USR_REG_OFFSET(0), USR_REG_OFFSET(1), USR_REG_OFFSET(2),
USR_REG_OFFSET(3), USR_REG_OFFSET(4), USR_REG_OFFSET(5),
USR_REG_OFFSET(6), USR_REG_OFFSET(7), USR_REG_OFFSET(8),
USR_REG_OFFSET(9), USR_REG_OFFSET(10), USR_REG_OFFSET(11),
USR_REG_OFFSET(12),
REG_OFFSET(und_regs[0]), /* r13 */
REG_OFFSET(und_regs[1]), /* r14 */
},
};
/*
* Return a pointer to the register number valid in the current mode of
* the virtual CPU.
*/
unsigned long *vcpu_reg(struct kvm_vcpu *vcpu, u8 reg_num)
{
unsigned long *reg_array = (unsigned long *)&vcpu->arch.regs;
unsigned long mode = *vcpu_cpsr(vcpu) & MODE_MASK;
switch (mode) {
case USR_MODE...SVC_MODE:
mode &= ~MODE32_BIT; /* 0 ... 3 */
break;
case ABT_MODE:
mode = VCPU_REG_OFFSET_ABT;
break;
case UND_MODE:
mode = VCPU_REG_OFFSET_UND;
break;
case SYSTEM_MODE:
mode = VCPU_REG_OFFSET_USR;
break;
default:
BUG();
}
return reg_array + vcpu_reg_offsets[mode][reg_num];
}
/*
* Return the SPSR for the current mode of the virtual CPU.
*/
unsigned long *vcpu_spsr(struct kvm_vcpu *vcpu)
{
unsigned long mode = *vcpu_cpsr(vcpu) & MODE_MASK;
switch (mode) {
case SVC_MODE:
return &vcpu->arch.regs.KVM_ARM_SVC_spsr;
case ABT_MODE:
return &vcpu->arch.regs.KVM_ARM_ABT_spsr;
case UND_MODE:
return &vcpu->arch.regs.KVM_ARM_UND_spsr;
case IRQ_MODE:
return &vcpu->arch.regs.KVM_ARM_IRQ_spsr;
case FIQ_MODE:
return &vcpu->arch.regs.KVM_ARM_FIQ_spsr;
default:
BUG();
}
}
/*
* A conditional instruction is allowed to trap, even though it
* wouldn't be executed. So let's re-implement the hardware, in
* software!
*/
bool kvm_condition_valid(struct kvm_vcpu *vcpu)
{
unsigned long cpsr, cond, insn;
/*
* Exception Code 0 can only happen if we set HCR.TGE to 1, to
* catch undefined instructions, and then we won't get past
* the arm_exit_handlers test anyway.
*/
BUG_ON(!kvm_vcpu_trap_get_class(vcpu));
/* Top two bits non-zero? Unconditional. */
if (kvm_vcpu_get_hsr(vcpu) >> 30)
return true;
cpsr = *vcpu_cpsr(vcpu);
/* Is condition field valid? */
if ((kvm_vcpu_get_hsr(vcpu) & HSR_CV) >> HSR_CV_SHIFT)
cond = (kvm_vcpu_get_hsr(vcpu) & HSR_COND) >> HSR_COND_SHIFT;
else {
/* This can happen in Thumb mode: examine IT state. */
unsigned long it;
it = ((cpsr >> 8) & 0xFC) | ((cpsr >> 25) & 0x3);
/* it == 0 => unconditional. */
if (it == 0)
return true;
/* The cond for this insn works out as the top 4 bits. */
cond = (it >> 4);
}
/* Shift makes it look like an ARM-mode instruction */
insn = cond << 28;
return arm_check_condition(insn, cpsr) != ARM_OPCODE_CONDTEST_FAIL;
}
/**
* adjust_itstate - adjust ITSTATE when emulating instructions in IT-block
* @vcpu: The VCPU pointer
*
* When exceptions occur while instructions are executed in Thumb IF-THEN
* blocks, the ITSTATE field of the CPSR is not advanved (updated), so we have
* to do this little bit of work manually. The fields map like this:
*
* IT[7:0] -> CPSR[26:25],CPSR[15:10]
*/
static void kvm_adjust_itstate(struct kvm_vcpu *vcpu)
{
unsigned long itbits, cond;
unsigned long cpsr = *vcpu_cpsr(vcpu);
bool is_arm = !(cpsr & PSR_T_BIT);
BUG_ON(is_arm && (cpsr & PSR_IT_MASK));
if (!(cpsr & PSR_IT_MASK))
return;
cond = (cpsr & 0xe000) >> 13;
itbits = (cpsr & 0x1c00) >> (10 - 2);
itbits |= (cpsr & (0x3 << 25)) >> 25;
/* Perform ITAdvance (see page A-52 in ARM DDI 0406C) */
if ((itbits & 0x7) == 0)
itbits = cond = 0;
else
itbits = (itbits << 1) & 0x1f;
cpsr &= ~PSR_IT_MASK;
cpsr |= cond << 13;
cpsr |= (itbits & 0x1c) << (10 - 2);
cpsr |= (itbits & 0x3) << 25;
*vcpu_cpsr(vcpu) = cpsr;
}
/**
* kvm_skip_instr - skip a trapped instruction and proceed to the next
* @vcpu: The vcpu pointer
*/
void kvm_skip_instr(struct kvm_vcpu *vcpu, bool is_wide_instr)
{
bool is_thumb;
is_thumb = !!(*vcpu_cpsr(vcpu) & PSR_T_BIT);
if (is_thumb && !is_wide_instr)
*vcpu_pc(vcpu) += 2;
else
*vcpu_pc(vcpu) += 4;
kvm_adjust_itstate(vcpu);
}
/******************************************************************************
* Inject exceptions into the guest
*/
static u32 exc_vector_base(struct kvm_vcpu *vcpu)
{
u32 sctlr = vcpu->arch.cp15[c1_SCTLR];
u32 vbar = vcpu->arch.cp15[c12_VBAR];
if (sctlr & SCTLR_V)
return 0xffff0000;
else /* always have security exceptions */
return vbar;
}
/**
* kvm_inject_undefined - inject an undefined exception into the guest
* @vcpu: The VCPU to receive the undefined exception
*
* It is assumed that this code is called from the VCPU thread and that the
* VCPU therefore is not currently executing guest code.
*
* Modelled after TakeUndefInstrException() pseudocode.
*/
void kvm_inject_undefined(struct kvm_vcpu *vcpu)
{
unsigned long new_lr_value;
unsigned long new_spsr_value;
unsigned long cpsr = *vcpu_cpsr(vcpu);
u32 sctlr = vcpu->arch.cp15[c1_SCTLR];
bool is_thumb = (cpsr & PSR_T_BIT);
u32 vect_offset = 4;
u32 return_offset = (is_thumb) ? 2 : 4;
new_spsr_value = cpsr;
new_lr_value = *vcpu_pc(vcpu) - return_offset;
*vcpu_cpsr(vcpu) = (cpsr & ~MODE_MASK) | UND_MODE;
*vcpu_cpsr(vcpu) |= PSR_I_BIT;
*vcpu_cpsr(vcpu) &= ~(PSR_IT_MASK | PSR_J_BIT | PSR_E_BIT | PSR_T_BIT);
if (sctlr & SCTLR_TE)
*vcpu_cpsr(vcpu) |= PSR_T_BIT;
if (sctlr & SCTLR_EE)
*vcpu_cpsr(vcpu) |= PSR_E_BIT;
/* Note: These now point to UND banked copies */
*vcpu_spsr(vcpu) = cpsr;
*vcpu_reg(vcpu, 14) = new_lr_value;
/* Branch to exception vector */
*vcpu_pc(vcpu) = exc_vector_base(vcpu) + vect_offset;
}
/*
* Modelled after TakeDataAbortException() and TakePrefetchAbortException
* pseudocode.
*/
static void inject_abt(struct kvm_vcpu *vcpu, bool is_pabt, unsigned long addr)
{
unsigned long new_lr_value;
unsigned long new_spsr_value;
unsigned long cpsr = *vcpu_cpsr(vcpu);
u32 sctlr = vcpu->arch.cp15[c1_SCTLR];
bool is_thumb = (cpsr & PSR_T_BIT);
u32 vect_offset;
u32 return_offset = (is_thumb) ? 4 : 0;
bool is_lpae;
new_spsr_value = cpsr;
new_lr_value = *vcpu_pc(vcpu) + return_offset;
*vcpu_cpsr(vcpu) = (cpsr & ~MODE_MASK) | ABT_MODE;
*vcpu_cpsr(vcpu) |= PSR_I_BIT | PSR_A_BIT;
*vcpu_cpsr(vcpu) &= ~(PSR_IT_MASK | PSR_J_BIT | PSR_E_BIT | PSR_T_BIT);
if (sctlr & SCTLR_TE)
*vcpu_cpsr(vcpu) |= PSR_T_BIT;
if (sctlr & SCTLR_EE)
*vcpu_cpsr(vcpu) |= PSR_E_BIT;
/* Note: These now point to ABT banked copies */
*vcpu_spsr(vcpu) = cpsr;
*vcpu_reg(vcpu, 14) = new_lr_value;
if (is_pabt)
vect_offset = 12;
else
vect_offset = 16;
/* Branch to exception vector */
*vcpu_pc(vcpu) = exc_vector_base(vcpu) + vect_offset;
if (is_pabt) {
/* Set DFAR and DFSR */
vcpu->arch.cp15[c6_IFAR] = addr;
is_lpae = (vcpu->arch.cp15[c2_TTBCR] >> 31);
/* Always give debug fault for now - should give guest a clue */
if (is_lpae)
vcpu->arch.cp15[c5_IFSR] = 1 << 9 | 0x22;
else
vcpu->arch.cp15[c5_IFSR] = 2;
} else { /* !iabt */
/* Set DFAR and DFSR */
vcpu->arch.cp15[c6_DFAR] = addr;
is_lpae = (vcpu->arch.cp15[c2_TTBCR] >> 31);
/* Always give debug fault for now - should give guest a clue */
if (is_lpae)
vcpu->arch.cp15[c5_DFSR] = 1 << 9 | 0x22;
else
vcpu->arch.cp15[c5_DFSR] = 2;
}
}
/**
* kvm_inject_dabt - inject a data abort into the guest
* @vcpu: The VCPU to receive the undefined exception
* @addr: The address to report in the DFAR
*
* It is assumed that this code is called from the VCPU thread and that the
* VCPU therefore is not currently executing guest code.
*/
void kvm_inject_dabt(struct kvm_vcpu *vcpu, unsigned long addr)
{
inject_abt(vcpu, false, addr);
}
/**
* kvm_inject_pabt - inject a prefetch abort into the guest
* @vcpu: The VCPU to receive the undefined exception
* @addr: The address to report in the DFAR
*
* It is assumed that this code is called from the VCPU thread and that the
* VCPU therefore is not currently executing guest code.
*/
void kvm_inject_pabt(struct kvm_vcpu *vcpu, unsigned long addr)
{
inject_abt(vcpu, true, addr);
}
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