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Diffstat (limited to 'kernel/arch/arm/kvm/emulate.c')
| -rw-r--r-- | kernel/arch/arm/kvm/emulate.c | 402 |
1 files changed, 402 insertions, 0 deletions
diff --git a/kernel/arch/arm/kvm/emulate.c b/kernel/arch/arm/kvm/emulate.c new file mode 100644 index 000000000..d6c005283 --- /dev/null +++ b/kernel/arch/arm/kvm/emulate.c @@ -0,0 +1,402 @@ +/* + * 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 IFAR and IFSR */ + 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); +} |