armv8_cpu.cc

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#include "arch/arm/kvm/armv8_cpu.hh"

#include <linux/kvm.h>

#include "debug/KvmContext.hh"
#include "params/ArmV8KvmCPU.hh"

// Unlike gem5, kvm doesn't count the SP as a normal integer register,
// which means we only have 31 normal integer registers.
constexpr static unsigned NUM_XREGS = NUM_ARCH_INTREGS - 1;
static_assert(NUM_XREGS == 31, "Unexpected number of aarch64 int. regs.");

// The KVM interface accesses vector registers of 4 single precision
// floats instead of individual registers.
constexpr static unsigned NUM_QREGS = NumVecV8ArchRegs;
static_assert(NUM_QREGS == 32, "Unexpected number of aarch64 vector regs.");

#define EXTRACT_FIELD(v, name) \
    (((v) & name ## _MASK) >> name ## _SHIFT)

#define CORE_REG(name, size)                               \
    (KVM_REG_ARM64 | KVM_REG_ARM_CORE |                    \
     KVM_REG_SIZE_ ## size |                               \
     KVM_REG_ARM_CORE_REG(name))

#define INT_REG(name) CORE_REG(name, U64)
#define SIMD_REG(name) CORE_REG(name, U128)

#define SYS_MPIDR_EL1 ARM64_SYS_REG(0b11, 0b000, 0b0000, 0b0000, 0b101)

constexpr uint64_t
kvmXReg(const int num)
{
    return INT_REG(regs.regs[0]) +
        (INT_REG(regs.regs[1]) - INT_REG(regs.regs[0])) * num;
}

constexpr uint64_t
kvmFPReg(const int num)
{
    return SIMD_REG(fp_regs.vregs[0]) +
        (SIMD_REG(fp_regs.vregs[1]) - SIMD_REG(fp_regs.vregs[0])) * num;
}

union KvmFPReg {
    union {
        uint32_t i;
        float f;
    } s[4];

    union {
        uint64_t i;
        double f;
    } d[2];

    uint8_t data[32];
};

#define FP_REGS_PER_VFP_REG 4

const std::vector<ArmV8KvmCPU::IntRegInfo> ArmV8KvmCPU::intRegMap = {
    { INT_REG(regs.sp), INTREG_SP0, "SP(EL0)" },
    { INT_REG(sp_el1), INTREG_SP1, "SP(EL1)" },
};

const std::vector<ArmV8KvmCPU::MiscRegInfo> ArmV8KvmCPU::miscRegMap = {
    MiscRegInfo(INT_REG(elr_el1), MISCREG_ELR_EL1, "ELR(EL1)"),
    MiscRegInfo(INT_REG(spsr[KVM_SPSR_EL1]), MISCREG_SPSR_EL1, "SPSR(EL1)"),
    MiscRegInfo(INT_REG(spsr[KVM_SPSR_ABT]), MISCREG_SPSR_ABT, "SPSR(ABT)"),
    MiscRegInfo(INT_REG(spsr[KVM_SPSR_UND]), MISCREG_SPSR_UND, "SPSR(UND)"),
    MiscRegInfo(INT_REG(spsr[KVM_SPSR_IRQ]), MISCREG_SPSR_IRQ, "SPSR(IRQ)"),
    MiscRegInfo(INT_REG(spsr[KVM_SPSR_FIQ]), MISCREG_SPSR_FIQ, "SPSR(FIQ)"),
    MiscRegInfo(CORE_REG(fp_regs.fpsr, U32), MISCREG_FPSR, "FPSR"),
    MiscRegInfo(CORE_REG(fp_regs.fpcr, U32), MISCREG_FPCR, "FPCR"),
};

const std::set<MiscRegIndex> ArmV8KvmCPU::deviceRegSet = {
    MISCREG_CNTV_CTL_EL0,
    MISCREG_CNTV_CVAL_EL0,
    MISCREG_CNTKCTL_EL1,
};

const std::vector<ArmV8KvmCPU::MiscRegInfo> ArmV8KvmCPU::miscRegIdMap = {
    MiscRegInfo(SYS_MPIDR_EL1, MISCREG_MPIDR_EL1, "MPIDR(EL1)"),
};

ArmV8KvmCPU::ArmV8KvmCPU(ArmV8KvmCPUParams *params)
    : BaseArmKvmCPU(params)
{
}

ArmV8KvmCPU::~ArmV8KvmCPU()
{
}

void
ArmV8KvmCPU::startup()
{
    BaseArmKvmCPU::startup();

    // Override ID registers that KVM should "inherit" from gem5.
    for (const auto &ri : miscRegIdMap) {
        const uint64_t value(tc->readMiscReg(ri.idx));
        DPRINTF(KvmContext, "  %s := 0x%x\n", ri.name, value);
        setOneReg(ri.kvm, value);
    }
}

void
ArmV8KvmCPU::dump() const
{
    inform("Integer registers:\n");
    inform("  PC: %s\n", getAndFormatOneReg(INT_REG(regs.pc)));
    for (int i = 0; i < NUM_XREGS; ++i)
        inform("  X%i: %s\n", i, getAndFormatOneReg(kvmXReg(i)));

    for (int i = 0; i < NUM_QREGS; ++i)
        inform("  Q%i: %s\n", i, getAndFormatOneReg(kvmFPReg(i)));

    for (const auto &ri : intRegMap)
        inform("  %s: %s\n", ri.name, getAndFormatOneReg(ri.kvm));

    inform("  %s: %s\n", "PSTATE", getAndFormatOneReg(INT_REG(regs.pstate)));

    for (const auto &ri : miscRegMap)
        inform("  %s: %s\n", ri.name, getAndFormatOneReg(ri.kvm));

    for (const auto &ri : miscRegIdMap)
        inform("  %s: %s\n", ri.name, getAndFormatOneReg(ri.kvm));

    for (const auto &reg : getRegList()) {
        const uint64_t arch(reg & KVM_REG_ARCH_MASK);
        if (arch != KVM_REG_ARM64) {
            inform("0x%x: %s\n", reg, getAndFormatOneReg(reg));
            continue;
        }

        const uint64_t type(reg & KVM_REG_ARM_COPROC_MASK);
        switch (type) {
          case KVM_REG_ARM_CORE:
            // These have already been printed
            break;

          case KVM_REG_ARM64_SYSREG: {
              const uint64_t op0(EXTRACT_FIELD(reg, KVM_REG_ARM64_SYSREG_OP0));
              const uint64_t op1(EXTRACT_FIELD(reg, KVM_REG_ARM64_SYSREG_OP1));
              const uint64_t crn(EXTRACT_FIELD(reg, KVM_REG_ARM64_SYSREG_CRN));
              const uint64_t crm(EXTRACT_FIELD(reg, KVM_REG_ARM64_SYSREG_CRM));
              const uint64_t op2(EXTRACT_FIELD(reg, KVM_REG_ARM64_SYSREG_OP2));
              const MiscRegIndex idx(
                  decodeAArch64SysReg(op0, op1, crn, crm, op2));

              inform("  %s (op0: %i, op1: %i, crn: %i, crm: %i, op2: %i): %s",
                     miscRegName[idx], op0, op1, crn, crm, op2,
                     getAndFormatOneReg(reg));
          } break;

          case KVM_REG_ARM_DEMUX: {
              const uint64_t id(EXTRACT_FIELD(reg, KVM_REG_ARM_DEMUX_ID));
              const uint64_t val(EXTRACT_FIELD(reg, KVM_REG_ARM_DEMUX_VAL));
              if (id == KVM_REG_ARM_DEMUX_ID_CCSIDR) {
                  inform("  CSSIDR[%i]: %s\n", val,
                         getAndFormatOneReg(reg));
              } else {
                  inform("  UNKNOWN[%i:%i]: %s\n", id, val,
                         getAndFormatOneReg(reg));
              }
          } break;

          default:
            inform("0x%x: %s\n", reg, getAndFormatOneReg(reg));
        }
    }
}

void
ArmV8KvmCPU::updateKvmState()
{
    DPRINTF(KvmContext, "In updateKvmState():\n");

    // update pstate register state
    CPSR cpsr(tc->readMiscReg(MISCREG_CPSR));
    cpsr.nz = tc->readCCReg(CCREG_NZ);
    cpsr.c = tc->readCCReg(CCREG_C);
    cpsr.v = tc->readCCReg(CCREG_V);
    if (cpsr.width) {
        cpsr.ge = tc->readCCReg(CCREG_GE);
    } else {
        cpsr.ge = 0;
    }
    DPRINTF(KvmContext, "  %s := 0x%x\n", "PSTATE", cpsr);
    setOneReg(INT_REG(regs.pstate), static_cast<uint64_t>(cpsr));

    for (const auto &ri : miscRegMap) {
        const uint64_t value(tc->readMiscReg(ri.idx));
        DPRINTF(KvmContext, "  %s := 0x%x\n", ri.name, value);
        setOneReg(ri.kvm, value);
    }

    for (int i = 0; i < NUM_XREGS; ++i) {
        const uint64_t value(tc->readIntReg(INTREG_X0 + i));
        DPRINTF(KvmContext, "  X%i := 0x%x\n", i, value);
        setOneReg(kvmXReg(i), value);
    }

    for (const auto &ri : intRegMap) {
        const uint64_t value(tc->readIntReg(ri.idx));
        DPRINTF(KvmContext, "  %s := 0x%x\n", ri.name, value);
        setOneReg(ri.kvm, value);
    }

    for (int i = 0; i < NUM_QREGS; ++i) {
        KvmFPReg reg;
        auto v = tc->readVecReg(RegId(VecRegClass, i)).as<VecElem>();
        for (int j = 0; j < FP_REGS_PER_VFP_REG; j++)
            reg.s[j].i = v[j];

        setOneReg(kvmFPReg(i), reg.data);
        DPRINTF(KvmContext, "  Q%i: %s\n", i, getAndFormatOneReg(kvmFPReg(i)));
    }

    for (const auto &ri : getSysRegMap()) {
        uint64_t value;
        if (ri.is_device) {
            // This system register is backed by a device. This means
            // we need to lock the device event queue.
            EventQueue::ScopedMigration migrate(deviceEventQueue());

            value = tc->readMiscReg(ri.idx);
        } else {
            value = tc->readMiscReg(ri.idx);
        }

        DPRINTF(KvmContext, "  %s := 0x%x\n", ri.name, value);
        setOneReg(ri.kvm, value);
    }

    setOneReg(INT_REG(regs.pc), tc->instAddr());
    DPRINTF(KvmContext, "  PC := 0x%x\n", tc->instAddr());
}

void
ArmV8KvmCPU::updateThreadContext()
{
    DPRINTF(KvmContext, "In updateThreadContext():\n");

    // Update pstate thread context
    const CPSR cpsr(getOneRegU64(INT_REG(regs.pstate)));
    DPRINTF(KvmContext, "  %s := 0x%x\n", "PSTATE", cpsr);
    tc->setMiscRegNoEffect(MISCREG_CPSR, cpsr);
    tc->setCCReg(CCREG_NZ, cpsr.nz);
    tc->setCCReg(CCREG_C, cpsr.c);
    tc->setCCReg(CCREG_V, cpsr.v);
    if (cpsr.width) {
        tc->setCCReg(CCREG_GE, cpsr.ge);
    }

    // Update core misc regs first as they
    // affect how other registers are mapped.
    for (const auto &ri : miscRegMap) {
        const auto value(getOneRegU64(ri.kvm));
        DPRINTF(KvmContext, "  %s := 0x%x\n", ri.name, value);
        tc->setMiscRegNoEffect(ri.idx, value);
    }

    for (int i = 0; i < NUM_XREGS; ++i) {
        const auto value(getOneRegU64(kvmXReg(i)));
        DPRINTF(KvmContext, "  X%i := 0x%x\n", i, value);
        // KVM64 returns registers in 64-bit layout. If we are in aarch32
        // mode, we need to map these to banked ARM32 registers.
        if (inAArch64(tc)) {
            tc->setIntReg(INTREG_X0 + i, value);
        } else {
            tc->setIntRegFlat(IntReg64Map[INTREG_X0 + i], value);
        }
    }

    for (const auto &ri : intRegMap) {
        const auto value(getOneRegU64(ri.kvm));
        DPRINTF(KvmContext, "  %s := 0x%x\n", ri.name, value);
        tc->setIntReg(ri.idx, value);
    }

    for (int i = 0; i < NUM_QREGS; ++i) {
        KvmFPReg reg;
        DPRINTF(KvmContext, "  Q%i: %s\n", i, getAndFormatOneReg(kvmFPReg(i)));
        getOneReg(kvmFPReg(i), reg.data);
        auto v = tc->getWritableVecReg(RegId(VecRegClass, i)).as<VecElem>();
        for (int j = 0; j < FP_REGS_PER_VFP_REG; j++)
            v[j] = reg.s[j].i;
    }

    for (const auto &ri : getSysRegMap()) {
        const auto value(getOneRegU64(ri.kvm));
        DPRINTF(KvmContext, "  %s := 0x%x\n", ri.name, value);
        if (ri.is_device) {
            // This system register is backed by a device. This means
            // we need to lock the device event queue.
            EventQueue::ScopedMigration migrate(deviceEventQueue());

            tc->setMiscReg(ri.idx, value);
        } else {
            tc->setMiscRegNoEffect(ri.idx, value);
        }
    }

    PCState pc(getOneRegU64(INT_REG(regs.pc)));
    pc.aarch64(inAArch64(tc));
    pc.thumb(cpsr.t);
    pc.nextAArch64(inAArch64(tc));
    // TODO: This is a massive assumption that will break when
    // switching to thumb.
    pc.nextThumb(cpsr.t);
    DPRINTF(KvmContext, "  PC := 0x%x (t: %i, a64: %i)\n",
            pc.instAddr(), pc.thumb(), pc.aarch64());
    tc->pcState(pc);
}

const std::vector<ArmV8KvmCPU::MiscRegInfo> &
ArmV8KvmCPU::getSysRegMap() const
{
    // Try to use the cached map
    if (!sysRegMap.empty())
        return sysRegMap;

    for (const auto &reg : getRegList()) {
        const uint64_t arch(reg & KVM_REG_ARCH_MASK);
        if (arch != KVM_REG_ARM64)
            continue;

        const uint64_t type(reg & KVM_REG_ARM_COPROC_MASK);
        if (type != KVM_REG_ARM64_SYSREG)
            continue;

        const uint64_t op0(EXTRACT_FIELD(reg, KVM_REG_ARM64_SYSREG_OP0));
        const uint64_t op1(EXTRACT_FIELD(reg, KVM_REG_ARM64_SYSREG_OP1));
        const uint64_t crn(EXTRACT_FIELD(reg, KVM_REG_ARM64_SYSREG_CRN));
        const uint64_t crm(EXTRACT_FIELD(reg, KVM_REG_ARM64_SYSREG_CRM));
        const uint64_t op2(EXTRACT_FIELD(reg, KVM_REG_ARM64_SYSREG_OP2));
        const MiscRegIndex idx(decodeAArch64SysReg(op0, op1, crn, crm, op2));
        const auto &info(miscRegInfo[idx]);
        const bool writeable(
            info[MISCREG_USR_NS_WR] || info[MISCREG_USR_S_WR] ||
            info[MISCREG_PRI_S_WR] || info[MISCREG_PRI_NS_WR] ||
            info[MISCREG_HYP_WR] ||
            info[MISCREG_MON_NS0_WR] || info[MISCREG_MON_NS1_WR]);
        const bool implemented(
            info[MISCREG_IMPLEMENTED] || info[MISCREG_WARN_NOT_FAIL]);

        // Only add implemented registers that we are going to be able
        // to write.
        if (implemented && writeable)
            sysRegMap.emplace_back(reg, idx, miscRegName[idx],
                deviceRegSet.find(idx) != deviceRegSet.end());
    }

    return sysRegMap;
}

ArmV8KvmCPU *
ArmV8KvmCPUParams::create()
{
    return new ArmV8KvmCPU(this);
}