kvm32.c

/*
 * ARM implementation of KVM hooks, 32 bit specific code.
 *
 * Copyright Christoffer Dall 2009-2010
 *
 * This work is licensed under the terms of the GNU GPL, version 2 or later.
 * See the COPYING file in the top-level directory.
 *
 */

#include <stdio.h>
#include <sys/types.h>
#include <sys/ioctl.h>
#include <sys/mman.h>

#include <linux/kvm.h>

#include "qemu-common.h"
#include "qemu/timer.h"
#include "sysemu/sysemu.h"
#include "sysemu/kvm.h"
#include "kvm_arm.h"
#include "cpu.h"
#include "internals.h"
#include "hw/arm/arm.h"

static inline void set_feature(uint64_t *features, int feature)
{
    *features |= 1ULL << feature;
}

bool kvm_arm_get_host_cpu_features(ARMHostCPUClass *ahcc)
{
    /* Identify the feature bits corresponding to the host CPU, and
     * fill out the ARMHostCPUClass fields accordingly. To do this
     * we have to create a scratch VM, create a single CPU inside it,
     * and then query that CPU for the relevant ID registers.
     */
    int i, ret, fdarray[3];
    uint32_t midr, id_pfr0, id_isar0, mvfr1;
    uint64_t features = 0;
    /* Old kernels may not know about the PREFERRED_TARGET ioctl: however
     * we know these will only support creating one kind of guest CPU,
     * which is its preferred CPU type.
     */
    static const uint32_t cpus_to_try[] = {
        QEMU_KVM_ARM_TARGET_CORTEX_A15,
        QEMU_KVM_ARM_TARGET_NONE
    };
    struct kvm_vcpu_init init;
    struct kvm_one_reg idregs[] = {
        {
            .id = KVM_REG_ARM | KVM_REG_SIZE_U32
            | ENCODE_CP_REG(15, 0, 0, 0, 0, 0),
            .addr = (uintptr_t)&midr,
        },
        {
            .id = KVM_REG_ARM | KVM_REG_SIZE_U32
            | ENCODE_CP_REG(15, 0, 0, 1, 0, 0),
            .addr = (uintptr_t)&id_pfr0,
        },
        {
            .id = KVM_REG_ARM | KVM_REG_SIZE_U32
            | ENCODE_CP_REG(15, 0, 0, 2, 0, 0),
            .addr = (uintptr_t)&id_isar0,
        },
        {
            .id = KVM_REG_ARM | KVM_REG_SIZE_U32
            | KVM_REG_ARM_VFP | KVM_REG_ARM_VFP_MVFR1,
            .addr = (uintptr_t)&mvfr1,
        },
    };

    if (!kvm_arm_create_scratch_host_vcpu(cpus_to_try, fdarray, &init)) {
        return false;
    }

    ahcc->target = init.target;

    /* This is not strictly blessed by the device tree binding docs yet,
     * but in practice the kernel does not care about this string so
     * there is no point maintaining an KVM_ARM_TARGET_* -> string table.
     */
    ahcc->dtb_compatible = "arm,arm-v7";

    for (i = 0; i < ARRAY_SIZE(idregs); i++) {
        ret = ioctl(fdarray[2], KVM_GET_ONE_REG, &idregs[i]);
        if (ret) {
            break;
        }
    }

    kvm_arm_destroy_scratch_host_vcpu(fdarray);

    if (ret) {
        return false;
    }

    /* Now we've retrieved all the register information we can
     * set the feature bits based on the ID register fields.
     * We can assume any KVM supporting CPU is at least a v7
     * with VFPv3, LPAE and the generic timers; this in turn implies
     * most of the other feature bits, but a few must be tested.
     */
    set_feature(&features, ARM_FEATURE_V7);
    set_feature(&features, ARM_FEATURE_VFP3);
    set_feature(&features, ARM_FEATURE_LPAE);
    set_feature(&features, ARM_FEATURE_GENERIC_TIMER);

    switch (extract32(id_isar0, 24, 4)) {
    case 1:
        set_feature(&features, ARM_FEATURE_THUMB_DIV);
        break;
    case 2:
        set_feature(&features, ARM_FEATURE_ARM_DIV);
        set_feature(&features, ARM_FEATURE_THUMB_DIV);
        break;
    default:
        break;
    }

    if (extract32(id_pfr0, 12, 4) == 1) {
        set_feature(&features, ARM_FEATURE_THUMB2EE);
    }
    if (extract32(mvfr1, 20, 4) == 1) {
        set_feature(&features, ARM_FEATURE_VFP_FP16);
    }
    if (extract32(mvfr1, 12, 4) == 1) {
        set_feature(&features, ARM_FEATURE_NEON);
    }
    if (extract32(mvfr1, 28, 4) == 1) {
        /* FMAC support implies VFPv4 */
        set_feature(&features, ARM_FEATURE_VFP4);
    }

    ahcc->features = features;

    return true;
}

static bool reg_syncs_via_tuple_list(uint64_t regidx)
{
    /* Return true if the regidx is a register we should synchronize
     * via the cpreg_tuples array (ie is not a core reg we sync by
     * hand in kvm_arch_get/put_registers())
     */
    switch (regidx & KVM_REG_ARM_COPROC_MASK) {
    case KVM_REG_ARM_CORE:
    case KVM_REG_ARM_VFP:
        return false;
    default:
        return true;
    }
}

static int compare_u64(const void *a, const void *b)
{
    if (*(uint64_t *)a > *(uint64_t *)b) {
        return 1;
    }
    if (*(uint64_t *)a < *(uint64_t *)b) {
        return -1;
    }
    return 0;
}

int kvm_arch_init_vcpu(CPUState *cs)
{
    struct kvm_vcpu_init init;
    int i, ret, arraylen;
    uint64_t v;
    struct kvm_one_reg r;
    struct kvm_reg_list rl;
    struct kvm_reg_list *rlp;
    ARMCPU *cpu = ARM_CPU(cs);

    if (cpu->kvm_target == QEMU_KVM_ARM_TARGET_NONE) {
        fprintf(stderr, "KVM is not supported for this guest CPU type\n");
        return -EINVAL;
    }

    init.target = cpu->kvm_target;
    memset(init.features, 0, sizeof(init.features));
    if (cpu->start_powered_off) {
        init.features[0] = 1 << KVM_ARM_VCPU_POWER_OFF;
    }
    ret = kvm_vcpu_ioctl(cs, KVM_ARM_VCPU_INIT, &init);
    if (ret) {
        return ret;
    }
    /* Query the kernel to make sure it supports 32 VFP
     * registers: QEMU's "cortex-a15" CPU is always a
     * VFP-D32 core. The simplest way to do this is just
     * to attempt to read register d31.
     */
    r.id = KVM_REG_ARM | KVM_REG_SIZE_U64 | KVM_REG_ARM_VFP | 31;
    r.addr = (uintptr_t)(&v);
    ret = kvm_vcpu_ioctl(cs, KVM_GET_ONE_REG, &r);
    if (ret == -ENOENT) {
        return -EINVAL;
    }

    /* Populate the cpreg list based on the kernel's idea
     * of what registers exist (and throw away the TCG-created list).
     */
    rl.n = 0;
    ret = kvm_vcpu_ioctl(cs, KVM_GET_REG_LIST, &rl);
    if (ret != -E2BIG) {
        return ret;
    }
    rlp = g_malloc(sizeof(struct kvm_reg_list) + rl.n * sizeof(uint64_t));
    rlp->n = rl.n;
    ret = kvm_vcpu_ioctl(cs, KVM_GET_REG_LIST, rlp);
    if (ret) {
        goto out;
    }
    /* Sort the list we get back from the kernel, since cpreg_tuples
     * must be in strictly ascending order.
     */
    qsort(&rlp->reg, rlp->n, sizeof(rlp->reg[0]), compare_u64);

    for (i = 0, arraylen = 0; i < rlp->n; i++) {
        if (!reg_syncs_via_tuple_list(rlp->reg[i])) {
            continue;
        }
        switch (rlp->reg[i] & KVM_REG_SIZE_MASK) {
        case KVM_REG_SIZE_U32:
        case KVM_REG_SIZE_U64:
            break;
        default:
            fprintf(stderr, "Can't handle size of register in kernel list\n");
            ret = -EINVAL;
            goto out;
        }

        arraylen++;
    }

    cpu->cpreg_indexes = g_renew(uint64_t, cpu->cpreg_indexes, arraylen);
    cpu->cpreg_values = g_renew(uint64_t, cpu->cpreg_values, arraylen);
    cpu->cpreg_vmstate_indexes = g_renew(uint64_t, cpu->cpreg_vmstate_indexes,
                                         arraylen);
    cpu->cpreg_vmstate_values = g_renew(uint64_t, cpu->cpreg_vmstate_values,
                                        arraylen);
    cpu->cpreg_array_len = arraylen;
    cpu->cpreg_vmstate_array_len = arraylen;

    for (i = 0, arraylen = 0; i < rlp->n; i++) {
        uint64_t regidx = rlp->reg[i];
        if (!reg_syncs_via_tuple_list(regidx)) {
            continue;
        }
        cpu->cpreg_indexes[arraylen] = regidx;
        arraylen++;
    }
    assert(cpu->cpreg_array_len == arraylen);

    if (!write_kvmstate_to_list(cpu)) {
        /* Shouldn't happen unless kernel is inconsistent about
         * what registers exist.
         */
        fprintf(stderr, "Initial read of kernel register state failed\n");
        ret = -EINVAL;
        goto out;
    }

    /* Save a copy of the initial register values so that we can
     * feed it back to the kernel on VCPU reset.
     */
    cpu->cpreg_reset_values = g_memdup(cpu->cpreg_values,
                                       cpu->cpreg_array_len *
                                       sizeof(cpu->cpreg_values[0]));

out:
    g_free(rlp);
    return ret;
}

typedef struct Reg {
    uint64_t id;
    int offset;
} Reg;

#define COREREG(KERNELNAME, QEMUFIELD)                       \
    {                                                        \
        KVM_REG_ARM | KVM_REG_SIZE_U32 |                     \
        KVM_REG_ARM_CORE | KVM_REG_ARM_CORE_REG(KERNELNAME), \
        offsetof(CPUARMState, QEMUFIELD)                     \
    }

#define VFPSYSREG(R)                                       \
    {                                                      \
        KVM_REG_ARM | KVM_REG_SIZE_U32 | KVM_REG_ARM_VFP | \
        KVM_REG_ARM_VFP_##R,                               \
        offsetof(CPUARMState, vfp.xregs[ARM_VFP_##R])      \
    }

/* Like COREREG, but handle fields which are in a uint64_t in CPUARMState. */
#define COREREG64(KERNELNAME, QEMUFIELD)                     \
    {                                                        \
        KVM_REG_ARM | KVM_REG_SIZE_U32 |                     \
        KVM_REG_ARM_CORE | KVM_REG_ARM_CORE_REG(KERNELNAME), \
        offsetoflow32(CPUARMState, QEMUFIELD)                \
    }

static const Reg regs[] = {
    /* R0_usr .. R14_usr */
    COREREG(usr_regs.uregs[0], regs[0]),
    COREREG(usr_regs.uregs[1], regs[1]),
    COREREG(usr_regs.uregs[2], regs[2]),
    COREREG(usr_regs.uregs[3], regs[3]),
    COREREG(usr_regs.uregs[4], regs[4]),
    COREREG(usr_regs.uregs[5], regs[5]),
    COREREG(usr_regs.uregs[6], regs[6]),
    COREREG(usr_regs.uregs[7], regs[7]),
    COREREG(usr_regs.uregs[8], usr_regs[0]),
    COREREG(usr_regs.uregs[9], usr_regs[1]),
    COREREG(usr_regs.uregs[10], usr_regs[2]),
    COREREG(usr_regs.uregs[11], usr_regs[3]),
    COREREG(usr_regs.uregs[12], usr_regs[4]),
    COREREG(usr_regs.uregs[13], banked_r13[0]),
    COREREG(usr_regs.uregs[14], banked_r14[0]),
    /* R13, R14, SPSR for SVC, ABT, UND, IRQ banks */
    COREREG(svc_regs[0], banked_r13[1]),
    COREREG(svc_regs[1], banked_r14[1]),
    COREREG64(svc_regs[2], banked_spsr[1]),
    COREREG(abt_regs[0], banked_r13[2]),
    COREREG(abt_regs[1], banked_r14[2]),
    COREREG64(abt_regs[2], banked_spsr[2]),
    COREREG(und_regs[0], banked_r13[3]),
    COREREG(und_regs[1], banked_r14[3]),
    COREREG64(und_regs[2], banked_spsr[3]),
    COREREG(irq_regs[0], banked_r13[4]),
    COREREG(irq_regs[1], banked_r14[4]),
    COREREG64(irq_regs[2], banked_spsr[4]),
    /* R8_fiq .. R14_fiq and SPSR_fiq */
    COREREG(fiq_regs[0], fiq_regs[0]),
    COREREG(fiq_regs[1], fiq_regs[1]),
    COREREG(fiq_regs[2], fiq_regs[2]),
    COREREG(fiq_regs[3], fiq_regs[3]),
    COREREG(fiq_regs[4], fiq_regs[4]),
    COREREG(fiq_regs[5], banked_r13[5]),
    COREREG(fiq_regs[6], banked_r14[5]),
    COREREG64(fiq_regs[7], banked_spsr[5]),
    /* R15 */
    COREREG(usr_regs.uregs[15], regs[15]),
    /* VFP system registers */
    VFPSYSREG(FPSID),
    VFPSYSREG(MVFR1),
    VFPSYSREG(MVFR0),
    VFPSYSREG(FPEXC),
    VFPSYSREG(FPINST),
    VFPSYSREG(FPINST2),
};

int kvm_arch_put_registers(CPUState *cs, int level)
{
    ARMCPU *cpu = ARM_CPU(cs);
    CPUARMState *env = &cpu->env;
    struct kvm_one_reg r;
    int mode, bn;
    int ret, i;
    uint32_t cpsr, fpscr;

    /* Make sure the banked regs are properly set */
    mode = env->uncached_cpsr & CPSR_M;
    bn = bank_number(mode);
    if (mode == ARM_CPU_MODE_FIQ) {
        memcpy(env->fiq_regs, env->regs + 8, 5 * sizeof(uint32_t));
    } else {
        memcpy(env->usr_regs, env->regs + 8, 5 * sizeof(uint32_t));
    }
    env->banked_r13[bn] = env->regs[13];
    env->banked_r14[bn] = env->regs[14];
    env->banked_spsr[bn] = env->spsr;

    /* Now we can safely copy stuff down to the kernel */
    for (i = 0; i < ARRAY_SIZE(regs); i++) {
        r.id = regs[i].id;
        r.addr = (uintptr_t)(env) + regs[i].offset;
        ret = kvm_vcpu_ioctl(cs, KVM_SET_ONE_REG, &r);
        if (ret) {
            return ret;
        }
    }

    /* Special cases which aren't a single CPUARMState field */
    cpsr = cpsr_read(env);
    r.id = KVM_REG_ARM | KVM_REG_SIZE_U32 |
        KVM_REG_ARM_CORE | KVM_REG_ARM_CORE_REG(usr_regs.ARM_cpsr);
    r.addr = (uintptr_t)(&cpsr);
    ret = kvm_vcpu_ioctl(cs, KVM_SET_ONE_REG, &r);
    if (ret) {
        return ret;
    }

    /* VFP registers */
    r.id = KVM_REG_ARM | KVM_REG_SIZE_U64 | KVM_REG_ARM_VFP;
    for (i = 0; i < 32; i++) {
        r.addr = (uintptr_t)(&env->vfp.regs[i]);
        ret = kvm_vcpu_ioctl(cs, KVM_SET_ONE_REG, &r);
        if (ret) {
            return ret;
        }
        r.id++;
    }

    r.id = KVM_REG_ARM | KVM_REG_SIZE_U32 | KVM_REG_ARM_VFP |
        KVM_REG_ARM_VFP_FPSCR;
    fpscr = vfp_get_fpscr(env);
    r.addr = (uintptr_t)&fpscr;
    ret = kvm_vcpu_ioctl(cs, KVM_SET_ONE_REG, &r);
    if (ret) {
        return ret;
    }

    /* Note that we do not call write_cpustate_to_list()
     * here, so we are only writing the tuple list back to
     * KVM. This is safe because nothing can change the
     * CPUARMState cp15 fields (in particular gdb accesses cannot)
     * and so there are no changes to sync. In fact syncing would
     * be wrong at this point: for a constant register where TCG and
     * KVM disagree about its value, the preceding write_list_to_cpustate()
     * would not have had any effect on the CPUARMState value (since the
     * register is read-only), and a write_cpustate_to_list() here would
     * then try to write the TCG value back into KVM -- this would either
     * fail or incorrectly change the value the guest sees.
     *
     * If we ever want to allow the user to modify cp15 registers via
     * the gdb stub, we would need to be more clever here (for instance
     * tracking the set of registers kvm_arch_get_registers() successfully
     * managed to update the CPUARMState with, and only allowing those
     * to be written back up into the kernel).
     */
    if (!write_list_to_kvmstate(cpu)) {
        return EINVAL;
    }

    return ret;
}

int kvm_arch_get_registers(CPUState *cs)
{
    ARMCPU *cpu = ARM_CPU(cs);
    CPUARMState *env = &cpu->env;
    struct kvm_one_reg r;
    int mode, bn;
    int ret, i;
    uint32_t cpsr, fpscr;

    for (i = 0; i < ARRAY_SIZE(regs); i++) {
        r.id = regs[i].id;
        r.addr = (uintptr_t)(env) + regs[i].offset;
        ret = kvm_vcpu_ioctl(cs, KVM_GET_ONE_REG, &r);
        if (ret) {
            return ret;
        }
    }

    /* Special cases which aren't a single CPUARMState field */
    r.id = KVM_REG_ARM | KVM_REG_SIZE_U32 |
        KVM_REG_ARM_CORE | KVM_REG_ARM_CORE_REG(usr_regs.ARM_cpsr);
    r.addr = (uintptr_t)(&cpsr);
    ret = kvm_vcpu_ioctl(cs, KVM_GET_ONE_REG, &r);
    if (ret) {
        return ret;
    }
    cpsr_write(env, cpsr, 0xffffffff);

    /* Make sure the current mode regs are properly set */
    mode = env->uncached_cpsr & CPSR_M;
    bn = bank_number(mode);
    if (mode == ARM_CPU_MODE_FIQ) {
        memcpy(env->regs + 8, env->fiq_regs, 5 * sizeof(uint32_t));
    } else {
        memcpy(env->regs + 8, env->usr_regs, 5 * sizeof(uint32_t));
    }
    env->regs[13] = env->banked_r13[bn];
    env->regs[14] = env->banked_r14[bn];
    env->spsr = env->banked_spsr[bn];

    /* VFP registers */
    r.id = KVM_REG_ARM | KVM_REG_SIZE_U64 | KVM_REG_ARM_VFP;
    for (i = 0; i < 32; i++) {
        r.addr = (uintptr_t)(&env->vfp.regs[i]);
        ret = kvm_vcpu_ioctl(cs, KVM_GET_ONE_REG, &r);
        if (ret) {
            return ret;
        }
        r.id++;
    }

    r.id = KVM_REG_ARM | KVM_REG_SIZE_U32 | KVM_REG_ARM_VFP |
        KVM_REG_ARM_VFP_FPSCR;
    r.addr = (uintptr_t)&fpscr;
    ret = kvm_vcpu_ioctl(cs, KVM_GET_ONE_REG, &r);
    if (ret) {
        return ret;
    }
    vfp_set_fpscr(env, fpscr);

    if (!write_kvmstate_to_list(cpu)) {
        return EINVAL;
    }
    /* Note that it's OK to have registers which aren't in CPUState,
     * so we can ignore a failure return here.
     */
    write_list_to_cpustate(cpu);

    return 0;
}

void kvm_arm_reset_vcpu(ARMCPU *cpu)
{
    /* Feed the kernel back its initial register state */
    memmove(cpu->cpreg_values, cpu->cpreg_reset_values,
            cpu->cpreg_array_len * sizeof(cpu->cpreg_values[0]));

    if (!write_list_to_kvmstate(cpu)) {
        abort();
    }
}