pvtime.c

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// SPDX-License-Identifier: GPL-2.0
// Copyright (C) 2019 Arm Ltd.
 
#include <linux/arm-smccc.h>
#include <linux/kvm_host.h>
#include <linux/sched/stat.h>
 
#include <asm/kvm_mmu.h>
#include <asm/pvclock-abi.h>
 
#include <kvm/arm_hypercalls.h>
 
void kvm_update_stolen_time(struct kvm_vcpu *vcpu)
{
    struct kvm *kvm = vcpu->kvm;
    u64 base = vcpu->arch.steal.base;
    u64 last_steal = vcpu->arch.steal.last_steal;
    u64 offset = offsetof(struct pvclock_vcpu_stolen_time, stolen_time);
    u64 steal = 0;
    int idx;
 
    if (base == INVALID_GPA)
        return;
 
    idx = srcu_read_lock(&kvm->srcu);
    if (!kvm_get_guest(kvm, base + offset, steal)) {
        steal = le64_to_cpu(steal);
        vcpu->arch.steal.last_steal = READ_ONCE(current->sched_info.run_delay);
        steal += vcpu->arch.steal.last_steal - last_steal;
        kvm_put_guest(kvm, base + offset, cpu_to_le64(steal));
    }
    srcu_read_unlock(&kvm->srcu, idx);
}
 
long kvm_hypercall_pv_features(struct kvm_vcpu *vcpu)
{
    u32 feature = smccc_get_arg1(vcpu);
    long val = SMCCC_RET_NOT_SUPPORTED;
 
    switch (feature) {
    case ARM_SMCCC_HV_PV_TIME_FEATURES:
    case ARM_SMCCC_HV_PV_TIME_ST:
        if (vcpu->arch.steal.base != INVALID_GPA)
            val = SMCCC_RET_SUCCESS;
        break;
    }
 
    return val;
}
 
gpa_t kvm_init_stolen_time(struct kvm_vcpu *vcpu)
{
    struct pvclock_vcpu_stolen_time init_values = {};
    struct kvm *kvm = vcpu->kvm;
    u64 base = vcpu->arch.steal.base;
 
    if (base == INVALID_GPA)
        return base;
 
    /*
     * Start counting stolen time from the time the guest requests
     * the feature enabled.
     */
    vcpu->arch.steal.last_steal = current->sched_info.run_delay;
    kvm_write_guest_lock(kvm, base, &init_values, sizeof(init_values));
 
    return base;
}
 
bool kvm_arm_pvtime_supported(void)
{
    return !!sched_info_on();
}
 
int kvm_arm_pvtime_set_attr(struct kvm_vcpu *vcpu,
                struct kvm_device_attr *attr)
{
    u64 __user *user = (u64 __user *)attr->addr;
    struct kvm *kvm = vcpu->kvm;
    u64 ipa;
    int ret = 0;
    int idx;
 
    if (!kvm_arm_pvtime_supported() ||
        attr->attr != KVM_ARM_VCPU_PVTIME_IPA)
        return -ENXIO;
 
    if (get_user(ipa, user))
        return -EFAULT;
    if (!IS_ALIGNED(ipa, 64))
        return -EINVAL;
    if (vcpu->arch.steal.base != INVALID_GPA)
        return -EEXIST;
 
    /* Check the address is in a valid memslot */
    idx = srcu_read_lock(&kvm->srcu);
    if (kvm_is_error_hva(gfn_to_hva(kvm, ipa >> PAGE_SHIFT)))
        ret = -EINVAL;
    srcu_read_unlock(&kvm->srcu, idx);
 
    if (!ret)
        vcpu->arch.steal.base = ipa;
 
    return ret;
}
 
int kvm_arm_pvtime_get_attr(struct kvm_vcpu *vcpu,
                struct kvm_device_attr *attr)
{
    u64 __user *user = (u64 __user *)attr->addr;
    u64 ipa;
 
    if (!kvm_arm_pvtime_supported() ||
        attr->attr != KVM_ARM_VCPU_PVTIME_IPA)
        return -ENXIO;
 
    ipa = vcpu->arch.steal.base;
 
    if (put_user(ipa, user))
        return -EFAULT;
    return 0;
}
 
int kvm_arm_pvtime_has_attr(struct kvm_vcpu *vcpu,
                struct kvm_device_attr *attr)
{
    switch (attr->attr) {
    case KVM_ARM_VCPU_PVTIME_IPA:
        if (kvm_arm_pvtime_supported())
            return 0;
    }
    return -ENXIO;
}