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arm64 requires a vcpu fd (KVM_HAS_DEVICE_ATTR vcpu ioctl) to probe support for steal-time. However this is unnecessary, as only a KVM fd is required, and it complicates userspace (userspace may prefer delaying vcpu creation until after feature probing). Introduce a cap that can be checked instead. While x86 can already probe steal-time support with a kvm fd (KVM_GET_SUPPORTED_CPUID), we add the cap there too for consistency. Signed-off-by: Andrew Jones <drjones@redhat.com> Signed-off-by: Marc Zyngier <maz@kernel.org> Reviewed-by: Steven Price <steven.price@arm.com> Link: https://lore.kernel.org/r/20200804170604.42662-7-drjones@redhat.com
138 lines
3.0 KiB
C
138 lines
3.0 KiB
C
// SPDX-License-Identifier: GPL-2.0
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// Copyright (C) 2019 Arm Ltd.
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#include <linux/arm-smccc.h>
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#include <linux/kvm_host.h>
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#include <linux/sched/stat.h>
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#include <asm/kvm_mmu.h>
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#include <asm/pvclock-abi.h>
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#include <kvm/arm_hypercalls.h>
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void kvm_update_stolen_time(struct kvm_vcpu *vcpu)
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{
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struct kvm *kvm = vcpu->kvm;
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u64 base = vcpu->arch.steal.base;
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u64 last_steal = vcpu->arch.steal.last_steal;
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u64 offset = offsetof(struct pvclock_vcpu_stolen_time, stolen_time);
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u64 steal = 0;
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int idx;
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if (base == GPA_INVALID)
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return;
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idx = srcu_read_lock(&kvm->srcu);
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if (!kvm_get_guest(kvm, base + offset, steal)) {
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steal = le64_to_cpu(steal);
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vcpu->arch.steal.last_steal = READ_ONCE(current->sched_info.run_delay);
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steal += vcpu->arch.steal.last_steal - last_steal;
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kvm_put_guest(kvm, base + offset, cpu_to_le64(steal));
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}
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srcu_read_unlock(&kvm->srcu, idx);
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}
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long kvm_hypercall_pv_features(struct kvm_vcpu *vcpu)
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{
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u32 feature = smccc_get_arg1(vcpu);
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long val = SMCCC_RET_NOT_SUPPORTED;
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switch (feature) {
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case ARM_SMCCC_HV_PV_TIME_FEATURES:
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case ARM_SMCCC_HV_PV_TIME_ST:
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if (vcpu->arch.steal.base != GPA_INVALID)
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val = SMCCC_RET_SUCCESS;
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break;
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}
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return val;
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}
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gpa_t kvm_init_stolen_time(struct kvm_vcpu *vcpu)
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{
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struct pvclock_vcpu_stolen_time init_values = {};
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struct kvm *kvm = vcpu->kvm;
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u64 base = vcpu->arch.steal.base;
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int idx;
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if (base == GPA_INVALID)
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return base;
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/*
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* Start counting stolen time from the time the guest requests
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* the feature enabled.
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*/
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vcpu->arch.steal.last_steal = current->sched_info.run_delay;
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idx = srcu_read_lock(&kvm->srcu);
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kvm_write_guest(kvm, base, &init_values, sizeof(init_values));
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srcu_read_unlock(&kvm->srcu, idx);
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return base;
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}
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bool kvm_arm_pvtime_supported(void)
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{
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return !!sched_info_on();
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}
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int kvm_arm_pvtime_set_attr(struct kvm_vcpu *vcpu,
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struct kvm_device_attr *attr)
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{
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u64 __user *user = (u64 __user *)attr->addr;
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struct kvm *kvm = vcpu->kvm;
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u64 ipa;
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int ret = 0;
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int idx;
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if (!kvm_arm_pvtime_supported() ||
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attr->attr != KVM_ARM_VCPU_PVTIME_IPA)
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return -ENXIO;
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if (get_user(ipa, user))
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return -EFAULT;
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if (!IS_ALIGNED(ipa, 64))
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return -EINVAL;
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if (vcpu->arch.steal.base != GPA_INVALID)
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return -EEXIST;
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/* Check the address is in a valid memslot */
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idx = srcu_read_lock(&kvm->srcu);
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if (kvm_is_error_hva(gfn_to_hva(kvm, ipa >> PAGE_SHIFT)))
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ret = -EINVAL;
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srcu_read_unlock(&kvm->srcu, idx);
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if (!ret)
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vcpu->arch.steal.base = ipa;
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return ret;
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}
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int kvm_arm_pvtime_get_attr(struct kvm_vcpu *vcpu,
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struct kvm_device_attr *attr)
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{
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u64 __user *user = (u64 __user *)attr->addr;
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u64 ipa;
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if (!kvm_arm_pvtime_supported() ||
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attr->attr != KVM_ARM_VCPU_PVTIME_IPA)
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return -ENXIO;
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ipa = vcpu->arch.steal.base;
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if (put_user(ipa, user))
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return -EFAULT;
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return 0;
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}
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int kvm_arm_pvtime_has_attr(struct kvm_vcpu *vcpu,
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struct kvm_device_attr *attr)
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{
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switch (attr->attr) {
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case KVM_ARM_VCPU_PVTIME_IPA:
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if (kvm_arm_pvtime_supported())
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return 0;
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}
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return -ENXIO;
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}
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