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KVM: x86: Accept KVM_[GS]ET_TSC_KHZ as a VM ioctl.

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This sets the default TSC frequency for subsequently created vCPUs.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Message-Id: <20220225145304.36166-2-dwmw2@infradead.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
David Woodhouse 2022-02-25 14:53:02 +00:00 committed by Paolo Bonzini
parent fe3787a0d1
commit ffbb61d09f
4 changed files with 37 additions and 6 deletions
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11
Documentation/virt/kvm/api.rst
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@ -1897,22 +1897,25 @@ the future.
4.55 KVM_SET_TSC_KHZ
--------------------
:Capability: KVM_CAP_TSC_CONTROL
:Capability: KVM_CAP_TSC_CONTROL / KVM_CAP_VM_TSC_CONTROL
:Architectures: x86
:Type: vcpu ioctl
:Type: vcpu ioctl / vm ioctl
:Parameters: virtual tsc_khz
:Returns: 0 on success, -1 on error
Specifies the tsc frequency for the virtual machine. The unit of the
frequency is KHz.
If the KVM_CAP_VM_TSC_CONTROL capability is advertised, this can also
be used as a vm ioctl to set the initial tsc frequency of subsequently
created vCPUs.
4.56 KVM_GET_TSC_KHZ
--------------------
:Capability: KVM_CAP_GET_TSC_KHZ
:Capability: KVM_CAP_GET_TSC_KHZ / KVM_CAP_VM_TSC_CONTROL
:Architectures: x86
:Type: vcpu ioctl
:Type: vcpu ioctl / vm ioctl
:Parameters: none
:Returns: virtual tsc-khz on success, negative value on error

2
arch/x86/include/asm/kvm_host.h
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@ -1126,6 +1126,8 @@ struct kvm_arch {
u64 cur_tsc_generation;
int nr_vcpus_matched_tsc;
u32 default_tsc_khz;
seqcount_raw_spinlock_t pvclock_sc;
bool use_master_clock;
u64 master_kernel_ns;

26
arch/x86/kvm/x86.c
View File

@ -4324,6 +4324,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
r = boot_cpu_has(X86_FEATURE_XSAVE);
break;
case KVM_CAP_TSC_CONTROL:
case KVM_CAP_VM_TSC_CONTROL:
r = kvm_has_tsc_control;
break;
case KVM_CAP_X2APIC_API:
@ -6522,6 +6523,28 @@ set_pit2_out:
case KVM_GET_CLOCK:
r = kvm_vm_ioctl_get_clock(kvm, argp);
break;
case KVM_SET_TSC_KHZ: {
u32 user_tsc_khz;
r = -EINVAL;
user_tsc_khz = (u32)arg;
if (kvm_has_tsc_control &&
user_tsc_khz >= kvm_max_guest_tsc_khz)
goto out;
if (user_tsc_khz == 0)
user_tsc_khz = tsc_khz;
WRITE_ONCE(kvm->arch.default_tsc_khz, user_tsc_khz);
r = 0;
goto out;
}
case KVM_GET_TSC_KHZ: {
r = READ_ONCE(kvm->arch.default_tsc_khz);
goto out;
}
case KVM_MEMORY_ENCRYPT_OP: {
r = -ENOTTY;
if (!kvm_x86_ops.mem_enc_ioctl)
@ -11266,7 +11289,7 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
kvm_xen_init_vcpu(vcpu);
kvm_vcpu_mtrr_init(vcpu);
vcpu_load(vcpu);
kvm_set_tsc_khz(vcpu, max_tsc_khz);
kvm_set_tsc_khz(vcpu, vcpu->kvm->arch.default_tsc_khz);
kvm_vcpu_reset(vcpu, false);
kvm_init_mmu(vcpu);
vcpu_put(vcpu);
@ -11714,6 +11737,7 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
pvclock_update_vm_gtod_copy(kvm);
raw_spin_unlock_irqrestore(&kvm->arch.tsc_write_lock, flags);
kvm->arch.default_tsc_khz = max_tsc_khz;
kvm->arch.guest_can_read_msr_platform_info = true;
kvm->arch.enable_pmu = enable_pmu;

4
include/uapi/linux/kvm.h
View File

@ -1144,6 +1144,7 @@ struct kvm_ppc_resize_hpt {
#define KVM_CAP_S390_MEM_OP_EXTENSION 211
#define KVM_CAP_PMU_CAPABILITY 212
#define KVM_CAP_DISABLE_QUIRKS2 213
#define KVM_CAP_VM_TSC_CONTROL 214
#ifdef KVM_CAP_IRQ_ROUTING
@ -1471,7 +1472,8 @@ struct kvm_s390_ucas_mapping {
#define KVM_SET_PIT2 _IOW(KVMIO, 0xa0, struct kvm_pit_state2)
/* Available with KVM_CAP_PPC_GET_PVINFO */
#define KVM_PPC_GET_PVINFO _IOW(KVMIO, 0xa1, struct kvm_ppc_pvinfo)
/* Available with KVM_CAP_TSC_CONTROL */
/* Available with KVM_CAP_TSC_CONTROL for a vCPU, or with
* KVM_CAP_VM_TSC_CONTROL to set defaults for a VM */
#define KVM_SET_TSC_KHZ _IO(KVMIO, 0xa2)
#define KVM_GET_TSC_KHZ _IO(KVMIO, 0xa3)
/* Available with KVM_CAP_PCI_2_3 */