Commit ffbb61d0 authored by David Woodhouse's avatar David Woodhouse Committed by Paolo Bonzini
Browse files

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



This sets the default TSC frequency for subsequently created vCPUs.

Signed-off-by: default avatarDavid Woodhouse <dwmw@amazon.co.uk>
Message-Id: <20220225145304.36166-2-dwmw2@infradead.org>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent fe3787a0

Documentation/virt/kvm/api.rst

+7 −4
Original line number Diff line number Diff line
@@ -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

arch/x86/include/asm/kvm_host.h

+2 −0
Original line number Diff line number Diff line
@@ -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;

arch/x86/kvm/x86.c

+25 −1
Original line number Diff line number Diff line
@@ -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 @@ long kvm_arch_vm_ioctl(struct file *filp, 
	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;

include/uapi/linux/kvm.h

+3 −1
Original line number Diff line number Diff line
@@ -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 */