From ffbb61d09fc56c85e28b110494f3788d0ed4d1f8 Mon Sep 17 00:00:00 2001 From: David Woodhouse Date: Fri, 25 Feb 2022 14:53:02 +0000 Subject: [PATCH] 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: David Woodhouse Message-Id: <20220225145304.36166-2-dwmw2@infradead.org> Signed-off-by: Paolo Bonzini --- Documentation/virt/kvm/api.rst | 11 +++++++---- arch/x86/include/asm/kvm_host.h | 2 ++ arch/x86/kvm/x86.c | 26 +++++++++++++++++++++++++- include/uapi/linux/kvm.h | 4 +++- 4 files changed, 37 insertions(+), 6 deletions(-) diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst index fdfd9e1bc7f7..b102ba7cf903 100644 --- a/Documentation/virt/kvm/api.rst +++ b/Documentation/virt/kvm/api.rst @@ -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 diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 5370744b789c..fac990cc189d 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -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; diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 1a7d1b5f7232..c069b97a8523 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -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; diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h index ee5cc9e2a837..8616af85dc5d 100644 --- a/include/uapi/linux/kvm.h +++ b/include/uapi/linux/kvm.h @@ -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 */