From: David Woodhouse <dwmw@xxxxxxxxxxxx>
This sets the default TSC frequency for subsequently created vCPUs.
Signed-off-by: David Woodhouse <dwmw@xxxxxxxxxxxx>
---
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 046b386f6ce3..982fcdf8cfa8 100644
--- a/Documentation/virt/kvm/api.rst
+++ b/Documentation/virt/kvm/api.rst
@@ -1903,22 +1903,25 @@ 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 a3385db39d3e..e4696a578f41 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1119,6 +1119,8 @@ 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 83accd3e7502..bb3e9916229a 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4308,6 +4308,7 @@ 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:
@@ -6483,6 +6484,28 @@ 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)
@@ -11165,7 +11188,7 @@ 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);
@@ -11614,6 +11637,7 @@ 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;
#if IS_ENABLED(CONFIG_HYPERV)
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 22a1aa98fa9e..01ae8b0e90f8 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1134,6 +1134,7 @@ struct kvm_ppc_resize_hpt {
#define KVM_CAP_VM_GPA_BITS 207
#define KVM_CAP_XSAVE2 208
#define KVM_CAP_SYS_ATTRIBUTES 209
+#define KVM_CAP_VM_TSC_CONTROL 210
#ifdef KVM_CAP_IRQ_ROUTING
@@ -1461,7 +1462,8 @@ 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 */
--
2.33.1
