This patch implements two new vm-ioctls to get and set the
virtual_tsc_khz if the machine supports tsc-scaling. Setting
the tsc-frequency is only possible before userspace creates
any vcpu.
Signed-off-by: Joerg Roedel <joerg.roedel@xxxxxxx>
---
Documentation/kvm/api.txt | 23 +++++++++++++++++++++++
arch/x86/include/asm/kvm_host.h | 7 +++++++
arch/x86/kvm/svm.c | 20 ++++++++++++++++++++
arch/x86/kvm/x86.c | 35 +++++++++++++++++++++++++++++++++++
include/linux/kvm.h | 5 +++++
5 files changed, 90 insertions(+), 0 deletions(-)
diff --git a/Documentation/kvm/api.txt b/Documentation/kvm/api.txt
index 9bef4e4..1b9eaa7 100644
--- a/Documentation/kvm/api.txt
+++ b/Documentation/kvm/api.txt
@@ -1263,6 +1263,29 @@ struct kvm_assigned_msix_entry {
__u16 padding[3];
};
+4.54 KVM_SET_TSC_KHZ
+
+Capability: KVM_CAP_TSC_CONTROL
+Architectures: x86
+Type: vcpu 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.
+
+4.55 KVM_GET_TSC_KHZ
+
+Capability: KVM_CAP_GET_TSC_KHZ
+Architectures: x86
+Type: vcpu ioctl
+Parameters: none
+Returns: virtual tsc-khz on success, negative value on error
+
+Returns the tsc frequency of the guest. The unit of the return value is
+KHz. If the host has unstable tsc this ioctl returns -EIO instead as an
+error.
+
5. The kvm_run structure
Application code obtains a pointer to the kvm_run structure by
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 7f48528..473a3be 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -632,6 +632,13 @@ u8 kvm_get_guest_memory_type(struct kvm_vcpu *vcpu, gfn_t gfn);
extern bool tdp_enabled;
+/* control of guest tsc rate supported? */
+extern bool kvm_has_tsc_control;
+/* minimum supported tsc_khz for guests */
+extern u32 kvm_min_guest_tsc_khz;
+/* maximum supported tsc_khz for guests */
+extern u32 kvm_max_guest_tsc_khz;
+
enum emulation_result {
EMULATE_DONE, /* no further processing */
EMULATE_DO_MMIO, /* kvm_run filled with mmio request */
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 38a4bcc..a5c1b5b 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -64,6 +64,8 @@ MODULE_LICENSE("GPL");
#define DEBUGCTL_RESERVED_BITS (~(0x3fULL))
#define TSC_RATIO_RSVD 0xffffff0000000000ULL
+#define TSC_RATIO_MIN 0x0000000000000001ULL
+#define TSC_RATIO_MAX 0x000000ffffffffffULL
static bool erratum_383_found __read_mostly;
@@ -197,6 +199,7 @@ static int nested_svm_intercept(struct vcpu_svm *svm);
static int nested_svm_vmexit(struct vcpu_svm *svm);
static int nested_svm_check_exception(struct vcpu_svm *svm, unsigned nr,
bool has_error_code, u32 error_code);
+static u64 __scale_tsc(u64 ratio, u64 tsc);
enum {
VMCB_INTERCEPTS, /* Intercept vectors, TSC offset,
@@ -807,6 +810,23 @@ static __init int svm_hardware_setup(void)
if (boot_cpu_has(X86_FEATURE_FXSR_OPT))
kvm_enable_efer_bits(EFER_FFXSR);
+ if (boot_cpu_has(X86_FEATURE_TSCRATEMSR)) {
+ u64 max;
+
+ kvm_has_tsc_control = true;
+
+ /*
+ * Make sure the user can only configure tsc_khz values that
+ * fit into a signed integer.
+ * A min value is not calculated needed because it will always
+ * be 1 on all machines and a value of 0 is used to disable
+ * tsc-scaling for the vcpu.
+ */
+ max = min(0x7fffffffULL, __scale_tsc(tsc_khz, TSC_RATIO_MAX));
+
+ kvm_max_guest_tsc_khz = max;
+ }
+
if (nested) {
printk(KERN_INFO "kvm: Nested Virtualization enabled\n");
kvm_enable_efer_bits(EFER_SVME | EFER_LMSLE);
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 2f0b552..5cc9a44 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -100,6 +100,11 @@ EXPORT_SYMBOL_GPL(kvm_x86_ops);
int ignore_msrs = 0;
module_param_named(ignore_msrs, ignore_msrs, bool, S_IRUGO | S_IWUSR);
+bool kvm_has_tsc_control;
+EXPORT_SYMBOL_GPL(kvm_has_tsc_control);
+u32 kvm_max_guest_tsc_khz;
+EXPORT_SYMBOL_GPL(kvm_max_guest_tsc_khz);
+
#define KVM_NR_SHARED_MSRS 16
struct kvm_shared_msrs_global {
@@ -1999,6 +2004,7 @@ int kvm_dev_ioctl_check_extension(long ext)
case KVM_CAP_X86_ROBUST_SINGLESTEP:
case KVM_CAP_XSAVE:
case KVM_CAP_ASYNC_PF:
+ case KVM_CAP_GET_TSC_KHZ:
r = 1;
break;
case KVM_CAP_COALESCED_MMIO:
@@ -2025,6 +2031,9 @@ int kvm_dev_ioctl_check_extension(long ext)
case KVM_CAP_XCRS:
r = cpu_has_xsave;
break;
+ case KVM_CAP_TSC_CONTROL:
+ r = kvm_has_tsc_control;
+ break;
default:
r = 0;
break;
@@ -3057,6 +3066,32 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
r = kvm_vcpu_ioctl_x86_set_xcrs(vcpu, u.xcrs);
break;
}
+ case KVM_SET_TSC_KHZ: {
+ u32 user_tsc_khz;
+
+ r = -EINVAL;
+ if (!kvm_has_tsc_control)
+ break;
+
+ user_tsc_khz = (u32)arg;
+
+ if (user_tsc_khz >= kvm_max_guest_tsc_khz)
+ goto out;
+
+ kvm_x86_ops->set_tsc_khz(vcpu, user_tsc_khz);
+
+ r = 0;
+ goto out;
+ }
+ case KVM_GET_TSC_KHZ: {
+ r = -EIO;
+ if (check_tsc_unstable())
+ goto out;
+
+ r = vcpu_tsc_khz(vcpu);
+
+ goto out;
+ }
default:
r = -EINVAL;
}
diff --git a/include/linux/kvm.h b/include/linux/kvm.h
index ea2dc1a..2f63ebe 100644
--- a/include/linux/kvm.h
+++ b/include/linux/kvm.h
@@ -541,6 +541,8 @@ struct kvm_ppc_pvinfo {
#define KVM_CAP_PPC_GET_PVINFO 57
#define KVM_CAP_PPC_IRQ_LEVEL 58
#define KVM_CAP_ASYNC_PF 59
+#define KVM_CAP_TSC_CONTROL 60
+#define KVM_CAP_GET_TSC_KHZ 61
#ifdef KVM_CAP_IRQ_ROUTING
@@ -677,6 +679,9 @@ struct kvm_clock_data {
#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 */
+#define KVM_SET_TSC_KHZ _IO(KVMIO, 0xa2)
+#define KVM_GET_TSC_KHZ _IO(KVMIO, 0xa3)
/*
* ioctls for vcpu fds
--
1.7.1
--
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