[6/6] KVM: X86: Implement userspace interface to set virtual_tsc_khz

Commit Message

Joerg Roedel March 15, 2011, 9:36 a.m. UTC

None

Patch

diff --git a/Documentation/kvm/api.txt b/Documentation/kvm/api.txt
index ad85797..adc9c23 100644
--- a/Documentation/kvm/api.txt
+++ b/Documentation/kvm/api.txt
@@ -1263,6 +1263,28 @@  struct kvm_assigned_msix_entry {
 	__u16 padding[3];
 };
 
+4.54 KVM_SET_TSC_KHZ
+
+Capability: KVM_CAP_TSC_CONTROL
+Architectures: x86
+Type: vm ioctl
+Parameters: __u32 (in)
+Returns: 0 on success, -1 on error
+
+Specifies the tsc frequency for the virtual machine. This IOCTL must be
+used before any vcpu is created. The unit of the frequency is KHz.
+
+4.55 KVM_GET_TSC_KHZ
+
+Capability: KVM_CAP_GET_TSC_KHZ
+Architectures: x86
+Type: vm ioctl
+Parameters: __u32 (out)
+Returns: 0 on success, -1 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 return 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 16db838..2471fc9 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -630,6 +630,13 @@  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 b8c6d28..ed7d608 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;
 
@@ -198,6 +200,7 @@  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,
@@ -799,6 +802,18 @@  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 min, max;
+
+		kvm_has_tsc_control = true;
+
+		min = max(1ULL,          __scale_tsc(tsc_khz, TSC_RATIO_MIN));
+		max = min(0xffffffffULL, __scale_tsc(tsc_khz, TSC_RATIO_MAX));
+
+		kvm_min_guest_tsc_khz = min;
+		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 aecd926..de313f1 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -100,6 +100,13 @@  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;
+u32  kvm_min_guest_tsc_khz;
+u32  kvm_max_guest_tsc_khz;
+EXPORT_SYMBOL_GPL(kvm_has_tsc_control);
+EXPORT_SYMBOL_GPL(kvm_min_guest_tsc_khz);
+EXPORT_SYMBOL_GPL(kvm_max_guest_tsc_khz);
+
 #define KVM_NR_SHARED_MSRS 16
 
 struct kvm_shared_msrs_global {
@@ -2000,6 +2007,7 @@  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:
@@ -2026,6 +2034,9 @@  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;
@@ -3580,6 +3591,51 @@  long kvm_arch_vm_ioctl(struct file *filp,
 		r = 0;
 		break;
 	}
+	case KVM_SET_TSC_KHZ: {
+		u32 user_tsc_khz;
+
+		if (!kvm_has_tsc_control)
+			break;
+
+		r = -EFAULT;
+		if (copy_from_user(&user_tsc_khz, argp, sizeof(__u32)))
+			goto out;
+
+		r = -EINVAL;
+		if (user_tsc_khz < kvm_min_guest_tsc_khz ||
+		    user_tsc_khz > kvm_max_guest_tsc_khz)
+			goto out;
+
+		mutex_lock(&kvm->lock);
+		/*
+		 * We force the tsc frequency to be set before any
+		 * vcpu is created
+		 */
+		if (atomic_read(&kvm->online_vcpus) > 0) {
+			mutex_unlock(&kvm->lock);
+			goto out;
+		}
+
+		kvm_arch_set_tsc_khz(kvm, user_tsc_khz);
+
+		mutex_unlock(&kvm->lock);
+
+		r = 0;
+		goto out;
+	}
+	case KVM_GET_TSC_KHZ: {
+
+		r = -EIO;
+		if (check_tsc_unstable())
+			goto out;
+
+		r = -EFAULT;
+		if (copy_to_user(argp, &kvm->arch.virtual_tsc_khz, sizeof(__u32)))
+			goto out;
+
+		r = 0;
+		goto out;
+	}
 
 	default:
 		;
diff --git a/include/linux/kvm.h b/include/linux/kvm.h
index ea2dc1a..ea16c57 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           _IOW(KVMIO,  0xa2, __u32)
+#define KVM_GET_TSC_KHZ           _IOR(KVMIO,  0xa2, __u32)
 
 /*
  * ioctls for vcpu fds