EXPORT_SYMBOL_GPL(kvm_tsc_scaling_ratio_frac_bits);
u64 __read_mostly kvm_max_tsc_scaling_ratio;
EXPORT_SYMBOL_GPL(kvm_max_tsc_scaling_ratio);
+static u64 __read_mostly kvm_default_tsc_scaling_ratio;
/* tsc tolerance in parts per million - default to 1/2 of the NTP threshold */
static u32 __read_mostly tsc_tolerance_ppm = 250;
return v;
}
-static void kvm_set_tsc_khz(struct kvm_vcpu *vcpu, u32 this_tsc_khz)
+static int set_tsc_khz(struct kvm_vcpu *vcpu, u32 user_tsc_khz, bool scale)
+{
+ u64 ratio;
+
+ /* Guest TSC same frequency as host TSC? */
+ if (!scale) {
+ vcpu->arch.tsc_scaling_ratio = kvm_default_tsc_scaling_ratio;
+ return 0;
+ }
+
+ /* TSC scaling supported? */
+ if (!kvm_has_tsc_control) {
+ if (user_tsc_khz > tsc_khz) {
+ vcpu->arch.tsc_catchup = 1;
+ vcpu->arch.tsc_always_catchup = 1;
+ return 0;
+ } else {
+ WARN(1, "user requested TSC rate below hardware speed\n");
+ return -1;
+ }
+ }
+
+ /* TSC scaling required - calculate ratio */
+ ratio = mul_u64_u32_div(1ULL << kvm_tsc_scaling_ratio_frac_bits,
+ user_tsc_khz, tsc_khz);
+
+ if (ratio == 0 || ratio >= kvm_max_tsc_scaling_ratio) {
+ WARN_ONCE(1, "Invalid TSC scaling ratio - virtual-tsc-khz=%u\n",
+ user_tsc_khz);
+ return -1;
+ }
+
+ vcpu->arch.tsc_scaling_ratio = ratio;
+ return 0;
+}
+
+static int kvm_set_tsc_khz(struct kvm_vcpu *vcpu, u32 this_tsc_khz)
{
u32 thresh_lo, thresh_hi;
int use_scaling = 0;
/* tsc_khz can be zero if TSC calibration fails */
- if (this_tsc_khz == 0)
- return;
+ if (this_tsc_khz == 0) {
+ /* set tsc_scaling_ratio to a safe value */
+ vcpu->arch.tsc_scaling_ratio = kvm_default_tsc_scaling_ratio;
+ return -1;
+ }
/* Compute a scale to convert nanoseconds in TSC cycles */
kvm_get_time_scale(this_tsc_khz, NSEC_PER_SEC / 1000,
pr_debug("kvm: requested TSC rate %u falls outside tolerance [%u,%u]\n", this_tsc_khz, thresh_lo, thresh_hi);
use_scaling = 1;
}
- kvm_x86_ops->set_tsc_khz(vcpu, this_tsc_khz, use_scaling);
+ return set_tsc_khz(vcpu, this_tsc_khz, use_scaling);
}
static u64 compute_guest_tsc(struct kvm_vcpu *vcpu, s64 kernel_ns)
vcpu->arch.ia32_tsc_adjust_msr += offset - curr_offset;
}
+/*
+ * Multiply tsc by a fixed point number represented by ratio.
+ *
+ * The most significant 64-N bits (mult) of ratio represent the
+ * integral part of the fixed point number; the remaining N bits
+ * (frac) represent the fractional part, ie. ratio represents a fixed
+ * point number (mult + frac * 2^(-N)).
+ *
+ * N equals to kvm_tsc_scaling_ratio_frac_bits.
+ */
+static inline u64 __scale_tsc(u64 ratio, u64 tsc)
+{
+ return mul_u64_u64_shr(tsc, ratio, kvm_tsc_scaling_ratio_frac_bits);
+}
+
+u64 kvm_scale_tsc(struct kvm_vcpu *vcpu, u64 tsc)
+{
+ u64 _tsc = tsc;
+ u64 ratio = vcpu->arch.tsc_scaling_ratio;
+
+ if (ratio != kvm_default_tsc_scaling_ratio)
+ _tsc = __scale_tsc(ratio, tsc);
+
+ return _tsc;
+}
+EXPORT_SYMBOL_GPL(kvm_scale_tsc);
+
+static u64 kvm_compute_tsc_offset(struct kvm_vcpu *vcpu, u64 target_tsc)
+{
+ u64 tsc;
+
+ tsc = kvm_scale_tsc(vcpu, rdtsc());
+
+ return target_tsc - tsc;
+}
+
+u64 kvm_read_l1_tsc(struct kvm_vcpu *vcpu, u64 host_tsc)
+{
+ return kvm_x86_ops->read_l1_tsc(vcpu, kvm_scale_tsc(vcpu, host_tsc));
+}
+EXPORT_SYMBOL_GPL(kvm_read_l1_tsc);
+
void kvm_write_tsc(struct kvm_vcpu *vcpu, struct msr_data *msr)
{
struct kvm *kvm = vcpu->kvm;
u64 data = msr->data;
raw_spin_lock_irqsave(&kvm->arch.tsc_write_lock, flags);
- offset = kvm_x86_ops->compute_tsc_offset(vcpu, data);
+ offset = kvm_compute_tsc_offset(vcpu, data);
ns = get_kernel_ns();
elapsed = ns - kvm->arch.last_tsc_nsec;
} else {
u64 delta = nsec_to_cycles(vcpu, elapsed);
data += delta;
- offset = kvm_x86_ops->compute_tsc_offset(vcpu, data);
+ offset = kvm_compute_tsc_offset(vcpu, data);
pr_debug("kvm: adjusted tsc offset by %llu\n", delta);
}
matched = true;
EXPORT_SYMBOL_GPL(kvm_write_tsc);
+static inline void adjust_tsc_offset_guest(struct kvm_vcpu *vcpu,
+ s64 adjustment)
+{
+ kvm_x86_ops->adjust_tsc_offset_guest(vcpu, adjustment);
+}
+
+static inline void adjust_tsc_offset_host(struct kvm_vcpu *vcpu, s64 adjustment)
+{
+ if (vcpu->arch.tsc_scaling_ratio != kvm_default_tsc_scaling_ratio)
+ WARN_ON(adjustment < 0);
+ adjustment = kvm_scale_tsc(vcpu, (u64) adjustment);
+ kvm_x86_ops->adjust_tsc_offset_guest(vcpu, adjustment);
+}
+
#ifdef CONFIG_X86_64
static cycle_t read_tsc(void)
static int kvm_guest_time_update(struct kvm_vcpu *v)
{
- unsigned long flags, this_tsc_khz;
+ unsigned long flags, this_tsc_khz, tgt_tsc_khz;
struct kvm_vcpu_arch *vcpu = &v->arch;
struct kvm_arch *ka = &v->kvm->arch;
s64 kernel_ns;
kernel_ns = get_kernel_ns();
}
- tsc_timestamp = kvm_x86_ops->read_l1_tsc(v, host_tsc);
+ tsc_timestamp = kvm_read_l1_tsc(v, host_tsc);
/*
* We may have to catch up the TSC to match elapsed wall clock
return 0;
if (unlikely(vcpu->hw_tsc_khz != this_tsc_khz)) {
- kvm_get_time_scale(NSEC_PER_SEC / 1000, this_tsc_khz,
+ tgt_tsc_khz = kvm_has_tsc_control ?
+ vcpu->virtual_tsc_khz : this_tsc_khz;
+ kvm_get_time_scale(NSEC_PER_SEC / 1000, tgt_tsc_khz,
&vcpu->hv_clock.tsc_shift,
&vcpu->hv_clock.tsc_to_system_mul);
vcpu->hw_tsc_khz = this_tsc_khz;
if (tsc_delta < 0)
mark_tsc_unstable("KVM discovered backwards TSC");
if (check_tsc_unstable()) {
- u64 offset = kvm_x86_ops->compute_tsc_offset(vcpu,
+ u64 offset = kvm_compute_tsc_offset(vcpu,
vcpu->arch.last_guest_tsc);
kvm_x86_ops->write_tsc_offset(vcpu, offset);
vcpu->arch.tsc_catchup = 1;
if (user_tsc_khz == 0)
user_tsc_khz = tsc_khz;
- kvm_set_tsc_khz(vcpu, user_tsc_khz);
+ if (!kvm_set_tsc_khz(vcpu, user_tsc_khz))
+ r = 0;
- r = 0;
goto out;
}
case KVM_GET_TSC_KHZ: {
if (hw_breakpoint_active())
hw_breakpoint_restore();
- vcpu->arch.last_guest_tsc = kvm_x86_ops->read_l1_tsc(vcpu,
- rdtsc());
+ vcpu->arch.last_guest_tsc = kvm_read_l1_tsc(vcpu, rdtsc());
vcpu->mode = OUTSIDE_GUEST_MODE;
smp_wmb();
if (r != 0)
return r;
+ if (kvm_has_tsc_control) {
+ /*
+ * 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.
+ */
+ u64 max = min(0x7fffffffULL,
+ __scale_tsc(kvm_max_tsc_scaling_ratio, tsc_khz));
+ kvm_max_guest_tsc_khz = max;
+
+ kvm_default_tsc_scaling_ratio = 1ULL << kvm_tsc_scaling_ratio_frac_bits;
+ }
+
kvm_init_msr_list();
return 0;
}
projects / firefly-linux-kernel-4.4.55.git / blobdiff