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-rw-r--r--arch/x86/include/asm/kvm_host.h9
-rw-r--r--arch/x86/kvm/lapic.c2
-rw-r--r--arch/x86/kvm/svm.c20
-rw-r--r--arch/x86/kvm/vmx.c16
-rw-r--r--arch/x86/kvm/x86.c82
5 files changed, 71 insertions, 58 deletions
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 782d973b071..ddebbe01fff 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -422,10 +422,11 @@ struct kvm_vcpu_arch {
u64 last_kernel_ns;
u64 last_tsc_nsec;
u64 last_tsc_write;
- u32 virtual_tsc_khz;
bool tsc_catchup;
- u32 tsc_catchup_mult;
- s8 tsc_catchup_shift;
+ bool tsc_always_catchup;
+ s8 virtual_tsc_shift;
+ u32 virtual_tsc_mult;
+ u32 virtual_tsc_khz;
atomic_t nmi_queued; /* unprocessed asynchronous NMIs */
unsigned nmi_pending; /* NMI queued after currently running handler */
@@ -651,7 +652,7 @@ struct kvm_x86_ops {
bool (*has_wbinvd_exit)(void);
- void (*set_tsc_khz)(struct kvm_vcpu *vcpu, u32 user_tsc_khz);
+ void (*set_tsc_khz)(struct kvm_vcpu *vcpu, u32 user_tsc_khz, bool scale);
void (*write_tsc_offset)(struct kvm_vcpu *vcpu, u64 offset);
u64 (*compute_tsc_offset)(struct kvm_vcpu *vcpu, u64 target_tsc);
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 3ee1d83c695..72975f758c8 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -731,7 +731,7 @@ static void start_apic_timer(struct kvm_lapic *apic)
u64 guest_tsc, tscdeadline = apic->lapic_timer.tscdeadline;
u64 ns = 0;
struct kvm_vcpu *vcpu = apic->vcpu;
- unsigned long this_tsc_khz = vcpu_tsc_khz(vcpu);
+ unsigned long this_tsc_khz = vcpu->arch.virtual_tsc_khz;
unsigned long flags;
if (unlikely(!tscdeadline || !this_tsc_khz))
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 7bbd17cc348..e12026e5244 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -964,20 +964,25 @@ static u64 svm_scale_tsc(struct kvm_vcpu *vcpu, u64 tsc)
return _tsc;
}
-static void svm_set_tsc_khz(struct kvm_vcpu *vcpu, u32 user_tsc_khz)
+static void svm_set_tsc_khz(struct kvm_vcpu *vcpu, u32 user_tsc_khz, bool scale)
{
struct vcpu_svm *svm = to_svm(vcpu);
u64 ratio;
u64 khz;
- /* TSC scaling supported? */
- if (!boot_cpu_has(X86_FEATURE_TSCRATEMSR))
+ /* Guest TSC same frequency as host TSC? */
+ if (!scale) {
+ svm->tsc_ratio = TSC_RATIO_DEFAULT;
return;
+ }
- /* TSC-Scaling disabled or guest TSC same frequency as host TSC? */
- if (user_tsc_khz == 0) {
- vcpu->arch.virtual_tsc_khz = 0;
- svm->tsc_ratio = TSC_RATIO_DEFAULT;
+ /* TSC scaling supported? */
+ if (!boot_cpu_has(X86_FEATURE_TSCRATEMSR)) {
+ if (user_tsc_khz > tsc_khz) {
+ vcpu->arch.tsc_catchup = 1;
+ vcpu->arch.tsc_always_catchup = 1;
+ } else
+ WARN(1, "user requested TSC rate below hardware speed\n");
return;
}
@@ -992,7 +997,6 @@ static void svm_set_tsc_khz(struct kvm_vcpu *vcpu, u32 user_tsc_khz)
user_tsc_khz);
return;
}
- vcpu->arch.virtual_tsc_khz = user_tsc_khz;
svm->tsc_ratio = ratio;
}
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 3b4c8d8ad90..e6bf61fa1c0 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -1817,13 +1817,19 @@ u64 vmx_read_l1_tsc(struct kvm_vcpu *vcpu)
}
/*
- * Empty call-back. Needs to be implemented when VMX enables the SET_TSC_KHZ
- * ioctl. In this case the call-back should update internal vmx state to make
- * the changes effective.
+ * Engage any workarounds for mis-matched TSC rates. Currently limited to
+ * software catchup for faster rates on slower CPUs.
*/
-static void vmx_set_tsc_khz(struct kvm_vcpu *vcpu, u32 user_tsc_khz)
+static void vmx_set_tsc_khz(struct kvm_vcpu *vcpu, u32 user_tsc_khz, bool scale)
{
- /* Nothing to do here */
+ if (!scale)
+ return;
+
+ if (user_tsc_khz > tsc_khz) {
+ vcpu->arch.tsc_catchup = 1;
+ vcpu->arch.tsc_always_catchup = 1;
+ } else
+ WARN(1, "user requested TSC rate below hardware speed\n");
}
/*
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 2bd77a3a41e..41bb90acb23 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -96,6 +96,10 @@ EXPORT_SYMBOL_GPL(kvm_has_tsc_control);
u32 kvm_max_guest_tsc_khz;
EXPORT_SYMBOL_GPL(kvm_max_guest_tsc_khz);
+/* tsc tolerance in parts per million - default to 1/2 of the NTP threshold */
+static u32 tsc_tolerance_ppm = 250;
+module_param(tsc_tolerance_ppm, uint, S_IRUGO | S_IWUSR);
+
#define KVM_NR_SHARED_MSRS 16
struct kvm_shared_msrs_global {
@@ -968,49 +972,50 @@ static inline u64 get_kernel_ns(void)
static DEFINE_PER_CPU(unsigned long, cpu_tsc_khz);
unsigned long max_tsc_khz;
-static inline int kvm_tsc_changes_freq(void)
+static inline u64 nsec_to_cycles(struct kvm_vcpu *vcpu, u64 nsec)
{
- int cpu = get_cpu();
- int ret = !boot_cpu_has(X86_FEATURE_CONSTANT_TSC) &&
- cpufreq_quick_get(cpu) != 0;
- put_cpu();
- return ret;
+ return pvclock_scale_delta(nsec, vcpu->arch.virtual_tsc_mult,
+ vcpu->arch.virtual_tsc_shift);
}
-u64 vcpu_tsc_khz(struct kvm_vcpu *vcpu)
+static u32 adjust_tsc_khz(u32 khz, s32 ppm)
{
- if (vcpu->arch.virtual_tsc_khz)
- return vcpu->arch.virtual_tsc_khz;
- else
- return __this_cpu_read(cpu_tsc_khz);
+ u64 v = (u64)khz * (1000000 + ppm);
+ do_div(v, 1000000);
+ return v;
}
-static inline u64 nsec_to_cycles(struct kvm_vcpu *vcpu, u64 nsec)
+static void kvm_set_tsc_khz(struct kvm_vcpu *vcpu, u32 this_tsc_khz)
{
- u64 ret;
+ u32 thresh_lo, thresh_hi;
+ int use_scaling = 0;
- WARN_ON(preemptible());
- if (kvm_tsc_changes_freq())
- printk_once(KERN_WARNING
- "kvm: unreliable cycle conversion on adjustable rate TSC\n");
- ret = nsec * vcpu_tsc_khz(vcpu);
- do_div(ret, USEC_PER_SEC);
- return ret;
-}
-
-static void kvm_init_tsc_catchup(struct kvm_vcpu *vcpu, u32 this_tsc_khz)
-{
/* Compute a scale to convert nanoseconds in TSC cycles */
kvm_get_time_scale(this_tsc_khz, NSEC_PER_SEC / 1000,
- &vcpu->arch.tsc_catchup_shift,
- &vcpu->arch.tsc_catchup_mult);
+ &vcpu->arch.virtual_tsc_shift,
+ &vcpu->arch.virtual_tsc_mult);
+ vcpu->arch.virtual_tsc_khz = this_tsc_khz;
+
+ /*
+ * Compute the variation in TSC rate which is acceptable
+ * within the range of tolerance and decide if the
+ * rate being applied is within that bounds of the hardware
+ * rate. If so, no scaling or compensation need be done.
+ */
+ thresh_lo = adjust_tsc_khz(tsc_khz, -tsc_tolerance_ppm);
+ thresh_hi = adjust_tsc_khz(tsc_khz, tsc_tolerance_ppm);
+ if (this_tsc_khz < thresh_lo || this_tsc_khz > thresh_hi) {
+ 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);
}
static u64 compute_guest_tsc(struct kvm_vcpu *vcpu, s64 kernel_ns)
{
u64 tsc = pvclock_scale_delta(kernel_ns-vcpu->arch.last_tsc_nsec,
- vcpu->arch.tsc_catchup_mult,
- vcpu->arch.tsc_catchup_shift);
+ vcpu->arch.virtual_tsc_mult,
+ vcpu->arch.virtual_tsc_shift);
tsc += vcpu->arch.last_tsc_write;
return tsc;
}
@@ -1077,7 +1082,7 @@ static int kvm_guest_time_update(struct kvm_vcpu *v)
local_irq_save(flags);
tsc_timestamp = kvm_x86_ops->read_l1_tsc(v);
kernel_ns = get_kernel_ns();
- this_tsc_khz = vcpu_tsc_khz(v);
+ this_tsc_khz = __get_cpu_var(cpu_tsc_khz);
if (unlikely(this_tsc_khz == 0)) {
local_irq_restore(flags);
kvm_make_request(KVM_REQ_CLOCK_UPDATE, v);
@@ -2804,26 +2809,21 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
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);
+ if (user_tsc_khz == 0)
+ user_tsc_khz = tsc_khz;
+
+ kvm_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);
-
+ r = vcpu->arch.virtual_tsc_khz;
goto out;
}
default:
@@ -5312,6 +5312,8 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
profile_hit(KVM_PROFILING, (void *)rip);
}
+ if (unlikely(vcpu->arch.tsc_always_catchup))
+ kvm_make_request(KVM_REQ_CLOCK_UPDATE, vcpu);
kvm_lapic_sync_from_vapic(vcpu);
@@ -6004,7 +6006,7 @@ int kvm_arch_vcpu_init(struct kvm_vcpu *vcpu)
}
vcpu->arch.pio_data = page_address(page);
- kvm_init_tsc_catchup(vcpu, max_tsc_khz);
+ kvm_set_tsc_khz(vcpu, max_tsc_khz);
r = kvm_mmu_create(vcpu);
if (r < 0)
generated by cgit v1.2.3 (git 2.25.1) at 2024-06-27 11:26:01 +0000