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authorLinus Torvalds <torvalds@linux-foundation.org>2015-11-12 14:34:06 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2015-11-12 14:34:06 -0800
commit3370b69eb0c1f6a05f9051e8fc3e8768461a80f7 (patch)
tree722a75d9d3cc605bfd513752054dea1df806385d /arch/x86/kvm/x86.c
parentbe23c9d20b341a58ad7107f9e9aa5735cea3da13 (diff)
parent370289756beccdc2a6ef9c7998fe67a7ca68bfc2 (diff)
Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm
Pull second batch of kvm updates from Paolo Bonzini: "Four changes: - x86: work around two nasty cases where a benign exception occurs while another is being delivered. The endless stream of exceptions causes an infinite loop in the processor, which not even NMIs or SMIs can interrupt; in the virt case, there is no possibility to exit to the host either. - x86: support for Skylake per-guest TSC rate. Long supported by AMD, the patches mostly move things from there to common arch/x86/kvm/ code. - generic: remove local_irq_save/restore from the guest entry and exit paths when context tracking is enabled. The patches are a few months old, but we discussed them again at kernel summit. Andy will pick up from here and, in 4.5, try to remove it from the user entry/exit paths. - PPC: Two bug fixes, see merge commit 370289756becc for details" * tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (21 commits) KVM: x86: rename update_db_bp_intercept to update_bp_intercept KVM: svm: unconditionally intercept #DB KVM: x86: work around infinite loop in microcode when #AC is delivered context_tracking: avoid irq_save/irq_restore on guest entry and exit context_tracking: remove duplicate enabled check KVM: VMX: Dump TSC multiplier in dump_vmcs() KVM: VMX: Use a scaled host TSC for guest readings of MSR_IA32_TSC KVM: VMX: Setup TSC scaling ratio when a vcpu is loaded KVM: VMX: Enable and initialize VMX TSC scaling KVM: x86: Use the correct vcpu's TSC rate to compute time scale KVM: x86: Move TSC scaling logic out of call-back read_l1_tsc() KVM: x86: Move TSC scaling logic out of call-back adjust_tsc_offset() KVM: x86: Replace call-back compute_tsc_offset() with a common function KVM: x86: Replace call-back set_tsc_khz() with a common function KVM: x86: Add a common TSC scaling function KVM: x86: Add a common TSC scaling ratio field in kvm_vcpu_arch KVM: x86: Collect information for setting TSC scaling ratio KVM: x86: declare a few variables as __read_mostly KVM: x86: merge handle_mmio_page_fault and handle_mmio_page_fault_common KVM: PPC: Book3S HV: Don't dynamically split core when already split ...
Diffstat (limited to 'arch/x86/kvm/x86.c')
-rw-r--r--arch/x86/kvm/x86.c159
1 files changed, 137 insertions, 22 deletions
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 4a6eff166fc6..00462bd63129 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -93,10 +93,10 @@ static void update_cr8_intercept(struct kvm_vcpu *vcpu);
static void process_nmi(struct kvm_vcpu *vcpu);
static void __kvm_set_rflags(struct kvm_vcpu *vcpu, unsigned long rflags);
-struct kvm_x86_ops *kvm_x86_ops;
+struct kvm_x86_ops *kvm_x86_ops __read_mostly;
EXPORT_SYMBOL_GPL(kvm_x86_ops);
-static bool ignore_msrs = 0;
+static bool __read_mostly ignore_msrs = 0;
module_param(ignore_msrs, bool, S_IRUGO | S_IWUSR);
unsigned int min_timer_period_us = 500;
@@ -105,20 +105,25 @@ module_param(min_timer_period_us, uint, S_IRUGO | S_IWUSR);
static bool __read_mostly kvmclock_periodic_sync = true;
module_param(kvmclock_periodic_sync, bool, S_IRUGO);
-bool kvm_has_tsc_control;
+bool __read_mostly kvm_has_tsc_control;
EXPORT_SYMBOL_GPL(kvm_has_tsc_control);
-u32 kvm_max_guest_tsc_khz;
+u32 __read_mostly kvm_max_guest_tsc_khz;
EXPORT_SYMBOL_GPL(kvm_max_guest_tsc_khz);
+u8 __read_mostly kvm_tsc_scaling_ratio_frac_bits;
+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 tsc_tolerance_ppm = 250;
+static u32 __read_mostly tsc_tolerance_ppm = 250;
module_param(tsc_tolerance_ppm, uint, S_IRUGO | S_IWUSR);
/* lapic timer advance (tscdeadline mode only) in nanoseconds */
-unsigned int lapic_timer_advance_ns = 0;
+unsigned int __read_mostly lapic_timer_advance_ns = 0;
module_param(lapic_timer_advance_ns, uint, S_IRUGO | S_IWUSR);
-static bool backwards_tsc_observed = false;
+static bool __read_mostly backwards_tsc_observed = false;
#define KVM_NR_SHARED_MSRS 16
@@ -1249,14 +1254,53 @@ static u32 adjust_tsc_khz(u32 khz, s32 ppm)
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,
@@ -1276,7 +1320,7 @@ static void kvm_set_tsc_khz(struct kvm_vcpu *vcpu, u32 this_tsc_khz)
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)
@@ -1322,6 +1366,48 @@ static void update_ia32_tsc_adjust_msr(struct kvm_vcpu *vcpu, s64 offset)
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;
@@ -1333,7 +1419,7 @@ void kvm_write_tsc(struct kvm_vcpu *vcpu, struct msr_data *msr)
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;
@@ -1390,7 +1476,7 @@ void kvm_write_tsc(struct kvm_vcpu *vcpu, struct msr_data *msr)
} 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;
@@ -1447,6 +1533,20 @@ void kvm_write_tsc(struct kvm_vcpu *vcpu, struct msr_data *msr)
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)
@@ -1608,7 +1708,7 @@ static void kvm_gen_update_masterclock(struct kvm *kvm)
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;
@@ -1645,7 +1745,7 @@ static int kvm_guest_time_update(struct kvm_vcpu *v)
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
@@ -1671,7 +1771,9 @@ static int kvm_guest_time_update(struct kvm_vcpu *v)
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;
@@ -2617,7 +2719,7 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
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;
@@ -3319,9 +3421,9 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
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: {
@@ -6452,8 +6554,7 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
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();
@@ -7015,7 +7116,7 @@ int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu,
*/
kvm_set_rflags(vcpu, rflags);
- kvm_x86_ops->update_db_bp_intercept(vcpu);
+ kvm_x86_ops->update_bp_intercept(vcpu);
r = 0;
@@ -7364,6 +7465,20 @@ int kvm_arch_hardware_setup(void)
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;
}