From 5d6310aea2f4dd4f452576b954aa3beacfc88c24 Mon Sep 17 00:00:00 2001 From: Zachary Amsden Date: Fri, 3 Feb 2012 15:43:50 -0200 Subject: [PATCH] --- yaml --- r: 297135 b: refs/heads/master c: cc578287e3224d0da196cc1d226bdae6b068faa7 h: refs/heads/master i: 297133: 02e49f8cb0ec5098bc3d7d821eaa9a9c4a55eec9 297131: 8776919389cf1dc4ccb08992b0e04bbc428ef84b 297127: bab764a5a9c9095dc431fea672ba089b7466f36e 297119: 61458c068ab64d92eca53e5840bb25bfb795ab15 v: v3 --- [refs] | 2 +- trunk/arch/x86/include/asm/kvm_host.h | 9 +-- trunk/arch/x86/kvm/lapic.c | 2 +- trunk/arch/x86/kvm/svm.c | 20 ++++--- trunk/arch/x86/kvm/vmx.c | 16 ++++-- trunk/arch/x86/kvm/x86.c | 82 ++++++++++++++------------- 6 files changed, 72 insertions(+), 59 deletions(-) diff --git a/[refs] b/[refs] index 15b27a5ee062..c8d347fff0ed 100644 --- a/[refs] +++ b/[refs] @@ -1,2 +1,2 @@ --- -refs/heads/master: a59cb29e4d81e025192550c2703f305637f016f6 +refs/heads/master: cc578287e3224d0da196cc1d226bdae6b068faa7 diff --git a/trunk/arch/x86/include/asm/kvm_host.h b/trunk/arch/x86/include/asm/kvm_host.h index 782d973b0719..ddebbe01fff9 100644 --- a/trunk/arch/x86/include/asm/kvm_host.h +++ b/trunk/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/trunk/arch/x86/kvm/lapic.c b/trunk/arch/x86/kvm/lapic.c index 3ee1d83c695d..72975f758c83 100644 --- a/trunk/arch/x86/kvm/lapic.c +++ b/trunk/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/trunk/arch/x86/kvm/svm.c b/trunk/arch/x86/kvm/svm.c index 7bbd17cc3488..e12026e5244e 100644 --- a/trunk/arch/x86/kvm/svm.c +++ b/trunk/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/trunk/arch/x86/kvm/vmx.c b/trunk/arch/x86/kvm/vmx.c index 3b4c8d8ad906..e6bf61fa1c03 100644 --- a/trunk/arch/x86/kvm/vmx.c +++ b/trunk/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/trunk/arch/x86/kvm/x86.c b/trunk/arch/x86/kvm/x86.c index 2bd77a3a41ed..41bb90acb238 100644 --- a/trunk/arch/x86/kvm/x86.c +++ b/trunk/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)