[v2,03/12] KVM: x86: Add a common TSC scaling function

Message ID	1445326752-8926-4-git-send-email-haozhong.zhang@intel.com (mailing list archive)
State	New, archived
Headers	show Return-Path: <kvm-owner@kernel.org> From: Haozhong Zhang <haozhong.zhang@intel.com> To: kvm@vger.kernel.org Cc: Gleb Natapov <gleb@kernel.org>, Paolo Bonzini <pbonzini@redhat.com>, Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>, x86@kernel.org, Joerg Roedel <joro@8bytes.org>, Wanpeng Li <wanpeng.li@hotmail.com>, Xiao Guangrong <guangrong.xiao@linux.intel.com>, mdontu@bitdefender.com, Kai Huang <kai.huang@linux.intel.com>, Andy Lutomirski <luto@kernel.org>, linux-kernel@vger.kernel.org, Haozhong Zhang <haozhong.zhang@intel.com> Subject: [PATCH v2 03/12] KVM: x86: Add a common TSC scaling function Date: Tue, 20 Oct 2015 15:39:03 +0800 Message-Id: <1445326752-8926-4-git-send-email-haozhong.zhang@intel.com> In-Reply-To: <1445326752-8926-1-git-send-email-haozhong.zhang@intel.com> References: <1445326752-8926-1-git-send-email-haozhong.zhang@intel.com> Sender: kvm-owner@vger.kernel.org Precedence: bulk

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c index 04b58cf..d347170 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -212,7 +212,6 @@ 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, @@ -892,21 +891,7 @@ static __init int svm_hardware_setup(void) kvm_enable_efer_bits(EFER_FFXSR); if (boot_cpu_has(X86_FEATURE_TSCRATEMSR)) { - u64 max; - kvm_has_tsc_control = true; - - /* - * 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 and a value of 0 is used to disable - * tsc-scaling for the vcpu. - */ - max = min(0x7fffffffULL, __scale_tsc(tsc_khz, TSC_RATIO_MAX)); - - kvm_max_guest_tsc_khz = max; - kvm_max_tsc_scaling_ratio = TSC_RATIO_MAX; kvm_tsc_scaling_ratio_frac_bits = 32; } @@ -973,31 +958,6 @@ static void init_sys_seg(struct vmcb_seg *seg, uint32_t type) seg->base = 0; } -static u64 __scale_tsc(u64 ratio, u64 tsc) -{ - u64 mult, frac, _tsc; - - mult = ratio >> 32; - frac = ratio & ((1ULL << 32) - 1); - - _tsc = tsc; - _tsc *= mult; - _tsc += (tsc >> 32) * frac; - _tsc += ((tsc & ((1ULL << 32) - 1)) * frac) >> 32; - - return _tsc; -} - -static u64 svm_scale_tsc(struct kvm_vcpu *vcpu, u64 tsc) -{ - u64 _tsc = tsc; - - if (vcpu->arch.tsc_scaling_ratio != TSC_RATIO_DEFAULT) - _tsc = __scale_tsc(vcpu->arch.tsc_scaling_ratio, tsc); - - return _tsc; -} - static void svm_set_tsc_khz(struct kvm_vcpu *vcpu, u32 user_tsc_khz, bool scale) { u64 ratio; @@ -1066,7 +1026,7 @@ static void svm_adjust_tsc_offset(struct kvm_vcpu *vcpu, s64 adjustment, bool ho if (host) { if (vcpu->arch.tsc_scaling_ratio != TSC_RATIO_DEFAULT) WARN_ON(adjustment < 0); - adjustment = svm_scale_tsc(vcpu, (u64)adjustment); + adjustment = kvm_scale_tsc(vcpu, (u64)adjustment); } svm->vmcb->control.tsc_offset += adjustment; @@ -1084,7 +1044,7 @@ static u64 svm_compute_tsc_offset(struct kvm_vcpu *vcpu, u64 target_tsc) { u64 tsc; - tsc = svm_scale_tsc(vcpu, rdtsc()); + tsc = kvm_scale_tsc(vcpu, rdtsc()); return target_tsc - tsc; } @@ -3076,7 +3036,7 @@ static u64 svm_read_l1_tsc(struct kvm_vcpu *vcpu, u64 host_tsc) { struct vmcb *vmcb = get_host_vmcb(to_svm(vcpu)); return vmcb->control.tsc_offset + - svm_scale_tsc(vcpu, host_tsc); + kvm_scale_tsc(vcpu, host_tsc); } static int svm_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) @@ -3086,7 +3046,7 @@ static int svm_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) switch (msr_info->index) { case MSR_IA32_TSC: { msr_info->data = svm->vmcb->control.tsc_offset + - svm_scale_tsc(vcpu, rdtsc()); + kvm_scale_tsc(vcpu, rdtsc()); break; } diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 8849e8b..29c5781 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -1328,6 +1328,39 @@ 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.B: we always assume not all 64 bits of ratio are used for the + * fractional part and the ratio has at least 1 bit for the fractional + * part, i.e. 0 < N < 64. + * + * N equals to kvm_tsc_scaling_ratio_frac_bits. + */ +static inline u64 __scale_tsc(u64 ratio, u64 tsc) +{ + BUG_ON(kvm_tsc_scaling_ratio_frac_bits >= 64 || + kvm_tsc_scaling_ratio_frac_bits == 0); + 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); + void kvm_write_tsc(struct kvm_vcpu *vcpu, struct msr_data *msr) { struct kvm *kvm = vcpu->kvm; @@ -7366,6 +7399,18 @@ int kvm_arch_hardware_setup(void) if (r != 0) return r; + /* + * 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. + */ + if (kvm_has_tsc_control) { + u64 max = min(0x7fffffffULL, + __scale_tsc(kvm_max_tsc_scaling_ratio, tsc_khz)); + kvm_max_guest_tsc_khz = max; + } + kvm_init_msr_list(); return 0; } diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index eba9cae..3556148 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -1183,4 +1183,7 @@ void kvm_arch_irq_bypass_start(struct irq_bypass_consumer *); int kvm_arch_update_irqfd_routing(struct kvm *kvm, unsigned int host_irq, uint32_t guest_irq, bool set); #endif /* CONFIG_HAVE_KVM_IRQ_BYPASS */ + +u64 kvm_scale_tsc(struct kvm_vcpu *vcpu, u64 tsc); + #endif diff --git a/include/linux/math64.h b/include/linux/math64.h index c45c089..78aa80b 100644 --- a/include/linux/math64.h +++ b/include/linux/math64.h @@ -142,6 +142,13 @@ static inline u64 mul_u64_u32_shr(u64 a, u32 mul, unsigned int shift) } #endif /* mul_u64_u32_shr */ +#ifndef mul_u64_u64_shr +static inline u64 mul_u64_u64_shr(u64 a, u64 mul, unsigned int shift) +{ + return (u64)(((unsigned __int128)a * mul) >> shift); +} +#endif /* mul_u64_u64_shr */ + #else #ifndef mul_u64_u32_shr @@ -161,6 +168,69 @@ static inline u64 mul_u64_u32_shr(u64 a, u32 mul, unsigned int shift) } #endif /* mul_u64_u32_shr */ +#ifndef mul64 +static inline void mul64(u64 *lo, u64 *hi, u64 a, u64 b) +{ + typedef union { + u64 ll; + struct { +#ifdef __BIG_ENDIAN + u32 high, low; +#else + u32 low, high; +#endif + } l; + } LL; + LL rl, rm, rn, rh, a0, b0; + u64 c; + + a0.ll = a; + b0.ll = b; + + rl.ll = (u64)a0.l.low * b0.l.low; + rm.ll = (u64)a0.l.low * b0.l.high; + rn.ll = (u64)a0.l.high * b0.l.low; + rh.ll = (u64)a0.l.high * b0.l.high; + + c = (u64)rl.l.high + rm.l.low + rn.l.low; + rl.l.high = c; + c >>= 32; + c = c + rm.l.high + rn.l.high + rh.l.low; + rh.l.low = c; + rh.l.high += (u32)(c >> 32); + + *lo = rl.ll; + *hi = rh.ll; +} +#endif /* mul64 */ + +#ifndef rshift128 +static inline void rshift128(u64 *lo, u64 *hi, unsigned int n) +{ + u64 h; + if (!n) + return; + h = *hi >> (n & 63); + if (n >= 64) { + *hi = 0; + *lo = h; + } else { + *lo = (*lo >> n) | (*hi << (64 - n)); + *hi = h; + } +} +#endif /* rshift128 */ + +#ifndef mul_u64_u64_shr +static inline u64 mul_u64_u64_shr(u64 a, u64 mul, unsigned int shift) +{ + u64 lo, hi; + mul64(&lo, &hi, a, mul); + rshift128(&lo, &hi, shift); + return lo; +} +#endif /* mul_u64_u64_shr */ + #endif #endif /* _LINUX_MATH64_H */

[v2,03/12] KVM: x86: Add a common TSC scaling function

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Patch