From patchwork Fri Aug 20 08:07:25 2010 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Zachary Amsden X-Patchwork-Id: 120544 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by demeter.kernel.org (8.14.4/8.14.3) with ESMTP id o7K8FIeG004254 for ; Fri, 20 Aug 2010 08:15:18 GMT Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751964Ab0HTIIe (ORCPT ); Fri, 20 Aug 2010 04:08:34 -0400 Received: from mx1.redhat.com ([209.132.183.28]:15716 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751375Ab0HTII2 (ORCPT ); Fri, 20 Aug 2010 04:08:28 -0400 Received: from int-mx01.intmail.prod.int.phx2.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) by mx1.redhat.com (8.13.8/8.13.8) with ESMTP id o7K88M6G009929 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Fri, 20 Aug 2010 04:08:22 -0400 Received: from mysore (vpn-9-158.rdu.redhat.com [10.11.9.158]) by int-mx01.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id o7K87qf5027969; Fri, 20 Aug 2010 04:08:19 -0400 From: Zachary Amsden To: kvm@vger.kernel.org Cc: Zachary Amsden , Avi Kivity , Marcelo Tosatti , Glauber Costa , Thomas Gleixner , John Stultz , linux-kernel@vger.kernel.org Subject: [KVM timekeeping 11/35] Add helper functions for time computation Date: Thu, 19 Aug 2010 22:07:25 -1000 Message-Id: <1282291669-25709-12-git-send-email-zamsden@redhat.com> In-Reply-To: <1282291669-25709-1-git-send-email-zamsden@redhat.com> References: <1282291669-25709-1-git-send-email-zamsden@redhat.com> X-Scanned-By: MIMEDefang 2.67 on 10.5.11.11 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org X-Greylist: IP, sender and recipient auto-whitelisted, not delayed by milter-greylist-4.2.3 (demeter.kernel.org [140.211.167.41]); Fri, 20 Aug 2010 08:15:19 +0000 (UTC) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 52b6c21..52680f6 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -893,6 +893,16 @@ static void kvm_set_time_scale(uint32_t tsc_khz, struct pvclock_vcpu_time_info * hv_clock->tsc_to_system_mul); } +static inline u64 get_kernel_ns(void) +{ + struct timespec ts; + + WARN_ON(preemptible()); + ktime_get_ts(&ts); + monotonic_to_bootbased(&ts); + return timespec_to_ns(&ts); +} + static DEFINE_PER_CPU(unsigned long, cpu_tsc_khz); static inline int kvm_tsc_changes_freq(void) @@ -904,18 +914,24 @@ static inline int kvm_tsc_changes_freq(void) return ret; } +static inline u64 nsec_to_cycles(u64 nsec) +{ + WARN_ON(preemptible()); + if (kvm_tsc_changes_freq()) + printk_once(KERN_WARNING + "kvm: unreliable cycle conversion on adjustable rate TSC\n"); + return (nsec * __get_cpu_var(cpu_tsc_khz)) / USEC_PER_SEC; +} + void kvm_write_tsc(struct kvm_vcpu *vcpu, u64 data) { struct kvm *kvm = vcpu->kvm; u64 offset, ns, elapsed; unsigned long flags; - struct timespec ts; spin_lock_irqsave(&kvm->arch.tsc_write_lock, flags); offset = data - native_read_tsc(); - ktime_get_ts(&ts); - monotonic_to_bootbased(&ts); - ns = timespec_to_ns(&ts); + ns = get_kernel_ns(); elapsed = ns - kvm->arch.last_tsc_nsec; /* @@ -931,10 +947,9 @@ void kvm_write_tsc(struct kvm_vcpu *vcpu, u64 data) offset = kvm->arch.last_tsc_offset; pr_debug("kvm: matched tsc offset for %llu\n", data); } else { - u64 tsc_delta = elapsed * __get_cpu_var(cpu_tsc_khz); - tsc_delta = tsc_delta / USEC_PER_SEC; - offset += tsc_delta; - pr_debug("kvm: adjusted tsc offset by %llu\n", tsc_delta); + u64 delta = nsec_to_cycles(elapsed); + offset += delta; + pr_debug("kvm: adjusted tsc offset by %llu\n", delta); } ns = kvm->arch.last_tsc_nsec; } @@ -951,11 +966,11 @@ EXPORT_SYMBOL_GPL(kvm_write_tsc); static int kvm_write_guest_time(struct kvm_vcpu *v) { - struct timespec ts; unsigned long flags; struct kvm_vcpu_arch *vcpu = &v->arch; void *shared_kaddr; unsigned long this_tsc_khz; + s64 kernel_ns; if ((!vcpu->time_page)) return 0; @@ -963,8 +978,7 @@ static int kvm_write_guest_time(struct kvm_vcpu *v) /* Keep irq disabled to prevent changes to the clock */ local_irq_save(flags); kvm_get_msr(v, MSR_IA32_TSC, &vcpu->hv_clock.tsc_timestamp); - ktime_get_ts(&ts); - monotonic_to_bootbased(&ts); + kernel_ns = get_kernel_ns(); this_tsc_khz = __get_cpu_var(cpu_tsc_khz); local_irq_restore(flags); @@ -979,9 +993,7 @@ static int kvm_write_guest_time(struct kvm_vcpu *v) } /* With all the info we got, fill in the values */ - vcpu->hv_clock.system_time = ts.tv_nsec + - (NSEC_PER_SEC * (u64)ts.tv_sec) + v->kvm->arch.kvmclock_offset; - + vcpu->hv_clock.system_time = kernel_ns + v->kvm->arch.kvmclock_offset; vcpu->hv_clock.flags = 0; /* @@ -3263,7 +3275,6 @@ long kvm_arch_vm_ioctl(struct file *filp, break; } case KVM_SET_CLOCK: { - struct timespec now; struct kvm_clock_data user_ns; u64 now_ns; s64 delta; @@ -3277,19 +3288,16 @@ long kvm_arch_vm_ioctl(struct file *filp, goto out; r = 0; - ktime_get_ts(&now); - now_ns = timespec_to_ns(&now); + now_ns = get_kernel_ns(); delta = user_ns.clock - now_ns; kvm->arch.kvmclock_offset = delta; break; } case KVM_GET_CLOCK: { - struct timespec now; struct kvm_clock_data user_ns; u64 now_ns; - ktime_get_ts(&now); - now_ns = timespec_to_ns(&now); + now_ns = get_kernel_ns(); user_ns.clock = kvm->arch.kvmclock_offset + now_ns; user_ns.flags = 0;