From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:46063) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Ul8Sj-0006Xl-5Z for qemu-devel@nongnu.org; Fri, 07 Jun 2013 22:01:02 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Ul8Si-0000jl-82 for qemu-devel@nongnu.org; Fri, 07 Jun 2013 22:01:01 -0400 Received: from mx1.redhat.com ([209.132.183.28]:24184) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Ul8Sh-0000jg-WF for qemu-devel@nongnu.org; Fri, 07 Jun 2013 22:01:00 -0400 Date: Fri, 7 Jun 2013 23:00:48 -0300 From: Marcelo Tosatti Message-ID: <20130608020048.GA1412@amt.cnet> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Subject: [Qemu-devel] [PATCH] kvmclock: clock should count only if vm is running List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Jan Kiszka Cc: Glauber Costa , qemu-devel , kvm-devel kvmclock should not count while vm is paused, because: 1) if the vm is paused for long periods, timekeeping math can overflow while converting the (large) clocksource delta to nanoseconds. 2) Users rely on CLOCK_MONOTONIC to count run time, that is, time which OS has been in a runnable state (see CLOCK_BOOTTIME). Change kvmclock driver so as to save clock value when vm transitions from runnable to stopped state, and to restore clock value from stopped to runnable transition. Signed-off-by: Marcelo Tosatti diff --git a/hw/i386/kvm/clock.c b/hw/i386/kvm/clock.c index 87d4d0f..7d2d005 100644 --- a/hw/i386/kvm/clock.c +++ b/hw/i386/kvm/clock.c @@ -28,38 +28,6 @@ typedef struct KVMClockState { bool clock_valid; } KVMClockState; -static void kvmclock_pre_save(void *opaque) -{ - KVMClockState *s = opaque; - struct kvm_clock_data data; - int ret; - - if (s->clock_valid) { - return; - } - ret = kvm_vm_ioctl(kvm_state, KVM_GET_CLOCK, &data); - if (ret < 0) { - fprintf(stderr, "KVM_GET_CLOCK failed: %s\n", strerror(ret)); - data.clock = 0; - } - s->clock = data.clock; - /* - * If the VM is stopped, declare the clock state valid to avoid re-reading - * it on next vmsave (which would return a different value). Will be reset - * when the VM is continued. - */ - s->clock_valid = !runstate_is_running(); -} - -static int kvmclock_post_load(void *opaque, int version_id) -{ - KVMClockState *s = opaque; - struct kvm_clock_data data; - - data.clock = s->clock; - data.flags = 0; - return kvm_vm_ioctl(kvm_state, KVM_SET_CLOCK, &data); -} static void kvmclock_vm_state_change(void *opaque, int running, RunState state) @@ -70,8 +38,18 @@ static void kvmclock_vm_state_change(void *opaque, int running, int ret; if (running) { + struct kvm_clock_data data; + s->clock_valid = false; + data.clock = s->clock; + data.flags = 0; + ret = kvm_vm_ioctl(kvm_state, KVM_SET_CLOCK, &data); + if (ret < 0) { + fprintf(stderr, "KVM_SET_CLOCK failed: %s\n", strerror(ret)); + abort(); + } + if (!cap_clock_ctrl) { return; } @@ -84,6 +62,26 @@ static void kvmclock_vm_state_change(void *opaque, int running, return; } } + } else { + struct kvm_clock_data data; + int ret; + + if (s->clock_valid) { + return; + } + ret = kvm_vm_ioctl(kvm_state, KVM_GET_CLOCK, &data); + if (ret < 0) { + fprintf(stderr, "KVM_GET_CLOCK failed: %s\n", strerror(ret)); + abort(); + } + s->clock = data.clock; + + /* + * If the VM is stopped, declare the clock state valid to + * avoid re-reading it on next vmsave (which would return + * a different value). Will be reset when the VM is continued. + */ + s->clock_valid = !runstate_is_running(); } } @@ -100,8 +98,6 @@ static const VMStateDescription kvmclock_vmsd = { .version_id = 1, .minimum_version_id = 1, .minimum_version_id_old = 1, - .pre_save = kvmclock_pre_save, - .post_load = kvmclock_post_load, .fields = (VMStateField[]) { VMSTATE_UINT64(clock, KVMClockState), VMSTATE_END_OF_LIST()