From patchwork Fri Sep 5 13:52:45 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Marcelo Tosatti X-Patchwork-Id: 386358 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [IPv6:2001:4830:134:3::11]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 8CA3A1400B9 for ; Fri, 5 Sep 2014 23:57:58 +1000 (EST) Received: from localhost ([::1]:57865 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XPu1U-0007gw-Nl for incoming@patchwork.ozlabs.org; Fri, 05 Sep 2014 09:57:56 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:42468) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XPu0v-0006rw-9A for qemu-devel@nongnu.org; Fri, 05 Sep 2014 09:57:25 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XPu0o-0001J4-7a for qemu-devel@nongnu.org; Fri, 05 Sep 2014 09:57:21 -0400 Received: from mx1.redhat.com ([209.132.183.28]:54204) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XPu0n-0001Ic-V5 for qemu-devel@nongnu.org; Fri, 05 Sep 2014 09:57:14 -0400 Received: from int-mx11.intmail.prod.int.phx2.redhat.com (int-mx11.intmail.prod.int.phx2.redhat.com [10.5.11.24]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id s85Dv9qs005353 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Fri, 5 Sep 2014 09:57:10 -0400 Received: from amt.cnet (vpn1-6-58.gru2.redhat.com [10.97.6.58]) by int-mx11.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id s85Dv8eg031147; Fri, 5 Sep 2014 09:57:08 -0400 Received: from amt.cnet (localhost [127.0.0.1]) by amt.cnet (Postfix) with ESMTP id B2BA9100524; Fri, 5 Sep 2014 10:56:32 -0300 (BRT) Received: (from marcelo@localhost) by amt.cnet (8.14.7/8.14.7/Submit) id s85DuWA9009214; Fri, 5 Sep 2014 10:56:32 -0300 Message-Id: <20140905135539.188955270@amt.cnet> User-Agent: quilt/0.60-1 Date: Fri, 05 Sep 2014 10:52:45 -0300 From: Marcelo Tosatti To: qemu-devel@nongnu.org References: <20140905135244.104423770@amt.cnet> Content-Disposition: inline; filename=kvmclock-ensure-time-in-mig.patch X-Scanned-By: MIMEDefang 2.68 on 10.5.11.24 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x X-Received-From: 209.132.183.28 Cc: Paolo Bonzini , Andrey Korolyov , =?ISO-8859-15?q?Marcin=20Gibu=C5=82a?= , Alexander Graf , Marcelo Tosatti Subject: [Qemu-devel] [patch 1/3] kvmclock: Ensure time in migration never goes backward X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org From: Alexander Graf When we migrate we ask the kernel about its current belief on what the guest time would be. However, I've seen cases where the kvmclock guest structure indicates a time more recent than the kvm returned time. To make sure we never go backwards, calculate what the guest would have seen as time at the point of migration and use that value instead of the kernel returned one when it's more recent. This bases the view of the kvmclock after migration on the same foundation in host as well as guest. Signed-off-by: Alexander Graf Cc: qemu-stable@nongnu.org Reviewed-by: Marcelo Tosatti Signed-off-by: Paolo Bonzini --- hw/i386/kvm/clock.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 48 insertions(+) Index: qemu/hw/i386/kvm/clock.c =================================================================== --- qemu.orig/hw/i386/kvm/clock.c 2014-08-15 15:43:30.440191065 -0300 +++ qemu/hw/i386/kvm/clock.c 2014-08-15 15:56:31.754875109 -0300 @@ -14,6 +14,7 @@ */ #include "qemu-common.h" +#include "qemu/host-utils.h" #include "sysemu/sysemu.h" #include "sysemu/kvm.h" #include "hw/sysbus.h" @@ -34,6 +35,47 @@ bool clock_valid; } KVMClockState; +struct pvclock_vcpu_time_info { + uint32_t version; + uint32_t pad0; + uint64_t tsc_timestamp; + uint64_t system_time; + uint32_t tsc_to_system_mul; + int8_t tsc_shift; + uint8_t flags; + uint8_t pad[2]; +} __attribute__((__packed__)); /* 32 bytes */ + +static uint64_t kvmclock_current_nsec(KVMClockState *s) +{ + CPUState *cpu = first_cpu; + CPUX86State *env = cpu->env_ptr; + hwaddr kvmclock_struct_pa = env->system_time_msr & ~1ULL; + uint64_t migration_tsc = env->tsc; + struct pvclock_vcpu_time_info time; + uint64_t delta; + uint64_t nsec_lo; + uint64_t nsec_hi; + uint64_t nsec; + + if (!(env->system_time_msr & 1ULL)) { + /* KVM clock not active */ + return 0; + } + + cpu_physical_memory_read(kvmclock_struct_pa, &time, sizeof(time)); + + delta = migration_tsc - time.tsc_timestamp; + if (time.tsc_shift < 0) { + delta >>= -time.tsc_shift; + } else { + delta <<= time.tsc_shift; + } + + mulu64(&nsec_lo, &nsec_hi, delta, time.tsc_to_system_mul); + nsec = (nsec_lo >> 32) | (nsec_hi << 32); + return nsec + time.system_time; +} static void kvmclock_vm_state_change(void *opaque, int running, RunState state) @@ -45,9 +87,15 @@ if (running) { struct kvm_clock_data data; + uint64_t time_at_migration = kvmclock_current_nsec(s); s->clock_valid = false; + /* We can't rely on the migrated clock value, just discard it */ + if (time_at_migration) { + s->clock = time_at_migration; + } + data.clock = s->clock; data.flags = 0; ret = kvm_vm_ioctl(kvm_state, KVM_SET_CLOCK, &data);