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Garcia" To: qemu-devel@nongnu.org Date: Thu, 11 Jul 2019 16:47:02 -0300 Message-Id: <20190711194702.26598-1-maxiwell@linux.ibm.com> X-Mailer: git-send-email 2.20.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:, , definitions=2019-07-11_05:, , signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=1 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1907110218 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x [generic] X-Received-From: 148.163.156.1 Subject: [Qemu-devel] [PATCH v2] migration: Do not re-read the clock on pre_save in case of paused guest X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "open list:PowerPC TCG CPUs" , "Maxiwell S. Garcia" , David Gibson Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Re-read the timebase before migrate was ported from x86 commit: 6053a86fe7bd: kvmclock: reduce kvmclock difference on migration The clock move makes the guest knows about the paused time between the stop and migrate commands. This is an issue in an already-paused VM because some side effects, like process stalls, could happen after migration. So, this patch checks the runstate of guest in the pre_save handler and do not re-reads the timebase in case of paused state (cold migration). Signed-off-by: Maxiwell S. Garcia --- hw/ppc/ppc.c | 13 +++++++++---- target/ppc/cpu-qom.h | 1 + 2 files changed, 10 insertions(+), 4 deletions(-) diff --git a/hw/ppc/ppc.c b/hw/ppc/ppc.c index a9e508c496..8572e45274 100644 --- a/hw/ppc/ppc.c +++ b/hw/ppc/ppc.c @@ -1008,6 +1008,8 @@ static void timebase_save(PPCTimebase *tb) * there is no need to update it from KVM here */ tb->guest_timebase = ticks + first_ppc_cpu->env.tb_env->tb_offset; + + tb->runstate_paused = runstate_check(RUN_STATE_PAUSED); } static void timebase_load(PPCTimebase *tb) @@ -1051,9 +1053,9 @@ void cpu_ppc_clock_vm_state_change(void *opaque, int running, } /* - * When migrating, read the clock just before migration, - * so that the guest clock counts during the events - * between: + * When migrating a running guest, read the clock just + * before migration, so that the guest clock counts + * during the events between: * * * vm_stop() * * @@ -1068,7 +1070,10 @@ static int timebase_pre_save(void *opaque) { PPCTimebase *tb = opaque; - timebase_save(tb); + /* guest_timebase won't be overridden in case of paused guest */ + if (!tb->runstate_paused) { + timebase_save(tb); + } return 0; } diff --git a/target/ppc/cpu-qom.h b/target/ppc/cpu-qom.h index be9b4c30c3..5fbcdee9c9 100644 --- a/target/ppc/cpu-qom.h +++ b/target/ppc/cpu-qom.h @@ -201,6 +201,7 @@ typedef struct PowerPCCPUClass { typedef struct PPCTimebase { uint64_t guest_timebase; int64_t time_of_the_day_ns; + bool runstate_paused; } PPCTimebase; extern const struct VMStateDescription vmstate_ppc_timebase; -- 2.20.1