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Fri, 26 Jun 2020 14:51:13 +0000 (UTC) Date: Fri, 26 Jun 2020 15:51:11 +0100 From: "Dr. David Alan Gilbert" To: Kirti Wankhede Subject: Re: [PATCH QEMU v25 05/17] vfio: Add VM state change handler to know state of VM Message-ID: <20200626145111.GL3087@work-vm> References: <1592684486-18511-1-git-send-email-kwankhede@nvidia.com> <1592684486-18511-6-git-send-email-kwankhede@nvidia.com> <20200622165019.27b5f395@x1.home> <48629aa9-f5bb-08dd-17fc-b73b1b5bf5ae@nvidia.com> MIME-Version: 1.0 In-Reply-To: <48629aa9-f5bb-08dd-17fc-b73b1b5bf5ae@nvidia.com> User-Agent: Mutt/1.14.3 (2020-06-14) X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=dgilbert@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Received-SPF: pass client-ip=207.211.31.120; envelope-from=dgilbert@redhat.com; helo=us-smtp-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/06/26 01:49:42 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -30 X-Spam_score: -3.1 X-Spam_bar: --- X-Spam_report: (-3.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=-0.01, RCVD_IN_MSPIKE_WL=-0.01, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=_AUTOLEARN X-Spam_action: no action 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: cohuck@redhat.com, cjia@nvidia.com, aik@ozlabs.ru, Zhengxiao.zx@alibaba-inc.com, shuangtai.tst@alibaba-inc.com, qemu-devel@nongnu.org, peterx@redhat.com, eauger@redhat.com, yi.l.liu@intel.com, quintela@redhat.com, ziye.yang@intel.com, armbru@redhat.com, mlevitsk@redhat.com, pasic@linux.ibm.com, felipe@nutanix.com, zhi.a.wang@intel.com, kevin.tian@intel.com, yan.y.zhao@intel.com, Alex Williamson , changpeng.liu@intel.com, eskultet@redhat.com, Ken.Xue@amd.com, jonathan.davies@nutanix.com, pbonzini@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" * Kirti Wankhede (kwankhede@nvidia.com) wrote: > > > On 6/23/2020 4:20 AM, Alex Williamson wrote: > > On Sun, 21 Jun 2020 01:51:14 +0530 > > Kirti Wankhede wrote: > > > > > VM state change handler gets called on change in VM's state. This is used to set > > > VFIO device state to _RUNNING. > > > > > > Signed-off-by: Kirti Wankhede > > > Reviewed-by: Neo Jia > > > Reviewed-by: Dr. David Alan Gilbert > > > --- > > > hw/vfio/migration.c | 87 +++++++++++++++++++++++++++++++++++++++++++ > > > hw/vfio/trace-events | 2 + > > > include/hw/vfio/vfio-common.h | 4 ++ > > > 3 files changed, 93 insertions(+) > > > > > > diff --git a/hw/vfio/migration.c b/hw/vfio/migration.c > > > index 48ac385d80a7..fcecc0bb0874 100644 > > > --- a/hw/vfio/migration.c > > > +++ b/hw/vfio/migration.c > > > @@ -10,6 +10,7 @@ > > > #include "qemu/osdep.h" > > > #include > > > +#include "sysemu/runstate.h" > > > #include "hw/vfio/vfio-common.h" > > > #include "cpu.h" > > > #include "migration/migration.h" > > > @@ -74,6 +75,85 @@ err: > > > return ret; > > > } > > > +static int vfio_migration_set_state(VFIODevice *vbasedev, uint32_t mask, > > > + uint32_t value) > > > +{ > > > + VFIOMigration *migration = vbasedev->migration; > > > + VFIORegion *region = &migration->region; > > > + uint32_t device_state; > > > + int ret; > > > + > > > + ret = pread(vbasedev->fd, &device_state, sizeof(device_state), > > > + region->fd_offset + offsetof(struct vfio_device_migration_info, > > > + device_state)); > > > + if (ret < 0) { > > > + error_report("%s: Failed to read device state %d %s", > > > + vbasedev->name, ret, strerror(errno)); > > > + return ret; > > > + } > > > + > > > + device_state = (device_state & mask) | value; > > > + > > > + if (!VFIO_DEVICE_STATE_VALID(device_state)) { > > > + return -EINVAL; > > > + } > > > + > > > + ret = pwrite(vbasedev->fd, &device_state, sizeof(device_state), > > > + region->fd_offset + offsetof(struct vfio_device_migration_info, > > > + device_state)); > > > + if (ret < 0) { > > > + error_report("%s: Failed to set device state %d %s", > > > + vbasedev->name, ret, strerror(errno)); > > > + > > > + ret = pread(vbasedev->fd, &device_state, sizeof(device_state), > > > + region->fd_offset + offsetof(struct vfio_device_migration_info, > > > + device_state)); > > > + if (ret < 0) { > > > + error_report("%s: On failure, failed to read device state %d %s", > > > + vbasedev->name, ret, strerror(errno)); > > > + return ret; > > > + } > > > + > > > + if (VFIO_DEVICE_STATE_IS_ERROR(device_state)) { > > > + error_report("%s: Device is in error state 0x%x", > > > + vbasedev->name, device_state); > > > + return -EFAULT; > > > + } > > > + } > > > + > > > + vbasedev->device_state = device_state; > > > + trace_vfio_migration_set_state(vbasedev->name, device_state); > > > + return 0; > > > +} > > > + > > > +static void vfio_vmstate_change(void *opaque, int running, RunState state) > > > +{ > > > + VFIODevice *vbasedev = opaque; > > > + > > > + if ((vbasedev->vm_running != running)) { > > > + int ret; > > > + uint32_t value = 0, mask = 0; > > > + > > > + if (running) { > > > + value = VFIO_DEVICE_STATE_RUNNING; > > > + if (vbasedev->device_state & VFIO_DEVICE_STATE_RESUMING) { > > > + mask = ~VFIO_DEVICE_STATE_RESUMING; > > > + } > > > + } else { > > > + mask = ~VFIO_DEVICE_STATE_RUNNING; > > > + } > > > + > > > + ret = vfio_migration_set_state(vbasedev, mask, value); > > > + if (ret) { > > > + error_report("%s: Failed to set device state 0x%x", > > > + vbasedev->name, value & mask); > > > > > > Is there nothing more we should do here? It seems like in either the > > case of an outbound migration where we can't stop the device or an > > inbound migration where we can't start the device, we'd want this to > > trigger an abort of the migration. Should there at least be a TODO > > comment if the reason is that QEMU migration doesn't yet support failure > > here? Thanks, > > > > Checked other modules in QEMU, at some places error message is reported as > above while at some places abort() is called (for example > kvmclock_vm_state_change() in hw/i386/kvm/clock.c). Abort will abort QEMU > process, that is VM crash. Should we abort here on error case? Anyways VM > will not recover properly on migration if there is such error. I prefer to avoid aborts on migration if possible; unless the VM is realyl dead. Failing the migration is preferable. Dave > Thanks, > Kirti > -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK